[EMAIL PROTECTED] wrote:
..to make formation flight realistic, we also need to model downwash and
wing tip vortices. Meanwhile, have fun and join in developing it. ;o)
Jetwash too. From what I understand, that can really ruin a nice formation.
Oh, you seem to be experts. I can imagine what effect jetwash has (fast hot
air surrounded by stagnant cold air). But what consequence do wing tip
vortices have to the aircraft? Does it mean to have more aerodynamic
resistance at a specific amount of speed?
There's a pretty famous story of some C-130 (I think) pilots who rode
through a 747's
wingtip vortices about 2 miles ahead of them. Their aircraft was
totally destroyed,
did about 5 rolls, and they were barely able to get it on the ground in
one piece.
I think the wing spar partially broke during the landing, and the
wingtips were
just about touching the ground when they stopped. They were very
skillful in
remaining airborne until they punched through the other side of the
vortices without
causing complete failure of the airframe.
So, the wingtip vortices have been describes as "awesome horizontal
tornadoes"!
There's a picture that was in the Smithsonian/Air & Space magazine a
couple of
years ago, of an Ag Cat with red dye in the sprayers, and it painted a
3-d picture
of the vortices trailing it. It was totally awesome, the vortices
formed a pair
of counterrotating funnels whose diameter a little behind the tail were
equal to
the length of each wing!
Here's some related photos :
http://www.dfrc.nasa.gov/Gallery/Photo/B-727/HTML/ECN-3831.html
http://www.professionalpilot.ca/aerodynamics/drag/induced.htm
I'm still looking for that Air&Space photo on the web.
Jon
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