From: Sunderland, UK
ORIGINAL: el cid again
Regretfully, finding roll data for a few planes, and "extrapolating from there" is not going to work. It violates CHS/RHS standards for data - and it is probably not going to be valid either. Different manufacturers don't do things the same way, and some radical planes (J7W comes to mind) probably are very different in how they behave than anything we would be looking at. [There is a tiny plane in Anchorage of similar configuration - and it is almost impossible to describe how it can fly - you have to fly it to begin to understand the impact of a canard]. If we cannot come up with a theoretically valid way to determine roll rate from data that is available, we cannot use it. I think arguments would be endless if we tried to estimate this value - and there would be no rational way to settle them either. People would be sure I was a JFB or an AFB if their pet plane was not better than others.
Oh, God... All those books are in America. Roll rate involves angular momentum, so high aspect ratio wings are bad and engines on the wings are bad.
"At 160 mph (260 km/h), A6M2 had a roll rate of 56 degrees per second." (from Wikipedia)
Spitfire I roll rate was 140 deg/sec. (http://www.aviation-history.com/)
P47D: 85 degrees per second.
P38--a slow roller until the L model.
See also Roll Rates
For interesting figures see some guesstimates, it appears.
The first six below are from Perkins and Hage and are reliable.
P-47: 71 at 250 knots (per guesstimates, F6F, F4F, SBD, P-39D, Ki84, A6M3, and A6M5 similar, FM2 about 90)
P-38: 78 at 257 knots
P-51B: 98 at 260 knots
P-40: 134 at 314 knots
Spitfire V: 150 at 176 knots
FW-190: 151 at 226 knots
TBF: about 40 at 250 knots
F4U about 120
A6M2 about 50
Ki43 about 55
Bf109 about 85-90
Bf110C about 45
Spitfire V and Hurricane about 85-90
I don't believe the early P38 figures as it was comparable with the Bf110.
D3A and B5N about 33
B25H about 36
B17G about 10
The helix angle (pb/2V) is a constant times the airspeed up to the point that the ailerons start to flex or are too stiff to move. (p is the roll rate in radians per second, is the airspeed in feet per second, and b is the wing span in feet) The minimum acceptable value for the helix angle was about 0.07 for bombardment and transport aircraft and 0.09 for fighters in WWII. Source. About 125 degrees per second at 250 knots corresponds to 0.09 for a 30 foot wingspan, which means most WWII fighters were deficient.
You might find the following interesting: NASA history of aircraft
< Message edited by herwin -- 8/15/2006 1:48:01 PM >
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