Clouds Givemethewillies
Senior Member
A weedy plane and trail, unusually low altitude. I think it was 24,000ft. at the time.
Last edited:
It is a Bombardier Dash 8 Q400 that has ceiling of just 25,000 ft. And it is seen making contrails fairly often:A weedy plane and trail, unusually low altitude. I think it was 24,000ft. at the time.
Thanks for that. I read the interesting thread. The Bombardier Dash 8 is one of the most common planes here that don't transmit ADSB so I don't normally see them on SHCC. I will have to try to add MLAT which I can get from the HTML port 8080 output.It is a Bombardier Dash 8 Q400 that has ceiling of just 25,000 ft. And it is seen making contrails fairly often:
https://www.metabunk.org/contrails-from-turboprop-planes-at-lower-than-typical-altitudes.t6082/
https://www.metabunk.org/persistent-cumuliform-contrails-at-25-000-feet-over-california.t6299/
It is a Bombardier Dash 8 Q400 that has ceiling of just 25,000 ft. And it is seen making contrails fairly often:
https://www.metabunk.org/contrails-from-turboprop-planes-at-lower-than-typical-altitudes.t6082/
https://www.metabunk.org/persistent-cumuliform-contrails-at-25-000-feet-over-california.t6299/
It could be an ice aerodynamic contrail triggered by the prop tips, as in the first post in this thread.
Seems like it's a combination. More than just propellors at least, as there's contrail coming from most of the wing.
This reminded me a series of photos that I took in Lake District on August 10, 2016 at around 6:50 UTC. It features a Q400 contrail at 23,000 ft that went "from the horizon to the horizon". A close-up of the plane appears to show the contrail being triggered by the prop tips:I can see a regular helix in the trail, in the last shot, but I might just be seeing what I want to see..
It looks like a triple helix to me (when it first appears behind the tail). It appears that the Q400 propeller blade angle is not fixed but controlled. Perhaps it could also vary between the blades, so only three blade tips were making contrails in this case:Very clear in photo #2 blown up. What is puzzling me is that they look like a 'single start thread' not a six start...
It looks like a triple helix to me (when it first appears behind the tail). Perhaps, the threads from the opposite blades merge:
A crop of a video frame.
Sorry, but I've revised my previous post before your reply. It would have to be a six start thread, but only if all blades were at the same angle. But, as appears, their angles are controlled and possibly can vary between the blades.Agreed. I am still trying to figure out what a screw thread looks like when is rotating and translating, and then frozen in time.. Should still be a six start thread, I think.