I actually saw Tom Madigan hit the Whites just east of Bishop. Most
of us thought he had experienced heat prostration, but after re-
reading Henry Combs explanation I can see that Tom might have placed
his sailplane in exactly the wrong position relative to the mountain.
It was the second day of the 1985 regionals and hotter than hell, like
105! About 12:30 we started towing to the Whites which weren't working
very well because the sun hadn't been hitting the western slopes very
long. Several of us were slope-soaring back and forth without much
success. Then I saw a ship circling and immediately headed for his
location, figuring he had finally snagged a thermal. Just before
getting there I saw the ship CRASH on a small plateau! The terrain was
about 30 degrees up slope with a small plateau of maybe 100 feet
across, then the mountain continued on up the 30 degree slope. Tom
obviously turned because he had hit lift, lets say 300 fpm. Using
Henry's explanation, that thermal would have been kicked off when
rising hot air hit the edge of the plateau. When Tom's ship got
between the thermal and the air coming down the mountain feeding his
thermal, he may have been in exactly the wrong place at the wrong
time. Let's say he had 300 fpm UP air under his LEFT wing and 200 fpm
DOWN air on top of his RIGHT wing. Old Tom might not have had the
aileron AUTHORITY to make the ship do his bidding?

Food for thought, this would explain how a relatively weak 'first
thermal' could have overpowered Tom's ship and also the Phoebus
example in Henry's article which crashed about 10:45 in the morning
JJ






On Feb 15, 9:29*pm, "noel.wade" wrote:
One thing I've wondered is whether some of these "wing lift" incidents
are actually *wing drop* incidents. *I don't have much ridge-time in
full-scale gliders, but I have already experienced some good amounts
of turbulence.

There's nothing that says a turbulent parcel of air couldn't hit the
wing that's closer to the ridge. *After all, the wing closer to the
ridge is also closer to the ground. *Accordingly, that wing is
possibly more exposed to turbulence caused by ground features - these
can extend downwind (i.e. up-slope) to a distance of 10 or 20 times
the height of the original object. *For example, a 100-foot-tall tree
can create turbulence over 1000 feet downwind of it. *When I did slope-
soaring with R/C gliders, we used to have to be VERY cautious of this
- so its always in my mind when I visually scan the ridge ahead of me
when in my cockpit.

So imagine a situation where you're getting rocked by lift and
turbulence, and all of a sudden the ridge-facing wing drops. *Could
you confidently distinguish that from a wing-lift on the opposite side
if you're going through pulses of lift and sink, or turbulent roiling
air?

Of course, there's a BIG difference in what might be the best way to
recover from those two different situations. *With a wing-drop, you
have a stalled condition - giving the aircraft full aileron to lower
the upwind wing just increases the angle of attack on the stalled wing
and doesn't make the situation any better. *And if we're close to
terrain we might subconsciously be pulling on the stick, too (again,
not helpful to a stalled wing).

...Just some food for thought that a relative newbie like me wonders
about at midnight (being a night-owl I tend to be obsessing over
gliders at that time quite frequently *grin*).

Take care,

--Noel