Blade Icing

[slick1537]

Basically from what I learned, icing is requires 3 things, visible moisture, temperatures near or below freezing and a freezing aircraft surface.

 

I know it probably varies by atmospheric condition, obviously we go relatively slow in piston helicopters so structural icing probably isn't of to much concern, but the main rotor and tail rotor spin very fast. Is there a rule of thumb about which temperature ABOVE freezing is safe to fly at? Basically what I am asking is, at what temperature will the main/tail rotor blades drop below freezing, even though the ambient temperature is above freezing by a few degrees.

[Mike Murphy]

Temperature is temperature...speed has no effect except for frictional heat. "Wind chill" is specific to living organisms only. Inanimate objects do not experience it.

 

So except for friction and variation of surface temp due to engine exhaust etc, if it's 32 degrees OAT, all parts of the helicopter are roughly 32 degrees, blades included. The shape of the surface and it's relation to airflow will have a great impact on ice formation

[slick1537]

As air accelerates over the top of the blades, it cools doesn't it? Couldn't this drop the temperature of the blades to below freezing, if the ambient temperature is already near freezing.