Hi guys, I attended the EAA Flyin at Oshkosh, WI the last week. A new electric scooter trike mobillity assist chair thingy (Pride Revo manufactured) rescued my heart and knees and made prowling the miles of airplanes a realistic thing this year. I shot a lot of photos and have put up some of the more interesting (to me at least) on my Fotki site at

http://public.fotki.com/benlanterman/2004_eaa_flyin/

One of the interesting things I saw was a result of a formation of T-28 trainers flying over with smoke systems on. The result was that if you consider the formation as being an equivalent big airplane that at every 3 or 4 airplane lengths behind the formation the smoke formed into long rectangles like links of a chain.

The ends of the chain away from the front of the formation formed the very tight vorticity action shown in the photo (I hope it will). The loose end is upwind toward the nose position. It would seem that the concept of bound vortex than extends behind the wing is real. The interference between several of the natural frequencies involved seems to have resulted in the smoke filling the center of the vortex located at every 3 or 4 equivalent fuselage lengths.

Things like this make aerodynamics interesting.

I'll also attach a photo of a warbird pulling high g's on a moist day (it rained for part of 2 to 3 days). The tightness of the wing tip vortes is a joy to see.

Also is a condition where only one tip of a four blade propellor is leaving a vortex trail. Very interesting.