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teamgrumman(at)yahoo.com
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 Posted: Tue Jul 03, 2012 7:59 pm Post subject: Grumman airfoil |
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Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
[quote][b]
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n76lima(at)mindspring.com
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| Posted: Tue Jul 03, 2012 9:19 pm Post subject: Grumman airfoil |
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You don't mention changing the radius of the leading edge on the AA-1A and later airfoil in your description of your efforts to lay out the unique Grumman airfoil. It seems quite a bit larger radius than the AA-1 nee 64-415 airfoil.
Harry Riblett did some work on the NACA data and found issues with a wave or ripple in the upper surface based on the published tables. This inconsistency causes flow disruptions (loss of laminar flow earlier than expected and other issues with Stall and the Hysteresis loop of air attachment after stall. The first paragraph of this paper gives a brief description of what aerodynamic hysteresis is and what it does.
http://www.public.iastate.edu/~huhui/paper/2008/AIAA-2008-0315.pdf
It is a near certainty that the AA-1 airfoil has that same inconsistency, and since the AA-1A was done "on the hangar floor" from the AA-1 profiles, it seems likely that it has the same issues that the donor airfoil had. Harry's book "GA Airfoils" is very interesting reading for those that are wanting to understand airfoil design. Highly recommended.
http://www.aircraftspruce.com/catalog/bvpages/ga_airfoils.php
Gary, you got access to one of the CFD programs to "blow" on your reconstructed airfoil? There are a number of questions that need to be answered, mostly revolving around the slope of the forward camber and how it feeds into the large radius nose.
This paper is offered for those that don't know what we are talking about, and how Eppler and CFD have changed the entire concept of airfoil design from carving models and blowing on them, to designing the flow and pressure distribution you want, and then calculating the shape that would MAKE that happen.
http://www.airfoils.com/design.pdf
--Bob Steward
[Gary] Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter
than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
| Quote: | From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
|
Interesting.
Feedback appreciated.
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haveblue1(at)mac.com
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| Posted: Wed Jul 04, 2012 3:09 am Post subject: Grumman airfoil |
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Gary,
Just curious. What points on a Grumman... say AA-5 .... determine or make up the waterline? I understand waterline as it applies to boats, but not airplanes.
Thanks and Happy 4th to all.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
| Quote: | Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
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BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
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| Posted: Wed Jul 04, 2012 4:47 am Post subject: Grumman airfoil |
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Bruce:
Waterline is the same thing as Cord. The imaginary straight-line from the Leading Edge Tip (Bulge) to the Training Edge Tip or Aerilon Training Edge when in a neutral position.
I do not know how waterline came into play with planes, though may of the terms for aviation came from sailing and the sea. In this case I would guess it has more to do with the Egyptians and the building of things like the Pyramids. There is a tool know as an Egyptian Water Level. Today it would be made out of a flexible clear plastic tube, filled almost to the top with water (at each end). Since water seeks its own level - You could put the water level at the wings leading edge - Then move the other end of the tube up and down (water level) to measure the location of the wings training edge. Sight from water level (waterline) to water level (waterline) and you have the Cord a.k.a. Waterline. Water levels are pretty cool, they can be used to set heights/elevations over long distances and around corners - Especially in areas where you can not run a straight line, like finding Center-line from Firewall to Tailcone.
Barry
"Chop'd Liver"
On Wed, Jul 4, 2012 at 7:09 AM, Bruce Smith <haveblue1(at)mac.com (haveblue1(at)mac.com)> wrote:
[quote]Gary,
Just curious. What points on a Grumman... say AA-5 .... determine or make up the waterline? I understand waterline as it applies to boats, but not airplanes.
Thanks and Happy 4th to all.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
| Quote: | Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
|
[b]
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n76lima(at)mindspring.com
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| Posted: Wed Jul 04, 2012 5:07 am Post subject: Grumman airfoil |
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Waterline is one of the 3 geometric planes used to define a location on the aircraft. It is just what you are imagining from your experience with boats... it is the horizontal plane (parallel to the canopy rails and the ground) that would appear if the aircraft were partially submerged in water. It is typically abbreviated "WL" on drawings.
The other 2 planes are Station, the vertical plane parallel to the firewall, which could be compared to slicing bread, abbreviated "Sta.", and Butt Line, which is the vertical plane that slices the aircraft fore and aft parallel to the centerline. There are Right and Left Butt Lines, referencing whether they are right or left of the centerline, also known as B.L. 0.0, on drawings.
By defining the Station, Water Line, and Butt Line, one can pinpoint any point on or around the aircraft.
You call the "Station", the "Arm" in your W&B calculations. The Station zero is a point in space 50.0 inches in front of the firewall, ahead of the spinner. This allows all stations to be positive (making all calculations positive).
You can see the various Stations and Water Lines in the Structural Repairs section of the Maintenance Manual.
The other measurement you may commonly see in aircraft construction and repair, is AC, or "along contour", used to define something that you can easily see and measure with a ruler, but would devilishly difficult to calculate the Sta. WL, and BL, due to the curve of the surface in question. Perhaps the top surface of the wing or a measurement on the cowling.
--Bob Steward
Birmingham, AL
Bruce Smith <haveblue1(at)mac.com> wrote:
| Quote: | Gary,
Just curious. What points on a Grumman... say AA-5 .... determine or make up the waterline? I understand waterline as it applies to boats, but not airplanes.
Thanks and Happy 4th to all.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
> Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
>
> The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
>
> Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
>
> That's why I wanted some good locations. I still need them if you have the time and patience.
>
> From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
>
> Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
>
> Interesting.
>
> Feedback appreciated.
>
>
>
|
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teamgrumman(at)yahoo.com
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| Posted: Thu Jul 05, 2012 11:41 am Post subject: Grumman airfoil |
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The canopy rails are a good waterline. You can also use the bottom of the plane. The wing is installed at 3 degrees to the fuselage. Measure the wing on the front half.
From: Bruce Smith <haveblue1(at)mac.com>
To: teamgrumman-list(at)matronics.com
Sent: Wednesday, July 4, 2012 4:09 AM
Subject: Re: Grumman airfoil
Gary,
Just curious. What points on a Grumman... say AA-5 .... determine or make up the waterline? I understand waterline as it applies to boats, but not airplanes.
Thanks and Happy 4th to all.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
| Quote: | Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
| Quote: |
href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List
href="http://forums.matronics.com/">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
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[quote][b]
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teamgrumman(at)yahoo.com
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| Posted: Thu Jul 05, 2012 11:48 am Post subject: Grumman airfoil |
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waterline has nothing to do with boats. Water line comes from using a water level.
The 'zero' line on the Grumman airfoil is NOT from the bulge at the leading edge. The zero for the Grumman chord is 2.9 inches up from the bottom (forward flat surface) of the wing at the leading edge. It extends though the aft trailing edge of the flap with the bottom of the flap on the same plane as the aft section on the bottom of the wing.
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Wednesday, July 4, 2012 5:47 AM
Subject: Re: Grumman airfoil
Bruce:
Waterline is the same thing as Cord. The imaginary straight-line from the Leading Edge Tip (Bulge) to the Training Edge Tip or Aerilon Training Edge when in a neutral position.
I do not know how waterline came into play with planes, though may of the terms for aviation came from sailing and the sea. In this case I would guess it has more to do with the Egyptians and the building of things like the Pyramids. There is a tool know as an Egyptian Water Level. Today it would be made out of a flexible clear plastic tube, filled almost to the top with water (at each end). Since water seeks its own level - You could put the water level at the wings leading edge - Then move the other end of the tube up and down (water level) to measure the location of the wings training edge. Sight from water level (waterline) to water level (waterline) and you have the Cord a.k.a. Waterline. Water levels are pretty cool, they can be used to set heights/elevations over long distances and around corners - Especially in areas where you can not run a straight line, like finding Center-line from Firewall to Tailcone.
Barry
"Chop'd Liver"
On Wed, Jul 4, 2012 at 7:09 AM, Bruce Smith <haveblue1(at)mac.com (haveblue1(at)mac.com)> wrote:
| Quote: | Gary,
Just curious. What points on a Grumman... say AA-5 ... determine or make up the waterline? I understand waterline as it applies to boats, but not airplanes.
Thanks and Happy 4th to all.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
| Quote: | Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
|
http://www.matronics.com --> |
[quote][b]
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haveblue1(at)mac.com
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| Posted: Tue Jul 10, 2012 4:47 pm Post subject: Grumman airfoil |
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Gary,
Question. Are you going to design a new, semi-Cirrus like wing for the Grumman 4 seater line? You did say "I like doing stuff like this", and that you have tooooooo much time on your hands.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
| Quote: | Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
| Quote: |
href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List
href="http://forums.matronics.com/">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
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teamgrumman(at)yahoo.com
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| Posted: Tue Jul 10, 2012 10:04 pm Post subject: Grumman airfoil |
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I'll tell you want I would really like to do. I would like to have the resources to build a full scale de Havilland DH.98 Mosquito. but out of carbon fiber. To power it, I would hire Falconer to work with Walden to build a 2400 cubic inch V12 with a goal of 4000 horsepower with nitrous and 2000 without.
But since I'm poor, I'll just draw pictures.
Save your pennies for an IO360 and constant speed prop for your Tiger.
Gary
Sent from my iPad
On Jul 10, 2012, at 5:47 PM, Bruce Smith <haveblue1(at)mac.com (haveblue1(at)mac.com)> wrote:
| Quote: | Gary,
Question. Are you going to design a new, semi-Cirrus like wing for the Grumman 4 seater line? You did say "I like doing stuff like this", and that you have tooooooo much time on your hands.
Bruce
On Jul 3, 2012, at 11:59 PM, Gary Vogt wrote:
| Quote: | Under the heading of way too much time on my hands and a curiosity that won't let me leave this topic alone, I've been converting to CAD the dimensions of several NACA airfoils and matching them to the Grumman airfoil. Going on the premiss that the original AA1 had a 64-415 airfoil, I laid out a drawing to match it as close as possible.
The original AA1 airfoil is close to the 64-415, but it isn't really a 64-415. Using that same airfoil, and drooping the nose so that the nose was parallel to the "0" waterline and then extending that line to the spar, well, let's just say, it's an interesting airfoil, but nothing close to a 64-415.
Then, adding the flaps and ailerons from a Tiger and you have a completely new airfoil. It's skinnier than a 64-415 and fatter than a 64-412. So, I algebraically added the points of both the 64-415 and 64-412 airfoils and divided by 2. In theory, a 64-413.5. This airfoil is damn close to the Grumman airfoil with the exception of the flat bottom from the nose to the spar. However, the spar location makes it a 63.5-413.5 or something similar.
That's why I wanted some good locations. I still need them if you have the time and patience.
From the looks of it, the Grumman airfoil actually a pretty decent airfoil. Much thinner than the -415 and a longer upper surface with a nice gentle curve. The -415 has a rather steep curve past the 40% chord peak.
Comparing it to a Clark-Y one needs to begin making assumptions on installed incident angles and the fact that the -Y is flatter on the bottom.
Interesting.
Feedback appreciated.
|
|
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