In the 80s, I had read an article where sonic booms had been detected by seismographs. Pictures of the craft producing the sonic booms were
unobtainable, though its contrails were visible as the "doughnuts-on-a-string" configuration. These have been speculated to have been produced by a
then "still experimental pulse-detonation engine", and had been mated to the X-Plane dubbed "Aurora". Calculations has put the speed of this
aircraft at 3500+mph, and an altitude exceeding100,000 ft. Any additional information?

The pulse-detonation engine is the simplest of all engine design. It requires only valves to allow the flow of air into a combustion chamber where it
is mixed with fuel twice (once to promote compression and then the actual detonation process) all this must be done in a fraction of a second the
repeated immediately and continuously. The results is a deafening noise when operating properly. Be useful in high altitudes, but more of a nuisance
at altitudes lower than 80K.
[edit on 18/8/04 by Intelearthling]