Today's Message Index:
----------------------
1. 12:01 AM - building to build (Brants)
2. 12:56 AM - floats (Clif Dawson)
3. 06:47 AM - Re: floats (DJ Vegh)
4. 07:38 AM - Re: popsicle sticks and tramelling (Rick Holland)
5. 07:46 AM - Re: Axle Dissertation (walt evans)
6. 08:13 AM - Tail Volume (John Dilatush)
7. 09:22 AM - Re: Tail Volume (Christian Bobka)
8. 09:38 AM - Re: Cutting plywood (dave rowe)
9. 10:09 AM - Re: Adjusting tension in drag/antidrag cables. (dave rowe)
10. 11:24 AM - Rib jig (Deon Engelmann)
11. 11:58 AM - Picture Posting Issue Resolved... (Matt Dralle)
12. 12:00 PM - Re: Axle Dissertation (hjarrett)
13. 12:08 PM - Fw: Emailing: Jim and Bill over Dallas 1915 (Jim Markle)
14. 12:33 PM - Re: Adjusting tension in drag/antidrag cables. (Robert Haines)
15. 12:52 PM - Re: Pietenpol-List Digest: 20 Msgs - 01/23/04 (Robert Haines)
16. 01:52 PM - Re: Fw: Emailing: Jim and Bill over Dallas 1915 (Rcaprd@aol.com)
17. 02:03 PM - Re: Re: Tail Volume (Rcaprd@aol.com)
18. 02:38 PM - Re: Re: Tail Volume (Christian Bobka)
19. 05:27 PM - Re: Re: Tail Volume & aft CG (Michael Conkling)
20. 07:00 PM - Re: popsicle sticks and tramelling (Alex Sloan)
21. 10:04 PM - Re: Re: Tail Volume & aft CG (Clif Dawson)
Message 1
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Subject: | building to build |
Man, now that the tail section is getting completed it's really starting to get
even more fun... Building something from plans out of God given materials can't
be beat! I haven't flown a plane for over two months and frankly don't miss
it much.. I'm having too much fun working on the Piet. I took the advice of
some who've said, "build to build, don't build to fly" and "spend some time on
it each day". It's amazing the momentum you can build when you just spend some
amount of time on your project each day, even if it's just studying the plans
to see how to make your next move.
I find it motivational to set small goals... I set the goal of completing the
'end spinach' over the winter... certainly not difficult to achieve if you get
at it each day. By spring I should be able to get to finishing up the odds
and ends of the fuselage over the summer and then get at making the center section
and ribs... I really wasn't looking forward to starting the wing but after
seeing Dick Navratrils project(s) I see just how fun it looks to build. He's
even said that the building of the wing goes by way too fast.
I say all of this for those who need some encouragement, motivation or just want
to read something that's more personal and less technical. The people on this
list make it a phenomenal tool! Thanks for all the discussion on the horizontal
stab.
Sorry for the ramblings but it's nearly 2:00 am and I can't get my mind off of
the piet.
Ain't building great!
Tom Brant
Brooklyn Park, MN
Message 2
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Want to see a Piet on floats? Go here
http://www.paf-flugmodelle.de/index.htm?/Webseiten/videos.htm
:-) :-) :-)
Clif
Message 3
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|
tests=FORGED_OUTLOOK_TAGS, MIME_BASE64_LATIN, MIME_BASE64_NO_NAME,
MIME_BASE64_TEXT
dGhhdCB3YXMgcHJldHR5IGNvb2wNCg0KREogVmVnaA0KTjc0RFYNCk1lc2EsIEFaDQp3d3cuaW1h
Z2Vkdi5jb20vYWlyY2FtcGVyDQoNCg0KDQotDQoNCiAgLS0tLS0gT3JpZ2luYWwgTWVzc2FnZSAt
LS0tLSANCiAgRnJvbTogQ2xpZiBEYXdzb24gDQogIFRvOiBwaWV0ZW5wb2wtbGlzdEBtYXRyb25p
Y3MuY29tIA0KICBTZW50OiBTYXR1cmRheSwgSmFudWFyeSAyNCwgMjAwNCAxOjU0IEFNDQogIFN1
YmplY3Q6IFBpZXRlbnBvbC1MaXN0OiBmbG9hdHMNCg0KDQogIFdhbnQgdG8gc2VlIGEgUGlldCBv
biBmbG9hdHM/ICBHbyBoZXJlDQoNCiAgaHR0cDovL3d3dy5wYWYtZmx1Z21vZGVsbGUuZGUvaW5k
ZXguaHRtPy9XZWJzZWl0ZW4vdmlkZW9zLmh0bQ0KDQogIDotKSA6LSkgOi0pDQoNCiAgQ2xpZg==
Message 4
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Subject: | Re: popsicle sticks and tramelling |
--> Pietenpol-List message posted by: Rick Holland <at7000ft@speedtrail.net>
Hell, gold bricks were'nt very expensive back in the 60s either.
RH
> (I used
>1/8"
>cable with turnbuckles for all such bracing; turnbuckles were not very
>expensive in the late 1960's when I bought mine.)
>
>Graham Hansen (Pietenpol CF-AUN in freezing Alberta)
>
>
>
>
>
>
>
>
>
>
>
Message 5
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Subject: | Re: Axle Dissertation |
What does that mean?
walt evans
NX140DL
----- Original Message -----
From: Christian Bobka
To: pietenpol-list@matronics.com
Sent: Saturday, January 24, 2004 12:36 AM
Subject: Re: Pietenpol-List: Axle Dissertation
"If the wheel location was too far forward, wouldn't it show up in the rollout?"
Walt,
Why have you been asking for instructions on how to land, then?
Chris
----- Original Message -----
From: walt evans
To: pietenpol-list@matronics.com
Sent: Thursday, January 22, 2004 3:54 PM
Subject: Re: Pietenpol-List: Axle Dissertation
I built the long fuselage with an A65 (mount extented about 1 3/4" to anticipate
my bodily weight of 215") And had to move the wing back (sorry, body forward)
3 inches.
I used the split gear plans supplied. 14 gallon nose tank and 10 gal center
tank (usually run empty).
Had read an article by a "seat of the pants guy" who said something like "
if you can hold the plane on the mains with the tail up without a problem on
rollout, then the CG can't be far off.
When doing takeoff roll, no problem getting up on the mains, and after a wheel
landing, I can keep it on the mains for quite a while till it's quite slow.
Not like the tail slams to the ground.
If the wheel location was too far forward, wouldn't it show up in the rollout?
walt evans
NX140DL
----- Original Message -----
From: Rick Holland
To: pietenpol-list@matronics.com
Sent: Thursday, January 22, 2004 2:12 PM
Subject: Re: Pietenpol-List: Axle Dissertation
Good points Christian, and your datum point does sound logical. For people
building the long (172") version no axle placement info is provided with the
supplemental plans. Most people just assume it is placed the same a shown on
the original Ford plans, at least until they read several of the postings on the
subject the last few days. To give us a ballpark idea how about doing an FAA
standard 180 lb. pilot (and maybe even 2 180 lb occupants) calculation for axle
placement for the long fuselage with everything else "per the plans" (10 gal.
wing tank, wing in standard position, corvair engine, etc.?) I would be interested
in seeing how far off it is from the short fuselage position.
RH
Christian Bobka wrote:
--> Pietenpol-List message posted by: "Christian Bobka" <bobka@compuserve.com>
Kirk,
First, let me recommend to you and everybody else we fly balance ships. Who
cares what the FAA says about 180 lb people. You are flying the plane and
it should balance with you in it.
Second, I recommend using something other than the wing leading edge as the
datum. It does not make any sense to do so. If you are moving the wing
around, then you are moving around the datum . The whole IDEA of the datum
is that it is a PLACE THAT DOES NOT MOVE. It is by definition, a fixed
reference point. I was at a loss as to what to use until some others
mentioned using the bolt on the left side were the front cabane attaches to
the fuselage. It seems that people will stretch and shorten the fuselage,
shift the wing forward and aft but this point seems to not get tampered
with. So let us use it going forth. If people give me good numbers, I will
calculate W and Balance for them if they think they can't do it. I agreee
that the Leading edge of the wing eventually becomes important because we
need to make sure the CG is within the fore and aft limits of the airfoil
but we can work that into the calculations later.
I suggest that you look in the archives under the discussions on axle
placement where one puts the axle at some angle forward from the vetical of
about 12-16 degrees with the angle measured at the longitudinal and vertical
CG point on the side of the fuselage. I forget what the number is and I
loaned the book out on it last night so I can't look it up. You will need
to compute the exact point on the aircraft where the CG is when looking at
it from the side. This means longitudinal (how far back from the bolt) and
vertical or up from the floor (Of course the aircraft is level
longitudinally and laterally). You are familiar with the longitudinal CG
but the vertical CG is new for most and this can be computed through a
method Hank Jarrett posted last week and I posted through Jim Markle where
he put it up at:
http://www.mykitplane.com/Planes/photoGalleryList2.cfm?AlbumID185
In short, yes, if you move the wing back, the axle needs to be moved back
too.
Chris
----- Original Message -----
From: "Kirk Huizenga" <Kirk.Huizenga@moundsviewschools.org>
Subject: Pietenpol-List: Axle Dissertation
--> Pietenpol-List message posted by: "Kirk Huizenga"
<Kirk.Huizenga@moundsviewschools.org>
Chris,
Thanks for the research. I have one question that I hope will be simply
answered. The question is what affect shifting the wing back would have on
the proper placement of the axle.
Example: For W&B reasons, one shifts the wing back 4in. In theory, this
doesn't change the CG much at all, but the center of lift changes enough to
allow for us that don't fit the FAA 180lb profile to fit leading edge datum
CG limits. Should this also cause a move rearward of the axle?
Thanks for your input
Kirk
Message 6
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Chris,
Since the subject of tail volume has come up in the recent e-mails, I thought that
this might be interesting.
When I first started my Piet in '95 using the long fuselage, I was concerned about
the small vertical fin and rudder. I then computed both the vertical and
horizontal tail volumes using the formulas quoted by David Thurston in his book
"Design for Flying"
These calculations showed that the tail volumes of the Pietenpol are woefully short
of modern standards. The Piet vertical tail volume came out to .1389 and
a modern standard is .30. The horizontal tail volume was .31389 vs. .55
All this adds to the difficulty in increasing the nose moment of a Pietenpol when
mounting a lighter engine such as an A65 or Corvair to the plane to maintain
W&B.
Since a Model A powered Pietenpol is notoriously known to be slightly tail heavy,
I thought it was worth considering using a more powerful engine that is heavier
and has more horsepower. This both corrects to tail heavy condition without
moving the wing back and also keeps from aggravating the tail volume problem.
My solution using the turbocharged Subaru engine seems to have worked to solve
both problems, although the plane doesn't slip as well as one using a lighter
engine and longer nose moment.
Cordially,
John
Message 7
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"pietenpol" <pietenpol-list@matronics.com>
John,
You have to remember that the tail volume is necessitated by the pitching moment
of the airfoil. As pitching moment increases, tail volume must increase. If
there is zero pitching moment, you don't even need a tail, like the flying wings.
So the piet's airfoil must fall somewhere between what is common today
and a zero pitching moment airfoil.
It flies ok so it must have enough TV.
Also, if the tails are bigger, more CG range may be available. This is important
for a four seater where it has to remain in balance without the use of ballast
when only a pilot is aboard with full fuel vs. all four seats filled, full
bags, and as much fuel as possible to bring the ship up to gross weight.
Chris
----- Original Message -----
From: John Dilatush
To: Christian Bobka
Cc: pietenpol-list@matronics.com
Sent: Saturday, January 24, 2004 10:12 AM
Subject: Tail Volume
Chris,
Since the subject of tail volume has come up in the recent e-mails, I thought
that this might be interesting.
When I first started my Piet in '95 using the long fuselage, I was concerned
about the small vertical fin and rudder. I then computed both the vertical and
horizontal tail volumes using the formulas quoted by David Thurston in his book
"Design for Flying"
These calculations showed that the tail volumes of the Pietenpol are woefully
short of modern standards. The Piet vertical tail volume came out to .1389 and
a modern standard is .30. The horizontal tail volume was .31389 vs. .55
All this adds to the difficulty in increasing the nose moment of a Pietenpol
when mounting a lighter engine such as an A65 or Corvair to the plane to maintain
W&B.
Since a Model A powered Pietenpol is notoriously known to be slightly tail heavy,
I thought it was worth considering using a more powerful engine that is heavier
and has more horsepower. This both corrects to tail heavy condition without
moving the wing back and also keeps from aggravating the tail volume problem.
My solution using the turbocharged Subaru engine seems to have worked to solve
both problems, although the plane doesn't slip as well as one using a lighter
engine and longer nose moment.
Cordially,
John
Message 8
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Subject: | Re: Cutting plywood |
<003901c3dd1a$20f6cfc0$2cc5fea9@home>
--> Pietenpol-List message posted by: dave rowe <rowed044@shaw.ca>
If you are talking about sheets of ply, and need to use the table saw,
get a Freud 71/4" narrow kerf finishing blade. They are cheap, cut
perfectly with no tearing, and are also perfect for cutting strips for
wing ribs, etc, and the blade is 1/16th thick, so every two cuts saves
1/8". If you cut lots of strips from wide boards, as I do, you save
huge amounts of wood. Any narrow cutting use a band saw with a fine
blade.
Message 9
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Subject: | Re: Adjusting tension in drag/antidrag cables. |
--> Pietenpol-List message posted by: dave rowe <rowed044@shaw.ca>
You may want to look at West Marine, they have the wire, turnbuckles
etc, all in stainless steel, and good prices. They also have delrin
pulleys for controls, bearingless no maintenance.
Rcaprd@aol.com wrote:
>
> --> Pietenpol-List message posted by: Rcaprd@aol.com
>
> In a message dated 1/22/04 6:32:13 PM Central Standard Time, djv@imagedv.com
> writes:
>
> << I am debating whether or not to use cables and turnbuckles or steel rod
> with fork ends. >>
>
> D.J.,
> The steel rods would be required to have rolled threads, and built to
> specific lengths. Probably end up being similar costs to the cables / turnbuckles.
>
> Chuck G.
>
>
>
>
>
>
Message 10
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Hi all
I been lurking on the list for quit some time and really like the way
this list works, its like coming home to family and hearing all the
things that happened today.
The reason that I'm writing is that I started making my rib jig, then
went to the archive and read up on it. Very confusing.
Does anyone have an accurate cad drawing for a rib with 1" holes for the
spars?
I want to make a three piece wing with 1" routed spars
Thanx
Deon Engelmann
EAA322 Midrand # SA12055
Pretoria
South Africa
Message 11
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Subject: | Picture Posting Issue Resolved... |
--> Pietenpol-List message posted by: Matt Dralle <dralle@matronics.com>
Well, you guys aren't going to believe what the problem was... A number of
people complained that the pictures they posted never showed up on the
List, while others seemed to not have any problems...
So first some theory on how my list filtering works. I wrote a filtering
program that every single new post gets screened through before its passed
onto the actual email List. This filter looks for all kinds of bogus
things that spammers and other unscrupulous emailers send out these
days. It also filters out messages posted with enclosure types like .bat,
.exe, .src which usually always contain a virus of some sort. Its also a
place where I can easily and quickly add a filter if someone starts posting
a bunch of offensive messages to the list just to annoy everyone.
Anyway, way back when, there was a real problem with people posting that
bogus JATO urban legion about "the guy that put JATO engines on his 57
Chevy" or whatever. When ever that message would get reposted, a bunch of
people would post back bitching about how many times they'd already seen
that story and stop posting it and it wasn't related to blaa-list, etc,
etc, etc... You get the picture...
So, I just put in a filter entry in to filter out any message that
contained the string "jato". Worked great, well, until recently when I
started letting enclosures through on the Tailwind-List and
Pietenpol-List. Turns out that a great number of pictures (jpg's) when
MIME encoded have this four letter string, "jato" in them!
So, I've just removed the JATO filter and things seem to be going through
great now. I guess I don't have to remind everyone to not post the JATO
Chevy story, now, do I...? ;-)
Party on!
Matt Dralle
Email List Admin
Matt G Dralle | Matronics | PO Box 347 | Livermore | CA | 94551
925-606-1001 V | 925-606-6281 F | dralle@matronics.com Email
http://www.matronics.com/ WWW | Featuring Products For Aircraft
Message 12
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Subject: | Re: Axle Dissertation |
If the mains are too far forward the tail will drop too quick on roll out and will
be difficult to lift in the first of the take off roll.
Hank
----- Original Message -----
From: walt evans
To: pietenpol-list@matronics.com
Sent: Saturday, January 24, 2004 10:46 AM
Subject: Re: Pietenpol-List: Axle Dissertation
What does that mean?
walt evans
NX140DL
----- Original Message -----
From: Christian Bobka
To: pietenpol-list@matronics.com
Sent: Saturday, January 24, 2004 12:36 AM
Subject: Re: Pietenpol-List: Axle Dissertation
"If the wheel location was too far forward, wouldn't it show up in the rollout?"
Walt,
Why have you been asking for instructions on how to land, then?
Chris
----- Original Message -----
From: walt evans
To: pietenpol-list@matronics.com
Sent: Thursday, January 22, 2004 3:54 PM
Subject: Re: Pietenpol-List: Axle Dissertation
I built the long fuselage with an A65 (mount extented about 1 3/4" to anticipate
my bodily weight of 215") And had to move the wing back (sorry, body
forward) 3 inches.
I used the split gear plans supplied. 14 gallon nose tank and 10 gal center
tank (usually run empty).
Had read an article by a "seat of the pants guy" who said something like
" if you can hold the plane on the mains with the tail up without a problem on
rollout, then the CG can't be far off.
When doing takeoff roll, no problem getting up on the mains, and after a
wheel landing, I can keep it on the mains for quite a while till it's quite slow.
Not like the tail slams to the ground.
If the wheel location was too far forward, wouldn't it show up in the rollout?
walt evans
NX140DL
----- Original Message -----
From: Rick Holland
To: pietenpol-list@matronics.com
Sent: Thursday, January 22, 2004 2:12 PM
Subject: Re: Pietenpol-List: Axle Dissertation
Good points Christian, and your datum point does sound logical. For people
building the long (172") version no axle placement info is provided with the
supplemental plans. Most people just assume it is placed the same a shown on
the original Ford plans, at least until they read several of the postings on
the subject the last few days. To give us a ballpark idea how about doing an
FAA standard 180 lb. pilot (and maybe even 2 180 lb occupants) calculation for
axle placement for the long fuselage with everything else "per the plans" (10
gal. wing tank, wing in standard position, corvair engine, etc.?) I would be
interested in seeing how far off it is from the short fuselage position.
RH
Christian Bobka wrote:
--> Pietenpol-List message posted by: "Christian Bobka" <bobka@compuserve.com>
Kirk,
First, let me recommend to you and everybody else we fly balance ships. Who
cares what the FAA says about 180 lb people. You are flying the plane and
it should balance with you in it.
Second, I recommend using something other than the wing leading edge as the
datum. It does not make any sense to do so. If you are moving the wing
around, then you are moving around the datum . The whole IDEA of the datum
is that it is a PLACE THAT DOES NOT MOVE. It is by definition, a fixed
reference point. I was at a loss as to what to use until some others
mentioned using the bolt on the left side were the front cabane attaches to
the fuselage. It seems that people will stretch and shorten the fuselage,
shift the wing forward and aft but this point seems to not get tampered
with. So let us use it going forth. If people give me good numbers, I will
calculate W and Balance for them if they think they can't do it. I agreee
that the Leading edge of the wing eventually becomes important because we
need to make sure the CG is within the fore and aft limits of the airfoil
but we can work that into the calculations later.
I suggest that you look in the archives under the discussions on axle
placement where one puts the axle at some angle forward from the vetical of
about 12-16 degrees with the angle measured at the longitudinal and vertical
CG point on the side of the fuselage. I forget what the number is and I
loaned the book out on it last night so I can't look it up. You will need
to compute the exact point on the aircraft where the CG is when looking at
it from the side. This means longitudinal (how far back from the bolt) and
vertical or up from the floor (Of course the aircraft is level
longitudinally and laterally). You are familiar with the longitudinal CG
but the vertical CG is new for most and this can be computed through a
method Hank Jarrett posted last week and I posted through Jim Markle where
he put it up at:
http://www.mykitplane.com/Planes/photoGalleryList2.cfm?AlbumID185
In short, yes, if you move the wing back, the axle needs to be moved back
too.
Chris
----- Original Message -----
From: "Kirk Huizenga" <Kirk.Huizenga@moundsviewschools.org>
Subject: Pietenpol-List: Axle Dissertation
--> Pietenpol-List message posted by: "Kirk Huizenga"
<Kirk.Huizenga@moundsviewschools.org>
Chris,
Thanks for the research. I have one question that I hope will be simply
answered. The question is what affect shifting the wing back would have on
the proper placement of the axle.
Example: For W&B reasons, one shifts the wing back 4in. In theory, this
doesn't change the CG much at all, but the center of lift changes enough to
allow for us that don't fit the FAA 180lb profile to fit leading edge datum
CG limits. Should this also cause a move rearward of the axle?
Thanks for your input
Kirk
Message 13
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Subject: | Fw: Emailing: Jim and Bill over Dallas 1915 |
Ok Matt, I'll try it to see if pictures are making it through the server now......
A old friend of mine is taking a PhotoShop class at a local college....and he is
WELL aware of my passion for Piets.....
This picture is 1915 Dallas....I won't tell him it's a few years too early for
a Piet!
Jim in far north Dallas.....
The title he put on the postcard: Hail the ancient aviators!
Message 14
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|
Subject: | Re: Adjusting tension in drag/antidrag cables. |
--> Pietenpol-List message posted by: "Robert Haines" <robertsjunk@hotmail.com>
Corky, glad to hear your back.
Robert Haines
Du Quoin, Illinois
Message 15
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Subject: | Re: Pietenpol-List Digest: 20 Msgs - 01/23/04 |
--> Pietenpol-List message posted by: "Robert Haines" <robertsjunk@hotmail.com>
Exactly what you just illustrated happens when you allow the CG to move aft
4" (due to a tail heavy craft or a tail heavy pilot) and counter that with a
4" aft movement of the wing. Of course the fuselage remains the same, but
the CG is now further aft of that fuselage, there is then more surface ahead
of the CG, there is less surface aft, and the moment arm of the tail is
shortened by 4". On top of that, the CG to wheel base geometry is now
different.
Robert Haines
Du Quoin, Illinois
P.S. - If the problem is a heavy pilot, move the pilot forward.
> Time: 09:35:57 PM PST US
> From: "Christian Bobka" <bobka@compuserve.com>
> Subject: Re: Pietenpol-List: Re: Axle Dissertation
>
> --> Pietenpol-List message posted by: "Christian Bobka"
<bobka@compuserve.com>
>
> But if you make the engine forward, the tail volume requirement will
change.
> Moving the engine forward would destabilize in the vertical axis due to
the
> increased vertical surface area forward of the CG. This needs to be
> countered with more of the quantity (surface area of the what is added
> forward of the CG) x (mean distance forward of the CG the area is added)
> added aft of the CG.
>
> For instance, you move the firewall forward by 4" and then you build a
cowl
> for the A-65 forward of that. The A-65 on a motor mount is lonbger than
the
> Ford Model A installation. The end result is that you add about 8" more
> length forward of the CG. This is 24" high so 192 sq in is added, say,
an
> average 38" forward of the CG. So you have to add 192 x 38 = 7296 cu. in.
> aft of the CG. I am not looking at drawings, just throwing numbers out
for
> an example. So you add more vertical stabilizer area 130" aft of the CG
to
> counter. The amount to add is 7296/130 = 56 sq in. You would have to
add
> 2" to the chord of the 30" high vertical stabilizer to counter the added
> destabilizing area up front. And this weighs something 130" aft of the
CG,
> which has a large effect on CG etc etc
>
> Chris Bobka
>
Message 16
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Subject: | Re: Fw: Emailing: Jim and Bill over Dallas 1915 |
--> Pietenpol-List message posted by: Rcaprd@aol.com
In a message dated 1/24/04 2:09:29 PM Central Standard Time,
jim_markle@mindspring.com writes:
<< This picture is 1915 Dallas....I won't tell him it's a few years too early
for a Piet! >>
I didn't get any picture.
Chuck G.
Message 17
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--> Pietenpol-List message posted by: Rcaprd@aol.com
In a message dated 1/24/04 11:22:51 AM Central Standard Time,
bobka@compuserve.com writes:
<< So the piet's airfoil must fall somewhere between what is common today and
a zero pitching moment airfoil.
>>
The Pietenpol, as well as any undercambered airfoil, has a lot of negative
pitching moment (nose down). I believe this is why the Piet is somewhat
tolorant of an aft C.G. That's the thing I've always been curious about, is why
Pietenpols are more forgiving for an aft C.G. condition. B.H.P called out 1/3
(33.3%) of the chord, as the aft limit. I've never seen, or heard of any other
plane with the aft C.G. limit that far back. Most designs call out no more
than 30% of the chord for the aft limit, but they are not undercambered.
(Tailwind calls out 28% as the aft C.G. limit). I think this is because an
undercambered airfoil has such a high negative pitching moment, that it is more
forgiving of an aft C.G. I've tried unsuccessfully to find the aft C.G. limit
of
planes like the Jenny, but it is a Biplane - difficult to compare. Another
design that has an undercambered airfoil is the Ryan Navion. Does anyone have
the
C.G. range of the Ryan Navion, or any other plane that has an undercambered
airfoil ?
Chuck Gantzer
NX770CG
Message 18
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--> Pietenpol-List message posted by: "Christian Bobka" <bobka@compuserve.com>
Chuck,
Excellent observation. I have no data on the Navion but will look later.
The Type Certificate Data Sheets are available on the FAA website.
Chris
----- Original Message -----
From: <Rcaprd@aol.com>
Subject: Re: Pietenpol-List: Re: Tail Volume
>
> --> Pietenpol-List message posted by: Rcaprd@aol.com
>
> In a message dated 1/24/04 11:22:51 AM Central Standard Time,
> bobka@compuserve.com writes:
>
> << So the piet's airfoil must fall somewhere between what is common today
and
> a zero pitching moment airfoil.
> >>
>
> The Pietenpol, as well as any undercambered airfoil, has a lot of negative
> pitching moment (nose down). I believe this is why the Piet is somewhat
> tolorant of an aft C.G. That's the thing I've always been curious about,
is why
> Pietenpols are more forgiving for an aft C.G. condition. B.H.P called out
1/3
> (33.3%) of the chord, as the aft limit. I've never seen, or heard of any
other
> plane with the aft C.G. limit that far back. Most designs call out no
more
> than 30% of the chord for the aft limit, but they are not undercambered.
> (Tailwind calls out 28% as the aft C.G. limit). I think this is because
an
> undercambered airfoil has such a high negative pitching moment, that it is
more
> forgiving of an aft C.G. I've tried unsuccessfully to find the aft C.G.
limit of
> planes like the Jenny, but it is a Biplane - difficult to compare.
Another
> design that has an undercambered airfoil is the Ryan Navion. Does anyone
have the
> C.G. range of the Ryan Navion, or any other plane that has an
undercambered
> airfoil ?
>
> Chuck Gantzer
> NX770CG
>
>
Message 19
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Subject: | Re: Tail Volume & aft CG |
--> Pietenpol-List message posted by: "Michael Conkling" <hpvs@southwind.net>
All the indoor flying models for the kids doing Science Olympiad have aft
CG -- some of them even have the CG aft of the wing -- it works for them
'cause of massive tail volume (a long tail boom and area equal to 50% of the
wing area) and the same airfoil as the wing (a lifting tail vs "flat
plate").
Mike C.
Pretty Prairie, KS
----- Original Message -----
From: <Rcaprd@aol.com>
Subject: Re: Pietenpol-List: Re: Tail Volume
> --> Pietenpol-List message posted by: Rcaprd@aol.com
>
> In a message dated 1/24/04 11:22:51 AM Central Standard Time,
> bobka@compuserve.com writes:
>
> << So the piet's airfoil must fall somewhere between what is common today
and
> a zero pitching moment airfoil.
> >>
>
> The Pietenpol, as well as any undercambered airfoil, has a lot of negative
> pitching moment (nose down). I believe this is why the Piet is somewhat
> tolorant of an aft C.G. That's the thing I've always been curious about,
is why
> Pietenpols are more forgiving for an aft C.G. condition. B.H.P called out
1/3
> (33.3%) of the chord, as the aft limit. I've never seen, or heard of any
other
> plane with the aft C.G. limit that far back. Most designs call out no
more
> than 30% of the chord for the aft limit, but they are not undercambered.
> (Tailwind calls out 28% as the aft C.G. limit). I think this is because
an
> undercambered airfoil has such a high negative pitching moment, that it is
more
> forgiving of an aft C.G. I've tried unsuccessfully to find the aft C.G.
limit of
> planes like the Jenny, but it is a Biplane - difficult to compare.
Another
> design that has an undercambered airfoil is the Ryan Navion. Does anyone
have the
> C.G. range of the Ryan Navion, or any other plane that has an
undercambered
> airfoil ?
>
> Chuck Gantzer
> NX770CG
>
>
Message 20
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Subject: | Re: popsicle sticks and tramelling |
--> Pietenpol-List message posted by: "Alex Sloan" <alexms1@bellsouth.net>
Michael,
Great info for those of us who have to build the wings. Keep the tips
coming.
'Question, on your video tape you mention "dead soft stainless " for the
firewall. I have made inquires with sheet metal men, aircraft mechanics and
fellow homebuilders and no one can answer, what it is or where may I get
"dead soft stainless". Can you give me a number associated with it? Such
as 2024-T3 is the aluminum in my RV aircraft. The stainless should have a
designator for ordering purpose.
Thanks.
Alex Sloan
----- Original Message -----
From: "Michael D Cuy" <Michael.D.Cuy@grc.nasa.gov>
Subject: Pietenpol-List: popsicle sticks and tramelling
> --> Pietenpol-List message posted by: Michael D Cuy
<Michael.D.Cuy@grc.nasa.gov>
>
> Did what Corky is planning to do on his new wings---run the X-cables in
the
> wings then take most the slack out then slightly reposition the ribs to
> clear the trusswork of affected ribs. I then squared up the spars to each
> other with small nails pounded into the tops of the spars at each of the
> four ends to measure each dimension as I tightened and keep them equal
> (=square wing/parallel spars) Ended up gluing and nailing the ribs to the
> spars while I could still slide the ribs left and right. After cured I
> checked the tramell and snugged up the cables and safety wired
> them. Where they cross over each other I slit some small aquarium hose
or
> clear tygon tube from Home Depot about an inch long. I slid those over
> each cable where they crossed to protect them from chaffing each other and
> used two small tie wraps to snug up the whole intersection against
> vibration. In moving the very few ribs that are in your way, I only
moved
> them enough to just clear the ribs--then glued in some dry popsicle sticks
> to the flat of the truss that came closest to touching the cable for added
> protection. (similar to the doubler idea)
>
> Mike C.
>
>
Message 21
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Subject: | Re: Tail Volume & aft CG |
--> Pietenpol-List message posted by: Clif Dawson <cdawson5854@shaw.ca>
Don't forget the Bleriot
Clif
> --> Pietenpol-List message posted by: "Michael Conkling"
<hpvs@southwind.net>
>
> All the indoor flying models for the kids doing Science Olympiad have aft
> CG -- some of them even have the CG aft of the wing -- it works for them
> 'cause of massive tail volume (a long tail boom and area equal to 50% of
the
> wing area) and the same airfoil as the wing (a lifting tail vs "flat
> plate").
>
> Mike C.
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