Cadillac commercial accident?

[GARY BOGGS]

Does anybody have any info on a possible accident in Cle Elum
Washington?

Boggs

[GARY BOGGS]

http://www.kirotv.com/news/29479391/detail.html

Boggs

[Ramy]

On Oct 13, 7:50 pm, GARY BOGGS <waveg...@charter.net> wrote:
> http://www.kirotv.com/news/29479391/detail.html
>
> Boggs

As usual the media does not understand the difference between gliders
and hang gliders. Other articles mention glider, and since it mentions
an airport takeoff it is more likely a glider.
I am afraid this is going to be a double digit year for fatalities in
the US.

Sigh!

Ramy

[GARY BOGGS]

William Lynn Weller in his DG 1000

RIP

My condolences to his family and all that knew him.

I am very anxious to find out who was in charge of this auto tow
operation and how much experience they had. I sure hope the Cadillac
add people weren't running the show there. Cle Elum is only a 2500ft
strip. What kind of release, if any, were they using on the Caddy.
What kind of rope were they using and what were they using on the
glider end. This add agency contacted me to do the add and I told them
that ground launching was very serious and that they needed to be sure
they used people that knew what they were doing and had a lot of auto
towing experience. I sure hope they did.

Boggs

[mark...@aol.com]

Condolences as well.

If you want to wreck an aircraft, get out some cameras....

[mark...@aol.com]

On Oct 13, 10:05 pm, "markgr...@aol.com" <markgr...@aol.com> wrote:
> Condolences as well.
>
> If you want to wreck an aircraft, get out some cameras....

And add some non-reality based Hollywood types and some art directors
who didn't take physics in high school

[2G]

Here is his web site:

http://www.nwsoaring.com/

[Awards Chair]

On Oct 13, 11:34 pm, 2G <soar2mor...@yahoo.com> wrote:
> Here is his web site:
>
> http://www.nwsoaring.com/

Another CFIG is gone! We lost more CFIGs/commercial pilots than any
other pilots this year. Yet some people still claim that accidents are
only due to lack of good training. At this rate there will be no one
left to train us...
This really sucks!

Ramy

[noel.wade]

>
> And add some non-reality based Hollywood types and some art directors
> who didn't take physics in high school

Yes, because wild speculation is ALWAYS a good thing to do, when it
comes to aircraft accidents...

Come on people (you, too, Gary) - we don't know what happened. We
don't have facts. We have no clue what the cause was or what people
were doing with gliders, cars, ropes, or anything. We don't know if it
was pilot error or mechanical problems, and guessing about it or
admonishing people that may or may not have been involved helps NO
ONE.

--Noel

[GARY BOGGS]

Noel, I heard Lynn was also a member of the Evergreen Soaring Club?
Did you know him? How much ground launch experience did Lynn have?
Do you know who else was involved in shooting this ad? How many
glider hours did Lynn have? Can you add anything about his
background? The picture in the news articles appears to show the
glider with police tape around it, but it does not look very damaged.
It's hard to imaging that that glider was involved in a fatal
accident, if indeed that is a picture of the accident site.

Boggs

[danlj]

On Oct 13, 10:01 pm, Ramy <ryan...@yahoo.com> wrote:
> On Oct 13, 7:50 pm, GARY BOGGS <waveg...@charter.net> wrote:
>
> >http://www.kirotv.com/news/29479391/detail.html
>
> > Boggs
>
> As usual the media does not understand the difference between gliders
> and hang gliders. Other articles mention glider, and since it mentions

> an airport takeoff it is more likely a glider....
>
> Ramy

Looks like a glider - http://media.komonews.com/images/111013_glider_crash.jpg

[brianDG303]

Gary,
Lynn was a member of Evergreen Soaring. He had a lot of hours and was
a very experienced, active CFIG and was considered to be a very safe
pilot. He was a good guy.

The other questions you are asking we don't have answers to because
this happened at 4 pm yesterday, and in any case it is under
investigation by at least two federal agencies.
Unfortunately we have seen this play out before, and there is a
natural tendency to react, probably some adrenaline as well, and that
leads to a lot of emails, posts, and phone calls. I am already
starting to feel like a clearing house for information that I don't
even want. I personally think it is best to just wait and reflect on
all the issues that this brings up, whatever those happen to be for
each person. In a week or two we will know most of what everyone
knows, and then we wait for the NTSB report. If you can, I encourage
you to wait for accurate information.

Please fly safe,

Brian Hood, President
Evergreen Soaring

[noel.wade]

I echo Brian's statements, but let me try to answer your questions
again (and put this to rest for now):

On Oct 14, 7:31 am, GARY BOGGS <waveg...@charter.net> wrote:

> How much ground launch experience did Lynn have?

The man who knows the facts about that is dead. And none of us are
privy to his logbook. We have no clue what happened in the moments
leading up to and including the crash, so we have no idea if his hours
or experience mattered. We have no idea if this was even a "ground
launch". You are making assumptions in the absence of facts.

> Do you know who else was involved in shooting this ad?  

What does it matter? Knowing that does not help us in any way, unless
you are looking for someone to scapegoat. But we don't even know what
happened. So placing blame is not only pointless, it is dangerous.
We don't even know if they were actually shooting the ad at the time
of the crash. You are making assumptions in the absence of facts.

> How many glider hours did Lynn have?  

The man who knows the facts about that is dead. And none of us are
privy to his logbook. We have no clue what happened in the moments
leading up to and including the crash, so we have no idea if his hours
or experience mattered.

As hard as it may be, please just wait. Let the investigators do their
job, and let the facts come out. In this day and age those facts will
be rapidly reported and repeated once they are known. Until then,
trying to make any kind of commentary on the accident or take
"corrective action" is reckless and irresponsible.

--Noel

[GARY BOGGS]

On Oct 1  If you can, I encourage

> you to wait for accurate information.
>

OK, I have accurate info now. They were attempting to get a shot of
the Escalade launching the DG-1000. They were using a 200' rope.
Lynn pulled up very sharply, the rope broke, and there was
insufficient altitude for the glider to recover. The glider nosed in,
destroying the cockpit. EMTs were on site, but were unable to revive
Lynn. No one on scene had very much ground launch experience. I sure
wish I had been there... I am so upset that this happened in my own
back yard. If I had only known this was happening up there, I would
have come up. Hind sight is always so painful. I feel for all of you
that were involved. Talking to someone that was there, it was not a
hap hazard operation and they were thinking about safety very much.
They just did not have anybody with enough ground launch time present.
Thankfully he was alone in the cockpit.

I am so sorry for everyone involved in this accident. Feel free to
call or email me anytime.

503-708-8869

Wave...@charter.net

Gary Boggs

[Bart]

On Oct 14, 9:13 am, GARY BOGGS <waveg...@charter.net> wrote:
> OK, I have accurate info now. They were attempting to get a shot of
> the Escalade launching the DG-1000.  They were using a 200' rope.

200'? Or 2000' ?

Bart

[GARY BOGGS]

two hundred foot rope.... Like I said, I wish they had called me in
to help.... I have more ground launch experience than anybody else in
this neck of the woods, but then it's easy to say that now. I had no
idea this was going on or I would have dropped everything and drove up
there. If you don't know what you are doing, call in someone that
does.

Boggs

[Brad]

considering the length of the airfield, probably not 2000'

http://www.airnav.com/airport/S93

Brad

[noel.wade]

On Oct 14, 9:13 am, GARY BOGGS <waveg...@charter.net> wrote:
> On Oct 1  If you can, I encourage
>
> > you to wait for accurate information.
>
> OK, I have accurate info now.

GARY - NO YOU DO NOT. You are still operating on second-hand
information. You are still making assumptions (or the person you
spoke to was). You were not there. And neither you nor the person
you heard this from was in the cockpit with Lynn.

This is a global newsgroup. GLOBAL. It can be read and searched by
anyone. When you propose second-hand information as factual (as you
have just done), you create considerable potential for further
damage. Journalists can read this. Potential litigants (lawsuit-
filers) can read this. Anti-General-Aviation groups can read this.
All it takes is one little Google search.

What you are doing helps no one and can lead to a lot of potential
harm. Please stop spreading information that you cannot guarantee is
factual.

--Noel

[Bob Kuykendall]

On Oct 13, 10:05 pm, "markgr...@aol.com" <markgr...@aol.com> wrote:

> If you want to wreck an aircraft, get out some cameras....

Off topic, but:

I knew a pilot whose last words actually were "watch this."

Bob K.

[Liam]

On Oct 14, 10:07 am, Bart <bart602214...@gmail.com> wrote:

It would be hard to get a good camera shot with the glider 2,000 feet
behind the Cadillac.

[GARY BOGGS]

I am very sorry for all those involved in this terrible accident. I
know that everyone must feel terrible today. I KNOW that they thought
they were being very safe. They are good people, good pilots, safe
pilots, careful pilots. They had no idea that what they were doing
would lead to the death of a good friend. They did not know what they
did not know. They know it now. I think we should all be able to
learn from the mistakes of others. It is VERY easy to F-up. Any of
us is capable of letting our guard down, and all it takes is a
second. It's too late now for Lynn, but not for the rest of us. Get
more training if you don't know what you are doing. I hope there are
no law suites from this tragedy, but lets not let the fear of
litigation keep the rest of us from being better pilots. I sure wish
I had been there... You sound very scared Noel. I really hope you guys
are going to be alright.

Boggs

[Greg Arnold]

On your view, no one can ever think about this accident.

[GARY BOGGS]

I don't like the sound of my last post. I am not trying to make
anybody that was involved feel any worse than they already do. I
really just want us all to learn from this.

DO NOT TRY TO TEACH YOURSELF HOW TO DO THINGS IN THIS SPORT! GET
HELP.

Those involved had no idea what was about to happen because they did
not have the training or experience to know. They thought they were
being careful. They really did. They are all good people, smart
people, careful people. They didn't know what they didn't know.

Boggs

[GARY BOGGS]

My last post didn't come up for over an hour so I wrote the one that
comes before it.

Sorry for the confusion.

It is my opinion that we be open and honest about accidents. I know
others disagree with me on this and many other subjects. I will not
attack them because I think it is OK for people to disagree. Lets
keep this on the subject and not attack each other, OK?

Boggs

[Gary]

Not a comment, not a speculation, but a small observation......"IF"
the picture is of the crash scene, it "appears" that the starboard
dive brake is deployed and the port is not.

Gary Adams

[Bob Kuykendall]

On Oct 14, 1:48 pm, Gary <garra...@gmail.com> wrote:

> Not a comment, not a speculation, but a small observation......"IF"
> the picture is of the crash scene, it "appears" that the starboard
> dive brake is deployed and the port is not.

I wouldn't read too much into that. I've noted many crashes in which
one wing is bent back in such a way as to disrupt the airbrake
controls at the root rib. So the asymmetrical airbrake deployment
could be an effect, and not a cause.

Thanks, Bob K.

[Ramy]

Any second hand information is more accurate and more useful than most
NTSB reports I read about glider accidents. Timely discussion is the
most important thing we can do to learn and make our own decisions.
Thanks Gary for your timely updates.

Ramy

[Ramy]

My thought exactly.
I am trying to be respectful and not voice my opinion about it.

Ramy

[Ramy]

In a sport like owers, knowledge is everything. What you don't know
will likely kill you. As such, we should all make sure to be as
knowledgable as possible with what we doing, and don't attempt what we
don't know. In my opinion, it all starts with the first sentence that
many of us heard when we went to the gliderport the first time "the
driving to the airport is more dangerous". Many still believe in it. I
did, until the first accident I heard about shortly after I started.
With this attitude, we let our guards down.
Before Noel attacks me, my comments above are in general and not
related to this paricular accident.

Ramy

[Eric Greenwell]

The runway is 2550 feet long, too short for 2000 feet of cable and a
standard auto launch.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

[Bob Kuykendall]

On Oct 14, 1:06 am, "noel.wade" <noel.w...@gmail.com> 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.

[Walt Connelly]

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=biS1ncqw-g8&feature=player_embedded




--
Walt Connelly

[Caterina Jardini]

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

[John Cochrane]

On Oct 15, 4:09 pm, Walt Connelly <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

[ContestID67]

On Oct 15, 4:09 pm, Walt Connelly <Walt.Connelly.
8dfe...@aviationbanter.com> 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

[ContestID67]

> 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/Ch03LinearMotion/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

[Martin Gregorie]

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 |

[Marc]

On Oct 16, 8:06 am, John Cochrane <john.cochr...@chicagobooth.edu>
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

[Peter Scholz]

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

[Bart]

On Oct 16, 8:09 am, ContestID67 <jhder...@gmail.com> 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

[Andy]

On Oct 16, 8:40 am, ContestID67 <jhder...@gmail.com> wrote:
>  Someone check my math.

For constant acceleration the average speed for a run that starts with
zero speed is half the end speed. The Escalade does 0-60 in under 10
seconds I think. Assume 10 seconds and add 25% for the extra mass of
the glider and that gives a ballpark zero to 60 mph distance of
88*12.5/2 ft = 550ft. That leaves enough room to get down and
stopped. However, if the goal really was a turn back, I'd assume the
intention would have been to be at winch limit speed with as much
altitude as possible. Guessing winch redline at 90mph that would use
up about 825ft. Still enough to get down and stopped but not a
situation where I'd be tempted to try a turn back.

However, If the run reached winch redline at the point where the tow
truck had to start maximum braking to stop before the end, then the
runway available for a turn back looks much better. At winch redline,
and with say 100ft of altitude, the available energy is looking
comparable to an aerotow rope break at 200ft. (Ballpark you have half
the potential energy but over 2 times the kinetic energy). Someone
knowing the winch redline and the normal aerotow speed could run the
numbers.

Not saying I'd want to try a turn back under those conditions but the
idea may not be as stupid as some are suggesting.

Andy

[Bill D]

I've done many auto tows with an aero tow rope but never in a scenario
like this. My tows were to just so I could glide down a long taxiway
to the ramp and stop in front of a hangar saving the walk back. The
climb was very shallow with a slack rope release when I thought I had
enough height - usually about 170' AGL. Then never a turn more than
30 degrees until touchdown. It was fun and safe.

This was obviously neither. I'm afraid it was one of those, "It can't
be that hard" situations. Excellent, in depth training is the key
to safe ground launch operations. Given that training, winch launch
can be safer than aero tow judging by the German experience. DIY
training can be deadly as we've seen.

Most ground launch accidents don't involve the launch - more than 80%
are landing accidents where the pilot gets safely airborne but can't
manage a safe landing. Usually, it's because the pilot had no plan if
the launch didn't go as expected. A launch failure doesn't mean a
safe landing is impossible - or even difficult.

The best this pilot could have hoped for is to be at 170 feet AGL
2000' down the runway then try for an aero tow-like turn to a downwind
landing. Doable? Maybe, by an experienced pilot - but with no safety
margin whatsoever.

[Andy]

On Oct 16, 12:58 pm, Peter Scholz <nos...@somewhere.com> wrote:

> 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.

That answer does not seem reasonable since it implies a limiting cable
angle of 30 degrees to the horizontal. Anyone who has observed a
winch launch knows the normal cable angle at top of the launch greatly
exceeds 30 degrees. If the limiting cable angle is conservatively
assumed to be 60 degrees then a 200ft rope would give 173 ft of
altitude if the climb profile was flown correctly.

Andy

[Peter Scholz]

You have to add the rope angle and the plane angle (measured against the
ground), the resulting angle is the angle between the rope and the
plane. The shorter the rope, the earlier you get to a resulting angle
that gets near 90°. Typically, a Tost hook will release a bit earlier
than 90°.

In a typical winch launch, with rope length more than 2000 ft at the
beginning, and more than 1000ft at the end of the launch, increasing the
angle of the plane does not release the Tost hook in the climb phase,
because the rope angle is much smaller than in the 200ft example that we
have here.

[Andy]

So the answer is clear. To achieve maximum altitude on a short rope
auto tow do not use high pitch attitudes. The original question was
- what is the greatest altitude that could be reached with a 200ft
rope. My answer of about 173 feet is close to the experience
reported by Bill Daniels. Assuming a back release angle of 85 deg and
a rope angle of 60 deg gives a release pitch attitude of 25 deg. The
climb could be made at much less than 25 deg pitch.

As I said in my first answer "if the climb profile was flown
correctly". Auto tow does not require an aggressive climb profile to
reach maximum altitude as long as the runway length is not limiting.
Unlike winch launching the rope length remains constant.

Andy

[Martin Gregorie]

On Tue, 18 Oct 2011 06:28:45 -0700, Andy wrote:

>
> As I said in my first answer "if the climb profile was flown correctly".
> Auto tow does not require an aggressive climb profile to reach maximum
> altitude as long as the runway length is not limiting. Unlike winch
> launching the rope length remains constant.
>

To me, auto-launching on a 200 ft rope sounds uncomfortably like aero-
towing on a CG hook except that now you're *trying* to get above the
'tug'. This sounds to me like a recipe for getting into the
uncontrollable sling-shot region that upsets tugs. Further, it seems to
me that if you do that to a rear-wheel drive vehicle your problems will
be compounded by a loss of acceleration due to loss of traction as the
rope tension reduces the weight on the driving wheels.

[Bill D]

On Oct 18, 6:28 pm, Martin Gregorie <mar...@address-in-sig.invalid>
wrote:

Yep, but so far as I know, no one has yet upset a tow car. If the
rear end is light, the rear wheels can spin on low traction surfaces
but the solution is to fill the back end of the tow vehicle with
rocks.

[Jim White]

In Europe we now have EASA to protect us from ourselves. I am sure there is
already, or will be very soon, an EASA edict to say that we cannot launch
anything behind a car without 12 hours of training of both driver and
pilot, a written exam on the maths involved, a practical test (with annual
renewal), and a fee to pay too.

This is a shame. Many years ago a venerable pilot at my club was told by
the CFI that it was much too windy for him to fly his K6 on the local ridge
and was refused a launch.

So he hitched his trailer up to his Ford Cortina and drove to a field at
the top of the ridge. He rigged and his mate then towed him with said
Cortina towards the ridge using a standard aerotow rope. This was so
successful he did it again the next day. This sort of derring-do was what
gliding was made of then.

Unfortunately in EASA land gliding is becoming a paperwork exercise and is
getting boring. You do not know how lucky you are in the land of the free
that you are still allowed to put yourself in danger.

Jim

[John Cochrane]

On Oct 18, 10:53 pm, Bill D <bil...@comcast.net> wrote:
> On Oct 18, 6:28 pm, Martin Gregorie <mar...@address-in-sig.invalid>
> wrote:
>
>
>
>
>
>
>
>
>
> > On Tue, 18 Oct 2011 06:28:45 -0700, Andy wrote:
>
> > > As I said in my first answer "if the climb profile was flown correctly".
> > >  Auto tow does not require an aggressive climb profile to reach maximum
> > > altitude as long as the runway length is not limiting. Unlike winch
> > > launching the rope length remains constant.
>
> > To me, auto-launching on a 200 ft rope sounds uncomfortably like aero-
> > towing on a CG hook except that now you're *trying* to get above the
> > 'tug'. This sounds to me like a recipe for getting into the
> > uncontrollable sling-shot region that upsets tugs. Further, it seems to
> > me that if you do that to a rear-wheel drive vehicle your problems will
> > be compounded by a loss of acceleration due to loss of traction as the
> > rope tension reduces the weight on the driving wheels.
>
> > --
> > martin@   | Martin Gregorie
> > gregorie. | Essex, UK
> > org       |
>

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. At this point it's nearly
impossible to recover. The glider stalls and spins, resulting in the
nose-down turn reported by the observers. That's a much more common
scenario than spoiler malfunction.

It would seem easy to use a 200 foot rope to just get up to speed,
getting to no more than 50 feet and then overflying the car. Using it
to get altitude, flying a regular climb profile but doing in 200 feet
what you normally do in 1000 feet, could easily lead to the surprise
rope break or back release while still climbing, as the moment to nose
over and release would come very fast and you can't see the car.

I presume those of you who have tried auto towing behind short ropes
(not me!) were basically just getting up to speed, say to do a modern
bungee launch from the top of a hill, not trying to get to the
standard 60 degrees or so maximum altitude release point.

At least it's more plausible than a plan to do a 180 turn from 200
feet!

Presumably at least the NTSB will get to see the video and we will
know what really happened.

John Cochrane

[Mike the Strike]

On Oct 19, 7:49 am, John Cochrane <john.cochr...@chicagobooth.edu>
wrote:

A steep climb on a short rope attached to the CG hook will likely
exceed the weak-link strength (1,000 pounds?) long before you get to
200 feet.

Mike

[Bill D]

On Oct 19, 8:49 am, John Cochrane <john.cochr...@chicagobooth.edu>
wrote:

John,

Not quite...

If he really got to 170' AGL before the rope break, the glider's
attitude would have been fairly level. It's only possible to get the
nose way up early in the launch. The "CG hook" is actually slightly
ahead of the actual CG so the rope's pull will bring the nose down as
the glider reached the top of the auto tow even with full-up
elevator. Also, if the rope angle is near 70 degrees, the automatic
"back release" function of the Tost CG hook will activate. Given
enough room and a knowledgeable pilot, there is nothing inherently
dangerous about an auto tow with a 200' rope.

It may have gone like this. The pilot rotates prematurely into a very
steep climb right after liftoff with the stick full back having been
trained that way launching old gliders with a nose hook or a
"combination hook". He may not have been prepared for how
aggressively a DG1000 with a true CG hook flown solo responds to full
up elevator. When the rope breaks, full-up elevator causes the nose
to "pop-up" so now the nose is up 60 degrees at low altitude. Only
airspeed and quick reactions could have saved him.

Calculations done by one of our winch engineering group show if the
glider had at least 60 knots at the break, and the pilot reacted by
pushing over at 0 G within .2 seconds, (Healthy human reaction time.)
he could have recovered straight ahead at Vs x 1.3 with a height loss
of only about 25 feet suggesting even this extreme event was
potentially recoverable if the recovery started above 25' AGL.

However, the pilot, surprised by the rope break, is unable to get the
nose down before the glider stalls. A wing drops in an incipient spin
but, being extremely spin resistant, the glider transitions into a
spiral dive almost immediately. The pilot reacts late to the
incipient spin applying spin recovery controls with the glider in a
spiral dive. The result is a turning dive into the ground.

[Papa3]

FWIW - When my college club was actively doing auto tows (2-33 with a CG hook on a 3,000 foot paved runway with 1,000 feet of overrun), we would routinely do "repositioning" tows. For example after a simulated rope break with a straight ahead landing, we would turn around and do a tow to 100 feet to get back to the staging end of the runway (as long as the tailwind was not too strong). While this was usually on the same 1200 foot rope we used for the standard tows, we sometimes used a spare aerowtow rope (for example when uncoiling the rat's nest created by a release under tension with the long rope). I remember vividly John Campbell instructing me to make a VERY gradual climb starting with stick forward and slowly rotating to a much shallower climb angle. We did this dozens of times each winter without any problems. So, I'm agreeing with Bill that it's not inherently suicidal, but like anything else it needs to be thought through.

[BruceGreeff]

I believe the attainable launch height for auto tow is between 50% and
75% of the length of the rope.
A 200 foot rope is only useful for a hop and land ahead...
On the CG hook it would have a high propensity to kite - on the nose
hook, no back release and hard to pull up. Either way it is not a "good"
approach.

Presumably they were hoping to do something similar to the Michelin
advert with the glider overflying the launching/stopping car? That was a
BMW saloon on ice, also a shortish rope, but no pull up from the glider.

I can't see any way it would be possible on a short runway, with an
extremely short rope, to hope to do anything other than land ahead.

Just my .002 Euro...

[Dan Marotta]

I once caused a tow car (Jeep Grand Cherokee) with pulley on the bumper and
rope staked down at mid field to lose traction during taping of an episode
of "Secrets of Speed" for ESPN. We were launching my LS-6a for the opening
shot. Of course the upset is not shown in the aired program, but I have the
raw footage... Emerson Fitipaldi was riding shotgun in the Jeep and he
reached across and took control from the driver.


"Bill D" <bil...@comcast.net> wrote in message
news:9fa701ce-b979-4041...@g27g2000pro.googlegroups.com...

[Steve Leonard]

On Oct 19, 11:28 am, Mike the Strike <Stringm...@msn.com> wrote:
>
> A steep climb on a short rope attached to the CG hook will likely
> exceed the weak-link strength (1,000 pounds?) long before you get to
> 200 feet.
>

> Mike-
>

Mike, how is the load on the rope higher if the rope is short than it
is if the rope is long,as you propose? Answer: It isn't. Angle of
attack (lift) and speed determine line tension during the climb.

The difference in the long rope and a short rope is that if you assume
the same deck angle for the airplane, you get to the critical back
release angle at a much lower altitude on a short rope than you do on
a long rope. Same climb rate with the same plane at the same speed
gives the same line tension on a rope that is 200 feet long or 2000
feet long. You just hit max altitude much faster on the shorter rope.

Steve Leonard

[Marc]

There are clearly some differences in the dynamics of short vs. long
ropes. In particular, the shorter rope constrains the flight path to
smaller radius, which I assume causes a somewhat greater than normal
"water skier" effect once the glider pitches up to climb attitude. I
can imagine how a heavy SUV and short elastic rope, combined with a
slight over-rotation on takeoff, could easily degenerate into rapidly
increasing pitch angle, airspeed, lift, and rope tension...

Marc

[Mike the Strike]

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

[Bill D]

Arguably, a better description is "trebuchet effect".

[Jim White]

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

[Chris Rollings]

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.

[Peter Higgs]

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

[Sean Fidler]

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.

[Peter Wyld]

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 ?

[Martin Gregorie]

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.

[danlj]

On Oct 19, 9:49 am, John Cochrane <john.cochr...@chicagobooth.edu>
wrote:

> On Oct 18, 10:53 pm, Bill D <bil...@comcast.net> 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