air show jets

[mstram]

Yesterday was the first of 3 days for the Toronto Air show.

Pefect weather for it, 20deg C / severe clear and sunny.

Watching the mil jets, during the high speed / high G manouvers, a "white layer" was visible on the wings.

Is this a "shock wave" caused by supersonic / trans sonic flow over the wings ? ... and the prelude to a sonic boom ?

Mike

[ 02 September 2001: Message edited by: mstram ]

[LAN]

Could be some new secret camouflage system... :D

...but more likely is just the low pressure over the wings causing condensation of the airs moisture. You can see the same thing happening at / near the wing tips and leading edge extensions along the body (e.g. F/A 18). When the aircraft is pulling high G, the AoA is pretty high, leading to greater pressure difference between upper and lower wing surface (or lower and upper if inverted :D).

... I, eer, think...

[Genghis the Engineer]

Ivan is quite correct, it's properly called "Condensation Shock", back in the mists of time (the 1950s anyway) before Schlieren photography was invented, it was used in transonic and supersonic wind tunnels for shock wave visualisation.

I can't find the equations to hand, but it occurs at a given combination of *local* Mach number, relative humidity, and temperature.

G

[Flight Safety]

If I may be permitted to get a little off subject, has anyone seem the F-104 Starfighters at an airshow yet?