I question the "sun-heated" part of your post. The sun heats the earth,
which in turn heats the atmosphere from the bottom up. Most ice is found in
the top one-third of any cloud. It does take a while for ice to sublimate
off...I have picked up ice climbing through a layer out of Seattle that
didn't disappear for about 30 minutes, and this was in a Baron.

Glad that it worked out, though.

Bob Gardner


"john cop" wrote in message
om...
Have been inactive for many years.

About 20 years ago, when flying up from the south, I got suckered in.
The tops slowly rose untill I was flying at over 15,000 (Mooney 201)
near Cleveland, It was clear on top and the temp was in the mid 40s
on the ground, and the freezing level was high enough so I wasn't
worried.

When cleared for decent, ice formed at an incredible rate - must have
picked up over an inch of rime in seconds near the tops. Once below
the sun heated top layer, the accumulation virtually quit. Breaking
out below at about 4,000, the temp was already well above freezing,
but no ice was dissapearing.

While being vectored into the approach, I ran some test to make sure
the plane was behaving normally and was capable of climbing. On hind
site, I should have refused the approach clearance and waited for the
ice to fall off.

Anyhow, after having read accounts about people stalling on final and
etc., I brought her in about 20 knots fast over the numbers and
chopped everything. I damn near overran a 5,000 ft. runway - the
sucker didn't want to land.

Rime ice, I have since found, can lower the stall speed (raises the
dragg). It increases the leading edge of the wing. This was verified
by test I did for a senior project in a wind tunnel using an airfoil,
rubber cement, and sugar. The Reynolds number was way off for that
test, so it could be suspect. However, I had occassion to take to one
of the crew of the icing planes over at NASA who confirmed all this
and it sure would account for my landing problem above.

Anyhow, after parking the plane, ice was still falling off in big
chunks for 10 or 15 min.