Soaring Safety

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

Noel,
You do make in interesting point in making that distinction. In that
situation , rolling inverted so as not to stall the mountain side wing
would seem the best way out alive without stalling or more probably
spinning in.

The main hindrance I think is most pilot's reluctance to actually
deliberately go inverted and steer from that position and without
stalling while inverted.

I'm interested in thoughts on this issue, am I nuts?

On Feb 15, 11:43 pm, tommytoyz wrote:
The main hindrance I think is most pilot's reluctance to actually
deliberately go inverted and steer from that position and without
stalling while inverted.

I'm interested in thoughts on this issue, am I nuts?

Its been proven how much lower the survival rate is for people who
haven't had spin training and get into a spin.

Do you really want to advocate that people should go into an unusual
attitude that they are neither used to nor is their glider rated for,
in a moment of confusion and stress? Can we expect them to stay
oriented? Can we expect their aircraft to perform well invertted?
Can we expect their aircraft to hold together under negative "G" loads
while invertted? (especially if this is a rough/strong day on a
mountain ridge)?

--Noel

Any chance of getting a link to the source of these
numbers.

I just got the official statistics of Germany for 2007.
20 fatal accidents with German gliders involved
(compared to 10 in 2006).
15 of them abroad, 12 in the French Alps.
------------------



Daniel Scopel
Silent 2 Targa
C-GODY serial 2027
Volez souvent et soyez prudent.
http://pages. videotron. com/dscopel/

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

At 16:24 16 February 2008, Jj Sinclair wrote:
I actually saw Tom Madigan hit the Whites just east
of Bishop.

I dont think anyone has discussed airspeed in this
thread. My glider has crap airelon authority at 50kts
but at Va it is very good. Isn't safety near rocks
a factor of speed? If you are belting along at a Va
would you not be able to pull up / fly away from the
cliff if you needed to?

Jim

On Feb 16, 9:04*am, Jim White
wrote:
At 16:24 16 February 2008, Jj Sinclair wrote:

I actually saw Tom Madigan hit the Whites just east
of Bishop.

I dont think anyone has discussed airspeed in this
thread. My glider has crap airelon authority at 50kts
but at Va it is very good. Isn't safety near rocks
a factor of speed? If you are belting along at a Va
would you not be able to pull up / fly away from the
cliff if you needed to?

Jim

Sure Jim, but these guys were trying to climb and flying fairly slow
in weak slope lift ond/or trying to work weak thermals. You bring up a
good point though, I never slow down below 65 knots on my first pass
across a piece of ridge that I haven't made at least one pass by to
check for squirrely air.
JJ

On Feb 16, 12:43*am, tommytoyz wrote:
Noel,
You do make in interesting point in making that distinction. In that
situation , rolling inverted so as not to stall the mountain side wing
would seem the best way out alive without stalling or more probably
spinning in.

The main hindrance I think is most pilot's reluctance to actually
deliberately go inverted and steer from that position and without
stalling while inverted.

I'm interested in thoughts on this issue, am I nuts?

Have you ever had any aerobatic training in a glider? Or a power
plane?

I have. What you suggest is extremely dangerous, and unlikely to work
with a glider due to their extremely slow roll rate and extreme
negative angle of attack needed when inverted - combined with limited
elevator authority. As well as being extremely disorienting.

In addition, while most gliders are extremely spin resistant right
side up, they will spin in a heartbeat inverted (think anhedral and
wash-in).

So yes, in this case, you are nuts! ;)

But please, if you get a chance, get some glider acro training and see
for yourself, at a safe altitude, in a proper acro glider (which most
XC ships are definitely not).

Cheers,

Kirk
66

Ok Kirk,
I concede it is a very dangerous and likely nutty idea. But when
you're roll authority is gone, is smacking into the mountain a better
alternative? Maybe the chances of coming out are not good, but isn't
it better than certain doom?

When you're suddenly looking at the mountain slope and the mountain
side wing is going down, despite full input to the opposite, what is
the best alternative? We have discussed how to avoid getting into this
situation, my suggestion is what do you do when you encounter it
despite all efforts not to get into one.

This may not even be an idea to pursue, but just maybe it's a chance
to NOT crash into a mountain in an emergency situation.

Like I said, it may not be a good idea nor am I advocating people do
this. But those who say it's nutty, of those I ask, what is the better
alternative is the exact same situation?
Tom

On 16 Feb 2008 12:59:45 GMT, Dan Silent
wrote:

Any chance of getting a link to the source of these
numbers.

As far as I know they are not on the web yet, unfortunately - I got
them during an CFI training one week ago on paper only directly from
one of the German fligt safety commisioners.

They are going to be published on bfu-web.de - please send me a
reminder if you cannot find them there within a couple of weeks (the
site is in German only).




Bye
Andreas