Message posted by Scott on November 18, 2002 at 12:29:52 PST:
I remember reading about that anaylsis of the doughnuts on a rope picture. I think it was taken up in Montana someplace? Dunno. Anyway...
Just what would the observability threshold be for a pulsing jet exhaust? I'm thinking that if I can see it and photograph it, then it exists!
I leave it to the "experts" to explicate and ruminate and cogitate. Let's say that our sneaky, skunk-smelling aircraft with the fictional pulsing engine traveled 650 mph. That's what, 953 feet per second? Let's say it pulsed at twenty times per second ... that's about fifty feet between pulses--a cloud of water vapor, even one approaching 50 feet in any given dimension (diameter or whatever), would be readily visible for miles in a clear sky. At a lower frequency, fewer than 20 pulses per second, perhaps with larger exhaust bursts, and we're talking even more space between the doughnuts. The desert is full of mysteries, isn't it?
In Reply to: Re: Puffing contrail posted by robb on November 18, 2002 at 8:08:57 PST: