Today's Message Index:
----------------------
1. 04:56 AM - Re: Re: Long fuselage and Model A (JERRY)
2. 04:59 AM - Re: Re: Long fuselage and Model A (JERRY)
3. 09:48 PM - Re: Long fuselage and Model A (taildrags)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Long fuselage and Model A |
Thanks again Oscar I am sure I can figure it out. I too think that I have an
one-off fuselage were most if not all of the added length is in the nose. I
will have to do a W & B calculation but I am betting that I will have to
move the wing forward a little and place the Model A or B engine as far back
as possible. Also I can lose some weight up front with an aluminum head and
maybe some other mods. It will help that I am 220 lbs. Also I have found
that the gear are totally junk as over half of the main tube was rusted
through. So I will have to make new gear. So I can get it placed where I
want it. I have not emailed Bob yet but will do that today. I do have a
picture working on the wing on the Pietenpol facebook group with my
grandson. He comes over every Thursday night to help or me help him I am not
sure. It forces me to have something ready for him to work on so the plane
is coming along nicely.
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of taildrags
Sent: Tuesday, January 24, 2017 10:59 PM
Subject: Pietenpol-List: Re: Long fuselage and Model A
--> <taildrags@hotmail.com>
Jerry; it looks like what you've got there is a one-off variant. For your
information, here's a snip from a very thorough dissertation on Piet
fuselage length variations by Chris Bobka, from around 2004. He's
responding to a question from builder Walt Evans and it has to do with the
axle location because that's pretty important to how the airplane will
handle on the ground, but look past some of that to see the information on
some key dimensions. Get a piece of scratch paper and a pencil and sketch
it out. You might check some other dimensions on your airframe, but you may
very likely have a hermaphrodite there... but not unprecedented. And by the
way, Walt Evans built and flew his absolutely gorgeous Air Camper
successfully, and you can see pictures of it on the Westcoastpiet.com site.
Here's one such picture:
http://www.westcoastpiet.com/images/WB%20Evans/images/1200Fly.jpg
Note that Chris refers to a "Pavliga long fuselage" (Frank Pavliga, a
legend in the Piet world)- with a fuselage of 172.375" long. If I've added
up the numbers in your sketch correctly, your fuselage is 172" long, so
there is at least one other airplane out there flying with a fuselage that
is within 3/8" of being the same length as yours and Pavliga's. Not to
worry though... the laws of physics still apply, which means that one or
more of the very useful CG calculation spreadsheets out there will help you
build and fly a safe airplane. We put men on the moon with nothing more
than slide rules... so anything is possible if you have a spreadsheet.
Here's some reading for you, snipped from the archives.
================
The 1932 fuselage (Hoopman drawings and 1932 Flying and Glider Manual) is
161 inches long. The 1933 Improved Air Camper fuselage is 163 inches long.
The Pavliga long fuselage is 172.375 inches long. This is the one I
understand you have built.
It appears that the intersection of the first truss verticals with the lower
longeron on the 1932 fuselage is 8.375 or 8.5 inches aft of the firewall,
depending on which set of plans you look at. On the 1933 Improved fuselage,
it is 10 inches, and on the Pavliga long fuselage, it is 12 inches. This
would mean that the wood gear, unmodified from the 1932 plans and as mounted
on the Pavliga long fuselage, would put the axle 12-8.5 or 3.5 inches
farther aft on the long fuselage than on the 1932 fuselage. It would be at
13.5 (see paragraph 1 sentence 1) + 3.5 or 17 inches aft of the firewall.
Is this a good place for it? Frank P. said it was too far forward at 17
inches aft of the firewall so he moved it aft when he did the engine switch.
A better indicator of proper gear position is comparing it to the rear seat
back position in the particular fuselage since this indicates the shift aft
of the CG position as the fuselages have been stretched. The rear seat back
(at the top longeron) in the 1932 fuselage is 70.5 inches aft of the
firewall. The rear seat back in the 1933 Improved fuselage is 72.25 inches
aft of the firewall.
The rear seat back of the Pavliga long fuselage is 76.25 inches aft of the
firewall. This is a substantial shift aft in the position of the CG versus
the axle position as the fuselage is stretched.
Therefore, the axle on the 1932 fuselage is 70.5 -13.5 or 57 inches forward
of the rear seat back. The axle on the 1933 Improved is 72.25 -17 or 55.25
inches forward of the rear seat back. Let us ignore the value from the 1932
fuselage for reasons to be discussed later. Using the number from 1933 and
applying this to the Pavliga long fuselage, we should have the axle at 76.25
- 55.25 or
21 inches aft of the firewall. Two paragraphs ago we determined that it will
actually wind up at 17 inches aft of the firewall with the wood gear,
unmodified, and Frank P. says this is too far forward. Therefore, it
appears that we need to redesign the gear so that the axle will sit farther
aft in the V to the tune of about 21 -17 or 4 inches.
As we noted above, if you look at the sweep of the V in the 1932 plans, you
will note that the front attach of the V is at 8.5 inches aft of the
firewall. We know that the axle is about 13.5 inches aft of the firewall.
Therefore, the sweep is 13.5 - 8.5 or 5 inches for the wood gear. Doing the
same analysis for the 1933 Improved Air Camper, we know the front attach of
the V is at 10 inches aft of the firewall and the axle is at 17 inches aft
of the firewall. Therefore the sweep is 17 -10 or 7 inches for the split
axle gear. The next sentence is important. If you put the 1932 wood gear on
a 1933 Improved fuselage, you would have an axle that will be 7 - 5 or 2
inches forward of where it would have been if you had used the split axle
gear!!!! So the gears are not necessarily interchangeable!!! Logic says
that it does not matter which style gear you use. The axle should always be
in the same relative position. I see this as an admission by BP that the
original 1932 axle was too far forward by 2 inches.
And now we know what Frank P. was talking about!!!!
It is obvious that BP saw fit, when designing the 1933 Improved Air Camper,
that if he lengthened the fuselage from 161 to 163 inches and moved the
pilot's rear seat back aft by 1.75 inches, then he must move the axle aft by
17 -13.5 -
2 or 1.5 inches. (Consider 2 of the 3.5 inch difference between 17 and 13.5
as a design correction and the remaining 1.5 of the 3.5 inches to be an
adjustment for the new fuselage length and movement aft of the rear seat
back.) So what would BP do if he made the fuselage 172.375 inches long (a
whopping 9.375 inches longer) and moved the rear seat back aft yet another
76.25 -72.25 or 4 inches?
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power, 72x36 Culver prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=465417#465417
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Long fuselage and Model A |
Oops I should have thanked taildrags. I have been up to the fly inn a couple
time with Jack Textor bet did not talk to many people there. Someday I hope
to fly it up there.
Thanks very much for the help.
Jerry
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of taildrags
Sent: Tuesday, January 24, 2017 10:59 PM
Subject: Pietenpol-List: Re: Long fuselage and Model A
--> <taildrags@hotmail.com>
Jerry; it looks like what you've got there is a one-off variant. For your
information, here's a snip from a very thorough dissertation on Piet
fuselage length variations by Chris Bobka, from around 2004. He's
responding to a question from builder Walt Evans and it has to do with the
axle location because that's pretty important to how the airplane will
handle on the ground, but look past some of that to see the information on
some key dimensions. Get a piece of scratch paper and a pencil and sketch
it out. You might check some other dimensions on your airframe, but you may
very likely have a hermaphrodite there... but not unprecedented. And by the
way, Walt Evans built and flew his absolutely gorgeous Air Camper
successfully, and you can see pictures of it on the Westcoastpiet.com site.
Here's one such picture:
http://www.westcoastpiet.com/images/WB%20Evans/images/1200Fly.jpg
Note that Chris refers to a "Pavliga long fuselage" (Frank Pavliga, a
legend in the Piet world)- with a fuselage of 172.375" long. If I've added
up the numbers in your sketch correctly, your fuselage is 172" long, so
there is at least one other airplane out there flying with a fuselage that
is within 3/8" of being the same length as yours and Pavliga's. Not to
worry though... the laws of physics still apply, which means that one or
more of the very useful CG calculation spreadsheets out there will help you
build and fly a safe airplane. We put men on the moon with nothing more
than slide rules... so anything is possible if you have a spreadsheet.
Here's some reading for you, snipped from the archives.
================
The 1932 fuselage (Hoopman drawings and 1932 Flying and Glider Manual) is
161 inches long. The 1933 Improved Air Camper fuselage is 163 inches long.
The Pavliga long fuselage is 172.375 inches long. This is the one I
understand you have built.
It appears that the intersection of the first truss verticals with the lower
longeron on the 1932 fuselage is 8.375 or 8.5 inches aft of the firewall,
depending on which set of plans you look at. On the 1933 Improved fuselage,
it is 10 inches, and on the Pavliga long fuselage, it is 12 inches. This
would mean that the wood gear, unmodified from the 1932 plans and as mounted
on the Pavliga long fuselage, would put the axle 12-8.5 or 3.5 inches
farther aft on the long fuselage than on the 1932 fuselage. It would be at
13.5 (see paragraph 1 sentence 1) + 3.5 or 17 inches aft of the firewall.
Is this a good place for it? Frank P. said it was too far forward at 17
inches aft of the firewall so he moved it aft when he did the engine switch.
A better indicator of proper gear position is comparing it to the rear seat
back position in the particular fuselage since this indicates the shift aft
of the CG position as the fuselages have been stretched. The rear seat back
(at the top longeron) in the 1932 fuselage is 70.5 inches aft of the
firewall. The rear seat back in the 1933 Improved fuselage is 72.25 inches
aft of the firewall.
The rear seat back of the Pavliga long fuselage is 76.25 inches aft of the
firewall. This is a substantial shift aft in the position of the CG versus
the axle position as the fuselage is stretched.
Therefore, the axle on the 1932 fuselage is 70.5 -13.5 or 57 inches forward
of the rear seat back. The axle on the 1933 Improved is 72.25 -17 or 55.25
inches forward of the rear seat back. Let us ignore the value from the 1932
fuselage for reasons to be discussed later. Using the number from 1933 and
applying this to the Pavliga long fuselage, we should have the axle at 76.25
- 55.25 or
21 inches aft of the firewall. Two paragraphs ago we determined that it will
actually wind up at 17 inches aft of the firewall with the wood gear,
unmodified, and Frank P. says this is too far forward. Therefore, it
appears that we need to redesign the gear so that the axle will sit farther
aft in the V to the tune of about 21 -17 or 4 inches.
As we noted above, if you look at the sweep of the V in the 1932 plans, you
will note that the front attach of the V is at 8.5 inches aft of the
firewall. We know that the axle is about 13.5 inches aft of the firewall.
Therefore, the sweep is 13.5 - 8.5 or 5 inches for the wood gear. Doing the
same analysis for the 1933 Improved Air Camper, we know the front attach of
the V is at 10 inches aft of the firewall and the axle is at 17 inches aft
of the firewall. Therefore the sweep is 17 -10 or 7 inches for the split
axle gear. The next sentence is important. If you put the 1932 wood gear on
a 1933 Improved fuselage, you would have an axle that will be 7 - 5 or 2
inches forward of where it would have been if you had used the split axle
gear!!!! So the gears are not necessarily interchangeable!!! Logic says
that it does not matter which style gear you use. The axle should always be
in the same relative position. I see this as an admission by BP that the
original 1932 axle was too far forward by 2 inches.
And now we know what Frank P. was talking about!!!!
It is obvious that BP saw fit, when designing the 1933 Improved Air Camper,
that if he lengthened the fuselage from 161 to 163 inches and moved the
pilot's rear seat back aft by 1.75 inches, then he must move the axle aft by
17 -13.5 -
2 or 1.5 inches. (Consider 2 of the 3.5 inch difference between 17 and 13.5
as a design correction and the remaining 1.5 of the 3.5 inches to be an
adjustment for the new fuselage length and movement aft of the rear seat
back.) So what would BP do if he made the fuselage 172.375 inches long (a
whopping 9.375 inches longer) and moved the rear seat back aft yet another
76.25 -72.25 or 4 inches?
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power, 72x36 Culver prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=465417#465417
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Long fuselage and Model A |
Jerry: "taildrags R us" ;o)
Oscar Zuniga
taildrags@hotmail.com
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power, 72x36 Culver prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=465445#465445
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|