Today's Message Index:
----------------------
1. 01:09 AM - Re: Re: AIrfoil can of worms? (Isablcorky@aol.com)
2. 04:44 AM - Re: Brodhead/AirVenture (helspersew@aol.com)
3. 05:29 AM - Re: Mid West wood source (bill.kipp)
4. 05:55 AM - Re: AIrfoil can of worms? (johnwoods@westnet.com.au)
5. 06:03 AM - Fw: AIrfoil can of worms? (johnwoods@westnet.com.au)
6. 06:25 AM - Re: Re: AIrfoil can of worms? (johnwoods@westnet.com.au)
7. 07:25 AM - Re: Fw: AIrfoil can of worms? (Will42)
8. 07:44 AM - Re: AIrfoil can of worms? (Jeff Boatright)
9. 08:40 AM - Re: AIrfoil can of worms? (Tim Willis)
10. 09:11 AM - Re: Re: AIrfoil can of worms? (Kip and Beth Gardner)
11. 09:51 AM - Re: AIrfoil can of worms? (Mark Roberts)
12. 09:52 AM - Re: AIrfoil can of worms? (Mark Roberts)
13. 10:04 AM - Re: Re: AIrfoil can of worms? (Mark Roberts)
14. 10:09 AM - Re: Re: AIrfoil can of worms? (Mark Roberts)
15. 02:43 PM - Re: Re: AIrfoil can of worms? (Ameet Savant)
16. 03:09 PM - Re: AIrfoil can of worms? (Mark Roberts)
17. 04:00 PM - Re: Re: AIrfoil can of worms? (Kip and Beth Gardner)
18. 05:05 PM - Re: AIrfoil can of worms? (Ryan Mueller)
19. 05:50 PM - Re: AIrfoil can of worms? (AMsafetyC@aol.com)
20. 06:33 PM - Brodhead Pietenpol Gathering (steven sadler)
21. 07:15 PM - found on craigslist (ken anderson)
22. 07:34 PM - Re: AIrfoil can of worms? (John Hofmann)
23. 07:42 PM - Re: Re: AIrfoil can of worms? (Ameet Savant)
24. 08:07 PM - Re: AIrfoil can of worms? (Pieti Lowell)
25. 08:20 PM - Re: AIrfoil can of worms? (AMsafetyC@aol.com)
26. 08:41 PM - Re: Re: AIrfoil can of worms? (Jim)
27. 09:59 PM - Re: Re: AIrfoil can of worms? (Mark Roberts)
28. 10:22 PM - Re: AIrfoil can of worms? (Tim Willis)
29. 10:23 PM - Re: Re: AIrfoil can of worms? (Tim Willis)
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Subject: | Re: AIrfoil can of worms? |
Mr. Lowell,
If you have some good info and experience with the 612 foil I sure would
like to hear about it as I will not be at Brodhead to hear you personally.
Would you, if you have the time, give me your message directly on E mail?
Thank you
Corky
**************An Excellent Credit Score is 750. See Yours in Just 2 Easy
Steps!
yExcfooterNO62)
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Subject: | Re: Brodhead/AirVenture |
Juan,
Good for you that you are able to attend the Pietenpol gathering this year. We
always welcome our South American friends. Last year we had Santiago Morete, from
Santa Rosa Argentina with us. He was able to get several rides in Piets and
other airplanes as well. Make sure and bring with you a DETAILED list of supplies,
hardware, etc. that you need for your project. Virtually anything can be
purchased at Oshkosh. Santiago was able to buy hardware, control cable, headsets,
seat belts etc. while he was there. I will look forward to meeting you and
your son Frederico.
Dan Helsper
Poplar Grove, IL.
-----Original Message-----
From: x GOYENI <goyeni@movinet.com.uy>
Sent: Sat, Jul 4, 2009 4:56 pm
Subject: Pietenpol-List: Brodhead/AirVenture
?
Hello everybody, ?
Finally, I am going to Brodhead with my son Federico.?
We are arriving at noon on Friday and stay there until Sunday.?
I look forward to meet members of this list and enjoy the friendship and camaraderie
of these events.?
Then, the entire week at AirVenture.?
See you there. ?
Juan GOYENI?
URUGUAY ?
?
?
?
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Subject: | Re: Mid West wood source |
Thanks All
I get to Madison fairly often. Should work out great!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=251565#251565
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Subject: | Re: AIrfoil can of worms? |
Mark,
Attached is a copy of the xls file I posted a while ago.
It has the co-ordinates for the Riblett 612 &=C2-613.5 sections as provid
ed by Mr Bokolt together with the Pietenpol sections, as copied from the pl
ans.
I used the 612 co-ordinates to plot and make my ribs.
Still a long way from flying.
The 612 has been sucessfully used on other ultralights and from=C2-Mr Rib
lett's description of it's characteristics he predicted it would be a good
section for the Piet.
I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the 612's
performance.
JohnW
----- Original Message -----
From: "Mark Roberts" <mark.rbrts1@gmail.com>
Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Also, just spent the last 2 hours or so creating the 612 rib plot I found (
if the coordinates are correct) into my CAD program and created a rib templ
ate for the 60" profile. Not sure if the plot is indeed the 612, as I only
got the coordinates from a post on this list in the archives and they said
they had found it on another aviation website, so if anyone has a verifiabl
e set of plots, I'd like to check my work to see if it is indeed a 612.
Regardless, here's a picture of the plot I made... Minus gussets...
Mark
On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts < mark.rbrts1@gmail.com > wrot
e:
Oh Yes! Do tell! :o)
Mark
On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis < timothywillis@earthlink.net >
wrote:
net >
Aha! =C2-VGs! =C2-Jeff, it sounds like you are very happy with their ef
fects. =C2-Thus inquiring minds want to know:
Were the VGs the ones you used the straight little plastic fins (100 to a b
ox), or were they the truncated "V," perhaps made out of bent aluminum?
How far behind the LE did you place them, and was that according to directi
ons, or what?
Did you also apply them to any controls, esp. the back of the VStab or near
the LE of the rudder?
Tim in central TX
-----Original Message-----
>From: Jeff Boatright < jboatri@emory.edu >
>Sent: Jul 4, 2009 5:20 PM
>To: pietenpol-list@matronics.com
>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
>
>Mark,
>
>Our Piet had what I consider a sharp and unannounced stall. However,
>it has an aluminum leading edge wrap rather than the thing plywood as
>specified in the plans. When the fabric was shrunk, it pulled the
>aluminum down between the ribs in a very ugly fashion. The result is
>an even sharper nose than the Piet airfoil normally has.
>
>I added vortex generators and everything changed. The no-power stall
>is now about like a Cessna 172's or maybe even gentler. The power-on
>stall has noticeable burbling prior to the stall and a fairly gentle
>break.
>
>As you can tell from my description, this is an atypical Piet. But,
>every datum helps.
>
>Jeff
>
>
>>...After reading the posts, I am curious about the standard Piet
>>airfoil, and it's performance. I know that building to plans and to
>>the original design is the best way of getting a good flying plane,
>>but reading the letter posted from Mr. Riblett got me to thinking
>>about the actual performance. I read about a sharp stall and such,
>>and I am looking for you guys that are flying one of these to maybe
>>give your feedback on the airfoil and it's characteristics. ...
>>
>>Mark
>
>--
>---
>
>Jeffrey H. Boatright, Ph.D.
>Associate Professor of Ophthalmology
>Emory University School of Medicine
>Editor-in-Chief
>Molecular Vision
>
>
>
>
===========
st" target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
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Subject: | AIrfoil can of worms? |
Ooops.. forgot the attachement...
JohnW
----- Forwarded Message -----
From: johnwoods@westnet.com.au
Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Mark,
Attached is a copy of the xls file I posted a while ago.
It has the co-ordinates for the Riblett 612 &=C2-613.5 sections as provid
ed by Mr Bokolt together with the Pietenpol sections, as copied from the pl
ans.
I used the 612 co-ordinates to plot and make my ribs.
Still a long way from flying.
The 612 has been sucessfully used on other ultralights and from=C2-Mr Rib
lett's description of it's characteristics he predicted it would be a good
section for the Piet.
I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the 612's
performance.
JohnW
----- Original Message -----
From: "Mark Roberts" <mark.rbrts1@gmail.com>
Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Also, just spent the last 2 hours or so creating the 612 rib plot I found (
if the coordinates are correct) into my CAD program and created a rib templ
ate for the 60" profile. Not sure if the plot is indeed the 612, as I only
got the coordinates from a post on this list in the archives and they said
they had found it on another aviation website, so if anyone has a verifiabl
e set of plots, I'd like to check my work to see if it is indeed a 612.
Regardless, here's a picture of the plot I made... Minus gussets...
Mark
On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts < mark.rbrts1@gmail.com > wrot
e:
Oh Yes! Do tell! :o)
Mark
On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis < timothywillis@earthlink.net >
wrote:
net >
Aha! =C2-VGs! =C2-Jeff, it sounds like you are very happy with their ef
fects. =C2-Thus inquiring minds want to know:
Were the VGs the ones you used the straight little plastic fins (100 to a b
ox), or were they the truncated "V," perhaps made out of bent aluminum?
How far behind the LE did you place them, and was that according to directi
ons, or what?
Did you also apply them to any controls, esp. the back of the VStab or near
the LE of the rudder?
Tim in central TX
-----Original Message-----
>From: Jeff Boatright < jboatri@emory.edu >
>Sent: Jul 4, 2009 5:20 PM
>To: pietenpol-list@matronics.com
>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
>
>Mark,
>
>Our Piet had what I consider a sharp and unannounced stall. However,
>it has an aluminum leading edge wrap rather than the thing plywood as
>specified in the plans. When the fabric was shrunk, it pulled the
>aluminum down between the ribs in a very ugly fashion. The result is
>an even sharper nose than the Piet airfoil normally has.
>
>I added vortex generators and everything changed. The no-power stall
>is now about like a Cessna 172's or maybe even gentler. The power-on
>stall has noticeable burbling prior to the stall and a fairly gentle
>break.
>
>As you can tell from my description, this is an atypical Piet. But,
>every datum helps.
>
>Jeff
>
>
>>...After reading the posts, I am curious about the standard Piet
>>airfoil, and it's performance. I know that building to plans and to
>>the original design is the best way of getting a good flying plane,
>>but reading the letter posted from Mr. Riblett got me to thinking
>>about the actual performance. I read about a sharp stall and such,
>>and I am looking for you guys that are flying one of these to maybe
>>give your feedback on the airfoil and it's characteristics. ...
>>
>>Mark
>
>--
>---
>
>Jeffrey H. Boatright, Ph.D.
>Associate Professor of Ophthalmology
>Emory University School of Medicine
>Editor-in-Chief
>Molecular Vision
>
>
>
>
===========
st" target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
Message 6
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Subject: | Re: AIrfoil can of worms? |
Pieti,
With 3 years of flying experience with the 612, would you be able to comment on
the CoG range of this section.
Thanks
JohnW
Perth, W/Australia
----- Original Message -----
From: "Pieti Lowell" <Lowellcfrank@yahoo.com>
Sent: Sunday, 5 July, 2009 11:08:48 AM GMT +08:00 Perth
Subject: Pietenpol-List: Re: AIrfoil can of worms?
Mark,
I will talk about my 612 at my Brodhead Form ,with 3 years and a number of engines
on this foil. If you are under 180 Lbs I will give you a demo you will never
forget, The air foil you show is very close to the 612.
Pieti Lowell
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=251541#251541
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Subject: | Re: Fwd: AIrfoil can of worms? |
Thanks so much for the information JW.
Will
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=251578#251578
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Subject: | Re: AIrfoil can of worms? |
Tim,
The VGs I installed are plastic fins. I bought them from
http://www.landshorter.com/. I placed them at 10% chord from the
leading edge (6 inches), per the instructions. I bought enough for
wings and control surfaces, but have not installed them yet on the
control surfaces. I have attached a photo of a wing with VGs
installed.
By far the major advantage is that they tame the stall. As noted in
my previous email, it may be that the stall characteristics on our
Piet were different from "stock" - unpredictable, sharp, and with
lots of wing drop - due to a non-stock aluminum leading edge cover
that results in the first five or so inches of the wing being quite
lumpy. With the VGs, the no-power stall is gentle with just a hint of
left wing drop. As soon as back pressure on the stick is released,
the plane is flying again. The power-on stall has plenty of burble
prior to breaking. The break is not bad. I would say that the stalls
are about like a Cessna 172, maybe even less of an event.
I think that the no-power stall speed is lowered from about 40 mph to
about 35 mph - that's with 14 gal fuel, pilot, and passenger in a
Piet with empty weight of 723 lbs. This reduction is a benefit, but
not nearly as noticeable as the effects on stall characteristics.
The second biggest change is that the plane feels like it is much
more "controllable". I put this in quotes as "controllable" isn't
quite the right word, but it will have to do. The plane rides
turbulence better and responds to aileron input in a more positive,
less jittery fashion. This makes flying the plane much more enjoyable.
The climb rate is better. With 14 gal of fuel and just me on board,
the previous best climb rate was about 800 fpm. This is initial climb
to 1000' feet from a field elevation of 940', temperature about 70 F,
humidity about 80%. With VGs, it's over 1000 fpm. We have a pretty
serious climb prop (76x38, semi-scimitar from Cloudcars - some of the
best money I ever spent) and a C-85 for power, but a jump from 800
fpm to over 1000 fpm with the addition of the VGs is really
impressive. (I have seen 1250 fpm climb a couple of times, but I
would not say that that is typical). Climb rates are assessed by
three approaches (at least two simultaneously, and often all three):
a MicroTim digital altimeter set to VSI function
(http://www.microtim.com/), an Anywhere Map ATC GPS with 3D
functionality (http://www.anywheremap.com/atc/), and digital timer
combined with a steam gauge altimeter. The deck angle is not
appreciably higher. Also, I do not think that the take-off run from
standstill to breaking ground is shorter, but I have not measured
this precisely.
I am pretty sure that the optimal glide speed has dropped from 60-65
to 60-55, but I have not figured out a way to really measure this.
Also, on final, holding 50 mph now gives a comfortable and useful
descent rate, though the deck angle is a bit higher than pre-VGs.
Aileron control is strong, not mushy and delayed as in the past, even
down to 40 mph (and maybe lower). Full-deflection slips are very
controllable and a lot of fun. Transition to the flare needs a bit
more attention, but I have not had any trouble with slamming the
plane on even with the much steeper approach angles provided by the
50 mph final. I do not think that groundroll is appreciably shorter.
The Piet just never rolled much after landing.
I have measured airspeeds from WOT all the way down to just
maintaining level flight under conditions and rpms that I previously
ran prior to installing VGs. I cannot detect a difference in airspeed
at any rpm with VGs installed. Top speed is still 95 mph at 2600 rpm.
2100 rpm still keeps me in level flight at 60 mph without being
behind the power curve. All other power settings in between produce
airspeeds as they did pre-VGs.
One issue for Piets if you use the separate VGs rather than the
aluminum fins (which essentially are a pair of VGs attached) is that
the fabric of course dips between ribs, making a shallow trough, and
that made me wonder if that trough is a factor in VG placement. It
works out that four VGs fit between each pair of ribs based on
distance between ribs and the suggested number of VGs for wingspan.
The VGs are to be set at 15 degrees to the slip stream, alternating.
I asked Joa at landshorter.com: Does it matter if the two middle VGs
(middle meaning the two VGs furthest from ribs) are pointing towards
each other or away from each other? Below is a crude diagram to try
to show what I mean. Joa's emphatic response was that the way to
install the VGs is:
| \ / \ / |
the vertical lines represent ribs, the diagonals are VGs, and the
direction of flight is down. There's also an attached image of this
in case the diagram above doesn't display well on your computer.
Also, the instructions from landshorter (and from other VG makers)
suggest using carpet tape (sticky on both sides of tape) for
temporary installation, to allow testing different locations. I did
this and after just two short flights some of the VGs had blown off.
Possibly better-quality carpet tape will work, but what I ended up
doing was sticking small pieces of vinyl tape on either side of the
vertical fin of the VG (that is, across the "feet" of the VG and onto
wing fabric fore and aft). This is A LOT easier than messing with the
carpet tape. The vinyl tape comes in several colors, available at
your local hardware store, and peels off easily if you want to move
the VG. I used white that matches the color of the wing. It's holding
perfectly so far and I may not make the installation any more
permanent than this. Note that I have not flown in the rain, nor
hosed the wing down, so I don't know how waterproof this installation
is.
Overall, I'd say that the VGs are a success. I do not know if there
would be a difference between the store-bought ones and making your
own out of aluminum. Joa at landshorter.com has given excellent
customer service. I also bought their DVDs of Big Rocks and Long
Props (great videos, and take yer mind outta the gutter! >:-} ).
HTH,
Jeff
>
>Aha! VGs! Jeff, it sounds like you are very happy with their
>effects. Thus inquiring minds want to know:
>
>Were the VGs the ones you used the straight little plastic fins (100
>to a box), or were they the truncated "V," perhaps made out of bent
>aluminum?
>
>How far behind the LE did you place them, and was that according to
>directions, or what?
>
>Did you also apply them to any controls, esp. the back of the VStab
>or near the LE of the rudder?
>
>Tim in central TX
>
>-----Original Message-----
>>From: Jeff Boatright <jboatri@emory.edu>
>>Sent: Jul 4, 2009 5:20 PM
>>To: pietenpol-list@matronics.com
>>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>
>>
>>Mark,
>>
>>Our Piet had what I consider a sharp and unannounced stall. However,
>>it has an aluminum leading edge wrap rather than the thing plywood as
>>specified in the plans. When the fabric was shrunk, it pulled the
>>aluminum down between the ribs in a very ugly fashion. The result is
>>an even sharper nose than the Piet airfoil normally has.
>>
>>I added vortex generators and everything changed. The no-power stall
>>is now about like a Cessna 172's or maybe even gentler. The power-on
>>stall has noticeable burbling prior to the stall and a fairly gentle
>>break.
>>
>>As you can tell from my description, this is an atypical Piet. But,
>>every datum helps.
>>
>>Jeff
>>
>>
>>>...After reading the posts, I am curious about the standard Piet
>>>airfoil, and it's performance. I know that building to plans and to
>>>the original design is the best way of getting a good flying plane,
>>>but reading the letter posted from Mr. Riblett got me to thinking
>>>about the actual performance. I read about a sharp stall and such,
>>>and I am looking for you guys that are flying one of these to maybe
>>>give your feedback on the airfoil and it's characteristics. ...
>>>
>>>Mark
>>
>>--
>>---
>>
>>Jeffrey H. Boatright, Ph.D.
>>Associate Professor of Ophthalmology
>>Emory University School of Medicine
>>Editor-in-Chief
>>Molecular Vision
>>
>>
>>
>>
>
>
--
---
Jeffrey H. Boatright, Ph.D.
Associate Professor of Ophthalmology
Emory University School of Medicine
Editor-in-Chief
Molecular Vision
Message 9
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Subject: | Re: AIrfoil can of worms? |
Jeff,
Thank you very much for your detailed reply. What a great set of changes!
Tim in central TX
do not archive
-----Original Message-----
>From: Jeff Boatright <jboatri@emory.edu>
>Sent: Jul 5, 2009 10:42 AM
>To: pietenpol-list@matronics.com
>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
>Tim,
>
>The VGs I installed are plastic fins. I bought them from
>http://www.landshorter.com/. I placed them at 10% chord from the
>leading edge (6 inches), per the instructions. I bought enough for
>wings and control surfaces, but have not installed them yet on the
>control surfaces. I have attached a photo of a wing with VGs
>installed.
>
>By far the major advantage is that they tame the stall. As noted in
>my previous email, it may be that the stall characteristics on our
>Piet were different from "stock" - unpredictable, sharp, and with
>lots of wing drop - due to a non-stock aluminum leading edge cover
>that results in the first five or so inches of the wing being quite
>lumpy. With the VGs, the no-power stall is gentle with just a hint of
>left wing drop. As soon as back pressure on the stick is released,
>the plane is flying again. The power-on stall has plenty of burble
>prior to breaking. The break is not bad. I would say that the stalls
>are about like a Cessna 172, maybe even less of an event.
>
>I think that the no-power stall speed is lowered from about 40 mph to
>about 35 mph - that's with 14 gal fuel, pilot, and passenger in a
>Piet with empty weight of 723 lbs. This reduction is a benefit, but
>not nearly as noticeable as the effects on stall characteristics.
>
>The second biggest change is that the plane feels like it is much
>more "controllable". I put this in quotes as "controllable" isn't
>quite the right word, but it will have to do. The plane rides
>turbulence better and responds to aileron input in a more positive,
>less jittery fashion. This makes flying the plane much more enjoyable.
>
>The climb rate is better. With 14 gal of fuel and just me on board,
>the previous best climb rate was about 800 fpm. This is initial climb
>to 1000' feet from a field elevation of 940', temperature about 70 F,
>humidity about 80%. With VGs, it's over 1000 fpm. We have a pretty
>serious climb prop (76x38, semi-scimitar from Cloudcars - some of the
>best money I ever spent) and a C-85 for power, but a jump from 800
>fpm to over 1000 fpm with the addition of the VGs is really
>impressive. (I have seen 1250 fpm climb a couple of times, but I
>would not say that that is typical). Climb rates are assessed by
>three approaches (at least two simultaneously, and often all three):
>a MicroTim digital altimeter set to VSI function
>(http://www.microtim.com/), an Anywhere Map ATC GPS with 3D
>functionality (http://www.anywheremap.com/atc/), and digital timer
>combined with a steam gauge altimeter. The deck angle is not
>appreciably higher. Also, I do not think that the take-off run from
>standstill to breaking ground is shorter, but I have not measured
>this precisely.
>
>I am pretty sure that the optimal glide speed has dropped from 60-65
>to 60-55, but I have not figured out a way to really measure this.
>Also, on final, holding 50 mph now gives a comfortable and useful
>descent rate, though the deck angle is a bit higher than pre-VGs.
>Aileron control is strong, not mushy and delayed as in the past, even
>down to 40 mph (and maybe lower). Full-deflection slips are very
>controllable and a lot of fun. Transition to the flare needs a bit
>more attention, but I have not had any trouble with slamming the
>plane on even with the much steeper approach angles provided by the
>50 mph final. I do not think that groundroll is appreciably shorter.
>The Piet just never rolled much after landing.
>
>I have measured airspeeds from WOT all the way down to just
>maintaining level flight under conditions and rpms that I previously
>ran prior to installing VGs. I cannot detect a difference in airspeed
>at any rpm with VGs installed. Top speed is still 95 mph at 2600 rpm.
>2100 rpm still keeps me in level flight at 60 mph without being
>behind the power curve. All other power settings in between produce
>airspeeds as they did pre-VGs.
>
>One issue for Piets if you use the separate VGs rather than the
>aluminum fins (which essentially are a pair of VGs attached) is that
>the fabric of course dips between ribs, making a shallow trough, and
>that made me wonder if that trough is a factor in VG placement. It
>works out that four VGs fit between each pair of ribs based on
>distance between ribs and the suggested number of VGs for wingspan.
>The VGs are to be set at 15 degrees to the slip stream, alternating.
>I asked Joa at landshorter.com: Does it matter if the two middle VGs
>(middle meaning the two VGs furthest from ribs) are pointing towards
>each other or away from each other? Below is a crude diagram to try
>to show what I mean. Joa's emphatic response was that the way to
>install the VGs is:
>
> | \ / \ / |
>
>the vertical lines represent ribs, the diagonals are VGs, and the
>direction of flight is down. There's also an attached image of this
>in case the diagram above doesn't display well on your computer.
>
>Also, the instructions from landshorter (and from other VG makers)
>suggest using carpet tape (sticky on both sides of tape) for
>temporary installation, to allow testing different locations. I did
>this and after just two short flights some of the VGs had blown off.
>Possibly better-quality carpet tape will work, but what I ended up
>doing was sticking small pieces of vinyl tape on either side of the
>vertical fin of the VG (that is, across the "feet" of the VG and onto
>wing fabric fore and aft). This is A LOT easier than messing with the
>carpet tape. The vinyl tape comes in several colors, available at
>your local hardware store, and peels off easily if you want to move
>the VG. I used white that matches the color of the wing. It's holding
>perfectly so far and I may not make the installation any more
>permanent than this. Note that I have not flown in the rain, nor
>hosed the wing down, so I don't know how waterproof this installation
>is.
>
>Overall, I'd say that the VGs are a success. I do not know if there
>would be a difference between the store-bought ones and making your
>own out of aluminum. Joa at landshorter.com has given excellent
>customer service. I also bought their DVDs of Big Rocks and Long
>Props (great videos, and take yer mind outta the gutter! >:-} ).
>
>HTH,
>
>Jeff
>
>
>>
>>Aha! VGs! Jeff, it sounds like you are very happy with their
>>effects. Thus inquiring minds want to know:
>>
>>Were the VGs the ones you used the straight little plastic fins (100
>>to a box), or were they the truncated "V," perhaps made out of bent
>>aluminum?
>>
>>How far behind the LE did you place them, and was that according to
>>directions, or what?
>>
>>Did you also apply them to any controls, esp. the back of the VStab
>>or near the LE of the rudder?
>>
>>Tim in central TX
>>
>>-----Original Message-----
>>>From: Jeff Boatright <jboatri@emory.edu>
>>>Sent: Jul 4, 2009 5:20 PM
>>>To: pietenpol-list@matronics.com
>>>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>>
>>>
>>>Mark,
>>>
>>>Our Piet had what I consider a sharp and unannounced stall. However,
>>>it has an aluminum leading edge wrap rather than the thing plywood as
>>>specified in the plans. When the fabric was shrunk, it pulled the
>>>aluminum down between the ribs in a very ugly fashion. The result is
>>>an even sharper nose than the Piet airfoil normally has.
>>>
>>>I added vortex generators and everything changed. The no-power stall
>>>is now about like a Cessna 172's or maybe even gentler. The power-on
>>>stall has noticeable burbling prior to the stall and a fairly gentle
>>>break.
>>>
>>>As you can tell from my description, this is an atypical Piet. But,
>>>every datum helps.
>>>
>>>Jeff
>>>
>>>
>>>>...After reading the posts, I am curious about the standard Piet
>>>>airfoil, and it's performance. I know that building to plans and to
>>>>the original design is the best way of getting a good flying plane,
>>>>but reading the letter posted from Mr. Riblett got me to thinking
>>>>about the actual performance. I read about a sharp stall and such,
>>>>and I am looking for you guys that are flying one of these to maybe
>>>>give your feedback on the airfoil and it's characteristics. ...
>>>>
>>>>Mark
>>>
>>>--
>>>---
>>>
>>>Jeffrey H. Boatright, Ph.D.
>>>Associate Professor of Ophthalmology
>>>Emory University School of Medicine
>>>Editor-in-Chief
>>>Molecular Vision
>>>
>>>
>>>
>>>
>>
>>
>
>
>--
>---
>
>Jeffrey H. Boatright, Ph.D.
>Associate Professor of Ophthalmology
>Emory University School of Medicine
>Editor-in-Chief
>Molecular Vision
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Subject: | Re: AIrfoil can of worms? |
Hi John,
Thanks for reposting the spreadsheet with the Riblett numbers - I'm
not very adept at using the archive search function. I'd already
made a jig for the standard airfoil, but now I'm seriously
considering changing.
Like several others, I won't be able to be at Brodhead this year, so
I'd REALLY appreciate a few comments from Mr. Lowell if he's willing
to take the time to answer.
My specific questions are:
Can someone either describe or point me towards a simple explanation
of how to draw out a rib BY HAND (No CAD), from the spreadsheet
numbers? I know how to 'loft' boat ribs, but the numerical data for
boats is in a significantly different form.
Where on the Riblett section (% of Chord, absolute distance, however
you want to describe it) do the spars fall? Same as the std. airfoil
or is there some variation? I assume that the distance between spars
stays as per plans.
Thanks!
Kip Gardner
On Jul 5, 2009, at 9:24 AM, johnwoods@westnet.com.au wrote:
>
> Pieti,
>
> With 3 years of flying experience with the 612, would you be able
> to comment on the CoG range of this section.
> Thanks
> JohnW
> Perth, W/Australia
>
> ----- Original Message -----
> From: "Pieti Lowell" <Lowellcfrank@yahoo.com>
> To: pietenpol-list@matronics.com
> Sent: Sunday, 5 July, 2009 11:08:48 AM GMT +08:00 Perth
> Subject: Pietenpol-List: Re: AIrfoil can of worms?
>
> <Lowellcfrank@yahoo.com>
>
> Mark,
> I will talk about my 612 at my Brodhead Form ,with 3 years and a
> number of engines on this foil. If you are under 180 Lbs I will
> give you a demo you will never forget, The air foil you show is
> very close to the 612.
> Pieti Lowell
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=251541#251541
>
>
Message 11
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|
Subject: | Re: AIrfoil can of worms? |
Wow Jeff! Thanks for such a great review of these on the plane. Whether or
not I have dips in my leading edge (I'll at least have one in the pilot's
seat) I might consider these on the wing as well. Sounds like they helped
you quite a bit.
Mark
On Sun, Jul 5, 2009 at 8:39 AM, Tim Willis <timothywillis@earthlink.net>wrote:
> timothywillis@earthlink.net>
>
> Jeff,
>
> Thank you very much for your detailed reply. What a great set of changes!
>
> Tim in central TX
> do not archive
>
> -----Original Message-----
> >From: Jeff Boatright <jboatri@emory.edu>
> >Sent: Jul 5, 2009 10:42 AM
> >To: pietenpol-list@matronics.com
> >Subject: Re: Pietenpol-List: AIrfoil can of worms?
> >
> >Tim,
> >
> >The VGs I installed are plastic fins. I bought them from
> >http://www.landshorter.com/. I placed them at 10% chord from the
> >leading edge (6 inches), per the instructions. I bought enough for
> >wings and control surfaces, but have not installed them yet on the
> >control surfaces. I have attached a photo of a wing with VGs
> >installed.
> >
> >By far the major advantage is that they tame the stall. As noted in
> >my previous email, it may be that the stall characteristics on our
> >Piet were different from "stock" - unpredictable, sharp, and with
> >lots of wing drop - due to a non-stock aluminum leading edge cover
> >that results in the first five or so inches of the wing being quite
> >lumpy. With the VGs, the no-power stall is gentle with just a hint of
> >left wing drop. As soon as back pressure on the stick is released,
> >the plane is flying again. The power-on stall has plenty of burble
> >prior to breaking. The break is not bad. I would say that the stalls
> >are about like a Cessna 172, maybe even less of an event.
> >
> >I think that the no-power stall speed is lowered from about 40 mph to
> >about 35 mph - that's with 14 gal fuel, pilot, and passenger in a
> >Piet with empty weight of 723 lbs. This reduction is a benefit, but
> >not nearly as noticeable as the effects on stall characteristics.
> >
> >The second biggest change is that the plane feels like it is much
> >more "controllable". I put this in quotes as "controllable" isn't
> >quite the right word, but it will have to do. The plane rides
> >turbulence better and responds to aileron input in a more positive,
> >less jittery fashion. This makes flying the plane much more enjoyable.
> >
> >The climb rate is better. With 14 gal of fuel and just me on board,
> >the previous best climb rate was about 800 fpm. This is initial climb
> >to 1000' feet from a field elevation of 940', temperature about 70 F,
> >humidity about 80%. With VGs, it's over 1000 fpm. We have a pretty
> >serious climb prop (76x38, semi-scimitar from Cloudcars - some of the
> >best money I ever spent) and a C-85 for power, but a jump from 800
> >fpm to over 1000 fpm with the addition of the VGs is really
> >impressive. (I have seen 1250 fpm climb a couple of times, but I
> >would not say that that is typical). Climb rates are assessed by
> >three approaches (at least two simultaneously, and often all three):
> >a MicroTim digital altimeter set to VSI function
> >(http://www.microtim.com/), an Anywhere Map ATC GPS with 3D
> >functionality (http://www.anywheremap.com/atc/), and digital timer
> >combined with a steam gauge altimeter. The deck angle is not
> >appreciably higher. Also, I do not think that the take-off run from
> >standstill to breaking ground is shorter, but I have not measured
> >this precisely.
> >
> >I am pretty sure that the optimal glide speed has dropped from 60-65
> >to 60-55, but I have not figured out a way to really measure this.
> >Also, on final, holding 50 mph now gives a comfortable and useful
> >descent rate, though the deck angle is a bit higher than pre-VGs.
> >Aileron control is strong, not mushy and delayed as in the past, even
> >down to 40 mph (and maybe lower). Full-deflection slips are very
> >controllable and a lot of fun. Transition to the flare needs a bit
> >more attention, but I have not had any trouble with slamming the
> >plane on even with the much steeper approach angles provided by the
> >50 mph final. I do not think that groundroll is appreciably shorter.
> >The Piet just never rolled much after landing.
> >
> >I have measured airspeeds from WOT all the way down to just
> >maintaining level flight under conditions and rpms that I previously
> >ran prior to installing VGs. I cannot detect a difference in airspeed
> >at any rpm with VGs installed. Top speed is still 95 mph at 2600 rpm.
> >2100 rpm still keeps me in level flight at 60 mph without being
> >behind the power curve. All other power settings in between produce
> >airspeeds as they did pre-VGs.
> >
> >One issue for Piets if you use the separate VGs rather than the
> >aluminum fins (which essentially are a pair of VGs attached) is that
> >the fabric of course dips between ribs, making a shallow trough, and
> >that made me wonder if that trough is a factor in VG placement. It
> >works out that four VGs fit between each pair of ribs based on
> >distance between ribs and the suggested number of VGs for wingspan.
> >The VGs are to be set at 15 degrees to the slip stream, alternating.
> >I asked Joa at landshorter.com: Does it matter if the two middle VGs
> >(middle meaning the two VGs furthest from ribs) are pointing towards
> >each other or away from each other? Below is a crude diagram to try
> >to show what I mean. Joa's emphatic response was that the way to
> >install the VGs is:
> >
> > | \ / \ / |
> >
> >the vertical lines represent ribs, the diagonals are VGs, and the
> >direction of flight is down. There's also an attached image of this
> >in case the diagram above doesn't display well on your computer.
> >
> >Also, the instructions from landshorter (and from other VG makers)
> >suggest using carpet tape (sticky on both sides of tape) for
> >temporary installation, to allow testing different locations. I did
> >this and after just two short flights some of the VGs had blown off.
> >Possibly better-quality carpet tape will work, but what I ended up
> >doing was sticking small pieces of vinyl tape on either side of the
> >vertical fin of the VG (that is, across the "feet" of the VG and onto
> >wing fabric fore and aft). This is A LOT easier than messing with the
> >carpet tape. The vinyl tape comes in several colors, available at
> >your local hardware store, and peels off easily if you want to move
> >the VG. I used white that matches the color of the wing. It's holding
> >perfectly so far and I may not make the installation any more
> >permanent than this. Note that I have not flown in the rain, nor
> >hosed the wing down, so I don't know how waterproof this installation
> >is.
> >
> >Overall, I'd say that the VGs are a success. I do not know if there
> >would be a difference between the store-bought ones and making your
> >own out of aluminum. Joa at landshorter.com has given excellent
> >customer service. I also bought their DVDs of Big Rocks and Long
> >Props (great videos, and take yer mind outta the gutter! >:-} ).
> >
> >HTH,
> >
> >Jeff
> >
> >
> >
> timothywillis@earthlink.net>
> >>
> >>Aha! VGs! Jeff, it sounds like you are very happy with their
> >>effects. Thus inquiring minds want to know:
> >>
> >>Were the VGs the ones you used the straight little plastic fins (100
> >>to a box), or were they the truncated "V," perhaps made out of bent
> >>aluminum?
> >>
> >>How far behind the LE did you place them, and was that according to
> >>directions, or what?
> >>
> >>Did you also apply them to any controls, esp. the back of the VStab
> >>or near the LE of the rudder?
> >>
> >>Tim in central TX
> >>
> >>-----Original Message-----
> >>>From: Jeff Boatright <jboatri@emory.edu>
> >>>Sent: Jul 4, 2009 5:20 PM
> >>>To: pietenpol-list@matronics.com
> >>>Subject: Re: Pietenpol-List: AIrfoil can of worms?
> >>>
> >
> >>>
> >>>Mark,
> >>>
> >>>Our Piet had what I consider a sharp and unannounced stall. However,
> >>>it has an aluminum leading edge wrap rather than the thing plywood as
> >>>specified in the plans. When the fabric was shrunk, it pulled the
> >>>aluminum down between the ribs in a very ugly fashion. The result is
> >>>an even sharper nose than the Piet airfoil normally has.
> >>>
> >>>I added vortex generators and everything changed. The no-power stall
> >>>is now about like a Cessna 172's or maybe even gentler. The power-on
> >>>stall has noticeable burbling prior to the stall and a fairly gentle
> >>>break.
> >>>
> >>>As you can tell from my description, this is an atypical Piet. But,
> >>>every datum helps.
> >>>
> >>>Jeff
> >>>
> >>>
> >>>>...After reading the posts, I am curious about the standard Piet
> >>>>airfoil, and it's performance. I know that building to plans and to
> >>>>the original design is the best way of getting a good flying plane,
> >>>>but reading the letter posted from Mr. Riblett got me to thinking
> >>>>about the actual performance. I read about a sharp stall and such,
> >>>>and I am looking for you guys that are flying one of these to maybe
> >>>>give your feedback on the airfoil and it's characteristics. ...
> >>>>
> >>>>Mark
> >>>
> >>>--
> >>>---
> >>>
> >>>Jeffrey H. Boatright, Ph.D.
> >>>Associate Professor of Ophthalmology
> >>>Emory University School of Medicine
> >>>Editor-in-Chief
> >>>Molecular Vision
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >
> >
> >--
> >---
> >
> >Jeffrey H. Boatright, Ph.D.
> >Associate Professor of Ophthalmology
> >Emory University School of Medicine
> >Editor-in-Chief
> >Molecular Vision
>
>
Message 12
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|
Subject: | Re: AIrfoil can of worms? |
Thanks John!! I really appreciate the file. I dug through all of the
archives and didn't see it, but it wasn't until late in my search that I saw
any attachments at all on any post, so I might have overlooked it in my lack
of understanding the archive.
Thanks again! I will check my plot.
Many thanks!!
Mark
On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
> Ooops.. forgot the attachement...
>
>
> JohnW
>
> ----- Forwarded Message -----
> From: johnwoods@westnet.com.au
> To: pietenpol-list@matronics.com
> Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
> Mark,
>
>
> Attached is a copy of the xls file I posted a while ago.
>
> It has the co-ordinates for the Riblett 612 & 613.5 sections as provided by
> Mr Bokolt together with the Pietenpol sections, as copied from the plans.
>
>
> I used the 612 co-ordinates to plot and make my ribs.
>
> Still a long way from flying.
>
> The 612 has been sucessfully used on other ultralights and from Mr
> Riblett's description of it's characteristics he predicted it would be a
> good section for the Piet.
>
> I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the 612's
> performance.
>
>
> JohnW
> ----- Original Message -----
> From: "Mark Roberts" <mark.rbrts1@gmail.com>
> To: pietenpol-list@matronics.com
> Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
> Also, just spent the last 2 hours or so creating the 612 rib plot I found
> (if the coordinates are correct) into my CAD program and created a rib
> template for the 60" profile. Not sure if the plot is indeed the 612, as I
> only got the coordinates from a post on this list in the archives and they
> said they had found it on another aviation website, so if anyone has a
> verifiable set of plots, I'd like to check my work to see if it is indeed a
> 612.
>
> Regardless, here's a picture of the plot I made... Minus gussets...
>
> Mark
>
> On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts <mark.rbrts1@gmail.com>wrote:
>
>> Oh Yes! Do tell! :o)
>> Mark
>>
>>
>> On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis <timothywillis@earthlink.net>wrote:
>>
>>> timothywillis@earthlink.net>
>>>
>>> Aha! VGs! Jeff, it sounds like you are very happy with their effects.
>>> Thus inquiring minds want to know:
>>>
>>> Were the VGs the ones you used the straight little plastic fins (100 to a
>>> box), or were they the truncated "V," perhaps made out of bent aluminum?
>>>
>>> How far behind the LE did you place them, and was that according to
>>> directions, or what?
>>>
>>> Did you also apply them to any controls, esp. the back of the VStab or
>>> near the LE of the rudder?
>>>
>>> Tim in central TX
>>>
>>> -----Original Message-----
>>> >From: Jeff Boatright <jboatri@emory.edu>
>>> >Sent: Jul 4, 2009 5:20 PM
>>> >To: pietenpol-list@matronics.com
>>> >Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>> >
>>> >
>>> >
>>> >Mark,
>>> >
>>> >Our Piet had what I consider a sharp and unannounced stall. However,
>>> >it has an aluminum leading edge wrap rather than the thing plywood as
>>> >specified in the plans. When the fabric was shrunk, it pulled the
>>> >aluminum down between the ribs in a very ugly fashion. The result is
>>> >an even sharper nose than the Piet airfoil normally has.
>>> >
>>> >I added vortex generators and everything changed. The no-power stall
>>> >is now about like a Cessna 172's or maybe even gentler. The power-on
>>> >stall has noticeable burbling prior to the stall and a fairly gentle
>>> >break.
>>> >
>>> >As you can tell from my description, this is an atypical Piet. But,
>>> >every datum helps.
>>> >
>>> >Jeff
>>> >
>>> >
>>> >>...After reading the posts, I am curious about the standard Piet
>>> >>airfoil, and it's performance. I know that building to plans and to
>>> >>the original design is the best way of getting a good flying plane,
>>> >>but reading the letter posted from Mr. Riblett got me to thinking
>>> >>about the actual performance. I read about a sharp stall and such,
>>> >>and I am looking for you guys that are flying one of these to maybe
>>> >>give your feedback on the airfoil and it's characteristics. ...
>>> >>
>>> >>Mark
>>> >
>>> >--
>>> >---
>>> >
>>> >Jeffrey H. Boatright, Ph.D.
>>> >Associate Professor of Ophthalmology
>>> >Emory University School of Medicine
>>> >Editor-in-Chief
>>> >Molecular Vision
>>> >
>>> >
>>> >
>>> >
>>>
>>>
>>> ==========
>>> st" target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
>>> ==========
>>> http://forums.matronics.com
>>> ==========
>>> le, List Admin.
>>> ="_blank">http://www.matronics.com/contribution
>>> ==========
>>>
>>>
>>>
>>>
>>
>
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Subject: | Re: AIrfoil can of worms? |
Good questions.
Now, does anyone video tape the talks at Broadhead? I would offer to host
the lecture on my website for others to see (I doubt I'd hit my bandwidth
limit) or we could post it on YouTube as a reference for the future
builders...
Thoughts?
Mark
(I'd even provide the camera to one of my West Coast buddies to use and
bring back to our West Coast Piet Shindig in September....)
On Sun, Jul 5, 2009 at 9:11 AM, Kip and Beth Gardner <
kipandbeth@earthlink.net> wrote:
> kipandbeth@earthlink.net>
>
> Hi John,
>
> Thanks for reposting the spreadsheet with the Riblett numbers - I'm not
> very adept at using the archive search function. I'd already made a jig for
> the standard airfoil, but now I'm seriously considering changing.
>
> Like several others, I won't be able to be at Brodhead this year, so I'd
> REALLY appreciate a few comments from Mr. Lowell if he's willing to take the
> time to answer.
>
> My specific questions are:
>
> Can someone either describe or point me towards a simple explanation of how
> to draw out a rib BY HAND (No CAD), from the spreadsheet numbers? I know
> how to 'loft' boat ribs, but the numerical data for boats is in a
> significantly different form.
>
> Where on the Riblett section (% of Chord, absolute distance, however you
> want to describe it) do the spars fall? Same as the std. airfoil or is
> there some variation? I assume that the distance between spars stays as per
> plans.
>
> Thanks!
>
> Kip Gardner
>
>
> On Jul 5, 2009, at 9:24 AM, johnwoods@westnet.com.au wrote:
>
>>
>> Pieti,
>>
>> With 3 years of flying experience with the 612, would you be able to
>> comment on the CoG range of this section.
>> Thanks
>> JohnW
>> Perth, W/Australia
>>
>> ----- Original Message -----
>> From: "Pieti Lowell" <Lowellcfrank@yahoo.com>
>> To: pietenpol-list@matronics.com
>> Sent: Sunday, 5 July, 2009 11:08:48 AM GMT +08:00 Perth
>> Subject: Pietenpol-List: Re: AIrfoil can of worms?
>>
>> Lowellcfrank@yahoo.com>
>>
>> Mark,
>> I will talk about my 612 at my Brodhead Form ,with 3 years and a number of
>> engines on this foil. If you are under 180 Lbs I will give you a demo you
>> will never forget, The air foil you show is very close to the 612.
>> Pieti Lowell
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=251541#251541
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 14
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Subject: | Re: AIrfoil can of worms? |
opps: Brodhead... I know the difference... :o\
On Sun, Jul 5, 2009 at 9:57 AM, Mark Roberts <mark.rbrts1@gmail.com> wrote:
> Good questions.
> Now, does anyone video tape the talks at Broadhead? I would offer to host
> the lecture on my website for others to see (I doubt I'd hit my bandwidth
> limit) or we could post it on YouTube as a reference for the future
> builders...
>
> Thoughts?
>
> Mark
>
> (I'd even provide the camera to one of my West Coast buddies to use and
> bring back to our West Coast Piet Shindig in September....)
>
>
> On Sun, Jul 5, 2009 at 9:11 AM, Kip and Beth Gardner <
> kipandbeth@earthlink.net> wrote:
>
>> kipandbeth@earthlink.net>
>>
>> Hi John,
>>
>> Thanks for reposting the spreadsheet with the Riblett numbers - I'm not
>> very adept at using the archive search function. I'd already made a jig for
>> the standard airfoil, but now I'm seriously considering changing.
>>
>> Like several others, I won't be able to be at Brodhead this year, so I'd
>> REALLY appreciate a few comments from Mr. Lowell if he's willing to take the
>> time to answer.
>>
>> My specific questions are:
>>
>> Can someone either describe or point me towards a simple explanation of
>> how to draw out a rib BY HAND (No CAD), from the spreadsheet numbers? I
>> know how to 'loft' boat ribs, but the numerical data for boats is in a
>> significantly different form.
>>
>> Where on the Riblett section (% of Chord, absolute distance, however you
>> want to describe it) do the spars fall? Same as the std. airfoil or is
>> there some variation? I assume that the distance between spars stays as per
>> plans.
>>
>> Thanks!
>>
>> Kip Gardner
>>
>>
>> On Jul 5, 2009, at 9:24 AM, johnwoods@westnet.com.au wrote:
>>
>>>
>>> Pieti,
>>>
>>> With 3 years of flying experience with the 612, would you be able to
>>> comment on the CoG range of this section.
>>> Thanks
>>> JohnW
>>> Perth, W/Australia
>>>
>>> ----- Original Message -----
>>> From: "Pieti Lowell" <Lowellcfrank@yahoo.com>
>>> To: pietenpol-list@matronics.com
>>> Sent: Sunday, 5 July, 2009 11:08:48 AM GMT +08:00 Perth
>>> Subject: Pietenpol-List: Re: AIrfoil can of worms?
>>>
>>> Lowellcfrank@yahoo.com>
>>>
>>> Mark,
>>> I will talk about my 612 at my Brodhead Form ,with 3 years and a number
>>> of engines on this foil. If you are under 180 Lbs I will give you a demo you
>>> will never forget, The air foil you show is very close to the 612.
>>> Pieti Lowell
>>>
>>>
>>>
>>>
>>> Read this topic online here:
>>>
>>> http://forums.matronics.com/viewtopic.php?p=251541#251541
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
Message 15
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Subject: | Re: AIrfoil can of worms? |
Kip,
Plot the "chord" column values on the x-axis.
for every x- axis value:
Plot the "above" column values on the positive y axis
Plot the "below" column values on the negative y axis
If you wish to plot to a different size than the 60in shown, use the the % Chord
columns (leftmost three) as they are scaled to one(1) unit scale. All you have
to do is pick the chord length and that becomes your scaling factor.
This reminds me of when I was a boy and was learning drafting. The first thing
I wanted to learn was drafting an airfoil and the drafting process was explained
in this Northop Grumman book/manual about aircraft construction. I drafted
my first full scale aircraft airfoil after reading about it. Since then I have
accepted the fact that a 12in chord is just not going to be enough for a full
scale plane :o), but hey, that is the only size paper I had available then :)
Ameet Savant
Omaha, NE
--- On Sun, 7/5/09, Kip and Beth Gardner <kipandbeth@earthlink.net> wrote:
> Can someone either describe or point me towards a simple
> explanation of how to draw out a rib BY HAND (No CAD), from
> the spreadsheet numbers? I know how to 'loft' boat
> ribs, but the numerical data for boats is in a significantly
> different form.
>
> Kip Gardner
Message 16
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Subject: | Re: AIrfoil can of worms? |
Continuing along the journey of discovery, I checked my airfoil plot from
yesterday against the plot coordinates from John (thanks again!) and found
them to be almost identical. So, I now have a new question about the center
line and it's relation to incidence once on the spar...
The image attached shows the spars are perpendicular to the baseline. The
trailing edge is elevated 1/2" from the baseline. Is this an issue? Or does
the wing mount and attachment work out centerline issues when installed?
Not sure I am clear here, but I am curious about the spars and whether they
should be perpendicular to the median chord line (drawn centered between the
LE and the TE) or if they should be perpendicular to the baseline the plot
was generated from (see the diagram below).
Also, the Full sized Piet Rib Pattern I received does not show a rib riser
on the LE of the front spar, or the TE of the rear spar. I drew this 612 rib
pattern out the same way. I get it that the spar acts as one BIG riser stick
but I still look at it and think one should be there, but I am guessing it
is unnecessary...
Thoughts? I hope to be starting ribs here soon :o)
Mark
PS: Thanks for all of the patience with the questions...
On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <mark.rbrts1@gmail.com> wrote:
> Thanks John!! I really appreciate the file. I dug through all of the
> archives and didn't see it, but it wasn't until late in my search that I saw
> any attachments at all on any post, so I might have overlooked it in my lack
> of understanding the archive.
> Thanks again! I will check my plot.
>
> Many thanks!!
>
> Mark
>
> On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
>
>> Ooops.. forgot the attachement...
>>
>>
>>
>> JohnW
>>
>> ----- Forwarded Message -----
>> From: johnwoods@westnet.com.au
>> To: pietenpol-list@matronics.com
>> Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
>> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>
>> Mark,
>>
>>
>>
>> Attached is a copy of the xls file I posted a while ago.
>>
>> It has the co-ordinates for the Riblett 612 & 613.5 sections as provided
>> by Mr Bokolt together with the Pietenpol sections, as copied from the plans.
>>
>>
>>
>> I used the 612 co-ordinates to plot and make my ribs.
>>
>> Still a long way from flying.
>>
>> The 612 has been sucessfully used on other ultralights and from Mr
>> Riblett's description of it's characteristics he predicted it would be a
>> good section for the Piet.
>>
>> I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the 612's
>> performance.
>>
>>
>>
>> JohnW
>> ----- Original Message -----
>> From: "Mark Roberts" <mark.rbrts1@gmail.com>
>> To: pietenpol-list@matronics.com
>> Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
>> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>
>> Also, just spent the last 2 hours or so creating the 612 rib plot I found
>> (if the coordinates are correct) into my CAD program and created a rib
>> template for the 60" profile. Not sure if the plot is indeed the 612, as I
>> only got the coordinates from a post on this list in the archives and they
>> said they had found it on another aviation website, so if anyone has a
>> verifiable set of plots, I'd like to check my work to see if it is indeed a
>> 612.
>>
>> Regardless, here's a picture of the plot I made... Minus gussets...
>>
>> Mark
>>
>> On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts <mark.rbrts1@gmail.com>wrote:
>>
>>> Oh Yes! Do tell! :o)
>>> Mark
>>>
>>>
>>> On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis <timothywillis@earthlink.net>wrote:
>>>
>>>> timothywillis@earthlink.net>
>>>>
>>>> Aha! VGs! Jeff, it sounds like you are very happy with their effects.
>>>> Thus inquiring minds want to know:
>>>>
>>>> Were the VGs the ones you used the straight little plastic fins (100 to
>>>> a box), or were they the truncated "V," perhaps made out of bent aluminum?
>>>>
>>>> How far behind the LE did you place them, and was that according to
>>>> directions, or what?
>>>>
>>>> Did you also apply them to any controls, esp. the back of the VStab or
>>>> near the LE of the rudder?
>>>>
>>>> Tim in central TX
>>>>
>>>> -----Original Message-----
>>>> >From: Jeff Boatright <jboatri@emory.edu>
>>>> >Sent: Jul 4, 2009 5:20 PM
>>>> >To: pietenpol-list@matronics.com
>>>> >Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>>> >
>>>> jboatri@emory.edu>
>>>> >
>>>> >Mark,
>>>> >
>>>> >Our Piet had what I consider a sharp and unannounced stall. However,
>>>> >it has an aluminum leading edge wrap rather than the thing plywood as
>>>> >specified in the plans. When the fabric was shrunk, it pulled the
>>>> >aluminum down between the ribs in a very ugly fashion. The result is
>>>> >an even sharper nose than the Piet airfoil normally has.
>>>> >
>>>> >I added vortex generators and everything changed. The no-power stall
>>>> >is now about like a Cessna 172's or maybe even gentler. The power-on
>>>> >stall has noticeable burbling prior to the stall and a fairly gentle
>>>> >break.
>>>> >
>>>> >As you can tell from my description, this is an atypical Piet. But,
>>>> >every datum helps.
>>>> >
>>>> >Jeff
>>>> >
>>>> >
>>>> >>...After reading the posts, I am curious about the standard Piet
>>>> >>airfoil, and it's performance. I know that building to plans and to
>>>> >>the original design is the best way of getting a good flying plane,
>>>> >>but reading the letter posted from Mr. Riblett got me to thinking
>>>> >>about the actual performance. I read about a sharp stall and such,
>>>> >>and I am looking for you guys that are flying one of these to maybe
>>>> >>give your feedback on the airfoil and it's characteristics. ...
>>>> >>
>>>> >>Mark
>>>> >
>>>> >--
>>>> >---
>>>> >
>>>> >Jeffrey H. Boatright, Ph.D.
>>>> >Associate Professor of Ophthalmology
>>>> >Emory University School of Medicine
>>>> >Editor-in-Chief
>>>> >Molecular Vision
>>>> >
>>>> >
>>>> >
>>>> >
>>>>
>>>>
>>>> ==========
>>>> st" target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
>>>> ==========
>>>> http://forums.matronics.com
>>>> ==========
>>>> le, List Admin.
>>>> ="_blank">http://www.matronics.com/contribution
>>>> ==========
>>>>
>>>>
>>>>
>>>>
>>>
>>
>
Message 17
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|
Subject: | Re: AIrfoil can of worms? |
Thanks Ameet,
So if I understand you correctly, the positive and negative values
are the distances, in inches, above or below an arbitrary y-axis at
any given point along the x-axis?
That makes sense, and maybe I'm being dense, but I just want to be
sure I understand what you are describing.
So I guess what's puzzling me is that this airfoil section seems
thicker than the standard Piet airfoil? It looks like the thickness
at the 25% station is 7.130 inches? The thickness of the std. Piet
airfoil is roughly 6.5" at the same point. if I'm figuring this
correctly, then some filler may be necessary above or below the spars?
Regards,
Kip Gardner
On Jul 5, 2009, at 5:33 PM, Ameet Savant wrote:
> <ameetsavant@yahoo.com>
>
>
> Kip,
>
> Plot the "chord" column values on the x-axis.
>
> for every x- axis value:
> Plot the "above" column values on the positive y axis
> Plot the "below" column values on the negative y axis
>
> If you wish to plot to a different size than the 60in shown, use
> the the % Chord columns (leftmost three) as they are scaled to one
> (1) unit scale. All you have to do is pick the chord length and
> that becomes your scaling factor.
>
> This reminds me of when I was a boy and was learning drafting. The
> first thing I wanted to learn was drafting an airfoil and the
> drafting process was explained in this Northop Grumman book/manual
> about aircraft construction. I drafted my first full scale aircraft
> airfoil after reading about it. Since then I have accepted the fact
> that a 12in chord is just not going to be enough for a full scale
> plane :o), but hey, that is the only size paper I had available
> then :)
>
> Ameet Savant
> Omaha, NE
>
> --- On Sun, 7/5/09, Kip and Beth Gardner <kipandbeth@earthlink.net>
> wrote:
>
>> Can someone either describe or point me towards a simple
>> explanation of how to draw out a rib BY HAND (No CAD), from
>> the spreadsheet numbers? I know how to 'loft' boat
>> ribs, but the numerical data for boats is in a significantly
>> different form.
>>
>> Kip Gardner
>
>
Message 18
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|
Subject: | Re: AIrfoil can of worms? |
Mark,
I would say: turn your energy from plotting Riblett coordinates towards
cutting and gluing wood on the rib jig you are going to recieve. The Riblett
may be a small improvement on the Piet, and I don't question it's
usefulness....but you have a jig coming, and you have a tremendous amount of
enthusiam right now. Channel that towards making solid progress on your
build. The Piet airfoil, designed by an amateur as it was, has been
successfully built and flown by many many people in the past 80 years;
safely at that. Don't overthink this. Just build!
Ryan
On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <mark.rbrts1@gmail.com> wrote:
> Continuing along the journey of discovery, I checked my airfoil plot from
> yesterday against the plot coordinates from John (thanks again!) and found
> them to be almost identical. So, I now have a new question about the center
> line and it's relation to incidence once on the spar...
> The image attached shows the spars are perpendicular to the baseline. The
> trailing edge is elevated 1/2" from the baseline. Is this an issue? Or does
> the wing mount and attachment work out centerline issues when installed?
>
> Not sure I am clear here, but I am curious about the spars and whether they
> should be perpendicular to the median chord line (drawn centered between the
> LE and the TE) or if they should be perpendicular to the baseline the plot
> was generated from (see the diagram below).
>
> Also, the Full sized Piet Rib Pattern I received does not show a rib riser
> on the LE of the front spar, or the TE of the rear spar. I drew this 612 rib
> pattern out the same way. I get it that the spar acts as one BIG riser stick
> but I still look at it and think one should be there, but I am guessing it
> is unnecessary...
>
> Thoughts? I hope to be starting ribs here soon :o)
>
> Mark
>
> PS: Thanks for all of the patience with the questions...
>
>
> On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <mark.rbrts1@gmail.com>wrote:
>
>> Thanks John!! I really appreciate the file. I dug through all of the
>> archives and didn't see it, but it wasn't until late in my search that I saw
>> any attachments at all on any post, so I might have overlooked it in my lack
>> of understanding the archive.
>> Thanks again! I will check my plot.
>>
>> Many thanks!!
>>
>> Mark
>>
>> On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
>>
>>> Ooops.. forgot the attachement...
>>>
>>>
>>>
>>> JohnW
>>>
>>> ----- Forwarded Message -----
>>> From: johnwoods@westnet.com.au
>>> To: pietenpol-list@matronics.com
>>> Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
>>> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>>
>>> Mark,
>>>
>>>
>>>
>>> Attached is a copy of the xls file I posted a while ago.
>>>
>>> It has the co-ordinates for the Riblett 612 & 613.5 sections as provided
>>> by Mr Bokolt together with the Pietenpol sections, as copied from the plans.
>>>
>>>
>>>
>>> I used the 612 co-ordinates to plot and make my ribs.
>>>
>>> Still a long way from flying.
>>>
>>> The 612 has been sucessfully used on other ultralights and from Mr
>>> Riblett's description of it's characteristics he predicted it would be a
>>> good section for the Piet.
>>>
>>> I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the
>>> 612's performance.
>>>
>>>
>>>
>>> JohnW
>>> ----- Original Message -----
>>> From: "Mark Roberts" <mark.rbrts1@gmail.com>
>>> To: pietenpol-list@matronics.com
>>> Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
>>> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>>
>>> Also, just spent the last 2 hours or so creating the 612 rib plot I found
>>> (if the coordinates are correct) into my CAD program and created a rib
>>> template for the 60" profile. Not sure if the plot is indeed the 612, as I
>>> only got the coordinates from a post on this list in the archives and they
>>> said they had found it on another aviation website, so if anyone has a
>>> verifiable set of plots, I'd like to check my work to see if it is indeed a
>>> 612.
>>>
>>> Regardless, here's a picture of the plot I made... Minus gussets...
>>>
>>> Mark
>>>
>>> On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts <mark.rbrts1@gmail.com>wrote:
>>>
>>>> Oh Yes! Do tell! :o)
>>>> Mark
>>>>
>>>>
>>>> On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis <timothywillis@earthlink.net
>>>> > wrote:
>>>>
>>>>> timothywillis@earthlink.net>
>>>>>
>>>>> Aha! VGs! Jeff, it sounds like you are very happy with their effects.
>>>>> Thus inquiring minds want to know:
>>>>>
>>>>> Were the VGs the ones you used the straight little plastic fins (100 to
>>>>> a box), or were they the truncated "V," perhaps made out of bent aluminum?
>>>>>
>>>>> How far behind the LE did you place them, and was that according to
>>>>> directions, or what?
>>>>>
>>>>> Did you also apply them to any controls, esp. the back of the VStab or
>>>>> near the LE of the rudder?
>>>>>
>>>>> Tim in central TX
>>>>>
>>>>> -----Original Message-----
>>>>> >From: Jeff Boatright <jboatri@emory.edu>
>>>>> >Sent: Jul 4, 2009 5:20 PM
>>>>> >To: pietenpol-list@matronics.com
>>>>> >Subject: Re: Pietenpol-List: AIrfoil can of worms?
>>>>> >
>>>>> jboatri@emory.edu>
>>>>> >
>>>>> >Mark,
>>>>> >
>>>>> >Our Piet had what I consider a sharp and unannounced stall. However,
>>>>> >it has an aluminum leading edge wrap rather than the thing plywood as
>>>>> >specified in the plans. When the fabric was shrunk, it pulled the
>>>>> >aluminum down between the ribs in a very ugly fashion. The result is
>>>>> >an even sharper nose than the Piet airfoil normally has.
>>>>> >
>>>>> >I added vortex generators and everything changed. The no-power stall
>>>>> >is now about like a Cessna 172's or maybe even gentler. The power-on
>>>>> >stall has noticeable burbling prior to the stall and a fairly gentle
>>>>> >break.
>>>>> >
>>>>> >As you can tell from my description, this is an atypical Piet. But,
>>>>> >every datum helps.
>>>>> >
>>>>> >Jeff
>>>>> >
>>>>> >
>>>>> >>...After reading the posts, I am curious about the standard Piet
>>>>> >>airfoil, and it's performance. I know that building to plans and to
>>>>> >>the original design is the best way of getting a good flying plane,
>>>>> >>but reading the letter posted from Mr. Riblett got me to thinking
>>>>> >>about the actual performance. I read about a sharp stall and such,
>>>>> >>and I am looking for you guys that are flying one of these to maybe
>>>>> >>give your feedback on the airfoil and it's characteristics. ...
>>>>> >>
>>>>> >>Mark
>>>>> >
>>>>> >--
>>>>> >---
>>>>> >
>>>>> >Jeffrey H. Boatright, Ph.D.
>>>>> >Associate Professor of Ophthalmology
>>>>> >Emory University School of Medicine
>>>>> >Editor-in-Chief
>>>>> >Molecular Vision
>>>>> >
>>>>> >
>>>>> >
>>>>> >
>>>>>
>>>>>
>>>>> ==========
>>>>> st" target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
>>>>> ==========
>>>>> http://forums.matronics.com
>>>>> ==========
>>>>> le, List Admin.
>>>>> ="_blank">http://www.matronics.com/contribution
>>>>> ==========
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
Message 19
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|
Subject: | Re: AIrfoil can of worms? |
Back about 3 years ago and on the verge of starting my build I had a chance
to visit another builder, I marveled at his project and asked many
questions while in the midst of research study and contemplation. During my
conversation with that noted award winning Texas builder I came away with a great
piece of sage wisdom, He said" don't waste you time thinking it, just
start building and stop wasting time. he also said that once you begin the
build it will all make sense" I took those well placed words and followed the
advice of Hans Vandervort, he certainly knew what he was talking about. When
I got home I committed to the build and began now that's not to say I
haven't run into a snag here and there and even the dreaded builders block, but
given a chance you project will speak to you. You just have to listen to
her.
I been building for the last 3 years and there isn't a day I don't do
something to advance my project, knowledge or skill level. I cant think of a
better way to spend the stolen minutes of a work day or the hour and a half
commute or the road trip working on my Piet. She's been a real inspiration
to me
John
In a message dated 7/5/2009 8:06:24 P.M. Eastern Daylight Time,
rmueller23@gmail.com writes:
Mark,
I would say: turn your energy from plotting Riblett coordinates towards
cutting and gluing wood on the rib jig you are going to recieve. The Riblett
may be a small improvement on the Piet, and I don't question it's
usefulness....but you have a jig coming, and you have a tremendous amount of
enthusiam right now. Channel that towards making solid progress on your build.
The
Piet airfoil, designed by an amateur as it was, has been successfully
built and flown by many many people in the past 80 years; safely at that. Don't
overthink this. Just build!
Ryan
On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) > wrote:
Continuing along the journey of discovery, I checked my airfoil plot from
yesterday against the plot coordinates from John (thanks again!) and found
them to be almost identical. So, I now have a new question about the center
line and it's relation to incidence once on the spar...
The image attached shows the spars are perpendicular to the baseline. The
trailing edge is elevated 1/2" from the baseline. Is this an issue? Or does
the wing mount and attachment work out centerline issues when installed?
Not sure I am clear here, but I am curious about the spars and whether
they should be perpendicular to the median chord line (drawn centered between
the LE and the TE) or if they should be perpendicular to the baseline the
plot was generated from (see the diagram below).
Also, the Full sized Piet Rib Pattern I received does not show a rib riser
on the LE of the front spar, or the TE of the rear spar. I drew this 612
rib pattern out the same way. I get it that the spar acts as one BIG riser
stick but I still look at it and think one should be there, but I am
guessing it is unnecessary...
Thoughts? I hope to be starting ribs here soon :o)
Mark
PS: Thanks for all of the patience with the questions...
On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) > wrote:
Thanks John!! I really appreciate the file. I dug through all of the
archives and didn't see it, but it wasn't until late in my search that I saw any
attachments at all on any post, so I might have overlooked it in my lack
of understanding the archive.
Thanks again! I will check my plot.
Many thanks!!
Mark
On Sun, Jul 5, 2009 at 5:58 AM, <_johnwoods@westnet.com.au_
(mailto:johnwoods@westnet.com.au) > wrote:
Ooops.. forgot the attachement...
JohnW
----- Forwarded Message -----
From: _johnwoods@westnet.com.au_ (mailto:johnwoods@westnet.com.au)
Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Mark,
Attached is a copy of the xls file I posted a while ago.
It has the co-ordinates for the Riblett 612 & 613.5 sections as provided
by Mr Bokolt together with the Pietenpol sections, as copied from the plans.
I used the 612 co-ordinates to plot and make my ribs.
Still a long way from flying.
The 612 has been sucessfully used on other ultralights and from Mr
Riblett's description of it's characteristics he predicted it would be a good
section for the Piet.
I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the 612's
performance.
JohnW
----- Original Message -----
From: "Mark Roberts" <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) >
Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Also, just spent the last 2 hours or so creating the 612 rib plot I found
(if the coordinates are correct) into my CAD program and created a rib
template for the 60" profile. Not sure if the plot is indeed the 612, as I only
got the coordinates from a post on this list in the archives and they said
they had found it on another aviation website, so if anyone has a
verifiable set of plots, I'd like to check my work to see if it is indeed a 612.
Regardless, here's a picture of the plot I made... Minus gussets...
Mark
On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) > wrote:
Oh Yes! Do tell! :o)
Mark
On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis <_timothywillis@earthlink.net_
(mailto:timothywillis@earthlink.net) > wrote:
<_timothywillis@earthlink.net_ (mailto:timothywillis@earthlink.net) >
Aha! VGs! Jeff, it sounds like you are very happy with their effects.
Thus inquiring minds want to know:
Were the VGs the ones you used the straight little plastic fins (100 to a
box), or were they the truncated "V," perhaps made out of bent aluminum?
How far behind the LE did you place them, and was that according to
directions, or what?
Did you also apply them to any controls, esp. the back of the VStab or
near the LE of the rudder?
Tim in central TX
-----Original Message-----
>From: Jeff Boatright <_jboatri@emory.edu_ (mailto:jboatri@emory.edu) >
>Sent: Jul 4, 2009 5:20 PM
>To: _pietenpol-list@matronics.com_ (mailto:pietenpol-list@matronics.com)
>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
>--> Pietenpol-List message posted by: Jeff Boatright <_jboatri@emory.edu_
(mailto:jboatri@emory.edu) >
>
>Mark,
>
>Our Piet had what I consider a sharp and unannounced stall. However,
>it has an aluminum leading edge wrap rather than the thing plywood as
>specified in the plans. When the fabric was shrunk, it pulled the
>aluminum down between the ribs in a very ugly fashion. The result is
>an even sharper nose than the Piet airfoil normally has.
>
>I added vortex generators and everything changed. The no-power stall
>is now about like a Cessna 172's or maybe even gentler. The power-on
>stall has noticeable burbling prior to the stall and a fairly gentle
>break.
>
>As you can tell from my description, this is an atypical Piet. But,
>every datum helps.
>
>Jeff
>
>
>>...After reading the posts, I am curious about the standard Piet
>>airfoil, and it's performance. I know that building to plans and to
>>the original design is the best way of getting a good flying plane,
>>but reading the letter posted from Mr. Riblett got me to thinking
>>about the actual performance. I read about a sharp stall and such,
>>and I am looking for you guys that are flying one of these to maybe
>>give your feedback on the airfoil and it's characteristics. ...
>>
>>Mark
>
>--
>---
>
>Jeffrey H. Boatright, Ph.D.
>Associate Professor of Ophthalmology
>Emory University School of Medicine
>Editor-in-Chief
>Molecular Vision
>
>
==========
st" target="_blank">_http://www.matronics.com/Navigator?Pietenpol-List_
(http://www.matronics.com/Navigator?Pietenpol-List)
==========
_http://forums.matronics.com_ (http://forums.matronics.com/)
==========
le, List Admin.
="_blank">_http://www.matronics.com/contribution_
(http://www.matronics.com/contribution)
==========
(http://www.matronics.com/Navigator?Pietenpol-List)
(http://www.matronics.com/contribution)
**************Make your summer sizzle with fast and easy recipes for the
grill. (http://food.aol.com/grilling?ncid=emlcntusfood00000005)
Message 20
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Subject: | Brodhead Pietenpol Gathering |
1) I will be attending the Pietenpol gathering this year and I have a bit of
a dumb question. I have searched through the archives and other places and
cannot find a definitive location (other than, obviously Brodhead, WI).
Google maps shows what looks like an airfield just south of Brodhead. Is
this where all the Pietenpol fans will be gathering?
2) Has anyone used the Azusa 4.8 x 8 wheels on their Piet? I have a set with
the 5/8"axles and after reviewing the math with a structural engineer, the
axle seems to be too weak, even with a solid 4130 axle. Even switching out
the bearings and installing 3/4" axles seems a little iffy. Any one with
experience using smaller axles on their Piet?
3) Just for interest, Here is a picture of one of the rudder pedals for my
plane (sitting on the underside of the fuselage for the picture.) The black
strip is carbon fiber. Instead of the steel fuselage cross strap I used
carbon fiber to hold the fuselage bottom together. Ran the carbon fully
across the bottom and wrapped about 6" up the sides.
Steve in Winnipeg (Fuselage framed, controls partially complete, building
landing gear now)
Message 21
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Subject: | found on craigslist |
http://stlouis.craigslist.org/pts/1252264754.html
Message 22
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Subject: | Re: AIrfoil can of worms? |
"It's gonna be a monoplane."
Do not archive.
John Hofmann
Vice-President, Information Technology
The Rees Group, Inc.
2810 Crossroads Drive, Ste 3800
Madison, WI 53718
Phone: 608.443.2468 ext 150
Fax: 608.443.2474
Email: jhofmann@reesgroupinc.com
On Jul 5, 2009, at 7:48 PM, AMsafetyC@aol.com wrote:
> Back about 3 years ago and on the verge of starting my build I had a
> chance to visit another builder, I marveled at his project and asked
> many questions while in the midst of research study and
> contemplation. During my conversation with that noted award winning
> Texas builder I came away with a great piece of sage wisdom, He
> said" don't waste you time thinking it, just start building and stop
> wasting time. he also said that once you begin the build it will all
> make sense" I took those well placed words and followed the advice
> of Hans Vandervort, he certainly knew what he was talking about.
> When I got home I committed to the build and began now that's not to
> say I haven't run into a snag here and there and even the dreaded
> builders block, but given a chance you project will speak to you.
> You just have to listen to her.
>
> I been building for the last 3 years and there isn't a day I don't
> do something to advance my project, knowledge or skill level. I
> cant think of a better way to spend the stolen minutes of a work day
> or the hour and a half commute or the road trip working on my Piet.
> She's been a real inspiration to me
>
> John
>
>
> In a message dated 7/5/2009 8:06:24 P.M. Eastern Daylight Time, rmueller23@gmail.com
> writes:
> Mark,
>
> I would say: turn your energy from plotting Riblett coordinates
> towards cutting and gluing wood on the rib jig you are going to
> recieve. The Riblett may be a small improvement on the Piet, and I
> don't question it's usefulness....but you have a jig coming, and you
> have a tremendous amount of enthusiam right now. Channel that
> towards making solid progress on your build. The Piet airfoil,
> designed by an amateur as it was, has been successfully built and
> flown by many many people in the past 80 years; safely at that.
> Don't overthink this. Just build!
>
> Ryan
>
>
> On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <mark.rbrts1@gmail.com>
> wrote:
> Continuing along the journey of discovery, I checked my airfoil plot
> from yesterday against the plot coordinates from John (thanks
> again!) and found them to be almost identical. So, I now have a new
> question about the center line and it's relation to incidence once
> on the spar...
>
> The image attached shows the spars are perpendicular to the
> baseline. The trailing edge is elevated 1/2" from the baseline. Is
> this an issue? Or does the wing mount and attachment work out
> centerline issues when installed?
>
> Not sure I am clear here, but I am curious about the spars and
> whether they should be perpendicular to the median chord line (drawn
> centered between the LE and the TE) or if they should be
> perpendicular to the baseline the plot was generated from (see the
> diagram below).
>
> Also, the Full sized Piet Rib Pattern I received does not show a rib
> riser on the LE of the front spar, or the TE of the rear spar. I
> drew this 612 rib pattern out the same way. I get it that the spar
> acts as one BIG riser stick but I still look at it and think one
> should be there, but I am guessing it is unnecessary...
>
> Thoughts? I hope to be starting ribs here soon :o)
>
> Mark
>
> PS: Thanks for all of the patience with the questions...
>
>
> On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <mark.rbrts1@gmail.com>
> wrote:
> Thanks John!! I really appreciate the file. I dug through all of the
> archives and didn't see it, but it wasn't until late in my search
> that I saw any attachments at all on any post, so I might have
> overlooked it in my lack of understanding the archive.
>
> Thanks again! I will check my plot.
>
> Many thanks!!
>
> Mark
>
> On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
> Ooops.. forgot the attachement...
>
>
> JohnW
>
>
> ----- Forwarded Message -----
> From: johnwoods@westnet.com.au
> To: pietenpol-list@matronics.com
> Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
>
> Mark,
>
>
> Attached is a copy of the xls file I posted a while ago.
>
> It has the co-ordinates for the Riblett 612 & 613.5 sections as
> provided by Mr Bokolt together with the Pietenpol sections, as
> copied from the plans.
>
>
> I used the 612 co-ordinates to plot and make my ribs.
>
> Still a long way from flying.
>
> The 612 has been sucessfully used on other ultralights and from Mr
> Riblett's description of it's characteristics he predicted it would
> be a good section for the Piet.
>
> I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the
> 612's performance.
>
>
> JohnW
> ----- Original Message -----
> From: "Mark Roberts" <mark.rbrts1@gmail.com>
> To: pietenpol-list@matronics.com
> Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
> Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
> Also, just spent the last 2 hours or so creating the 612 rib plot I
> found (if the coordinates are correct) into my CAD program and
> created a rib template for the 60" profile. Not sure if the plot is
> indeed the 612, as I only got the coordinates from a post on this
> list in the archives and they said they had found it on another
> aviation website, so if anyone has a verifiable set of plots, I'd
> like to check my work to see if it is indeed a 612.
>
>
> Regardless, here's a picture of the plot I made... Minus gussets...
>
> Mark
>
> On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts <mark.rbrts1@gmail.com>
> wrote:
> Oh Yes! Do tell! :o)
>
> Mark
>
>
> On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis <timothywillis@earthlink.net
> > wrote:
> >
>
> Aha! VGs! Jeff, it sounds like you are very happy with their
> effects. Thus inquiring minds want to know:
>
> Were the VGs the ones you used the straight little plastic fins (100
> to a box), or were they the truncated "V," perhaps made out of bent
> aluminum?
>
> How far behind the LE did you place them, and was that according to
> directions, or what?
>
> Did you also apply them to any controls, esp. the back of the VStab
> or near the LE of the rudder?
>
> Tim in central TX
>
> -----Original Message-----
> >From: Jeff Boatright <jboatri@emory.edu>
> >Sent: Jul 4, 2009 5:20 PM
> >To: pietenpol-list@matronics.com
> >Subject: Re: Pietenpol-List: AIrfoil can of worms?
> >
> >
> >
> >Mark,
> >
> >Our Piet had what I consider a sharp and unannounced stall. However,
> >it has an aluminum leading edge wrap rather than the thing plywood as
> >specified in the plans. When the fabric was shrunk, it pulled the
> >aluminum down between the ribs in a very ugly fashion. The result is
> >an even sharper nose than the Piet airfoil normally has.
> >
> >I added vortex generators and everything changed. The no-power stall
> >is now about like a Cessna 172's or maybe even gentler. The power-on
> >stall has noticeable burbling prior to the stall and a fairly gentle
> >break.
> >
> >As you can tell from my description, this is an atypical Piet. But,
> >every datum helps.
> >
> >Jeff
> >
> >
> >>...After reading the posts, I am curious about the standard Piet
> >>airfoil, and it's performance. I know that building to plans and to
> >>the original design is the best way of getting a good flying plane,
> >>but reading the letter posted from Mr. Riblett got me to thinking
> >>about the actual performance. I read about a sharp stall and such,
> >>and I am looking for you guys that are flying one of these to maybe
> >>give your feedback on the airfoil and it's characteristics. ...
> >>
> >>Mark
> >
> >--
> >---
> >
> >Jeffrey H. Boatright, Ph.D.
> >Associate Professor of Ophthalmology
> >Emory University School of Medicine
> >Editor-in-Chief
> >Molecular Vision
> >
> >
> >
> >
>
>
> ==========
> st" target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
> ==========
> http://forums.matronics.com
> ==========
> le, List Admin.
> ="_blank">http://www.matronics.com/contribution
> ==========
>
>
> ===================================
> t href="http://www.matronics.com/Navigator?Pietenpol-List">http://www.matronics.com/Navigator?Pietenpol-List
> ===================================
> ms.matronics.com/">http://forums.matronics.com
> ===================================
> tp://www.matronics.com/contribution">http://www.matronics.com/contribution
> ===================================
>
>
> Make your summer sizzle with fast and easy recipes for the grill.
>
>
Message 23
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Subject: | Re: AIrfoil can of worms? |
Hi Kip,
Yes, that is exactly what I was describing.
Yes, the "12" in the 612 comes from 12% max thickness of the airfoil. That makes
the max thickness around 7.13in. The original airfoil was thinner, an artifact
of the age it was first used. A number of successful airfoils were created
in later years (via experience in racing?) with the 12% (NACA 4412 comes to mind)
max thickness. The idea was to use a thicker spar and consequently a stronger
wing. There are several other benefits (that I don't exactly recall now) that
thicker airfoils provide for slow flying airplanes like the Piet.
As for the construction changes needed for using a thicker airfoil, I would defer
to the experienced people on this list. I seem to recall finding some discussions
in the archives about using a thicker spar directly but then having to
relocate the holes drilled in the spar and changing too much of the design. It
seemed the easier option was to fill the empty space. I do not know much about
this, but I am researching.
Regards,
Ameet
--- On Sun, 7/5/09, Kip and Beth Gardner <kipandbeth@earthlink.net> wrote:
> From: Kip and Beth Gardner <kipandbeth@earthlink.net>
> Subject: Re: Pietenpol-List: Re: AIrfoil can of worms?
> To: pietenpol-list@matronics.com
> Date: Sunday, July 5, 2009, 5:59 PM
> --> Pietenpol-List message posted
> by: Kip and Beth Gardner <kipandbeth@earthlink.net>
>
> Thanks Ameet,
>
> So if I understand you correctly, the positive and negative
> values are the distances, in inches, above or below an
> arbitrary y-axis at any given point along the x-axis?
>
> That makes sense, and maybe I'm being dense, but I just
> want to be sure I understand what you are describing.
>
> So I guess what's puzzling me is that this airfoil section
> seems thicker than the standard Piet airfoil? It looks
> like the thickness at the 25% station is 7.130
> inches?The thickness of the std. Piet
> airfoil is roughly 6.5" at the same point. if I'm
> figuring this correctly, then some filler may be necessary
> above or below the spars?
>
> Regards,
>
> Kip Gardner
Message 24
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Subject: | Re: AIrfoil can of worms? |
Piet People,612 stuff
I know those of you that won't be at Brodhead would like to have a lot of questions
answered. I think patients will work, as many questions will be asked that
we now don't even have good answers.
But I started with Mr Ribblett in the very early 90s. communicated for a couple
years, he said that there is much better airfoils than the Piet after I sent
him the coordinates. He sent me reams of calculations and curves, and computer
read-outs plus his final thinking. I decided to keep the foil close to looking
like a Piet foil, Ribblitt's second choice. 613.5 his 1St.
I laid the numbers on a layout table and they matched the sent profile, except
for a very slight shrinkage, It was a start.
He suggested I use 33% figure for the CoG to start and let him know what it felt
like. I will need to look over all his letters to check if he changed his thinking.
I constructed the 612 just as I built the Piet foil, but added fillers due to the
added height. But since this foil seemed more efficient I shortened each wing
12". It works very well, so those of you that are going 612 keep it the same
length as the Piet's foil. if you are concerned about hot weather , heavy loads,
altitude or better rate of climb,
If you want to live on the edge shorten the wing for a much faster roll rate, and
a lot of solo. add HP it will perform very quick.
This is an overview , got questions ? will answer the best I know how.
Pieti Lowell
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=251678#251678
Message 25
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Subject: | Re: AIrfoil can of worms? |
"an inferior model but it will suit my purposes"
In a message dated 7/5/2009 10:35:09 P.M. Eastern Daylight Time,
jhofmann@reesgroupinc.com writes:
"It's gonna be a monoplane."
Do not archive.
John Hofmann
Vice-President, Information Technology
The Rees Group, Inc.
2810 Crossroads Drive, Ste 3800
Madison, WI 53718
Phone: 608.443.2468 ext 150
Fax: 608.443.2474
Email: _jhofmann@reesgroupinc.com_ (mailto:jhofmann@reesgroupinc.com)
On Jul 5, 2009, at 7:48 PM, _AMsafetyC@aol.com_ (mailto:AMsafetyC@aol.com)
wrote:
Back about 3 years ago and on the verge of starting my build I had a
chance to visit another builder, I marveled at his project and asked many
questions while in the midst of research study and contemplation. During my
conversation with that noted award winning Texas builder I came away with a
great piece of sage wisdom, He said" don't waste you time thinking it, just
start building and stop wasting time. he also said that once you begin the
build it will all make sense" I took those well placed words and followed the
advice of Hans Vandervort, he certainly knew what he was talking about.
When I got home I committed to the build and began now that's not to say I
haven't run into a snag here and there and even the dreaded builders block,
but given a chance you project will speak to you. You just have to listen to
her.
I been building for the last 3 years and there isn't a day I don't do
something to advance my project, knowledge or skill level. I cant think of a
better way to spend the stolen minutes of a work day or the hour and a half
commute or the road trip working on my Piet. She's been a real inspiration
to me
John
In a message dated 7/5/2009 8:06:24 P.M. Eastern Daylight Time,
_rmueller23@gmail.com_ (mailto:rmueller23@gmail.com) writes:
Mark,
I would say: turn your energy from plotting Riblett coordinates towards
cutting and gluing wood on the rib jig you are going to recieve. The Riblett
may be a small improvement on the Piet, and I don't question it's
usefulness....but you have a jig coming, and you have a tremendous amount of
enthusiam right now. Channel that towards making solid progress on your build.
The
Piet airfoil, designed by an amateur as it was, has been successfully
built and flown by many many people in the past 80 years; safely at that. Don't
overthink this. Just build!
Ryan
On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) > wrote:
Continuing along the journey of discovery, I checked my airfoil plot from
yesterday against the plot coordinates from John (thanks again!) and found
them to be almost identical. So, I now have a new question about the center
line and it's relation to incidence once on the spar...
The image attached shows the spars are perpendicular to the baseline. The
trailing edge is elevated 1/2" from the baseline. Is this an issue? Or does
the wing mount and attachment work out centerline issues when installed?
Not sure I am clear here, but I am curious about the spars and whether
they should be perpendicular to the median chord line (drawn centered between
the LE and the TE) or if they should be perpendicular to the baseline the
plot was generated from (see the diagram below).
Also, the Full sized Piet Rib Pattern I received does not show a rib riser
on the LE of the front spar, or the TE of the rear spar. I drew this 612
rib pattern out the same way. I get it that the spar acts as one BIG riser
stick but I still look at it and think one should be there, but I am
guessing it is unnecessary...
Thoughts? I hope to be starting ribs here soon :o)
Mark
PS: Thanks for all of the patience with the questions...
On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) > wrote:
Thanks John!! I really appreciate the file. I dug through all of the
archives and didn't see it, but it wasn't until late in my search that I saw any
attachments at all on any post, so I might have overlooked it in my lack
of understanding the archive.
Thanks again! I will check my plot.
Many thanks!!
Mark
On Sun, Jul 5, 2009 at 5:58 AM, <_johnwoods@westnet.com.au_
(mailto:johnwoods@westnet.com.au) > wrote:
Ooops.. forgot the attachement...
JohnW
----- Forwarded Message -----
From: _johnwoods@westnet.com.au_ (mailto:johnwoods@westnet.com.au)
Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Mark,
Attached is a copy of the xls file I posted a while ago.
It has the co-ordinates for the Riblett 612 & 613.5 sections as provided
by Mr Bokolt together with the Pietenpol sections, as copied from the plans.
I used the 612 co-ordinates to plot and make my ribs.
Still a long way from flying.
The 612 has been sucessfully used on other ultralights and from Mr
Riblett's description of it's characteristics he predicted it would be a good
section for the Piet.
I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the 612's
performance.
JohnW
----- Original Message -----
From: "Mark Roberts" <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) >
Sent: Sunday, 5 July, 2009 7:50:46 AM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Also, just spent the last 2 hours or so creating the 612 rib plot I found
(if the coordinates are correct) into my CAD program and created a rib
template for the 60" profile. Not sure if the plot is indeed the 612, as I
only got the coordinates from a post on this list in the archives and they
said they had found it on another aviation website, so if anyone has a
verifiable set of plots, I'd like to check my work to see if it is indeed a 612.
Regardless, here's a picture of the plot I made... Minus gussets...
Mark
On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts <_mark.rbrts1@gmail.com_
(mailto:mark.rbrts1@gmail.com) > wrote:
Oh Yes! Do tell! :o)
Mark
On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis <_timothywillis@earthlink.net_
(mailto:timothywillis@earthlink.net) > wrote:
<_timothywillis@earthlink.net_ (mailto:timothywillis@earthlink.net) >
Aha! VGs! Jeff, it sounds like you are very happy with their effects.
Thus inquiring minds want to know:
Were the VGs the ones you used the straight little plastic fins (100 to a
box), or were they the truncated "V," perhaps made out of bent aluminum?
How far behind the LE did you place them, and was that according to
directions, or what?
Did you also apply them to any controls, esp. the back of the VStab or
near the LE of the rudder?
Tim in central TX
-----Original Message-----
>From: Jeff Boatright <_jboatri@emory.edu_ (mailto:jboatri@emory.edu) >
>Sent: Jul 4, 2009 5:20 PM
>To: _pietenpol-list@matronics.com_ (mailto:pietenpol-list@matronics.com)
>Subject: Re: Pietenpol-List: AIrfoil can of worms?
>
>--> Pietenpol-List message posted by: Jeff Boatright <_jboatri@emory.edu_
(mailto:jboatri@emory.edu) >
>
>Mark,
>
>Our Piet had what I consider a sharp and unannounced stall. However,
>it has an aluminum leading edge wrap rather than the thing plywood as
>specified in the plans. When the fabric was shrunk, it pulled the
>aluminum down between the ribs in a very ugly fashion. The result is
>an even sharper nose than the Piet airfoil normally has.
>
>I added vortex generators and everything changed. The no-power stall
>is now about like a Cessna 172's or maybe even gentler. The power-on
>stall has noticeable burbling prior to the stall and a fairly gentle
>break.
>
>As you can tell from my description, this is an atypical Piet. But,
>every datum helps.
>
>Jeff
>
>
>>...After reading the posts, I am curious about the standard Piet
>>airfoil, and it's performance. I know that building to plans and to
>>the original design is the best way of getting a good flying plane,
>>but reading the letter posted from Mr. Riblett got me to thinking
>>about the actual performance. I read about a sharp stall and such,
>>and I am looking for you guys that are flying one of these to maybe
>>give your feedback on the airfoil and it's characteristics. ...
>>
>>Mark
>
>--
>---
>
>Jeffrey H. Boatright, Ph.D.
>Associate Professor of Ophthalmology
>Emory University School of Medicine
>Editor-in-Chief
>Molecular Vision
>
>
==========
st" target="_blank">_http://www.matronics.com/Navigator?Pietenpol-List_
(http://www.matronics.com/Navigator?Pietenpol-List)
==========
_http://forums.matronics.com_ (http://forums.matronics.com/)
==========
le, List Admin.
="_blank">_http://www.matronics.com/contribution_
(http://www.matronics.com/contribution)
==========
t href="_http://www.matronics.com/Navigator?Pietenpol-List_
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____________________________________
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Subject: | Re: AIrfoil can of worms? |
Jim Boyer
Santa Rosa, CA
Pietenpol builder with Corvair
John and Ryan,
You both gave some of the best advice in these two messages. All the time spent
on the internet could have been used building.
Thanks,
Jim
On Jul 5, 2009, AMsafetyC@aol.com wrote:
Back about 3 years ago and on the verge of starting my build I had a chance
to visit another builder, I marveled at his project and asked many questions
while in the midst of research study and contemplation. During my conversation
with that noted award winning Texas builder I came away with a great piece
of sage wisdom, He said" don't waste you time thinking it, just start building
and stop wasting time. he also said that once you begin the build it will all
make sense" I took those well placed words and followed the advice of Hans
Vandervort, he certainly knew what he was talking about. When I got home I
committed to the build and began now that's not to say I haven't run into a snag
here and there and even the dreaded builders block, but given a chance you
project will speak to you. You just have to listen to her.
I been building for the last 3 years and there isn't a day I don't do
something to advance my project, knowledge or skill level. I cant think of
a better way to spend the stolen minutes of a work day or the hour and a half
commute or the road trip working on my Piet. She's been a real inspiration to
me
John
In a message dated 7/5/2009 8:06:24 P.M. Eastern Daylight Time,
rmueller23@gmail.com writes:
Mark,
I would say: turn your energy from plotting Riblett
coordinates towards cutting and gluing wood on the rib jig you are going to
recieve. The Riblett may be a small improvement on the Piet, and I don't
question it's usefulness....but you have a jig coming, and you have a
tremendous amount of enthusiam right now. Channel that towards making solid
progress on your build. The Piet airfoil, designed by an amateur as it was,
has been successfully built and flown by many many people in the past 80
years; safely at that. Don't overthink this. Just
build!
Ryan
On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <mark.rbrts1@gmail.com>
wrote:
Continuing along the journey of discovery,
I checked my airfoil plot from yesterday against the plot coordinates from
John (thanks again!) and found them to be almost identical. So, I now have
a
new question about the center line and it's relation to incidence once on
the spar...
The image attached shows the spars are perpendicular to the baseline.
The trailing edge is elevated 1/2" from the baseline. Is this an issue? Or
does the wing mount and attachment work out centerline issues when
installed?
Not sure I am clear here, but I am curious about the spars and whether
they should be perpendicular to the median chord line (drawn centered
between the LE and the TE) or if they should be perpendicular to the
baseline the plot was generated from (see the diagram below).
Also, the Full sized Piet Rib Pattern I received does not show a rib
riser on the LE of the front spar, or the TE of the rear spar. I drew this
612 rib pattern out the same way. I get it that the spar acts as one BIG
riser stick but I still look at it and think one should be there, but I am
guessing it is unnecessary...
Thoughts? I hope to be starting ribs here soon :o)
Mark
PS: Thanks for all of the patience with the questions...
On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <mark.rbrts1@gmail.com> wrote:
Thanks John!! I really appreciate the file. I dug
through all of the archives and didn't see it, but it wasn't until late in
my search that I saw any attachments at all on any post, so I might have
overlooked it in my lack of understanding the archive.
Thanks again! I will check my plot.
Many thanks!!
Mark
On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
Ooops.. forgot the attachement...
JohnW
----- Forwarded Message -----
From: johnwoods@westnet.com.au
Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
Subject:
Re: Pietenpol-List: AIrfoil can of worms?
Mark,
Attached is a copy of the xls file I posted a while ago.
It has the co-ordinates for the Riblett 612 & 613.5 sections
as provided by Mr Bokolt together with the Pietenpol sections, as copied
from the plans.
I used the 612 co-ordinates to plot and make my ribs.
Still a long way from flying.
The 612 has been sucessfully used on other ultralights and
from Mr Riblett's description of it's characteristics he predicted
it would be a good section for the Piet.
I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the
612's performance.
JohnW
----- Original Message -----
From: "Mark Roberts" <mark.rbrts1@gmail.com>
Sent: Sunday, 5 July,
2009 7:50:46 AM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil
can of worms?
Also, just spent the last 2 hours or so creating
the 612 rib plot I found (if the coordinates are correct) into my CAD
program and created a rib template for the 60" profile. Not sure if the
plot is indeed the 612, as I only got the coordinates from a post on
this list in the archives and they said they had found it on another
aviation website, so if anyone has a verifiable set of plots, I'd like
to check my work to see if it is indeed a 612.
Regardless, here's a picture of the plot I made... Minus
gussets...
Mark
On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts
<mark.rbrts1@gmail.com> wrote:
Oh Yes! Do tell! :o)
Mark
On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis
<timothywillis@earthlink.net> wrote:
Willis <timothywillis@earthlink.net>
Aha!
VGs! Jeff, it sounds like you are very happy with their
effects. Thus inquiring minds want to know:
Were the
VGs the ones you used the straight little plastic fins (100 to a
box), or were they the truncated "V," perhaps made out of bent
aluminum?
How far behind the LE did you place them, and was
that according to directions, or what?
Did you also apply
them to any controls, esp. the back of the VStab or near the LE of
the rudder?
Tim in central TX
-----Original Message-----
>From: Jeff Boatright
<jboatri@emory.edu>
>Sent: Jul 4, 2009
5:20 PM
>To: pietenpol-list@matronics.com
>Subject: Re:
Pietenpol-List: AIrfoil can of worms?
>
>-->
Pietenpol-List message posted by: Jeff Boatright <jboatri@emory.edu>
>
>Mark,
>
>Our
Piet had what I consider a sharp and unannounced stall.
However,
>it has an aluminum leading edge wrap rather than the
thing plywood as
>specified in the plans. When the fabric was
shrunk, it pulled the
>aluminum down between the ribs in a
very ugly fashion. The result is
>an even sharper nose than
the Piet airfoil normally has.
>
>I added vortex
generators and everything changed. The no-power stall
>is now
about like a Cessna 172's or maybe even gentler. The
power-on
>stall has noticeable burbling prior to the stall and
a fairly gentle
>break.
>
>As you can tell from my
description, this is an atypical Piet. But,
>every datum
helps.
>
>Jeff
>
>
>>...After
reading the posts, I am curious about the standard
Piet
>>airfoil, and it's performance. I know that building
to plans and to
>>the original design is the best way of
getting a good flying plane,
>>but reading the letter
posted from Mr. Riblett got me to thinking
>>about the
actual performance. I read about a sharp stall and
such,
>>and I am looking for you guys that are flying one
of these to maybe
>>give your feedback on the airfoil and
it's characteristics.
...
>>
>>Mark
>
>--
>---
>
>Jeffrey
H. Boatright, Ph.D.
>Associate Professor of
Ophthalmology
>Emory University School of
Medicine
>Editor-in-Chief
>Molecular
Vision
>
>
==========
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==========
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==========
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List Admin.
="_blank">http://www.matronics.com/contribution
==========
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===================================
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===================================
Make your summer sizzle with fast and easy recipes for the grill.
Message 27
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|
Subject: | Re: AIrfoil can of worms? |
Don't get me wrong guys, the only reason I'm thinking instead of building is
I don't have the cash to buy the wood this month... Spent it on plans.
Next month, all of this edumacation gets to work.
Mark
On Sun, Jul 5, 2009 at 8:40 PM, Jim <jimboyer@hughes.net> wrote:
>
>
> Jim Boyer
> Santa Rosa, CA
> Pietenpol builder with Corvair
>
> John and Ryan,
> You both gave some of the best advice in these two messages. All the time
> spent on the internet could have been used building.
> Thanks,
> Jim
>
>
> On Jul 5, 2009, AMsafetyC@aol.com wrote:
>
>
> Back about 3 years ago and on the verge of starting my build I had a chance
> to visit another builder, I marveled at his project and asked many
> questions
> while in the midst of research study and contemplation. During my
> conversation
> with that noted award winning Texas builder I came away with a great piece
> of sage wisdom, He said" don't waste you time thinking it, just start
> building
> and stop wasting time. he also said that once you begin the build it will
> all
> make sense" I took those well placed words and followed the advice of Hans
> Vandervort, he certainly knew what he was talking about. When I got home I
> committed to the build and began now that's not to say I haven't run into a
> snag
> here and there and even the dreaded builders block, but given a chance you
> project will speak to you. You just have to listen to her.
>
> I been building for the last 3 years and there isn't a day I don't do
> something to advance my project, knowledge or skill level. I cant think of
> a better way to spend the stolen minutes of a work day or the hour and a
> half
> commute or the road trip working on my Piet. She's been a real inspiration
> to
> me
>
> John
>
>
> In a message dated 7/5/2009 8:06:24 P.M. Eastern Daylight Time,
> rmueller23@gmail.com writes:
>
> Mark,
>
> I would say: turn your energy from plotting Riblett
> coordinates towards cutting and gluing wood on the rib jig you are going
> to
> recieve. The Riblett may be a small improvement on the Piet, and I don't
> question it's usefulness....but you have a jig coming, and you have a
> tremendous amount of enthusiam right now. Channel that towards making
> solid
> progress on your build. The Piet airfoil, designed by an amateur as it
> was,
> has been successfully built and flown by many many people in the past 80
> years; safely at that. Don't overthink this. Just
> build!
>
> Ryan
>
>
> On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <mark.rbrts1@gmail.com>
> wrote:
>
> Continuing along the journey of discovery,
> I checked my airfoil plot from yesterday against the plot coordinates
> from
> John (thanks again!) and found them to be almost identical. So, I now
> have a
> new question about the center line and it's relation to incidence once
> on
> the spar...
>
>
> The image attached shows the spars are perpendicular to the baseline.
> The trailing edge is elevated 1/2" from the baseline. Is this an issue?
> Or
> does the wing mount and attachment work out centerline issues when
> installed?
>
>
> Not sure I am clear here, but I am curious about the spars and whether
> they should be perpendicular to the median chord line (drawn centered
> between the LE and the TE) or if they should be perpendicular to the
> baseline the plot was generated from (see the diagram below).
>
>
> Also, the Full sized Piet Rib Pattern I received does not show a rib
> riser on the LE of the front spar, or the TE of the rear spar. I drew
> this
> 612 rib pattern out the same way. I get it that the spar acts as one BIG
> riser stick but I still look at it and think one should be there, but I
> am
> guessing it is unnecessary...
>
>
> Thoughts? I hope to be starting ribs here soon :o)
>
>
> Mark
>
>
> PS: Thanks for all of the patience with the questions...
>
>
> On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <mark.rbrts1@gmail.com>
> wrote:
>
> Thanks John!! I really appreciate the file. I dug
> through all of the archives and didn't see it, but it wasn't until
> late in
> my search that I saw any attachments at all on any post, so I might
> have
> overlooked it in my lack of understanding the archive.
>
>
> Thanks again! I will check my plot.
>
>
> Many thanks!!
>
>
> Mark
>
>
> On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
>
>
> Ooops.. forgot the attachement...
>
>
> JohnW
>
>
> ----- Forwarded Message -----
> From: johnwoods@westnet.com.au
> To: pietenpol-list@matronics.com
>
>
> Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
> Subject:
> Re: Pietenpol-List: AIrfoil can of worms?
>
>
> Mark,
>
>
> Attached is a copy of the xls file I posted a while ago.
>
> It has the co-ordinates for the Riblett 612 & 613.5 sections
> as provided by Mr Bokolt together with the Pietenpol sections, as
> copied
> from the plans.
>
>
> I used the 612 co-ordinates to plot and make my ribs.
>
> Still a long way from flying.
>
> The 612 has been sucessfully used on other ultralights and
> from Mr Riblett's description of it's characteristics he predicted
> it would be a good section for the Piet.
>
> I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the
> 612's performance.
>
>
> JohnW
> ----- Original Message -----
> From: "Mark Roberts" <mark.rbrts1@gmail.com>
> To: pietenpol-list@matronics.com
> Sent: Sunday, 5 July,
> 2009 7:50:46 AM GMT +08:00 Perth
> Subject: Re: Pietenpol-List: AIrfoil
> can of worms?
>
> Also, just spent the last 2 hours or so creating
> the 612 rib plot I found (if the coordinates are correct) into my
> CAD
> program and created a rib template for the 60" profile. Not sure if
> the
> plot is indeed the 612, as I only got the coordinates from a post on
> this list in the archives and they said they had found it on another
> aviation website, so if anyone has a verifiable set of plots, I'd
> like
> to check my work to see if it is indeed a 612.
>
>
> Regardless, here's a picture of the plot I made... Minus
> gussets...
>
>
> Mark
>
>
> On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts
> <mark.rbrts1@gmail.com> wrote:
>
> Oh Yes! Do tell! :o)
>
>
> Mark
>
>
> On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis
> <timothywillis@earthlink.net> wrote:
>
> Willis <timothywillis@earthlink.net>
>
> Aha!
> VGs! Jeff, it sounds like you are very happy with their
> effects. Thus inquiring minds want to know:
>
> Were the
> VGs the ones you used the straight little plastic fins (100 to a
> box), or were they the truncated "V," perhaps made out of bent
> aluminum?
>
> How far behind the LE did you place them, and was
> that according to directions, or what?
>
> Did you also apply
> them to any controls, esp. the back of the VStab or near the LE
> of
> the rudder?
>
> Tim in central TX
>
>
> -----Original Message-----
> >From: Jeff Boatright
> <jboatri@emory.edu>
> >Sent: Jul 4, 2009
> 5:20 PM
> >To: pietenpol-list@matronics.com
> >Subject: Re:
> Pietenpol-List: AIrfoil can of worms?
> >
> >-->
> Pietenpol-List message posted by: Jeff Boatright <
> jboatri@emory.edu>
> >
> >Mark,
> >
> >Our
> Piet had what I consider a sharp and unannounced stall.
> However,
> >it has an aluminum leading edge wrap rather than the
> thing plywood as
> >specified in the plans. When the fabric was
> shrunk, it pulled the
> >aluminum down between the ribs in a
> very ugly fashion. The result is
> >an even sharper nose than
> the Piet airfoil normally has.
> >
> >I added vortex
> generators and everything changed. The no-power stall
> >is now
> about like a Cessna 172's or maybe even gentler. The
> power-on
> >stall has noticeable burbling prior to the stall and
> a fairly gentle
> >break.
> >
> >As you can tell from my
> description, this is an atypical Piet. But,
> >every datum
> helps.
> >
> >Jeff
> >
> >
> >>...After
> reading the posts, I am curious about the standard
> Piet
> >>airfoil, and it's performance. I know that building
> to plans and to
> >>the original design is the best way of
> getting a good flying plane,
> >>but reading the letter
> posted from Mr. Riblett got me to thinking
> >>about the
> actual performance. I read about a sharp stall and
> such,
> >>and I am looking for you guys that are flying one
> of these to maybe
> >>give your feedback on the airfoil and
> it's characteristics.
> ...
> >>
> >>Mark
> >
> >--
> >---
> >
> >Jeffrey
> H. Boatright, Ph.D.
> >Associate Professor of
> Ophthalmology
> >Emory University School of
> Medicine
> >Editor-in-Chief
> >Molecular
> Vision
> >
> >
> >
> >
>
>
> ==========
> st"
> target="_blank">
> http://www.matronics.com/Navigator?Pietenpol-List
> ==========
> http://forums.matronics.com
> ==========
> le,
> List Admin.
> ="_blank">http://www.matronics.com/contribution
> ==========
>
>
> ===================================
> t href="http://www.matronics.com/Navigator?Pietenpol-List">
> http://www.matronics.com/Navigator?Pietenpol-List
> ===================================
> ms.matronics.com/">http://forums.matronics.com
> ===================================
> tp://www.matronics.com/contribution">http://www.matronics.com/contribution
> ===================================
>
>
> Make your summer sizzle with fast and easy recipes for the grill.
>
>
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Subject: | Re: AIrfoil can of worms? |
Mark,
Your drawing is likely right, and the questions are good ones. This is likely
the most analysis anyone has ever put on placements and angles, etc. on a Piet.
That is not meant to be denigrating. You are being modern; the design is antique.
You are being complex; the design is simple. BP didn't have no stinkin'
CAD ;)
OTOH, you raise a great question about front and rear rib caps. As discussed below,
builders have done them different ways.
RIBS & SPARS: If we are talking about Pietenpol ribs, the ribs are built so that
the spars are parallel. The portion of the ribs at the bottom of the spar is
flat or nearly so, and in assembly the inside surface of the bottom of the rib
is butted up to each spar. You will likely cut the top of your spars at an
angle approximating the angle of the shape of the inside top of the rib. Wedges
may still be involved, to fill a gap, for you don't want to have to slide
the ribs around on the spar during construction, with a nearly interference fit.
The angle of incidence of the wing, shwon on the drawings, at 2 degrees, comes
from the slope of a line across the bottom of the wing as the cabane struts butt
it. Making the rear cabane an inch shorter than the front one gives almost
exactly this measure. However, the real angle of incidence in aero design should
be measured from the chord line, as you rightly refer. If this were a faster
and sleeker plane, esp. a low wing job with root fairings and all that, we
would worry about such distinctions.
RIB CAPS: I was AMAZED to see a few minutes ago that on the ORIGINAL Piet drawings
for the rib (dated 3-3-34) there are NO rib caps at all, front or rear of
either spar. However, I believe everyone builds with several rib caps-- at least
the two inner ones. Somewhere in the Piet drawings I recall, but cannot
now find, an "improved rib drawing." On my ribs there is a front rib cap, as
you call it, for both the front and rear spar. My ribs do NOT have a rear rib
cap. Looking at pictures of other builds, I see that a few guys have only inner
rib caps, while some have a front rib cap, and some apparently have all four
rib caps. IMO, you will need at least the two inner rib caps to have a more
solid build than a pure reliance upon compression struts engenders.
Others should chime in here.
SPARS. Those who have been building alternative ribs-- NACA 2412 or Riblett 612--
have more loft on each rib and could have a taller set of spars. However,
since the spars of the Piet are plenty strong, builders have just been adding
filler strips above the standard spars at each rib location. Lowell Frank and
Roman Bukolt have done it this way, for instance.
Whatever rib jig you use or whatever airfoil is your choice. Decide and then don't
look back.
Think of what changes you need to make for YOUR application. For instance I have
more and heavier steps, more handles, and taller cabanes than I would like,
to adapt to my lack of flexibility. Think it through from end-to-end. Most
changes, however, add weight and complexity, as well as ripple through the design
and build. Then start building, pieces at a time. Study WHILE you BUILD.
I can serve as a negative example; I post as much as I build, but I learn something
every day.
You are bringing an investigative mind and enthusiasm to the project, and you will
have a great plane.
Tim in central TX
-----Original Message-----
From: Mark Roberts
Sent: Jul 5, 2009 5:09 PM
Subject: Re: Pietenpol-List: AIrfoil can of worms?
Continuing along the journey of discovery, I checked my airfoil plot from yesterday
against the plot coordinates from John (thanks again!) and found them to
be almost identical. So, I now have a new question about the center line and it's
relation to incidence once on the spar...
The image attached shows the spars are perpendicular to the baseline. The trailing
edge is elevated 1/2" from the baseline. Is this an issue? Or does the wing
mount and attachment work out centerline issues when installed?
Not sure I am clear here, but I am curious about the spars and whether they should
be perpendicular to the median chord line (drawn centered between the LE and
the TE) or if they should be perpendicular to the baseline the plot was generated
from (see the diagram below).
Also, the Full sized Piet Rib Pattern I received does not show a rib riser on the
LE of the front spar, or the TE of the rear spar. I drew this 612 rib pattern
out the same way. I get it that the spar acts as one BIG riser stick but I
still look at it and think one should be there, but I am guessing it is unnecessary...
Thoughts? I hope to be starting ribs here soon :o)
Mark
PS: Thanks for all of the patience with the questions...
Message 29
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|
Subject: | Re: AIrfoil can of worms? |
Mark,
Attaboy. The ribs and empennage don't take much wood or money, or space, but can
move you right along. The metal horns take up little space and not much money
(unless you job out TIG welding, maybe), but can provide a real sense of satisfaction
when done.
Tim in central TX
-----Original Message-----
From: Mark Roberts
Sent: Jul 6, 2009 12:58 AM
Subject: Re: Re: Pietenpol-List: AIrfoil can of worms?
Don't get me wrong guys, the only reason I'm thinking instead of building is I
don't have the cash to buy the wood this month... Spent it on plans.
Next month, all of this edumacation gets to work.
Mark
On Sun, Jul 5, 2009 at 8:40 PM, Jim <jimboyer@hughes.net> wrote:
Jim Boyer
Santa Rosa, CA
Pietenpol builder with Corvair
John and Ryan,
You both gave some of the best advice in these two messages. All the time spent
on the internet could have been used building.
Thanks,
Jim
On Jul 5, 2009, AMsafetyC@aol.com wrote:
Back about 3 years ago and on the verge of starting my build I had a chance
to visit another builder, I marveled at his project and asked many questions
while in the midst of research study and contemplation. During my conversation
with that noted award winning Texas builder I came away with a great piece
of sage wisdom, He said" don't waste you time thinking it, just start building
and stop wasting time. he also said that once you begin the build it will all
make sense" I took those well placed words and followed the advice of Hans
Vandervort, he certainly knew what he was talking about. When I got home I
committed to the build and began now that's not to say I haven't run into a snag
here and there and even the dreaded builders block, but given a chance you
project will speak to you. You just have to listen to her.
I been building for the last 3 years and there isn't a day I don't do
something to advance my project, knowledge or skill level. I cant think of
a better way to spend the stolen minutes of a work day or the hour and a half
commute or the road trip working on my Piet. She's been a real inspiration to
me
John
In a message dated 7/5/2009 8:06:24 P.M. Eastern Daylight Time,
rmueller23@gmail.com writes:
Mark,
I would say: turn your energy from plotting Riblett
coordinates towards cutting and gluing wood on the rib jig you are going to
recieve. The Riblett may be a small improvement on the Piet, and I don't
question it's usefulness....but you have a jig coming, and you have a
tremendous amount of enthusiam right now. Channel that towards making solid
progress on your build. The Piet airfoil, designed by an amateur as it was,
has been successfully built and flown by many many people in the past 80
years; safely at that. Don't overthink this. Just
build!
Ryan
On Sun, Jul 5, 2009 at 5:09 PM, Mark Roberts <mark.rbrts1@gmail.com>
wrote:
Continuing along the journey of discovery,
I checked my airfoil plot from yesterday against the plot coordinates from
John (thanks again!) and found them to be almost identical. So, I now have a
new question about the center line and it's relation to incidence once on
the spar...
The image attached shows the spars are perpendicular to the baseline.
The trailing edge is elevated 1/2" from the baseline. Is this an issue? Or
does the wing mount and attachment work out centerline issues when
installed?
Not sure I am clear here, but I am curious about the spars and whether
they should be perpendicular to the median chord line (drawn centered
between the LE and the TE) or if they should be perpendicular to the
baseline the plot was generated from (see the diagram below).
Also, the Full sized Piet Rib Pattern I received does not show a rib
riser on the LE of the front spar, or the TE of the rear spar. I drew this
612 rib pattern out the same way. I get it that the spar acts as one BIG
riser stick but I still look at it and think one should be there, but I am
guessing it is unnecessary...
Thoughts? I hope to be starting ribs here soon :o)
Mark
PS: Thanks for all of the patience with the questions...
On Sun, Jul 5, 2009 at 9:52 AM, Mark Roberts <mark.rbrts1@gmail.com> wrote:
Thanks John!! I really appreciate the file. I dug
through all of the archives and didn't see it, but it wasn't until late in
my search that I saw any attachments at all on any post, so I might have
overlooked it in my lack of understanding the archive.
Thanks again! I will check my plot.
Many thanks!!
Mark
On Sun, Jul 5, 2009 at 5:58 AM, <johnwoods@westnet.com.au> wrote:
Ooops.. forgot the attachement...
JohnW
----- Forwarded Message -----
From: johnwoods@westnet.com.au
Sent: Sunday, 5 July, 2009 8:54:49 PM GMT +08:00 Perth
Subject:
Re: Pietenpol-List: AIrfoil can of worms?
Mark,
Attached is a copy of the xls file I posted a while ago.
It has the co-ordinates for the Riblett 612 & 613.5 sections
as provided by Mr Bokolt together with the Pietenpol sections, as copied
from the plans.
I used the 612 co-ordinates to plot and make my ribs.
Still a long way from flying.
The 612 has been sucessfully used on other ultralights and
from Mr Riblett's description of it's characteristics he predicted
it would be a good section for the Piet.
I wish I could be at Brodhead to hear Mr Pieti Lowell's forum on the
612's performance.
JohnW
----- Original Message -----
From: "Mark Roberts" <mark.rbrts1@gmail.com>
Sent: Sunday, 5 July,
2009 7:50:46 AM GMT +08:00 Perth
Subject: Re: Pietenpol-List: AIrfoil
can of worms?
Also, just spent the last 2 hours or so creating
the 612 rib plot I found (if the coordinates are correct) into my CAD
program and created a rib template for the 60" profile. Not sure if the
plot is indeed the 612, as I only got the coordinates from a post on
this list in the archives and they said they had found it on another
aviation website, so if anyone has a verifiable set of plots, I'd like
to check my work to see if it is indeed a 612.
Regardless, here's a picture of the plot I made... Minus
gussets...
Mark
On Sat, Jul 4, 2009 at 4:28 PM, Mark Roberts
<mark.rbrts1@gmail.com> wrote:
Oh Yes! Do tell! :o)
Mark
On Sat, Jul 4, 2009 at 3:33 PM, Tim Willis
<timothywillis@earthlink.net> wrote:
Willis <timothywillis@earthlink.net>
Aha!
VGs! Jeff, it sounds like you are very happy with their
effects. Thus inquiring minds want to know:
Were the
VGs the ones you used the straight little plastic fins (100 to a
box), or were they the truncated "V," perhaps made out of bent
aluminum?
How far behind the LE did you place them, and was
that according to directions, or what?
Did you also apply
them to any controls, esp. the back of the VStab or near the LE of
the rudder?
Tim in central TX
-----Original Message-----
>From: Jeff Boatright
<jboatri@emory.edu>
>Sent: Jul 4, 2009
5:20 PM
>To: pietenpol-list@matronics.com
>Subject: Re:
Pietenpol-List: AIrfoil can of worms?
>
>-->
Pietenpol-List message posted by: Jeff Boatright <jboatri@emory.edu>
>
>Mark,
>
>Our
Piet had what I consider a sharp and unannounced stall.
However,
>it has an aluminum leading edge wrap rather than the
thing plywood as
>specified in the plans. When the fabric was
shrunk, it pulled the
>aluminum down between the ribs in a
very ugly fashion. The result is
>an even sharper nose than
the Piet airfoil normally has.
>
>I added vortex
generators and everything changed. The no-power stall
>is now
about like a Cessna 172's or maybe even gentler. The
power-on
>stall has noticeable burbling prior to the stall and
a fairly gentle
>break.
>
>As you can tell from my
description, this is an atypical Piet. But,
>every datum
helps.
>
>Jeff
>
>
>>...After
reading the posts, I am curious about the standard
Piet
>>airfoil, and it's performance. I know that building
to plans and to
>>the original design is the best way of
getting a good flying plane,
>>but reading the letter
posted from Mr. Riblett got me to thinking
>>about the
actual performance. I read about a sharp stall and
such,
>>and I am looking for you guys that are flying one
of these to maybe
>>give your feedback on the airfoil and
it's characteristics.
...
>>
>>Mark
>
>--
>---
>
>Jeffrey
H. Boatright, Ph.D.
>Associate Professor of
Ophthalmology
>Emory University School of
Medicine
>Editor-in-Chief
>Molecular
Vision
>
>
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