SpudFiles

I remember making a post a short while back briefly talking about some types of alternative methods of propulsion. Because the future of this hobby hasn't been thoroughly discussed in a while and because I am currently bored, I'd like to try starting up a topic.
I'll start by throwing some ideas out there which either haven't been tried or have only been occasionally experimented with:
(in order of kid-simple to scifi-crazy)

"Siege" slingshots-
After reading only a few pages of the slingshot thread it is apparent that surgical rubber tubing and bands are a legitimate medium for storing potential energy. They are fairly cheap, and probably have a weight advantage over steel springs, but typically the power stored is limited by the strength of your arm. However, if you incorporate a crossbow-ish frame and a motor/crank-driven gearbox, you could potentially create a handheld device capable of storing several hundred foot-pounds of energy. This may be merely average by air-spring(pneumatic) standards, but with slight design modifications, they are able to be used on a much wider variety of projectiles; it doesn't need to fit the barrel to be fired.
A really cool example would be a sawblade gun. Normally a pneumatic designed to do this would be horribly overcomplicated, underpowered or extremely inaccurate. With a slingshot setup, the only problem is imparting spin to the blade, and it is easily solved.


Centrifugal guns- There isn't much that I need to explain on this. A tube spinning at a high RPM flings projectiles outward at a speed of its circumference * RPS.
The mythbusters tried this once, but it was doomed from the start due to the rpm limits and release mechanism of their huge clunky prototype.
One of the main advantages(or disadvantages!) of a centrifuge gun is it can potentially exceed even a BBMG in refire rate; as long as you can supply enough power to keep the RPMs constant, your ROF is only limited by how fast you can force rounds into the breech.
A centrifuge gun would be ideal for small caliber rounds(coughJsr)


Portable laser devices- I'm not talking about wimpy 200mW green laser pointers, either. I discovered a while back that a 10kv, 100+ watt flyback generator can be made to weigh only a few pounds, batteries included. I've also discovered no one has attempted to drive a sealed-gas co2 laser with one, and I have no idea why. Sure, battery life would be low, but blasting carbon graffiti lines into walls "link-gun" style never gets old. Plus, co2 lasers reach efficiencies >20%.

High-power pulsed magnetrons-
This was only a recent idea I had. Seeing as modern microwave ovens have efficiency ratings that dwarf even co2 lasers, and parts are very cheap, I'm surprised there isn't more experimentation with these on the net. In particular I'd like to see if it's possible to drive a magnetron in pulse mode by dumping a multi-kilojoule capacitor bank into it. Of course, you'd need a very short wavelength to allow proper focusing(otherwise you're just blasting microwaves everywhere and probably giving yourself cataracs).

(For lack of a better name)Lightning guns-
Electricity follows the path of least resistance, so discharging it through something as fluid as air is wildly unpredictable at best. However, it is possible to lower the resistance of air by means of heating or ionization.
I don't know if anyone has been able to do it without a large power supply, but using a pulsed laser system to create conductive "channels" through air will have the desired effect. A laser would need to be of a wavelength that is partially absorbed by air and also have a very narrow beam width. However, if you can dump a few joules of energy into a small amount of air, it's gonna get hot real quick.
To of these for + and - channels, an initial high voltage spike to drop the resistance waay down, then a main low-voltage current of several KJ would have interesting effects, and the energy placed on the target could be approaching 100% efficiency (this design is very similar to how a common trigatron works).



I don't plan on attemping any of these for a long while, and I'm sure I have flaws in my theories. That's why I'm posing here. Maybe you have some other crazy idea to add, and I'm sure others would like to hear it.
Ready?

Discuss!

Its cool to see all of the other fields that have not been even looked into on SF. Conventional spudding may be at its furthest point, but we just have to work outside the box. I can't think of any, but I'm sure some members will come along and add to the list.

Any more info on the high powered lasers, they may be outside of my realm of construction, but I would really like to learn more about them

High-power pulsed magnetrons (...) I'm surprised there isn't more experimentation with these on the net

That's probably becasue they can burn your testicles
http://en.wikipedia.org/wiki/Microwave_burn

Fnord wrote:Portable laser devices
High-power pulsed magnetrons

These two may have legal problems. I know for example that such a magnetron would be illegal without a permit in the UK.

I can't remember why - although it may have something to do with breaching some limit as regards transmitter power - but it's possible similar limits will be placed on it in other countries. Check BEFORE you start.

Fnord wrote:Electricity follows the path of least resistance, so discharging it through something as fluid as air is wildly unpredictable at best. However, it is possible to lower the resistance of air by means of heating or ionization.

Actually there's an easier way to do it that was investigated by Mythbusters a while back, and I would propose building on their findings. What they discovered is that the electricity emitted form a large tesla coil will follow a small jet of water to a target. Well, since we on SF happen to be rather good with pneumatics, hydraulics shouldn't be too much of an issue. And what about using a solution of something highly ionic? Say a 1M solution of NaCl? Increase the conductivity and give the "Lightning Gun" some potential.

EDIT: I actually have some minimal experience with centrifugal guns... and can say this right away for them: They require very close-fitting and well-lubricated parts to prevent them from jamming or crushing the ammunition between the shield and the barrel. A small-caliber project of course, would demand even closer-fitting parts.

as far as a "lightning gun" goes. have you looked into ion ray and charge guns?

many plans are available on the net, and some are smaller than a good sized pistol.

These ion guns, the small ones, are capable of inducing a large shock from distances of over 30-40 feet, and cost around 250 to build.


I would love to see a ion ray gun on spudfiles.

The microwave band is regulated, especially to control the possibility of getting too close to the 2.5ghz band.

Co2 laser tubes are large, optics expensive, require cooling, and an RF power source. Lot of work for something large and with minimal power. Almost as bad as a railgun

If someone wants to ship me a pulsed UV laser, I'd be happy to try the "lightning gun" experiment

On a more realistic, and rather less awesome note, I think there is some potential entertainment to be had in heavier-duty slingshots. Thera gold bands have demonstrated reasonably high speeds and compact energy storage. I think that a powered hand-held design could easily reach 200J muzzle energy with a bit of work.

As rubber loses its stored energy rapidly after being stretched, a fast draw would be beneficial. Long throw custom pneumatic rams, perhaps? They wouldn't be overly difficult to produce with DOM tubing, steel threaded rod, standard fasteners and o-rings. It might not be the most energy-dense device ever, but there's a lot to be said for the increased range of possible projectile choices.

Also, there's the long-neglected (by the amateur community, at least) idea of induction coilguns. With current technology, and a good deal of money and ingenuity, one could be built in a handheld package with sufficient energy to be competitive with smaller rifles - a 15kJ high energy density capacitor could have a volume as low as 5L, easily fitting in a backpack. Cartridge ETGs could achieve the same level of performance, but the coilgun would be more interesting in my opinion. If anyone's got $20k or so to spend on R&D, it could be a good project to look into

oooh oooh you forgot gravity

I found a great link for these "new age guns" very informational, covers most of the topics above

solenoid powered piston anyone?

On centrifuge guns:

They require very close-fitting and well-lubricated parts to prevent them from jamming or crushing the ammunition between the shield and the barrel.

Not necessarily.

A shield is a design flaw in itself. Something better would be to have a steel pin or gate holding the rounds back until the trigger is pulled. This is a crude diagram but I think it gets the point across. The orange rod is moved into the path of the rotating barrel and hits the pin release once every revolution. There are more elegant solutions than this, however; it's just an example.

DYI wrote:On a more realistic, and rather less awesome note, I think there is some potential entertainment to be had in heavier-duty slingshots. Thera gold bands have demonstrated reasonably high speeds and compact energy storage. I think that a powered hand-held design could easily reach 200J muzzle energy with a bit of work.

As rubber loses its stored energy rapidly after being stretched, a fast draw would be beneficial. Long throw custom pneumatic rams, perhaps? They wouldn't be overly difficult to produce with DOM tubing, steel threaded rod, standard fasteners and o-rings. It might not be the most energy-dense device ever, but there's a lot to be said for the increased range of possible projectile choices.

Look in the Slingshot Channel thread, Jorge broke a record!!!

Fnord wrote:Portable laser devices- I'm not talking about wimpy 200mW green laser pointers, either. I discovered a while back that a 10kv, 100+ watt flyback generator can be made to weigh only a few pounds, batteries included. I've also discovered no one has attempted to drive a sealed-gas co2 laser with one, and I have no idea why. Sure, battery life would be low, but blasting carbon graffiti lines into walls "link-gun" style never gets old. Plus, co2 lasers reach efficiencies >20%.

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laser guns have always been fascinating to me, however what deters me is the high cost, and experience needed with electronics, something I do not have