Electronic control of air flow

Hello,
I am interested in using air to launch a projectile from a remote contolled helicopter. I am thinking of using a tank of compressed air
and having a pneumatic solenoid control the flow. Does anyone know of a good supplier for such a solenoid. It would need to be able to switch positions very quickly in order to accellerate the projectile to a high enough velocity. The entire assembly will need to be very light as well, since it is going to be mounted on a helicopter. Does anyone else have a good idea for how to launch multiple tennis balls 15+ feet horizontally with considerable velocity and accuracy?
Thanks for any info, -Todd
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Have a look at the sort of valve used on compressed air 'spud guns'. The idea is to build up a resevoir at high pressure, and then let it out rapidly. These valves are usually operated mechanically, but a simple solenoid would suffice. Note that the solenoid valve only needs enough power to start the firing operation. Once triggered, the main valve flips out of the way and your compressed gas resevoir discharges down the pipe.
Making things work for multiple balls might be more tricky, and perhaps the old 'two spinning wheels' launcher might be a more practical route. You essentially trade off the weight of the motor versus the weight of a high pressure resevoir.
Dave
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snipped-for-privacy@gmail.com writes:

You want a solenoid valve with a very high throughput.
I suggest the Mead Isonic series 4 valves: we've used them in the past, they're reliable, lightweight and Do Exactly What They Say On The Can.
<http://www.mead-usa.com/products/detail.aspx?id )&type=3>
If you want *really* light valves, then you want Lee:
<http://www.leeproducts.co.uk/
cheers, Rich.
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rich walker | Shadow Robot Company | snipped-for-privacy@shadow.org.uk
technical director 251 Liverpool Road |
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How big and heavy is your Helicopter? Remember Newtons 3rd law of motion. You will only want to launch something as heavy as a tennis ball if you have a relatively large and heavy helicopter. Launching a tennis ball at much speed will probably knock your helicopter out of the sky. What country are you going to fly it in? (I believe projectiles are illegal in the U.S. Correct me if I am wrong.) May I suggest ping pong balls. I think they will fit in a standard size PVC sprinkler pipe.
Brent S.
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The helicopter is about 25 lbs. It will be flying autonomously, and has very responsive correction on the flight controller. It isn't actually going to be a tennis ball, but an object about that size. It's part of a school project sponsored by the DoD, so I think we're legal. Thanks for the input guys, I appreciate it.
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On Thu, Oct 13, 2005 at 06:36:51PM -0700, snipped-for-privacy@gmail.com wrote:

Perhaps by adapting a commercial paintball gun.
-Brian
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Brian Dean
ATmega128 based MAVRIC controllers
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wrote:

A paintball gun mechanism would probably be ideal. Could be operated from a single small light weight CO2 cylinder, and if the projectile is large and light weight with a short range, the barrel could be made from something light weight like drink bottle plastic or drink can aluminum.
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A diaphram valve is used for some confetti launchers. It is the same sort of valve as used for electrically operated Garden Sprinkler Valves. It allows a lot of air through very quickly.
I have a design for a confetti launcher on my web site using one of them. I use a 12v valve, but only use a 9v battery to trigger it.
Joe Dunfee www.dunfee.com
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