Landracing Forum
Tech Information => Technical Discussion => Topic started by: saltfever on September 03, 2010, 06:43:07 PM
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I am looking into the pneumatic chute launcher by Stroud. It operates on 150 psi air pressure but there is no mechanical backup in case you lose air pressure. It is a single point failure with no redundancy. Has anybody, using the Stroud system, come up with a mechanical (or other) backup plan?
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We use a launcher but also a pilot chute. We've had a launcher failure and the pilot chute still pulled
the chute (bag) out of the can. I can give you a hint about our launcher if you want the info. Send a
personal message.
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The Amo Steele Streamliner has air launched chutes with a third chute with a spring and pilot for a backup.
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I am not convinced I would want an air launcher unless I had a mechanical back up or pilot too.
Just as I don't use power brakes, I use mechanical brakes with redundent master cylinders.
My Stroud LSR Chute works GREAT (no launcher, but hey my max speed in the Stude is calculated at 225 with E motor) If I put the big motor in after SW 2011 , you can bet I add another Chute.
Charles
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I don't have the Stroud launcher so I don't know its mechanical design. I was thinking of adding a latched, conventional-chute-spring into the package. But don't know the design or feasibility. I am not required to have a second chute and was trying to avoid going that route in order to get redundancy.
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It still has a spring pilot chute so there will be deployment...just not as fast.
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Joe: The air-launch system has no spring and pilot chute. That is why I started this thread.
http://www.stroudsafety.com/DragChutes.html
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How about set up a mechanical push rod activated by a pull cable to serve as a mechanical backup for the air launch piston.
If you can provide enough push so that the chute "falls out" of the launch tube it would open just slower than the way it was intended.
It seems like there would be some way to mechanically push or pull the chute bundle out of the launcher if the air system fails.
The other option would be to put a fitting in the back of the air launch that would pressurize the launch tube independent of the pusher piston. This would depend on the air supply part of the system still being functional but would be an alternative to get the chute out into the air stream.
Larry
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Larry: Stroud told me the cylinder is pressurized to 150 psi. The cylinder looks to be about an inch or so in diameter so I assume there is about 150 lbs of force pushing out the chute. I don't know if the high pressure is used for speed or there is that much resistance in the chute tube. The push-rod deal might not work well if there is that much resistance. Maybe pack a couple of valve (or die) springs in there someway might do it though. I like your idea of a backup redundant air supply.
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He also has a new spring system that launches pilot only that we are using it has a air release that can be backed by mech---that is what we are going to.
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Thanks, Sparky. I didn't know that.
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The Vesco #444 liner uses a air blow out for the pilot. It shoots it out about 40 feet and in turn pulls out the main canopy. Both the low and high speed chutes employ this system. The system has a manual over ride as well.
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Panic: I was thinking of plumbing in two systems. Another supply cylinder with its own line tapped right into the deployment cylinder. IOW, the deployment cylinder would have two air lines. Each line would have its own on/off valve. Driver would only actuate one valve. The other would be the backup. But I don't like the idea of a single deployment cylinder.
Glen: any chance they might be kind enough to allow a picture of the mechanical mechanism the next time you are over there?
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That is weird...the one I have does have a spring...have to ask Bob.
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Agree. Reliable and simple. That is within my comfort level unless a pure mechanical contrivance is available. Usually, I would want a backup to have a different failure mode.
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It appears that the valve has nothing to do with it.
5. Close the pack as per Figure 27 & 28 (without the
pilot chute)
6. Activate the launcher, either spring or air, prior to
using it. For the spring launcher, remove the long
safety rod; for the air launcher, activate the air
switch to let air into the air cylinder.
7. To use the system, simply pull the ripcord handle
by the driver. This opens the pack and lets the
chutes deploy.
I would think that both the spring and the cylinder together would be the best way. If the cylinder leaks then the spring takes over. If the cylinder is working then both would eject the chute.
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I'd explain, but then I'd be wrong.
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I'd explain, but then I'd be wrong.
Try me. The subject is too valuable to not consider all ideas. :wink:
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I have a Shroud air launcher that has been flawless . We charge it before every run and have had no pressure loss, on a drag car I work on there is two parachutes that are charged by a small co2 bottle that is regulated to150 psi . This car also has experienced no failures and has been run for several years.
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Thank for the update, Mark. I was looking at your roadster pics on your website but didn't see the chute mounting. How is yours mounted? Inside a can or tube or?
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Our car has three parachutes.
The high speed and medium speed parachutes work off our nitrogen tank in the car. I will get to the parachute operation in a minute. First, the nitrogen tank feeds all air systems on the car, transmission and parachutes for example. When we are looking at the system last year the big what if came across - We added a strorage tank in the back of the car which is fed by the nitrogen bottle. It goes thru a one way valve - so if we had a catastrophic trans failure that cut the air lines we still have a charged cylinder in the back of the car. It was enough air at 120 psi to fire the chutes 10 + times.
Now the high speed and medium parachutes have a seperate hole for the pilot which is ejected by the air cylinder which pull out the main parachute. The last chute which we named the "Oh Sh*T" chute, is manual release only with no pilot but is ejected by a spring.
I can provide pictures of our setup if you like.
JonAmo
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Thank for the update, Mark. I was looking at your roadster pics on your website but didn't see the chute mounting. How is yours mounted? Inside a can or tube or?
[/quote] It is mounted just like a normal chute but I have a hole cut in the decklid that the air cylinder goes in . It is a Stroud unit that is about a 1 1/2" diameter. I will try and post some pics tomorrow.
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Nice description, Jon but a pic would be nice also. One-way valve? Is that a check-valve "T'd" into the main line from the N2 tank?
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It is mounted just like a normal chute but I have a hole cut in the decklid that the air cylinder goes in . It is a Stroud unit that is about a 1 1/2" diameter. I will try and post some pics tomorrow.
Mark, do you think the Stroud set-up could have the chute inside of a can (for aero) instead of a package on the outside of the deck lid? I was going to bury a chute tube inside of the body for aero.
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Nice description, Jon but a pic would be nice also. One-way valve? Is that a check-valve "T'd" into the main line from the N2 tank?
Yes it is a check-valve with a "T" in the main line and a 2.5 lb CO2 tank was used in the back. :cheers:
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Yes easily