This stuff
took about 1 hour, mostly around FL150 / -15C to turn into a smooth 2-3mm thick coating, and then another 3 hours (mostly at FL200 / -22C) to come off completely.
That’s because it was so cold up there ;-)))
How much airspeed did you lose?
I once departed from Innsbruck at around -20°C and picked up a slight amount of ice, which was gone again in less than 5 minutes…
I had some ice too on the flight back from Dresden, in FL 120. It was really not much, .. immediately lost 10 KTAS.
Temperature is definitely not what prevents ice form subliming so I join Peter in wondering: what does influence it? Humidity?
Airspeed loss was below what I would notice given the loss due to altitude… maybe a few kt?
My guess: the airspeed loss is less on the fat TB wing than on the faster/thinner Cirrus Wing. Agree?
Snow sublimates a lot faster when it is exposed to wind.
There’s a research paper on it: http://arc.lib.montana.edu/snow-science/objects/issw-1992-011-017.pdf
I would say that IAS would have an affect on the sublimation rate?
[ local copy added – Peter ]
I seem to recall it is driven by IAS, temperature, humidity and wing shape.
