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15 July 2010

The Turn: at the very heart of winged flight lies the banked turn, a procedure that by now seems so routine and familiar that airline passengers appreciate neither its elegance and mystery nor its dangerously delusive character.
Really interesting stuff. I'd be curious to know if any commercial airline pilots have ever performed one of those 360o rolls that the author writes about.
posted by Atom Eyes 15 July | 13:46
I have never heard "delusive" before. Yay, new word! Though I still like delusory better.
posted by Eideteker 15 July | 14:04
Atom Eyes

This is cool. A lot of people don't realize turning on a motorcycle works the same way. There was a great photo on killboy's site a few years back that showed a bike with a bottle of gatorade balanced in a divot on the tank, with the bike in a heavy lean. The comments were like, "Whoa!" until killboy explained it was a planned shot with a friend, and that they were taking full advantage of the fact that motorcycles (like planes) turn without lateral g's. The force is always "downward" no matter how far you're leaned (until you lean too far and lowside).

Cars, however, with their four wheels on the ground, cannot roll as effectively, hence "centrifugal force."
posted by Eideteker 15 July | 14:15
There was a PBS special a while back about a plane crash investigation--something about the artificial horizon being busted, flying at night, going into a smooth banked turn... the wings were nearly vertical before anyone noticed. Dangerously delusive, for sure.
posted by mrmoonpie 15 July | 15:23
Atom Eyes--yup.
posted by mrmoonpie 15 July | 15:31
This is the one I was thinking of--not quite how I remembered it, but related.
posted by mrmoonpie 15 July | 15:43
More interesting that the barrel roll in mrmoonpie's link is the first 12 seconds of the video, which is actually a VMU (velocity minimum unstick) test, which is actual proof of the lowest speed at which the aircraft can become airborne.

The aircraft is not really under control at all for the first few seconds of flight- look at the uncommanded right turn (roll) after liftoff (at 7 seconds into the video) that Tex has to stop by judicious application of left rudder. Look closely and you'll see the yaw, which rights the wings because the outside wing on the turn speeds up relative to the inside one, producing more lift.

At the low speed and high angle of attack in this test, using the ailerons to try and correct the roll would be fatal, as the increased down aileron drag on the low wing (down aileron meaning downward deflection) would stall that wing, leading to an incipient spin (which of course would not develop since the airplane would crash first.)

This is why test pilots get paid well.
posted by pjern 15 July | 17:47
Cool story and very well-written.
posted by dg 15 July | 17:49
Of course, if you really want to talk about coordinated flight....
posted by pjern 16 July | 02:45
This is a sad thread... || The Social Network is for creeps.

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