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teamgrumman(at)yahoo.com
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 Posted: Tue Nov 29, 2011 9:47 am Post subject: pic of wing rib |
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Bob,
I have a couple of questions for you.
1) How did you determine the angle of attack of your wing from your flight data?
2) What did you use for a reference line?
3) What assumption did you use to determine the relationship between the fuselage and the wing?
Question(s) to anyone who may know.
• From the literature, the airfoil is 64-415 mod. 64-415 is a symmetric airfoil. The mod was to droop the leading edge.
1) Was the upper surface kept the same and lengthened to create the droop for the semi-symmetric airfoil?
or
2) Was the symmetry truncated to flatten the the bottom?
I guess what I'm saying is,
3) Where was the original line?
4) Is there an original AA1 airfoil that I can use to compare shapes?
Gary
From: Bob Hodo <bob.hodo(at)yahoo.com>
To: teamgrumman(at)yahoo.com
Sent: Monday, November 28, 2011 8:42 PM
Subject: Fw: pic of wing rib
This is an attempt to forward a pic of a wing rib at the approximate angle of attack against a background with one inch squares as mine has at 120 knots.
If it works, I will try to do the one at 140 knots.
Discussion to follow.
Bob Hodo
(Gary, I will try to get it transferred over to a paper template to send out to you tomorrow.)
[quote][b]
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bob.hodo(at)yahoo.com
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| Posted: Tue Nov 29, 2011 10:32 am Post subject: pic of wing rib |
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Gary asks:
1) How did you determine the angle of attack of your wing from your flight data?
2) What did you use for a reference line?
3) What assumption did you use to determine the relationship between the fuselage and the wing?
BH:
I have not made myself clear and have probably used errant terminology. I know the angle of attack of my canopy rails, not my wing, and I know the approximate relative position of the two flat halves of the bottom of the wing to the rails. 
Ned said he flew with a level on his canopy rails. I thought that was a good idea. So I did it and collected that data at three airspeeds: 120 kn, 130 kn, and 140 kn. (just about my limit, remember, I am a cheetah)
Then, on the ground I used a digital inclinometer and found the rails sitting 5 degrees nose up. I then tested the bottom aft portion of the wing, about an inch from the wing root, and found 3 degrees nose up. (Sitting on the ground, not in flight. Just wanted to know the wing's position relative to the rails.) I intend to do all this again after carefully leveling the plane, and then hopefully make some pics with the rails at the same nose down position that they are at 140 knots with a nice brick background to show my eye what I look like from the side at that speed.
I have determined the bottom front portion of the wing to be 4.15 degrees more nose up than the bottom aft portion through careful measurement of the rib. (1.45" rise over 20" run.)
All of my testing has been relative to the strait lines of the bottom of the wing, NOT it's chord line, or whatever line would represent zero lift. I don't know how to do that.
It is notable to me that the bottom of our wing is a very shallow V, at 4.15 degrees bend. It is also notable to me that this places the leading edge of the bottom of the wing just about the same distance from water level (if that is what the canopy rails represent) as it does the trailing edge, not counting the flaps or ailerons which complete the wing shape.
I DO NOT KNOW the angle of attack of the wing. Are AoA and incidence the same thing? Ned has said the incidence is 1 degree 25 minutes, and provided a source for that. He also said that it had been 3 to 3.5 degrees on the original airfoil. Not sure I saw the source for that.
................
I need a web site to upload some of these pics of the wing rib to so that folks can see them. Recommendations???
I might need to just re-register with the list using my gmail account. It allows me to upload these big files easily.
Bob Hodo
GADsden, AL
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teamgrumman(at)yahoo.com
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| Posted: Wed Nov 30, 2011 12:29 am Post subject: pic of wing rib |
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The nose over could be filled with bondo.
Gary
Sent from my iPad
On Nov 29, 2011, at 12:12 PM, "923te" <923te(at)att.net (923te(at)att.net)> wrote:
[quote] Hmmm...
looks like the grumman leading edge is in there somewhere.....
guess we have a STOL wing..
<sportsmanairfoil.gif>
[quote] ---
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