Friday, November 14, 2008
Possible or not?
One of my friends recently sent me this video of stunt pilot James Andersson in a Red Bull Air Race and asked me if this was possible or not. Given some of my ground school and understanding, I wrote him back with the following explanation:
"Because this plane is a certified stunt plane, the engine has enough thrust to provide vertical lift, in which case the wings aren't needed for vertical flight (in fact no matter how fast an airplane is flying, if the relative angle of attack (wing to wind) exceeds a certain angle the plane stalls unless the engine has enough thrust for vertical lift.
This is completely possible and as I watched the wing come off it is exactly what I thought the pilot should have done. Now whether or not the video itself is real, looks real enough to me."
I wonder what do others have to say about this video. Do you think its possible or not? Please post your comments.
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2 comments:
Andres -
That's quite an incredible video. But, although you're correct about the thrust of (some) stunt planes, you're forgetting two significant factors: torque and p-factor. (I'll leave it to you to explain p-factor to your readers LOL) But there isn't enough airflow over the control surfaces to counteract torque and p-factor (which would be just tremendous in that configuration) and the kicker is about 49 seconds into the clip where you get a good glimpse of the rudder and elevator, and they're pretty much neutral. The landing bounce isn't very convincing, either.
Great brain teaser, though. Keep up the good work. :-D
I thought I'd add parts of two private messages I sent to Andres via Money-Talk forum, with some more thoughts on the subject:
--first pm--
I think the wing coming off is real; the motion of the aircraft at that point (rolling) is exactly what should happen, and since the aircraft is in vertical motion, and no down-force on the horizontal stabilizer, you wouldn't expect a pitch excursion, and we don't see one. I think it's very likely real up until the point where the aircraft disappears off the bottom edge of the frame.
--sent later--
Snopes says status is "undetermined" but speculates it was a radio-controlled model:
http://www.snopes.com/photos/airplane/onewing.asp
Look very carefully at the video, using pause, starting at the point where the one-winged airplane reappears in the field of view, where it's supposedly transitioning to a nose-up vertical descent. The flaws in the image as a result of "photoshopping" become more apparent: there's a kind of a halo around the airplane where the background doesn't quite match. The sky is a very complex image. I've tried to match it and it's always obvious. Whoever put that together did an excellent job and put a lot of work into it, but I'm quite sure now that it's fake.
I'm not even so sure about the wing coming off now, either. The airplane makes an unusual attitude change with a kind of a strange motion just before and during the wing separation. I suppose it's possible that motion is responsible for the g-forces necessary to cause failure, but then what caused that strange motion? All the other control surface and flight surfaces are intact. The airplane was in vertical flight, at which point the g-forces on the wing would be zero. What caused the deviation from vertical flight and then what caused the structural failure? It doesn't look the entry into any acrobatic maneuver I've ever seen.
Anyway, thanks for giving me something interesting to think about.
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