frost on the wing

In article ,
Jose wrote:

Which got me thinking - maybe the FAA isn't so crazy after all. If frost can
form while the plane is just sitting there, why could it not form while the
plane is flying? (yeah, there's some frictional heating, but we could lower
the temp a bit more, no?) And if frost isn't such a good thing to have on
takeoff, it's probably not so good in flight either.

Any thoughts? Have you seen this before?

This in-flight frost is called ice. I've never experienced icing conditions
but alway thought it was the leading edges that collect ice.

--
Bob Noel
(goodness, please trim replies!!!)

This in-flight frost is called ice. I've never experienced icing conditions
but alway thought it was the leading edges that collect ice.

Well, duh... but I'm referring to "ice" accumulation when not flying through "visible" moisture. No rain, no cloud, just clear 10 mile visibility air. And the frost was not on the leading edges (since it was not due to impact with droplets) but rather, on the flat parts of the wing which have cooled radiatively. This is different enough from regular inflight airframe ice that I thought it warranted a new word, at least for now.

Jose
--
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Bob Noel wrote in
:

In article ,
Jose wrote:

Which got me thinking - maybe the FAA isn't so crazy after all. If
frost can form while the plane is just sitting there, why could it
not form while the plane is flying? (yeah, there's some frictional
heating, but we could lower the temp a bit more, no?) And if frost
isn't such a good thing to have on takeoff, it's probably not so good
in flight either.

Any thoughts? Have you seen this before?

This in-flight frost is called ice. I've never experienced icing
conditions but alway thought it was the leading edges that collect
ice.


Can form on other parts of the wing depending on the airfoil and your speed
/angle of attack as well as the temp and the droplet/crystal size. The
inertial seperation of the moisture from the air can deposit it in strange
places. Not an issue in most lightplanes where it's going to form mostly on
the leading edge. But if you get the airplane slow you might get some on
the bottom of the wing and some airplanes, like the ATR 42, get it on the
top at higher AoAs, which is a bad thing.
Jets don't usually get ice on the wing in flight at all. They can , but
usually only on approach when they're dirty. It does happen, though.
Nothing to do with friction heating, by the way, but again, the behaviour
of the droplets as the surrounding air meets the leading edge is the factor
that dictates this.


Bertie