... donuts on a rope ...... I've seen such contrails many times and on every occasion they've been pulled across the sky by a common or garden airliner.
A few hours ago I'd have agreed with you on the likelihood of an airliner - but having read the OP's link throughout, now I'm not so sure.
The main contributor seems to know what he's talking about - and in the wilds of Nevada strange things are going down. (It may be he's even discovered the final destination of the other Valkyrie.)
Mind you, my problem is how to connect Peterborough with China Lake.
