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Doug Robertson
Joined: 01 Nov 2005
Posts: 1751
Location: Southern California
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Posted: Fri Sep 23, 2016 5:51 pm Post subject: |
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Thanks Rob,
But, far be it for me to expound on the aerodynamics of airfoils, the most of which are certainly NOT symmetrical, as those with absolute symmetry have flight quirks. There is a trade-off between airfoil shapes and aircraft lift and other performance in flight. Some symmetrical airfoil wing aircraft are emphatically restricted from intentional spins, for example. Aircraft with symmetrical airfoil wings may exhibit poor stall recovery performance. Wing "wash-out" is often used by designers so that the wing will not stall out all at once, but by sections based on relative angle of attack, span-wise. This keeps distal ailerons effective, for example, in approach to a stall. Need I write there is no symmetry/interchangeability of wings with washout?
I have recommended Wolfgang Langewiesche's book in this Forum before to a flight student's question, as I recall. It is titled "Stick and Rudder, An explanation of the Art of Flying". It is the first exact analysis of the art of flying, and highly recommended. Written in 1944, it is still in print. Publisher: McGraw-Hill Book Company, New York. 389 pages include a very comprehensive index, and the book is well illustrated.
I don't have any more specific information re the Luscombe 8 series accident rate cause, or theories. A friend learned to fly in one back in the 1960s, and he found it tricky to land consistently well. Meanwhile, this quiz is still out there. _________________ PP ASEL
Link to my photos- http://airport-data.com/photographers/Doug+Robertson:84/
Last edited by Doug Robertson on Sat Nov 04, 2017 5:58 pm; edited 1 time in total |
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Doug Robertson
Joined: 01 Nov 2005
Posts: 1751
Location: Southern California
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Posted: Mon Sep 26, 2016 4:43 pm Post subject: |
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With this Quiz rapidly zooming to over 600 views and no right answers; my answers follow. I was most surprised that it wasn't answered. After some 250 views I used my search browser (unnamed) to ask "Production aircraft with symmetrical NACA airfoil?" and there were four answers on the first results page referring to the Quiz aircraft. DUH! Here are the answers.
1. Harold E. Emigh (pronounced "AMY").
2a. Emigh TROJAN A-2. 2b. Continental C85-12F 85 Hp, later offered with Continental C90 90 Hp.
3. December 20, 1946.
4. Two seats side by side.
5. A.T.C. #801 was granted December 21, 1948.
6, Fifty-eight total were built. In two plants in California and one in Arizona, successively.
Emigh, after years of study, set out to build a production all-metal aircraft cheaply, by comparison, and with common interchangeable parts. Less drawings and easy assembly. He had earlier in 1929 learned to fly an Alexander "Eaglerock" (Combo-Wing). Unfortunately, a 1948 new light aircraft launch was not the best of timing, as the American market for small two-place aircraft was rapidly disappearing with huge light aircraft builds and sale right after WWII with many general aviation companies folding, or consolidating.
The all metal Emigh Trojan A-2 had interchangeability of all fixed tail structure. Ditto for all moveable tail structure.The fixed vertical stabilizer could interchange with either horizontal stabilizer and the rudder could be interchanged with either elevator. The NACA 0012-63 wing airfoil was symmetrical and either no-flap wing could fit either side of the airplane. The external wing ribs were prominent and "different" from most smooth wing airfoils. That was what initially called my attention to the Trojan A-2 I saw parked at the Porterville, California airshow in the early '70s. The landing gear was short fixed tricycle gear. With the single tail it would never be mistaken for a ERCO Ercoupe of the vintage. Initial price quoted was $2,575 FAF, later average new price was $3,295 FAF. I thank all who pondered this quiz. _________________ PP ASEL
Link to my photos- http://airport-data.com/photographers/Doug+Robertson:84/ |
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