Today's Message Index:
----------------------
1. 05:39 AM - Re: Leading airfoil shape-- scalloped back edge (Tim Willis)
2. 06:04 AM - Re: Re: Leading airfoil shape-- scalloped back edge (Phillips, Jack)
3. 06:22 AM - Re: Re: Leading airfoil shape-- scalloped back edge (HelsperSew@aol.com)
4. 06:47 AM - Re: Re: Leading airfoil shape-- scalloped back edge (Phillips, Jack)
5. 06:52 AM - Re: Re: Leading airfoil shape-- scalloped back edge (HelsperSew@aol.com)
6. 06:53 AM - Re: Corvair College #11 (MICHAEL SILVIUS)
7. 08:29 AM - Re: Re: Leading airfoil shape-- scalloped back edge (Tim Willis)
8. 08:39 AM - Re: Re: Leading airfoil shape-- scalloped back edge (Phillips, Jack)
9. 10:45 AM - Re: Leading Edge spar .. how do you shape it? (Ed G.)
10. 11:02 AM - Re: Leading Edge spar .. how do you shape it? (Phillips, Jack)
11. 11:43 AM - Re: Leading Edge spar .. how do you shape it? (Ed G.)
12. 01:28 PM - Re: Leading Edge spar .. how do you shape it? (Isablcorky@aol.com)
13. 01:46 PM - Re: Re: Leading airfoil shape-- scalloped back edge (walt evans)
14. 03:06 PM - Re: Re: Leading airfoil shape-- scalloped back edge (walt evans)
15. 03:32 PM - (Gene Rambo)
16. 07:02 PM - Re: Re: Leading airfoil shape-- scalloped back edge (Rcaprd@aol.com)
17. 07:16 PM - Re: Re: Leading airfoil shape-- wood vs. metal (Brian Kraut)
18. 07:26 PM - Re: Re: Leading airfoil shape-- wood vs. metal (Rcaprd@aol.com)
Message 1
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
While we are discussing putting thin plywood on the face of the wings to shape
the airfoil, what about the scalloped rear edge of any such plywood skins?
I know this is a long way in sophistication from Mother's Oats stuff first used
by BP, but is it a real improvment? What does it really do? I understand the
concept of the fabric lifting between the scallops while in flight, but what
do the scallops really do?
I plan to put 1/16" or 1.5mm ply skin on the airfoil face, but I'd like to avoid
effecting these scallops unless they really change performance. Your comments,
pls.
(I hope I am being clear enough in describing this.)
Tim in central TX
===========================================
>> [EXCERPT-- Tim]
>> Don't do it as one big piece.. thought about putting plywood airfoil
>> shaped pieces on each rib, with about a one inch square opening for a
>> piece of wood, then I could use longeron stock. Would end up lighter,
>> could do with jigsaw and files. However it wouldn't provide much support
>> to the leading edge skin as it would only make contact at each rib.
>>
>> This is for a GN-1 Biplane, which confuses the issue a little. The top
>> wings are complete, they have a .026 aluminum wrapped leading edge with a
>> square 1" spar that touches the leading edge in two spots the full length
>> of the wings. (The square part is along the very front of each rib) so it
>> provides some support.)
>>
>> The lower wing is what needs the spars, and then to be skinned with
>> something. My plans show a single piece of wood shaped to match the
>> airfoil profile, attached via flat head machine screws/bolts, at each rib.
>> There is no indication of wood or aluminum for leading edge skin. Since my
>> top wings have aluminum, and I am comfortable working with it I was
>> leaning toward skinning it with aluminum.
>>
>> Preference would be to follow plans, which would be to make up an airfoil
>> shaped spar. How did you guys do this?
>>
>> I have a picture (not my plane, but same exact kind of shaped piece) as an
>> example of what I think I need.
>>
>> Any help would be appreciated.
>>
>> Jim
>>
>>
>
Message 2
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
No need to scallop the plywood between the ribs. Just leave the rear
edge of the plywood straight. The fabric will pull the plywood down
nicely as it shrinks. I've attached a photo showing my right wing with
a coat of white paint before applying the finish color. If you look
towards the wingtip you can see how the plywood has been pulled down
slightly by the fabric, making a nice smooth transition. The only way
to tell definitely where the leading edge stops is by noting where the
rib stitching begins.
Jack Phillips
Raleigh, NC
Enjoyed the nice weather yesterday flying the Pietenpol in 50 deg F
temperatures. Need to enjoy such flying weather while it lasts.
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Tim
Willis
Sent: Monday, November 12, 2007 8:39 AM
Subject: Pietenpol-List: Re: Leading airfoil shape-- scalloped back edge
--> <timothywillis@earthlink.net>
While we are discussing putting thin plywood on the face of the wings to
shape the airfoil, what about the scalloped rear edge of any such
plywood skins?
I know this is a long way in sophistication from Mother's Oats stuff
first used by BP, but is it a real improvment? What does it really do?
I understand the concept of the fabric lifting between the scallops
while in flight, but what do the scallops really do?
I plan to put 1/16" or 1.5mm ply skin on the airfoil face, but I'd like
to avoid effecting these scallops unless they really change performance.
Your comments, pls.
(I hope I am being clear enough in describing this.)
Tim in central TX
==================
>> [EXCERPT-- Tim]
>> Don't do it as one big piece.. thought about putting plywood airfoil
>> shaped pieces on each rib, with about a one inch square opening for a
>> piece of wood, then I could use longeron stock. Would end up lighter,
>> could do with jigsaw and files. However it wouldn't provide much
>> support to the leading edge skin as it would only make contact at
each rib.
>>
>> This is for a GN-1 Biplane, which confuses the issue a little. The
>> top wings are complete, they have a .026 aluminum wrapped leading
>> edge with a square 1" spar that touches the leading edge in two spots
>> the full length of the wings. (The square part is along the very
>> front of each rib) so it provides some support.)
>>
>> The lower wing is what needs the spars, and then to be skinned with
>> something. My plans show a single piece of wood shaped to match the
>> airfoil profile, attached via flat head machine screws/bolts, at each
rib.
>> There is no indication of wood or aluminum for leading edge skin.
>> Since my top wings have aluminum, and I am comfortable working with
>> it I was leaning toward skinning it with aluminum.
>>
>> Preference would be to follow plans, which would be to make up an
>> airfoil shaped spar. How did you guys do this?
>>
>> I have a picture (not my plane, but same exact kind of shaped piece)
>> as an example of what I think I need.
>>
>> Any help would be appreciated.
>>
>> Jim
>>
>>
>
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Message 3
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
Jack,
Did you apply a 2" tape over the edge of the plywood? I can't see any but
it is not clear. I supported the edge of the plywood with a piece of spruce
glued on to the top of the spar, so I would have something to nail to. I then
nailed down that edge on the entire wing. Maybe I made a mistake and just
should have left it for the fabric to pull it down.
Dan Helsper
Poplar Grove, IL.
Message 4
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
Yes, I applied 2" tape over the rear edge of the plywood, and over
ANYTHING that was directly underlying the fabric, even things that were
not normally in contact with it. The fabric can move during flight and
will quickly chafe if not reinforced.
Probably un-necessary to have added the spruce under the plywood between
the ribs, but it shouldn't hurt anything (other than adding weight).
Can't wait to see your Pietenpol at Brodhead. Will it be there this
year?
Jack Phillips
_____
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of
HelsperSew@aol.com
Sent: Monday, November 12, 2007 9:22 AM
Subject: Re: Pietenpol-List: Re: Leading airfoil shape-- scalloped back
edge
Jack,
Did you apply a 2" tape over the edge of the plywood? I can't see any
but it is not clear. I supported the edge of the plywood with a piece of
spruce glued on to the top of the spar, so I would have something to
nail to. I then nailed down that edge on the entire wing. Maybe I made a
mistake and just should have left it for the fabric to pull it down.
Dan Helsper
Poplar Grove, IL.
_____
our
http://www.matronics.com/Navigator?Pietenpol-List
===========
_________________________________________________
This message is for the designated recipient only and may contain privilege
d, proprietary
or otherwise private information. If you have received it in error, please
notify the sender
immediately and delete the original. Any other use of the email by you is p
rohibited.
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orsk - Portuguese
Message 5
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
Jack,
Don't know if I'll make it there with my Piet next year or not. Too early
to tell, and you know how that goes. Everything takes longer than you think. I
am making wing struts and cowling now. Having lots of fun, that's for sure!
Dan Helsper
Poplar Grove, IL.
Message 6
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| Subject: | Re: Corvair College #11 |
Hi Darrel:
A quick web immage search for "Pfeifer Sport" turns up little other than
this photo of you:
http://www.experimental-aviation.com/Corvair/Images/WCCC/Event/DarrelnDJ.jpg
and
http://www.aerofiles.com/pfeifer-1937.jpg
looks like a Piet with short/spalyed cabanes and and diferent profile
empenage?
do you have any other photos or links detaling a bit on what this plane is
looks interesting.
Michael Silvius
Scarborough, Maine
----- Original Message -----
From: "Darrel Jones" <wd6bor@vom.com>
> I am putting the Corvair back in a
> Pietenpol variant called the Pfeifer Sport because the manual had a lot
> of great firewall-forward information for the Corvair engine.
Message 7
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
Jack,
Thanks for the answer and the pic. Looks good. Was that masking tape underneath,
or something else?
I have a test piece of scrap 1.5mm plywood that I have wetted in very hot water,
bent and clamped to a couple of loose ribes. Not glued-- just a test-- waiting
to see how it dries out.
Tim in central TX
-----Original Message-----
>From: "Phillips, Jack" <Jack.Phillips@cardinalhealth.com>
>Sent: Nov 12, 2007 8:46 AM
>To: pietenpol-list@matronics.com
>Subject: RE: Pietenpol-List: Re: Leading airfoil shape-- scalloped back edge
>
>Yes, I applied 2" tape over the rear edge of the plywood, and over
>ANYTHING that was directly underlying the fabric, even things that were
>not normally in contact with it. The fabric can move during flight and
>will quickly chafe if not reinforced.
>
>Probably un-necessary to have added the spruce under the plywood between
>the ribs, but it shouldn't hurt anything (other than adding weight).
>
>Can't wait to see your Pietenpol at Brodhead. Will it be there this
>year?
>
>Jack Phillips
>
> _____
>
>From: owner-pietenpol-list-server@matronics.com
>[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of
>HelsperSew@aol.com
>Sent: Monday, November 12, 2007 9:22 AM
>To: pietenpol-list@matronics.com
>Subject: Re: Pietenpol-List: Re: Leading airfoil shape-- scalloped back
>edge
>
>
>Jack,
>
>Did you apply a 2" tape over the edge of the plywood? I can't see any
>but it is not clear. I supported the edge of the plywood with a piece of
>spruce glued on to the top of the spar, so I would have something to
>nail to. I then nailed down that edge on the entire wing. Maybe I made a
>mistake and just should have left it for the fabric to pull it down.
>
>Dan Helsper
>Poplar Grove, IL.
>
>
> _____
>
>
>our
>http://www.matronics.com/Navigator?Pietenpol-List
>===========
>
>_________________________________________________
>
>or otherwise private information. If you have received it in error, please notify
the sender
>
>Dansk - Deutsch - Espanol - Francais - Italiano - Japanese - Nederlands - Norsk
- Portuguese
Message 8
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
You shouldn't need to soak it. I just glued mine with T-88 and used
nailing strips like Tony Bingelis describes to hold it down to the ribs
until the glue dried. I did it in roughly 4' sections, and filled in
the cracks with SuperFill.
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Tim
Willis
Sent: Monday, November 12, 2007 11:29 AM
Subject: RE: Pietenpol-List: Re: Leading airfoil shape-- scalloped back
edge
--> <timothywillis@earthlink.net>
Jack,
Thanks for the answer and the pic. Looks good. Was that masking tape
underneath, or something else?
I have a test piece of scrap 1.5mm plywood that I have wetted in very
hot water, bent and clamped to a couple of loose ribes. Not glued--
just a test-- waiting to see how it dries out.
Tim in central TX
-----Original Message-----
>From: "Phillips, Jack" <Jack.Phillips@cardinalhealth.com>
>Sent: Nov 12, 2007 8:46 AM
>To: pietenpol-list@matronics.com
>Subject: RE: Pietenpol-List: Re: Leading airfoil shape-- scalloped back
>edge
>
>Yes, I applied 2" tape over the rear edge of the plywood, and over
>ANYTHING that was directly underlying the fabric, even things that were
>not normally in contact with it. The fabric can move during flight and
>will quickly chafe if not reinforced.
>
>Probably un-necessary to have added the spruce under the plywood
>between the ribs, but it shouldn't hurt anything (other than adding
weight).
>
>Can't wait to see your Pietenpol at Brodhead. Will it be there this
>year?
>
>Jack Phillips
>
> _____
>
>From: owner-pietenpol-list-server@matronics.com
>[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of
>HelsperSew@aol.com
>Sent: Monday, November 12, 2007 9:22 AM
>To: pietenpol-list@matronics.com
>Subject: Re: Pietenpol-List: Re: Leading airfoil shape-- scalloped back
>edge
>
>
>Jack,
>
>Did you apply a 2" tape over the edge of the plywood? I can't see any
>but it is not clear. I supported the edge of the plywood with a piece
>of spruce glued on to the top of the spar, so I would have something to
>nail to. I then nailed down that edge on the entire wing. Maybe I made
>a mistake and just should have left it for the fabric to pull it down.
>
>Dan Helsper
>Poplar Grove, IL.
>
>
> _____
>
>
>our
>http://www.matronics.com/Navigator?Pietenpol-List
>==========
>
>_________________________________________________
>
>or otherwise private information. If you have received it in error,
>please notify the sender
>
>Dansk - Deutsch - Espanol - Francais - Italiano - Japanese - Nederlands
>- Norsk - Portuguese
_________________________________________________
or otherwise private information. If you have received it in error, please notify
the sender
Dansk - Deutsch - Espanol - Francais - Italiano - Japanese - Nederlands - Norsk
- Portuguese
Message 9
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| Subject: | Leading Edge spar .. how do you shape it? |
I cut four facets out of a 1" X 2 1/4" spruce board on my inexpensive table
saw. It leaves very little sanding or planeing to finish it. I cut a piece
of scrap to the same size, marked out the shape of the leading edge on the
end of it and used it to set and try the blade angels before makeing the
cuts on the real thing..Worked great for me..Ed G.
>From: "jimd" <jlducey@hotmail.com>
>To: pietenpol-list@matronics.com
>Subject: Pietenpol-List: Leading Edge spar .. how do you shape it?
>Date: Sun, 11 Nov 2007 07:23:21 -0800
>
>
>I have leading edges that need wood spars with the wings airfoil shape. How
>do you guys create a spar with the shape you need, at a reasonable cost, in
>a reasonable amount of time?
>
>Not being much of a woodworker, each idea I have had seems problematic;
>
>Router; have one, never used it. Could try to make a jig to make repeated
>cuts to approximate shape of airfoil. Getting something that would hold the
>position precisely, in many different positions seems dicey.
>Spar is about 3 inches wide, so no way my router could do it in less than
>3-4 passes, and getting profile right would be tough, don't think it would
>match any normal router bits exactly.
>
>Shaper; there are companies that make custom shaper cutters that would make
>one for that shape. Very expensive and I don't have a shaper.
>
>CNC; companies will make about anything you want if you provide info. Only
>need two spars and would rather do it self somehow.
>
>Don't do it as one big piece.. thought about putting plywood airfoil shaped
>pieces on each rib, with about a one inch square opening for a piece of
>wood, then I could use longeron stock. Would end up lighter, could do with
>jigsaw and files. However it wouldn't provide much support to the leading
>edge skin as it would only make contact at each rib.
>
>This is for a GN-1 Biplane, which confuses the issue a little. The top
>wings are complete, they have a .026 aluminum wrapped leading edge with a
>square 1" spar that touches the leading edge in two spots the full length
>of the wings. (The square part is along the very front of each rib) so it
>provides some support.)
>
>The lower wing is what needs the spars, and then to be skinned with
>something. My plans show a single piece of wood shaped to match the airfoil
>profile, attached via flat head machine screws/bolts, at each rib.
>There is no indication of wood or aluminum for leading edge skin. Since my
>top wings have aluminum, and I am comfortable working with it I was leaning
>toward skinning it with aluminum.
>
>Preference would be to follow plans, which would be to make up an airfoil
>shaped spar. How did you guys do this?
>
>I have a picture (not my plane, but same exact kind of shaped piece) as an
>example of what I think I need.
>
>Any help would be appreciated.
>
>Jim
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=145066#145066
>
>
>Attachments:
>
>http://forums.matronics.com//files/leadingedge_389.jpg
>
>
Message 10
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| Subject: | Leading Edge spar .. how do you shape it? |
I did the same thing - cut a couple of angles on a 13' piece of spruce
to give it a trapezoidal cross-section, then glued and bolted it to the
ribs. Then I finished shaping it with a block plane, walking down the
length of the wing as I planed, rolling up the neatest little curleques
of spruce as I went. As I recall it only took about 6 or 8 passes per
side to get it to shape (spruce works so nicely) and was one of the most
satisfying tasks on the entire project.
Jack Phillips
NX899JP
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Ed G.
Sent: Monday, November 12, 2007 1:45 PM
Subject: RE: Pietenpol-List: Leading Edge spar .. how do you shape it?
I cut four facets out of a 1" X 2 1/4" spruce board on my inexpensive
table saw. It leaves very little sanding or planeing to finish it. I cut
a piece of scrap to the same size, marked out the shape of the leading
edge on the end of it and used it to set and try the blade angels before
makeing the cuts on the real thing..Worked great for me..Ed G.
>From: "jimd" <jlducey@hotmail.com>
>To: pietenpol-list@matronics.com
>Subject: Pietenpol-List: Leading Edge spar .. how do you shape it?
>Date: Sun, 11 Nov 2007 07:23:21 -0800
>
>
>I have leading edges that need wood spars with the wings airfoil shape.
>How do you guys create a spar with the shape you need, at a reasonable
>cost, in a reasonable amount of time?
>
>Not being much of a woodworker, each idea I have had seems problematic;
>
>Router; have one, never used it. Could try to make a jig to make
>repeated cuts to approximate shape of airfoil. Getting something that
>would hold the position precisely, in many different positions seems
dicey.
>Spar is about 3 inches wide, so no way my router could do it in less
>than
>3-4 passes, and getting profile right would be tough, don't think it
>would match any normal router bits exactly.
>
>Shaper; there are companies that make custom shaper cutters that would
>make one for that shape. Very expensive and I don't have a shaper.
>
>CNC; companies will make about anything you want if you provide info.
>Only need two spars and would rather do it self somehow.
>
>Don't do it as one big piece.. thought about putting plywood airfoil
>shaped pieces on each rib, with about a one inch square opening for a
>piece of wood, then I could use longeron stock. Would end up lighter,
>could do with jigsaw and files. However it wouldn't provide much
>support to the leading edge skin as it would only make contact at each
rib.
>
>This is for a GN-1 Biplane, which confuses the issue a little. The top
>wings are complete, they have a .026 aluminum wrapped leading edge with
>a square 1" spar that touches the leading edge in two spots the full
>length of the wings. (The square part is along the very front of each
>rib) so it provides some support.)
>
>The lower wing is what needs the spars, and then to be skinned with
>something. My plans show a single piece of wood shaped to match the
>airfoil profile, attached via flat head machine screws/bolts, at each
rib.
>There is no indication of wood or aluminum for leading edge skin. Since
>my top wings have aluminum, and I am comfortable working with it I was
>leaning toward skinning it with aluminum.
>
>Preference would be to follow plans, which would be to make up an
>airfoil shaped spar. How did you guys do this?
>
>I have a picture (not my plane, but same exact kind of shaped piece) as
>an example of what I think I need.
>
>Any help would be appreciated.
>
>Jim
>
>
>Read this topic online here:
>
>http://forums.matronics.com/viewtopic.php?p=145066#145066
>
>
>Attachments:
>
>http://forums.matronics.com//files/leadingedge_389.jpg
>
>
_________________________________________________
or otherwise private information. If you have received it in error, please notify
the sender
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- Portuguese
Message 11
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| Subject: | Leading Edge spar .. how do you shape it? |
That should have been angles ...Angels had nothing to do with it...Ed G.
Do Not Archive
>From: "Ed G." <flyboy_120@hotmail.com>
>To: pietenpol-list@matronics.com
>Subject: RE: Pietenpol-List: Leading Edge spar .. how do you shape it?
>Date: Mon, 12 Nov 2007 13:45:00 -0500
>
>
>
>I cut four facets out of a 1" X 2 1/4" spruce board on my inexpensive table
>saw. It leaves very little sanding or planeing to finish it. I cut a piece
>of scrap to the same size, marked out the shape of the leading edge on the
>end of it and used it to set and try the blade angels before makeing the
>cuts on the real thing..Worked great for me..Ed G.
>
>>From: "jimd" <jlducey@hotmail.com>
>>To: pietenpol-list@matronics.com
>>Subject: Pietenpol-List: Leading Edge spar .. how do you shape it?
>>Date: Sun, 11 Nov 2007 07:23:21 -0800
>>
>>
>>I have leading edges that need wood spars with the wings airfoil shape.
>>How do you guys create a spar with the shape you need, at a reasonable
>>cost, in a reasonable amount of time?
>>
>>Not being much of a woodworker, each idea I have had seems problematic;
>>
>>Router; have one, never used it. Could try to make a jig to make repeated
>>cuts to approximate shape of airfoil. Getting something that would hold
>>the position precisely, in many different positions seems dicey.
>>Spar is about 3 inches wide, so no way my router could do it in less than
>>3-4 passes, and getting profile right would be tough, don't think it would
>>match any normal router bits exactly.
>>
>>Shaper; there are companies that make custom shaper cutters that would
>>make one for that shape. Very expensive and I don't have a shaper.
>>
>>CNC; companies will make about anything you want if you provide info. Only
>>need two spars and would rather do it self somehow.
>>
>>Don't do it as one big piece.. thought about putting plywood airfoil
>>shaped pieces on each rib, with about a one inch square opening for a
>>piece of wood, then I could use longeron stock. Would end up lighter,
>>could do with jigsaw and files. However it wouldn't provide much support
>>to the leading edge skin as it would only make contact at each rib.
>>
>>This is for a GN-1 Biplane, which confuses the issue a little. The top
>>wings are complete, they have a .026 aluminum wrapped leading edge with a
>>square 1" spar that touches the leading edge in two spots the full length
>>of the wings. (The square part is along the very front of each rib) so it
>>provides some support.)
>>
>>The lower wing is what needs the spars, and then to be skinned with
>>something. My plans show a single piece of wood shaped to match the
>>airfoil profile, attached via flat head machine screws/bolts, at each rib.
>>There is no indication of wood or aluminum for leading edge skin. Since my
>>top wings have aluminum, and I am comfortable working with it I was
>>leaning toward skinning it with aluminum.
>>
>>Preference would be to follow plans, which would be to make up an airfoil
>>shaped spar. How did you guys do this?
>>
>>I have a picture (not my plane, but same exact kind of shaped piece) as an
>>example of what I think I need.
>>
>>Any help would be appreciated.
>>
>>Jim
>>
>>
>>
>>
>>Read this topic online here:
>>
>>http://forums.matronics.com/viewtopic.php?p=145066#145066
>>
>>
>>
>>
>>Attachments:
>>
>>http://forums.matronics.com//files/leadingedge_389.jpg
>>
>>
>>
>>
>>
>>
>>
>
>
Message 12
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| Subject: | Re: Leading Edge spar .. how do you shape it? |
When one builds AND flies his own aeronautical creation down discount the
favors the angels might provide.
Corky 1:13
Message 13
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
I don't think anywhere in the plans it calls out to scallop the skin.
It was said that just the straight trailing edge of the thin ply pulls down
nicely when covered.
If you stiffen the trailing edge you'll create a step.
Mine came out very well un scalloped and unsupported
walt evans
NX140DL
"No one ever learned anything by talking"
Ben Franklin
----- Original Message -----
From: "Tim Willis" <timothywillis@earthlink.net>
Sent: Monday, November 12, 2007 8:39 AM
Subject: Pietenpol-List: Re: Leading airfoil shape-- scalloped back edge
> <timothywillis@earthlink.net>
>
> While we are discussing putting thin plywood on the face of the wings to
> shape the airfoil, what about the scalloped rear edge of any such plywood
> skins?
> I know this is a long way in sophistication from Mother's Oats stuff first
> used by BP, but is it a real improvment? What does it really do? I
> understand the concept of the fabric lifting between the scallops while in
> flight, but what do the scallops really do?
>
> I plan to put 1/16" or 1.5mm ply skin on the airfoil face, but I'd like to
> avoid effecting these scallops unless they really change performance.
> Your comments, pls.
>
> (I hope I am being clear enough in describing this.)
>
> Tim in central TX
>
> ===========================================
>>> [EXCERPT-- Tim]
>>> Don't do it as one big piece.. thought about putting plywood airfoil
>>> shaped pieces on each rib, with about a one inch square opening for a
>>> piece of wood, then I could use longeron stock. Would end up lighter,
>>> could do with jigsaw and files. However it wouldn't provide much support
>>> to the leading edge skin as it would only make contact at each rib.
>>>
>>> This is for a GN-1 Biplane, which confuses the issue a little. The top
>>> wings are complete, they have a .026 aluminum wrapped leading edge with
>>> a
>>> square 1" spar that touches the leading edge in two spots the full
>>> length
>>> of the wings. (The square part is along the very front of each rib) so
>>> it
>>> provides some support.)
>>>
>>> The lower wing is what needs the spars, and then to be skinned with
>>> something. My plans show a single piece of wood shaped to match the
>>> airfoil profile, attached via flat head machine screws/bolts, at each
>>> rib.
>>> There is no indication of wood or aluminum for leading edge skin. Since
>>> my
>>> top wings have aluminum, and I am comfortable working with it I was
>>> leaning toward skinning it with aluminum.
>>>
>>> Preference would be to follow plans, which would be to make up an
>>> airfoil
>>> shaped spar. How did you guys do this?
>>>
>>> I have a picture (not my plane, but same exact kind of shaped piece) as
>>> an
>>> example of what I think I need.
>>>
>>> Any help would be appreciated.
>>>
>>> Jim
>>>
>>>
>>
>
>
>
Message 14
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
Here's pics of mine.
Cut strips of a kitty litter bottle, or can use clorox bottle. Staple thru
it. when dry pull off the strips. Glue doesn't stick to the strips.
walt evans
NX140DL
"No one ever learned anything by talking"
Ben Franklin
----- Original Message -----
From: "walt evans" <waltdak@verizon.net>
Sent: Monday, November 12, 2007 4:44 PM
Subject: Re: Pietenpol-List: Re: Leading airfoil shape-- scalloped back edge
>
> I don't think anywhere in the plans it calls out to scallop the skin.
> It was said that just the straight trailing edge of the thin ply pulls
> down nicely when covered.
> If you stiffen the trailing edge you'll create a step.
> Mine came out very well un scalloped and unsupported
> walt evans
> NX140DL
>
> "No one ever learned anything by talking"
> Ben Franklin
> ----- Original Message -----
> From: "Tim Willis" <timothywillis@earthlink.net>
> To: <pietenpol-list@matronics.com>
> Sent: Monday, November 12, 2007 8:39 AM
> Subject: Pietenpol-List: Re: Leading airfoil shape-- scalloped back edge
>
>
>> <timothywillis@earthlink.net>
>>
>> While we are discussing putting thin plywood on the face of the wings to
>> shape the airfoil, what about the scalloped rear edge of any such
>> plywood skins?
>> I know this is a long way in sophistication from Mother's Oats stuff
>> first used by BP, but is it a real improvment? What does it really do?
>> I understand the concept of the fabric lifting between the scallops while
>> in flight, but what do the scallops really do?
>>
>> I plan to put 1/16" or 1.5mm ply skin on the airfoil face, but I'd like
>> to avoid effecting these scallops unless they really change performance.
>> Your comments, pls.
>>
>> (I hope I am being clear enough in describing this.)
>>
>> Tim in central TX
>>
>> ===========================================
>>>> [EXCERPT-- Tim]
>>>> Don't do it as one big piece.. thought about putting plywood airfoil
>>>> shaped pieces on each rib, with about a one inch square opening for a
>>>> piece of wood, then I could use longeron stock. Would end up lighter,
>>>> could do with jigsaw and files. However it wouldn't provide much
>>>> support
>>>> to the leading edge skin as it would only make contact at each rib.
>>>>
>>>> This is for a GN-1 Biplane, which confuses the issue a little. The top
>>>> wings are complete, they have a .026 aluminum wrapped leading edge with
>>>> a
>>>> square 1" spar that touches the leading edge in two spots the full
>>>> length
>>>> of the wings. (The square part is along the very front of each rib) so
>>>> it
>>>> provides some support.)
>>>>
>>>> The lower wing is what needs the spars, and then to be skinned with
>>>> something. My plans show a single piece of wood shaped to match the
>>>> airfoil profile, attached via flat head machine screws/bolts, at each
>>>> rib.
>>>> There is no indication of wood or aluminum for leading edge skin. Since
>>>> my
>>>> top wings have aluminum, and I am comfortable working with it I was
>>>> leaning toward skinning it with aluminum.
>>>>
>>>> Preference would be to follow plans, which would be to make up an
>>>> airfoil
>>>> shaped spar. How did you guys do this?
>>>>
>>>> I have a picture (not my plane, but same exact kind of shaped piece) as
>>>> an
>>>> example of what I think I need.
>>>>
>>>> Any help would be appreciated.
>>>>
>>>> Jim
>>>>
>>>>
>>>
>>
>>
>>
>>
>>
>>
>
>
>
Message 15
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Who do we have in the Greensboro area? I will be there tomorrow, and
then Greenville-Spartanburg on Thursday. I'd like to visit anyone in
those areas if possible.
Gene
Message 16
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| Subject: | Re: Leading airfoil shape-- scalloped back edge |
In a message dated 11/12/2007 7:41:07 AM Central Standard Time,
timothywillis@earthlink.net writes:
While we are discussing putting thin plywood on the face of the wings to
shape the airfoil, what about the scalloped rear edge of any such plywood skins?
I know this is a long way in sophistication from Mother's Oats stuff first
used by BP, but is it a real improvment? What does it really do? I understand
the concept of the fabric lifting between the scallops while in flight, but
what do the scallops really do?
Tim,
The scallops are not needed in the 1/16" plywood leading edge material. It
doesn't do anything. When the fabric is shrunk to spec., it pulls the aft edge
of the plywood down very nicely. Cutting scallops DOES require much more
work. I don't believe the fabric ever lifts between the ribs, however, the only
time the fabric could possibly lift between the ribs, might be in a very high
G load maneuver...probably more than the airframe can even handle. Stick to
the plans, and 'Git 'er done' !!
Chuck G.
NX770CG
Message 17
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| Subject: | Re: Leading airfoil shape-- wood vs. metal |
The GN-1 plans show .013" aluminum sheet on the leading edge. The aluminum
will cost less and be easier to install. Aluminum leading edges also get
dented up a lot easier than the plywood. Any opinions on which is better?
Brian Kraut
Engineering Alternatives, Inc.
www.engalt.com
Message 18
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| Subject: | Re: Leading airfoil shape-- wood vs. metal |
In a message dated 11/12/2007 9:17:39 PM Central Standard Time,
brian.kraut@engalt.com writes:
The GN-1 plans show .013" aluminum sheet on the leading edge. The aluminum
will cost less and be easier to install. Aluminum leading edges also get
dented up a lot easier than the plywood. Any opinions on which is better?
Brian,
I still much prefer the plywood, because I don't think it is any more
difficult to install than aluminum, it is more durable than aluminum - as you
mentioned, and because wood and aluminum have different expansion rates with
temperature changes - which may cause some wavy looks, or loosen the nails in the
aluminum.
Chuck G.
NX770CG
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