Cadillac commercial accident?

On Oct 14, 1:06*am, "noel.wade" wrote:

...guessing about it or admonishing people that
may or may not have been involved helps NO ONE.

Noel, I do appreciate your concern for those involved, and for their
friends, family, and associates.

However, I don't think it is worth the heartache of trying to police
the Internet on their behalf. It is akin to sweeping back the ocean
with a broom. All of the speculation, misinformation, and innuendo
will come out regardless. And eventually there will arise a reasonable
consensus about what really happened.

Also, I think that there is value to discussing accidents like this,
even in the absence of all of the information, and even if some of the
essential premises are incorrect. Figuring out different ways that
smart, skilled, and conscientious people can get themselves into
trouble is one of the ways that ordinary folks like me can figure out
how to stay out of trouble. It might not be the correct trouble, but
it is trouble avoided nonetheless.

Thanks, Bob K.

Some raw video from the crash scene with some comments from the NTSB investigator around the three minute mark. The comments from the guy at the very end don't seem to make sense after having read the comments thus far.

Always sad to lose a member of the soaring community

Walt

http://www.youtube.com/watch?v=biS1n...layer_embedded

I have to wonder what he was going to do if the rope did not break, at
about 150' and the end of the runway.

Mark Jardini

On Oct 15, 4:09*pm, Walt Connelly Walt.Connelly.
wrote:
Some raw video from the crash scene with some comments from the NTSB
investigator around the three minute mark. *The comments from the guy at
the very end don't seem to make sense after having read the comments
thus far.

Always sad to lose a member of the soaring community

Walt

http://www.youtube.com/watch?v=biS1n...layer_embedded

--
Walt Connelly

The NTSB comment here is chilling. Successful launch, starts a 180
turn, then the nose falls and the turn steepens to a crash. Without
arousing the "don't speculate" crowd, it sounds like a fairly classic
stall-spin, set up, as others have mentioned, by the whole idea of
launching to 200' then doing a 180 in the first place.

I hope the NTSB and SSF can get and distribute the video of this crash
taken by the cadillac team. High quality video of a low altitude stall
spin could be very useful. The two-seater on youtube is great for
seeing how insidious the event can be, and this one may be clearer.
After this summer, I suspect we will all be focusing on that scenario
in training and BFRs, even more than already.

John Cochrane

On Oct 15, 4:09 pm, Walt Connelly Walt.Connelly.
wrote:

... The comments from the guy at
the very end don't seem to make sense after having read the comments
thus far.

Walt, I think you are referring to the fellow saying, "We seen (sic)
the plane pulling up the glider and the helicopter following it,
filming it...we seen it flying around for an hour or so...".

I can only imagine that there was an earlier aero tow (or tows) to
allow some air to air video to be taken from the chase helicopter for
later incorporation into the commercial, along with the auto launch
shot later. What would be false about this editing of the footage is
the implication that the car could launch the glider such that the
aero tow footage could be reality...but what would the general public
know?

Others have commented that with a 200ft rope auto tow that this was an
"accident waiting to happen". I wouldn't know. Question: might it
have been OK if the glider (on auto tow) had only taken a very low
"hop" off the ground, releasing at 1-5 feet and then quickly landing
with the tow car pulling to the side? With the camera at the far end
of the runway this would be a dramatic shot. I worry that the
director wanted something more dramatic with the glider high over the
auto...and the pilot obliged.

Doing some (very) simple approximation math, if the car could achieve
zero to 60MPH in 10 seconds it would have traveled ~2000 feet...which
implies that the glider would have just gotten off the ground close to
the end of the runway with little time to get back down and stop the
glider. Hopefully someone did the math and the Cadillac was able to
do better than 60 in 10 (while hauling a ~1,000 lb DG-1000 from a dead
start).

I sure hope that I never see commercial brought to fuition and
broadcasted on TV but the Cadillac powers that be may not want to
anyway.

Sad news. What a year.

- John DeRosa

Doing some (very) simple approximation math, if the car could achieve
zero to 60MPH in 10 seconds it would have traveled ~2000 feet...which
implies that the glider would have just gotten off the ground close to
the end of the runway with little time to get back down and stop the
glider. *Hopefully someone did the math and the Cadillac was able to
do better than 60 in 10 (while hauling a ~1,000 lb DG-1000 from a dead
start).

No, that doesn't pass the sanity check. OK, I need a physics major to
weigh in. I found at http://www.ux1.eiu.edu/~cfadd/3050/C...tion/Hmwk.html
that the equation for "the distance a car travels under constant
acceleration" is distance = 0.5 x acceleration x time squared. So
60MPH is 88 feet/second which is an acceleration of 8.8 feet per
second squared. That makes the distance traveled to 60MPH = 0.5 x 8.8
x 10 x 10 = 440 feet. So at least getting off the ground and then
coming back down would be possible on the 2944 foot runway. Someone
check my math.

- John

On Sun, 16 Oct 2011 08:40:58 -0700, ContestID67 wrote:

Doing some (very) simple approximation math, if the car could achieve
zero to 60MPH in 10 seconds it would have traveled ~2000 feet...which
implies that the glider would have just gotten off the ground close to
the end of the runway with little time to get back down and stop the
glider. Â*Hopefully someone did the math and the Cadillac was able to do
better than 60 in 10 (while hauling a ~1,000 lb DG-1000 from a dead
start).

No, that doesn't pass the sanity check. OK, I need a physics major to
weigh in. I found at
http://www.ux1.eiu.edu/~cfadd/3050/C...tion/Hmwk.html that the
equation for "the distance a car travels under constant acceleration" is
distance = 0.5 x acceleration x time squared. So 60MPH is 88
feet/second which is an acceleration of 8.8 feet per second squared.
That makes the distance traveled to 60MPH = 0.5 x 8.8 x 10 x 10 = 440
feet. So at least getting off the ground and then coming back down
would be possible on the 2944 foot runway. Someone check my math.

Looks near enough to Government work to me. I can also confirm that the
equation you should be using is

s = ut + 0.5at^2

where the first term (ut) is zero because this is acceleration from a
standing start, hence u = 0.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Oct 16, 8:06*am, John Cochrane
wrote:
The NTSB comment here is chilling. Successful launch, starts a 180
turn, then the nose falls and the turn steepens to a crash. Without
arousing the "don't speculate" crowd, it sounds like a fairly classic
stall-spin, set up, as others have mentioned, by the whole idea of
launching to 200' then doing a 180 in the first place.

It depends on how one defines a "successful" launch. In a
hypothetical auto tow (meaning I have no idea whether this matches the
actual circumstances) involving a 200 ft rope and a moderate pitch
angle (say as little as 20 or 30 degrees) relative to the horizon, if
the rope releases prematurely or breaks, glider is now at a 20 to 30
degree pitch angle relative to the horizon, pilot reacts by bringing
the nose down to the "normal" angle relative to the horizon, loads up
the wing by initiating a 180 degree turn, then spins simply because he
missed that the airspeed decayed to below stall speed during the pitch
over.

This is one critical area where ground launch differs greatly from
aero tow. The rule of thumb is that if the rope breaks/releases while
the glider is climbing, you must pitch over to roughly the same angle
below the horizon and keep the nose there (unless the ground is going
to intervene) until the airspeed is above stall speed. The glider
won't stall as this is supposed to be a near zero-G maneuver. If you
load up the wing before airspeed exceeds stall speed, the glider will
stall instantly.

One little thing I'd think about if I were silly enough to try this
sort of thing, if I'm on a 200 ft rope and is trying to climb to, say,
150 feet, would a Tost CG hook back release before I got there?

Marc

Am 16.10.2011 21:12, Marc wrote:
....
One little thing I'd think about if I were silly enough to try this
sort of thing, if I'm on a 200 ft rope and is trying to climb to, say,
150 feet, would a Tost CG hook back release before I got there?

Marc



A rough graphical calculation that I just did shows that the Tost CG
hook will probably release at about 100 ft height above ground, perhaps
even earlier, depending on the climb angle.
--
Peter Scholz
ASW24 JE

On Oct 16, 8:09*am, ContestID67 wrote:
Others have commented that with a 200ft rope auto tow that this was an
"accident waiting to happen". I wouldn't know. *Question: might it
have been OK if the glider (on auto tow) had only taken a very low
"hop" off the ground, releasing at 1-5 feet and then quickly landing
with the tow car pulling to the side?
[....]
glider. *Hopefully someone did the math and the Cadillac was able to
do better than 60 in 10 (while hauling a ~1,000 lb DG-1000 from a dead
start).

I know from personal experience that Blanik L-13, flying behind a
Cessna 150/150, can accelerate to a flying speed, lift off, release
and land on the remainder of a 3000 ft runway with a huge safety
margin. The towplane never leaves the ground.
I think that the SUV in question would provide similar or better
acceleration.

Bart