1.
Do you think
that the freezing rain contained super-cooled large droplets? I understand this to be the worst and
almost impossible to create in flight tests.
I'm convinced
that it was freezing rain. Just how large the droplets, I can't say. Probably
fairly large due to the splash pattern and the extreme rapidity of
accumulation.
- Do you think that Lancair’s
being equipped with excess power (more than minimally required in STC’d
aircraft) contributed to the successful outcome
Well, I'm glad
that I didn't have any LESS power, but the fact is; no matter how much power,
the airplane was going to reach the surface in short order. I just abreviated
the approach as much as possible to have the runway under the
plane when it got to the surface.
- Could you report on the tail
plane icing? I read the story
of the prolonged climb with the ice locking control surfaces on the IV – Ice
buildup on the under surfaces, too?
I have been concerned about the tail because of the sharp leading
edges and the potential for building ice first.
The
horned pattern ("horns" above and below the LE with a forward facing concave
shape between them) was the same on the h stab as the wing. I was aware
of the possibility of freezing the controls and kept moving them rapidly every
30 seconds or so. At no time did any of the controls freeze. My elevator
counter weight is "faired" behind the h stab pretty well and, as far
as I could tell accumulated no ice. One feature of the LNC2 that probably
helped is the fact that there is not very much tail down force required to
maintain level flight. This is one of the things that makes our planes so
sensitive in pitch. In an icing situation, it probably helped prevent a
tail plane stall. BTW I have the small
tail.
4. What did the plane feel like with the initial partial extension of
the flaps – pitch
and controllability?
Controllability was good, although I didn't do a whole lot of
unnecessary maneuvering. I did bring the flaps out of reflex in order to try
to reduce AOA. I think that I got them to "0" before I accumulated the worst
of the ice. The airplane felt about like it would without ice but with
about 12" manifold pressure.
Now for the poser. This only pertains to Lancair
235/320/360s and their special wings with reflexed flaps……….
We know that these wings have
certain characteristics with the flap at zero degrees. The reflex position (-7 degrees) is
utilized to reduce lift and drag with a change in the center of lift causing a
nose up pitch (AOA change too).
This is inherent in the design.
So, when slowed down by carrying
ice would it be better to return the flaps to the zero degree position in
order to lower the nose, reduce the angle of attack and increase the
lift?
Yes, I think that this is the
best thing to do. One thing to remember, every icing encounter is
different. I'm sure that how the ice shapes itself on the LE makes a large
difference in handling and performance. The forward facing concave shape that
I encountered is unusual, I've never seen anything like that before. Tail
plane stall is a definite possibility in most airplanes with a lot of ice.
That was one of the things I was most worried about and one of the
reasons why I didn't reduce airspeed below 120 kts until at the
runway.
Bill
Harrelson
5zq@cox.net
N5ZQ 320 950+
hrs
N6ZQ IV
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