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Check out my "PILE" Portable Induction Launching Equipment or Golf ball hits new high

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LAN_403

w1vlf

Sat May 24 2008, 08:50PM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

Guys,

Take a look at this link.

It has some pictures and explanation about the induction launcher you guys have been helping me build.
Today I had 3 launchs.
All were at 750 volts. I did not dare go any further. It was just too scary.
The average of the 3 launchs was 9.5 seconds flight. I lost one golf ball in the process, another returned to earth safely, and one found the hoood of my car some 125' away.
The ball that made it to earth safely was embedded in the ground so that none of the actual ball was visible. I could not find the ball until I nearly stepped on it.

Still a lot of improvements to make but I wanted to get something up on the web where people could see it.
OH yes.... No Laughing allowed.

Unfortunatedly the pressure from the coil split the oak board it was mounted on. You can see the crack in the pictures.
Thanks to all who helped on this.

PauLC
W1VLF

Quantum Singularity

Sat May 24 2008, 11:06PM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

Nice job! I see you found an easy way to suspend the gb so that the disk actually strikes it at pretty much full speed. Good thinking. Yeah you need some really strong base material. Are the head of the bolts on the other side of that board causing it to have a small air gap between what it is set on? If so thats probably allowing the base to flex back and eventually crack. Make sure there is a good solid platform that can dissipate the shock.

uzzors2k

Sun May 25 2008, 12:24PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

About 3% efficiency! That's an awesome launcher w1vlf. Don't worry about the looks, IMHO it looks pretty clean compared to a standard lash-up.

w1vlf

Sun May 25 2008, 02:37PM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

Tristan, OK you caught me. Yes there is a space under the backer for the coil. This was to allow space for the flat wire. I never thought this would crack being oak. The next backer will have the grains crossed 90 degrees and make it 3 layers thick.

On the golf ball holder, yeah it woks pretty well. I needed some to hold the ball but also would not explode if the disc hit it. BTW the disc flies up about 20 feet at a 750 volt launch. I am not sure what that is telling me.

PauLC
W1VLF

w1vlf

Sun May 25 2008, 02:42PM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

Uzzors2k,
Could you spend a moment an tell me how you are coming up with the effiency number. I think that would be very useful to know. Is it something like Joules in x joules out? If so .... How do you know the amount of Joules it take to raise a 46 gram golf ball?

Thank you
PauLC
W1VLF

uzzors2k

Sun May 25 2008, 03:50PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Assuming you shoot straight up the initial velocity of the golf ball is given by V = (T/2) * 9,81 It's kinetic energy is then E = 0.5 * M * V^2 I found the energy stored in your bank based on the specs on your site, plugged into E = 0.5 * C * U^2. After that it's a simple matter of percentage calculation.

Quantum Singularity

Mon May 26 2008, 01:18AM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

w1vlf wrote ...

Tristan, OK you caught me. Yes there is a space under the backer for the coil. This was to allow space for the flat wire. I never thought this would crack being oak. The next backer will have the grains crossed 90 degrees and make it 3 layers thick.

On the golf ball holder, yeah it woks pretty well. I needed some to hold the ball but also would not explode if the disc hit it. BTW the disc flies up about 20 feet at a 750 volt launch. I am not sure what that is telling me.

PauLC
W1VLF

Well, I haven't calculated the energy but figure its similar to swinging a sledge hammer into the base (well lightly anyway). Making your own laminated base from hardwood sounds like it would work well. My last one I made from hardwood plywood but haven gone very high power yet (<1kJ). As far as the disk traveling up 20'... go back to that one link that did the collisions, with a heavier disk striking a lighter gb then not all the energy will transfer and the disk will still have some energy driving it up (assuming you were referring to the heavier disk you used). If you were using a lighter disk than gb, then I'd say the strike is too close and after energy is transferred the disk is still being driven by the magnetic pulse from the coil.

OZZY

Mon May 26 2008, 11:14AM

Registered Member #511 Joined: Sat Feb 10 2007, 11:36AM
Location: Somerset UK
Posts: 55

Hi w1vlf

Thats a very fine launcher, maybe you should take it to a golf driving range and see how far it will hit a golfball

. Alternatively you could try to measure the velocity using; ballistic pendulum, acustic recording, chronograph?

If you want to optimise the performance for efficiency you will need to work backwards from the golfball not forwards from the capacitor bank. The parameters of the ball are fixed, everything else you can change. If the collision is perfect then the maximum transfer of energy will occur when the mass of the disc is equal to the mass of the ball. In a real collision you will want the disc to be slightly lighter than the ball.

Once you have established the optimum mass of the disc you need to find the optimum diameter. If you assume that the disc has the same diameter as the coil then at one extreme you have a big coil with high inductance producing a long pulse, matched to a disc that is too thin. At the other extreme you have a small coil with low inductance producing a short pulse, matched to a disc that is too thick. Somewhere in between is the optimal solution. The impedance of the cap bank will affect the choice of coil size.

Ozzy

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