Is the propeller on a light aircraft hot or cold when it's landed?
Answers:
Theoretically, the prop does warm due to friction with passing air - and another effect, compression of air against the blades.
However this warming effect is more than counter-balanced by the temperatures at altitude that chill the propeller down - add in wind-chill factor too from forward speed.
True though as mentioned - some propellers do have a de-ice element. Generally this is an electric element in the blade from the propeller hub, to a short way out - further out on the blade, centrifugal force prevents ice from forming but in close it can - so the element heats it up to prevent that.
Spinner hubs can sometimes be heated - although often this is a by-product from the hot oil driving the piston of the Constant Speed Unit - a propeller blade pitch-change mechanism that alters the blade angle to maintain a set RPM.
Hope this helps! :-)
Friction with air particles would make them slightly warm.
As with most things, the answer is 'it depends'. The tips of the prop will be the same temp as the surrounding air. The yoke, near the hub may be warmer from heat transferring from the engine. Some props have a variable pitch mechanism that uses hot oil to change the blade angle. These props might be slightly warmer after landing.
I've never touched one after landing but there's no way it is hot. I would say if it were winter, it might be quite cool. If it was flying at high altitude and descended rapidly, it should be cool. If it's flying in ice and snow it can be cold. Someone else can verify this but I believe some props are equipped with anti-icing. It seems freezing is more of a problem than overheating.
It's actually cold and may be several degrees cooler than the surrounding atmos due to it's metalic nature and the fact that air cools by aproximately 1.98 degrees per 1000 ft gained meaning that on a 10 degree day it may be 0 degrees Centigrade at 5000 ft. I've had it hot once but that was due electric heating pads on the leading edge of the prop for de-icing.
It may be a different when it's running. Never tried. I'll leave that open to someone else!
there is generally a very small yet indistinguishable difference in heat between the propellor and surrounding air
that heated oil for a governer for a fixed pitch propellor is centralized in the prop hub, and really wouldn't heat the propellor
any friction from the air is negated when you land and taxi back at low RPMs
cold.
Well, it does not matter what the weight of the plane is, the propeller will always be hot.
As with everything, it depends. Theory is one thing, actuality is something else. Going to test this next time
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