I do not think Auroa caused this. Pulse detonation engines have to fire many times a second so you would not really see rings that are spead out like that.

No luck here, it isnt Aurora.

I've come across these 'doughnuts on a rope' contrails before, but I can't think where. Incidentally, I'm pretty sure they were in reference to the Aurora, wherever I saw them.

Will see if I can find the link I visited.

Don't forget, at the speed aurora is supposed to travel at, the donut on a string effect is very possible due to the time between detinations and airspeed.

Since the pulse detonation engine fires many times a second it would seem that the "Donuts" would have to be very close togther. They are spread out and that is why I do not think it is Aurora.

PDEs firing at 60 times per second at mach 5 in the troposphere would make them about 30 yards or meters apart. The pulses per second might be lower then that, and the speed might be higher. So if you ask me those trails COULD be from a PDE engine, but i doubt they are because i am a skeptical dude.

[Edited on 15-9-2003 by kdub]

If it's not a PDE, then what is it? A pulse detonation engine can fire at lower freqeuncies, but you just won't get the thrust. Also, from the altitude, it looks like, oh, twenty to thirty thousand feet up? The Aurora has no reason to hang around at such alow altitude. Also, the air is too dense for it to be running full-on Mach 7. I believe this is the Aurora bleeding off speed, descending to initial approach (also, given te time of day in this pic - Aurora takes off at dawn). It may be doing about Mach 3 here.

Oh, from what I gather the TR-3A/B is supposed to be a subsonic, stealthy platform, separate from Aurora/ SENIOR CITIZEN or whatever you want to call it!

on second thought arnt PDE's supposed to fire sequentially and not all at once? just 12 PDEs fireing 60 times per second, one at a time would change the distance at mock 5 between them all the way down under 3 meters. and its also true that it probably isnt at mock 5 if its at 30k feet (i had no idea how high it looked in that picture, couldnt even venture a guess) so they would be even closer than that. aint a PDE. probably just some wierd turbulence from something boring creating the doughnuts.

I've stood at airports and watched 727's make exactly that pattern. It's not pulsed, it's a corkscrew shape. If you look at the 'pulses' many of them seem to lean one way.

Sorry, this is just the result of humid air and a commercial airline angine at low speed.

I`ve seen this type of shape before and I live under major flightpaths. They look far too much like ones I see regularly to convince me they are from an xcraft.

Interesting replies guys.

I used to live close to BWI Airport outside of Baltimore. My house was right under a flight route , I could look out of my window and see the contrails. I've seen many contrails that look similar to the one in the photo. So I think it might be From a regular aircraft, Maybe one of the Janet flights.

Tim

The key would be the rumbling engine noise associated with the PDEs. I've personally never seen contrails like that before, but I guess atmospheric conditions where I live don't give rise to that.

Another point: wingtip vortices: I think I can make them out in this photo. Aurora contrails are distinctive in that they don't have any.

Also: it's way too low!