Author Topic: Parachute mount  (Read 9310 times)

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Offline olepaw

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Parachute mount
« on: March 24, 2012, 08:12:16 PM »
This is several questions in one.  Is it a good idea to mount the parachute in line with cam shaft of engine?  Building 87 Firebird.  Is the structure of the rear bumper bar strong enough to support the force or should it be tied to the cage of the chassis?
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Offline Cajun Kid

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Re: Parachute mount
« Reply #1 on: March 24, 2012, 08:19:18 PM »
This is several questions in one.  Is it a good idea to mount the parachute in line with cam shaft of engine?  Building 87 Firebird.  Is the structure of the rear bumper bar strong enough to support the force or should it be tied to the cage of the chassis?

1. A good rule of thumb is cam height is close to CG so that is a good height to mount the Chute anchor line.
2. Bumber bar may not be strong enough, I would not trust it to mount  anchor line,, I would mount to chassis or cage crossmember...
3. The bumper area may be strong enough to mount the chute pack, but not the anchor line.

Good Luck,,

Charles
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Offline Glen

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Re: Parachute mount
« Reply #2 on: March 24, 2012, 08:32:37 PM »
Look at attaching the tow line attachment point on the push bar. Many are done this way.
Glen
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Offline Elmo Rodge

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Re: Parachute mount
« Reply #3 on: March 24, 2012, 08:34:22 PM »
Here's a link to the formula for finding  the CG.  Wayno http://www.longacreracing.com/articles/art.asp?ARTID=22

Offline olepaw

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Re: Parachute mount
« Reply #4 on: March 24, 2012, 08:49:53 PM »
thanks i'll check, that all out.
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Offline Bob Drury

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Re: Parachute mount
« Reply #5 on: March 24, 2012, 09:17:42 PM »
  When I built my 53 Studebaker many moons ago, I mounted the tag line below the rear bumper. 
  Once I got the car to run over 200, when I pulled the chute it would pitch me forward and the car wanted to get loose at the same time.
  A few years back I moved it up to camshaft centerline by building a bracket off of the push bars as Glen spoke of.
  This raised the tag line mount 8" higher and the results are amazing.
  The hit of the chute is firm but doesn't pitch the car (or me) and the car never wiggles at the hit.
  It is a good starting point but you ought to talk to guys running simillar vehicles to yours.
  They can share their experiences with you and save you a lot of work.  Land Speed Racers, unlike most other motor sports, do share knowledge and tips with each other.          Bob
Bob Drury

Offline olepaw

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Re: Parachute mount
« Reply #6 on: March 24, 2012, 09:43:09 PM »
yea i know about sharing , we used to race circle track , and if you were fast , it was mind  game time. . i' done with that.
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Offline jl222

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Re: Parachute mount
« Reply #7 on: March 24, 2012, 11:09:20 PM »
This is several questions in one.  Is it a good idea to mount the parachute in line with cam shaft of engine?  Building 87 Firebird.  Is the structure of the rear bumper bar strong enough to support the force or should it be tied to the cage of the chassis?

   Some say from camshaft [because its figured to be close to center of gravity on most cars without a lot of scaling and math] and in line with center of parachute when open. Others say at least camshaft height.

   Check out our 222 Camaro under ''Getting ready for Bville'' in Build Dairies page 110 and the build  is the 3rd from top.

  Shows how chute pull is mounted. cam height is about 17'' in front of motor and  back ot tube were cables come out of bumper is 20''[ aproximate, no water in big intercooler tank or water tank]

   No problems when hitting chute and I opened both by accident at over 275 mph.

   Chutes are top fuel- Funny car 12 ft.

             JL222

  
« Last Edit: March 24, 2012, 11:17:35 PM by jl222 »

Offline JimL

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Re: Parachute mount
« Reply #8 on: April 01, 2012, 04:06:29 PM »
In 1996 Jim Deist told me 30 feet back from CG, 7 feet above the ground, pull a line with a string from your vertical and longitudinal CG, where the string "exits" the car is the best pull point.  Put the anchor loop on a roller to prevent friction break as the line snaps into pull.  It worked perfect every time.

He said the 7 foot number was due to chute interaction with the ground.....not a good idea.

This is from memory, folks, and the 30 foot number is a little fuzzy...might have been 35.

Someone please correct me if I'm wrong.  Thanks!!

Regards, JimL
« Last Edit: April 01, 2012, 04:09:27 PM by JimL »

Offline redhotracing

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Re: Parachute mount
« Reply #9 on: May 17, 2012, 11:00:25 AM »
Check out Wolfe Racecraft- they make 4th Gen chute mounts, maybe give
you an idea of how to best build yours. Ours is camshaft height, it doesn't
kite, deploys clean every time.
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