Weird Windshear

"Roger" wrote in message
...
On 28 Feb 2005 18:19:31 -0800, "Bravo8500"
wrote:

This is just the way wind shear works. Yes, it's an extreme example,
but I've stalled in level flight at Va on a beautiful clear day.

The first clue to extreme shear conditions is the large change in
direction in a relatively small change in altitude. If you cruise at
165 into a 40 knot head wind and abruptly enter a 40 knot tail wind
you are going to lose 80 knots. If you have the altitude it will
eventually end up at the original cruise. OTOH if you went from a 40
knot tail wind to a 40 knot head wind abruptly, can you imagine what
that would do to the plane. You not only would have some extreme
turbulence, but would temporarily hit close to 240 knots which is well
above Vne.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Roger, your experience and mine are pretty much the same, but reversed.
I dropped through the turbulence of the shear from a 40+ tailwind into calm
air in just a matter of a few seconds. The result was an almost instant
increase in airspeed. The increased lift jammed me back up through the
shear -- It was almost like I had bounced off of something. The plane didn't
stall when it went back to the upper level, but thinking back it could have,
if I'd've lost enough forward speed. In any case it was a hell of a ride
for a bit.
I still had to go through the shear to get down to pattern altitude. On
the next trip down, I throttled back to just above stall. When I went
through the shear, I shoved the nose down and cut the throttle all the way
back -- then recovered into normal flight when things settled down.
What I should have paid more attention to was when my whiz-wheel told me
I had a ground speed of 155 knots. In a C-150. I dismissed it at the time as
manipulating the dials wrong.
I wasn't going to quarrel with the original poster over his assessment
of his conditions, but his was more like flying into a severe sink than into
a shear. Especially with his description of the airspeed bleeding off over
minutes while the autopilot tried to compensate. He did a good job of coping
with it in any case. I'm just picking on calling it a shear.

Casey Wilson
Freelance Writer and Photographer