aurora sighting

Spike Jones (
Wed, 06 Jan 1999 22:12:57 -0800 wrote: Aurora "evidence" -- I sense you're a skeptic, too...

greg, i have an explanation for that sighting by the av week editor: here was a very credible witness, an airplane expert, not easily fooled, who saw this totally unfamiliar aircraft traverse from horizon to horizon in 35 seconds. other witnesses reported a buzzing sound, as one might expect from a pulse detonation engine.

heres my theory on that: in the desert, one occasionally enjoys a windless day where the air is so clear and calm, dust free, nearly moisture free, that distant objects seem to be close enough to touch. for those who have never been in the american western desert, it is a unique experience. go far out in the desert and enjoy something extremely rare: total silence. no cars, no people, no birds chirping or bugs buzzing. one can hear one's heartbeat. this is no exaggeration: you really can, given the right conditions. you might get days like that down there in texas.

one sighting was over the tonopah range. if it was a day like the one i describe, there would be no way to determine the distance to an aircraft flying overhead. now, suppose somebody developed a drone with a wingspan of about 2 meters, driven by a pulse det engine, made entirely of flat plates to scatter radar (like the f117). if he assumed the normal sized aircraft, he would overestimate the distance to the tiny aircraft by a factor of 4 or more, and would also goof the speed by the same factor.

a radar scattering drone could be flown over tonopah range, there are receivers and transmitters all over the place out there. the pilotless vehicle would not need to be large, so it would be a good candidate for pulse det propulsion. on the other hand, pulse det is highly unlikely to push any aircraft supersonic, so this is why i suspect the observer must have underestimated the size and distance to the aircraft.

nowthen, the mysterious part is that the observer did not report the angle between the velocity vector and the vector from observer to aircraft at the moment of hearing the sonic boom. this angle is the arcsin of the inverse of the mach number:

alpha = arcsin (1/m) where m is the mach number of the aircraft and alpha is the angle between the v vector and the aircraft direction at sonic boom arrival. or m = 1/sin (alpha) if you prefer.

this equation works regardless of the size of the aircraft or its distance. the pulse det engine would have made a hell of a racket at mach 3 (if it somehow got going that fast) but would have been silent until alpha was about 20 degrees regardless. an experienced aircraft watcher would know this, so i cant explain how it was reported that the "aurora" was travelling in excess of mach 3.

i can see why the government would intentionally create a small recon drone and fly it all over the desert, hoping many observers would greatly overestimate its speed capability, thereby providing a smokescreen for what it is *really* developing.

have you any ideas? spike