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fuselage shape, vertical tail size vs spin behavior

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GrantR

Well-Known Member
Joined
Aug 28, 2007
Messages
45
Location
Plains, GA
I read this Nasa technical document on wind tunnel test done on model airplanes to determine the effects of fuselage shape has on spin behavior. GENERAL STUDY OF LIGHT PLANE SPIN, AFT FUSELAGE GEOMETRY, PART 1 : BEAURAIN, L : Free Download & Streaming : Internet Archive From what I gathered it seems a rounded top fuselage with a flat bottom seems to create strong pro spin moments that easily let the spin go flat and make them harder to recover from while a flat top rounded bottom fuselage shows the strongest anti spin characteristics. In some of the test the plane would not spin with this shape. It also showed a larger vertical tail creating more pro spin forces rather than anti spin. I would have expected a larger vertical would aid in recovering vs making it harder too. Why do these two shapes create such different outcomes? I guess a round fuselage would be more or less neutral.
 
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