Cadillac commercial accident?

Hi Mike, I agree with what you say, that the airspeed will increase beyond
the car's groundspeed.

Typicaly if the car is doing 60 knots and the glider pitches up quickly to
a rope angle of 60 degrees, it will now be just 200 x cos 60 = 100 feet
from the car horizontally.

If it does this climb in two seconds, that means an additional 50 ft / sec
which is an additional 30+ knots. Making a total of 90 knots at the
back-release.

This makes the glider now 30 knots faster than the car, so it would
overtake the car.

Pete



My back-of-envelope analysis suggested that the angle of the short
rope at the glider would increase more quickly than that of the long
rope and that this could result in a rapid increase of tension. This
is especially true if the pilot fails to control the angle of ascent
as this change occurs, it could create a slingshot effect that
accelerates the glider and rapidly increases line tension.

We'll have to wait for an analysis of the video to really know what
happened, of course.

Mike

How true that is! :-) I still appreciate the freedom to make a mistake now and then here in the USA ;-). But I simply do not have the guts to try a 200 ft. auto-tow. After learning of this accident...I am pretty sure that never will.

We have a great amount of safety material & resources available here in the USA...I don't think regulation is the answer either.

Every time I read one of these stories on RAS about a fatal accident I am very, very saddened. And a little frightened. I did not know this gentleman. I often wonder what is it that I could be missing, or risking in my flying. What might I do to end up here as the subject of the discussion. Mid Air, Tow, Rigging error? I constantly think about these things (accidents I have read about), virtually every day before I fly. It is part of my checklist.

I think at the end of the day it simply comes down to personal responsibility. Its that simple. We want a deeper answer. We want something to blame.. But 99% of the time it is pilot error. We are all taking higher risks that the normal person. We choose to do this every time we fly.

It sounds as if this poor guy had a mechanical issue or he just made a terrible mistake. We are all incredibly vulnerable in the early phase of tow, including the tow pilot if on an aerotow. As sad as this is...many of us have probably been closer to an accident once or twice than we would like to admit. In this case he got caught on the wrong side of the same odds.

We are all our own pilot in command. Its that simple. We can all learn from it...but almost undoubtedly something like this will happen again some day (unfortunately) when the dust settles and time passes. That is what really scares me about these stories.

Wilbur and Orville used a weight dropping down a tower to accelerate their
flyer from rest in nil wind.

Wasn't a bathtub full of something dropped from the roof intended to launch
the Colditz Cock from the top of the castle ?

At 10:13 21 October 2011, Chris Rollings wrote:
Acceleration due to gravity 32 ft/sec/sec = approx 20 knots/sec. If the
system were completely frictionless and the glider had zero drag that's
still 2 seconds to accelerate from 0 to 40 knots. At an average of speed
32 ft/sec, that's 64 feet or about 20 metres, not 5. Then you need to
figure the extra margin needed to overcome the frictional losses and the
glider's drag, quite likely doubling the run and you might want a bit of
margin above 40 knots which is around Vs on most modern gliders.

I believe something similar was used somewhere a long while ago, dropping
the weight down a disused mineshaft - don't recall the details.


At 07:52 21 October 2011, Jim White wrote:
At 18:16 20 October 2011, Bill D wrote:

Arguably, a better description is "trebuchet effect".

I have often wondered whether a sort of trebuchet could be useful for
launching a glider off a ridge. One can imagine a short bit or tarmac 5m
x
1m heading off the ridge and a large counter weight on a cable running
down
it. One would then only need to wind up the weight, secure it, get in,
have
some brave soul hook you up and release....

Jim

On Sat, 22 Oct 2011 05:00:56 +0000, Peter Wyld wrote:

Wilbur and Orville used a weight dropping down a tower to accelerate
their flyer from rest in nil wind.

Does anybody know when they stopped using that gravity catapult?

Wasn't a bathtub full of something dropped from the roof intended to
launch the Colditz Cock from the top of the castle ?

Yep - the bathtub was full of rocks and concrete but I don't recall
whether it was simply to be dropped off the rook or down the clock-tower.
I have dim recollections that it was to be the latter, which would make
sense: recall that the castle was floodlit to prevent escapes and that
the launch track was placed to be in shadow, so the bathtub would almost
have to be dropped inside the castle to keep it out of sight before the
launch.


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

On Oct 19, 9:49*am, John Cochrane
wrote:
On Oct 18, 10:53*pm, Bill D wrote:

So, putting this thread together it seems we have another plausible
scenario: the glider does a "ground tow" using a short rope, but
following a climb profile, with the plan being to release and then
land straight ahead. The rope breaks or back-releases with the glider
still pointing up at about 175 feet....
A nice thing, John, to bring the thread back to topic and
summarize.
There is one thing about this situaion that mystifies me: a witness
interviewed by local TV said "they had been flying about an hour"
before the accident happened. There's been no clue what actions that
hour of flying contained (or whether it existed). In any case, it
seemed to imply that the accident may not have happened on the first
go.
And, on a technical note, it *is* possible to do a safe 180 with
less than 175 ft altitude AGL, but from level flight safely above
stall speed, not from a steep slow climb.

Dan Johnson