Hi List
Last tuesday night this drag chute issue came up again on the chat line. As a
person that see's every run on the dry lakes and at Bonneville from my seat in
the
timing trailer I would once again say a couple of things.
When the chutes first started coming out in the early sixties on the salt it
was a
guessing game as to size, mounting, weather to pull it under power, or during
decelaration, how long the tow line should be etc.
Jim Deist has more experience then anyone on high speed chutes. He was the key
player for a lot of the pioneers on the salt and the lakes. The drag racing
scene
is a whole different world. The cars are basically the same by class design, and
are under different course conditions. Our courses are 1 3/10 long on the dry
lake
to 13 miles long on the salt.
The winds can very from a cross wind to a tail wine from one run to the next on
the dry lake. At Bonneville along the long course from start to turn out 7 miles
down the course the wind, depending where you are can be blowing different
directions as you make the run
Other then the typcal questions and many answers about chute mounting, tow line
length, size, type of canopy the other thing that is a critical factor is taking
proper care of the chute during and after the exent.
The conditions we run under are far different than drag racing. So forget about
drag racing. At El Mirage and Muroc we run under two differnt kinds of desert
dirt. The dirt at El Mirage is more gritty and at Muroc a fine talcum powder
like
base. Muroc is more dificult to get rid of on anything. El Mirage is dirty but
can
be cleaned a lot easier.
Now Bonneville is a different story all together as far as chutes. There are
vehicles that only run on the salt and the chutes and maintaing them are a
little
different. The salt can be very dry as the this year or wet as past years.
Regardless the chute must be clean, dry and properly packed to function well.
We in the tower see some very scarry chute deployments and some picture perfect
ones. Some come out in a blob and bounce along the course, others fly high and
whip or lift the back of the car off the ground, some spin and choke the canopy
down, and some simpley drop the pilot chute out and nothing happens. A lot of
times a small burr on the release cable will not pull through the nylon loop,
other times the chute pack is dirty, wet or starched with salt and let dry in
this
condition.
Simply rinsing out the chute will not always assure the chute is going to work.
I
have seen on several occasions chute panels rip and cause the car to veer off
course. he main reason is the panels when folded are not dry and the seams or
fold
with the starch effect allows the tear to start a little easier.
At El Mirage because the events are smaller and closer to everything as well as
almost every run on video tape the drivers can see whats going on with their
car.
We in the tower make note of anything unusual and then notify the crew in the
push
truck and the inspectors. There have been several cases that we could see
daylight
under all four wheels on cars. Short tow line, mounted to low, canopy to large
for
vehicle, it goes on and on.
The driver don't always know whats going on as he is busy getting things shut
down
ond trying to turn out. The point here is there is never going to be a perfect
answer to how to mount, size, tow line length etc. But we try to help from our
standpoint in the timing stand to let everyone know when we see a problem.
everything is critical at speed, everything is critical on how well it's
maintained.
If you are not sure what the vehicle send a crew member down the return road and
have them watch the car during shut off. Get a better idea what the car is
doing.
Don't just put on a surplus chute and think it will work in a emergency. It
won't.
Get used to using the chute every run as some time you might need it when the
car,cockpit is filled with dust or smoke. Having to look for something like the
chute release is poor under these conditions. It should be automatic as is using
the brakes. It could save a lot of problems.
If you still have questions, ask the racers who over the years worked with the
experts and found thie chute can be your best friend or your worst night mare if
not correct for the vehicle. This site can get you a wealth of information or
where to go for it.
Glen Barrett
Chief Timer SCTA / BNI
DOUG ODOM wrote:
> Wes; My $.02 worth. The big difference between drag cars and LSR cars
> is the size of the tire you have on the ground and the weight of the
> car. I don't know of many drag cars that run 7 or 8 hundred pounds of
> ballast. On the really fast LSR cars I would think they would copy the
> Air Force or space shuttle type of parachute deployment. The other day
> on TV I saw the space shuttle land and the chute was out before the
> wheels touched the ground but it looked like it was rolled up so it
> unfurled and got bigger the longer it was out. Is this a way to soften
> the hit?
> Doug Odom in big ditch
>
> Wester S Potter wrote:
> >
> > List,
> >
> > This braking parachute question always leaves me wondering why the drag
> > racers can slow from 300 mph passes with a parachute time after time without
> > very many incidents. What is the big difference in slowing from 300 at a
> > drag strip and slowing from 380 or so on the salt? I'm sure I'm missing the
> > point here somewhere but something is at work on tethers and chute design
> > for land-speed applications that is primarily solved in drag racing. The
> > discussion early this year on how to find the optimum point for placing a
> > tether connection made sense as I read it. The cars that have problems on
> > the salt are primarily placing that connection in the wrong place and
> > disturbing the balance of the car at speed. I realize that drag cars differ
> > so little that once someone gets it right it's easy for everyone to do the
> > same thing. Not so with land-speed cars. The basilc ability of getting the
> > parachute to deploy and do it's job seems to be the same however. The
> > tether straps are able to handle the same loads on dragsters, ribbon chutes
> > and the cross panel chutes hold up, what is so different on the salt? The
> > Burkland's car certainly had enough thought in the design area for braking
> > but now Tom has gone back to the drawing board to see what he missed.
> > Obviously the deployment of the chutes was at speeds higher than he had
> > intended. What's the answer?
> >
> > Wes
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