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Magnetic repulsive golfball launcher

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Magnetic repulsive golfball launcher

Unread postAuthor: benstern » Sun Mar 02, 2008 5:28 pm

Well I am releasing this concept to all you. It is revolutionary because it uses a new energy transfer method, magnetism.

Image

The magnets are repulsive so after the large piston builds up speed and reaches a certain predetermined point their fields will interact and move the small piston which will move the assembly and impact the golfball.

Due to the strength of the magnets no materials that reacts to magnets can be used for making it. This means using either aluminum or 304 series non-magnetic stainless steel.

Magnesium is used for the rod and impactor because it is extremely light and non-magnetic.

Service holes in the impactor and small piston would be used in conjunction with specially made wrenches to remove and install the impactor assembly.

Due to the design it will be able to launch a golfball about as far as a 5 foot long over/under pneumatic cannon. However this cannon is only 2.5 feet long at maximum. The barrel is used to direct the golfball not accelerate it.
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Unread postAuthor: PVC Arsenal 17 » Sun Mar 02, 2008 6:00 pm

I don't see any reason why it wouldn't work, but would it work any better than a say... a pneumatic?

If you need some good magnents check out http://www.unitednuclear.com
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Unread postAuthor: benstern » Sun Mar 02, 2008 6:06 pm

It should work better since it does not have to work against the compressibility of air in a deadspace. Also, the piston speed is directly correlated to muzzle velocity of the golfball. The more pressure used for the piston the faster it will go.

Forgot to mention: the energy involved when the large piston stops will be enormous. First, it's mass is huge, the magnet in the piston will be at least a half pound. Secondly, It's velocity will be very high. It will be going several times faster then regular pistons in piston valves, due to how the cannon operates. Lastly, it needs to stop in a very short space. The surface of the magnet in the big piston has to be no farther then a fourth of an inch from the aluminum wall. Such a sudden deceleration creates a great force. In all respects due to the force involved in the big piston, the "recoil" of the cannon will have the force going forwards instead of backwards.
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Unread postAuthor: pizlo » Sun Mar 02, 2008 6:13 pm

So whats your "budget" on this gun?
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Unread postAuthor: benstern » Sun Mar 02, 2008 6:30 pm

I don't intend on making it. I am an ideas man. I get great ideas but never follow most through. Thats why I share with you guys.

The few things that decrease performance in this gun is the inevitable effect of lenz's law and the friction from few inches of barrel the golfball goes though. The use of the stainless steel reduces the effect of lenz's law as steel is not as electrically conductive as aluminum.
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Unread postAuthor: Hotwired » Sun Mar 02, 2008 7:35 pm

It seems to be a short stroke pneumatic hammer.

It would propel a golfball some distance but I wouldn't bet anything on it matching a 5" over-under cannon. Maybe a human arm at best.

Same pressure and same volume chamber the over-under will waste a chunk of energy in the valve and then the rest is free to accelerate the ball.

The proposed design will use a lot of energy just in the pistons and only a small amount will be transferred to the ball. The gas doesnt have the chance to release its full energy as its trapped before and after.

So you can't be getting more energy from this to the ball than a conventional cannon.

It's an interesting design but I'm seeing significant flaws.
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Unread postAuthor: benstern » Sun Mar 02, 2008 7:57 pm

Obviously you don't understand the design. the "chamber" is seperate and sealed off from the barrel. The gas does not transfer the energy. The momentum of the large piston does.
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Unread postAuthor: ammosmoke » Sun Mar 02, 2008 8:00 pm

How would you expect to pull back the bolt??? The stupid thing would be impossible to separate!

http://unitednuclear.com/magnets.htm

EDIT: Oops repulsive. But then, what would be the point at all in using the magnets? Why not just have the piston strike the ball? Besides, if a magnet that large was used, the stupid thing would have great difficulty even working.
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Unread postAuthor: benstern » Sun Mar 02, 2008 8:44 pm

This is the most efficient ram type design I could come up with. It would work better and be more powerful then normal rams.
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Unread postAuthor: Hotwired » Sun Mar 02, 2008 9:29 pm

I understand the design.

The large piston contains a neodynium magnet and is balanced in rest by equal pressure of gas either side.

On firing the (large) pilot volume in front is released and it flies forwards to slam into the end of the chamber as the gas behind it is allowed to expand.

A smaller neodynium magnet is on a piston in front of it and it is repulsed by the larger magnet approaching it, transferring force to the golfball.


I was making a comparison, theres only so much energy in a volume of compressed gas and you're saying that by allowing it to expand less, and by consuming more energy by having trapped pistons that you're getting more energy to the golfball.
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Unread postAuthor: benstern » Sun Mar 02, 2008 9:32 pm

The large piston will have a fair bit of run-up length. (6-8 inches) That is room enough for it to get a great amount of speed. Also, the cannon is meant to operate at around 200 psi.
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Unread postAuthor: Lentamentalisk » Sun Mar 02, 2008 9:56 pm

make sure that you have holes behind where the golf ball starts, otherwise you will get a vacuum behind in and it wont go as far. Actually you should have the entire barrel riddled with holes so that there isn't a pressure front in front of the ball either.
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Unread postAuthor: clide » Sun Mar 02, 2008 10:10 pm

Aluminum and non-magnetic stainless steel can still interact with a moving magnet. http://en.wikipedia.org/wiki/Eddy_current

I agree with Hotwired. Seems like you would be putting most of your energy into the movement of the relatively heavy pistons.
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Unread postAuthor: benstern » Sun Mar 02, 2008 10:22 pm

i mentioned that clide:

"The few things that decrease performance in this gun is the inevitable effect of lenz's law and the friction from few inches of barrel the golfball goes though. The use of the stainless steel reduces the effect of lenz's law as steel is not as electrically conductive as aluminum.

That momentum is good. It will impact with great force and move the impact piston without much loss of energy overall.
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Unread postAuthor: ammosmoke » Sun Mar 02, 2008 10:45 pm

Soo what if you did something similar to your plan, but switched the magnets so that they were attracting each other? Of course you would need massive rubber padding, but what if you made the thing essentially a piston valve? There would be a pilot in front of the magnet that pushed it back, and when released the magnet would fly forward and strike the ball. Sounds a little simpler to me...
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