[FLOutdoorsman]

Photos taken in Ohio. Kinda goes full circle in history. Or simply nothing.

[Myrddin]

I saw what I'm pretty sure was a passing "Aurora" over Poway, CA one afternoon. The aircraft went horizon to horizon in about 10 seconds and left distinct, round white puffs behind it. There wasn't a continuous contrail as shown in the photograph.

[Joe Boucher]

I think they call it phased pulse array.

Supposed to have learned it from crashed spaceships.

[Eastbound]

Pulse or nebulizer-type pump?

[RunningWolf]

Those type formations are caused by high velocity exhaust streams out of a nozzle. As the exhaust stream cools off/slows down, it begins to form its own vortices that will curl in in on each other like you see. Due to various dynamics/irregularities in the atmosphere and the exhaust stream vortices themselves, a few will become large enough to make the donut formations that we see down on the ground.

For what it is worth, I do not see the pulse-jet as a viable platform for a M4+ engine. For one thing it would beat itself and the airframe up pretty hard, and both would have a very low service limit. I would have to think that thing would also be very un-stealthy to acoustical detection modes, maybe others too.

But if it was a pulse jet, the exhaust pulses would be much more pronounced and at regular intervals than we have always seen in these photos.

Wolf