Why does a prop ice up so apparently readily?

"Peter" wrote in message
...
These two things combined with the fact that the
prop has a high collection efficiency because of its thin cross section

This I don't see - as it happens, the SOP for this turboprop when in
icing conditions is to go max revs, the reason being that the less the
AOA the less ice will be picked up. They also go 10-15-deg flaps for
the same reason - it reduces the wing AOA.

Changing the AOA doesn't alter the cross-section of the prop. Thinner
airfoils DO accrete ice faster than thicker ones, even as airfoils at higher
AOA accrete ice faster than airfoils at lower AOA.

Pete

Peter Duniho wrote:
"Peter" wrote in message
...

These two things combined with the fact that the
prop has a high collection efficiency because of its thin cross section

This I don't see - as it happens, the SOP for this turboprop when in
icing conditions is to go max revs, the reason being that the less the
AOA the less ice will be picked up. They also go 10-15-deg flaps for
the same reason - it reduces the wing AOA.


Changing the AOA doesn't alter the cross-section of the prop. Thinner
airfoils DO accrete ice faster than thicker ones, even as airfoils at higher
AOA accrete ice faster than airfoils at lower AOA.

Intuitively, using flaps to get a bit of lift means the wings have to
do a bit less. So, you can fly at a slower speed and get the required
lift. A slower speed means less humid air flows over the wing per unit
time. As a result less ice per unit time will be formed on the wings.

Same for the prop setting. You want to use the "climb" (max revs)
setting so that the wings don't have to contribute as much lift at a
given speed.

That being said, you simultaneously want to minimize your flight time to
allow the minimum time for ice to accumulate.