Air Gun Home :: View topic - Helium, would the physics of pressurized gass play along?

hardraade · New Member

Hello, this being my first post, I will try to moderate myself:)
First of all, I must ask if someone knows a definitive limit of the pellet-mass\max.grain that could leave the barrel without air leaking through the seals of the pellet and barrel\effect of the air-cussion being lost?
Im asking because SWIM;) got some old projects laying around, and would like to combine some.

(+ <75 m\s; By using a serie of coils that via charging of some capacitator\condensator-tube release a surge of high voltage through the coil,creating a very strong electromagn.field in the center of the coil,while giving the projectile time to travel into the drag\pull-zone of the magnetic field\Eddy-currents, it should be triggered by the same sensor that triggers the blitz in the barrelmounted tracer-adapter of airsoft origin only slightly moved forward, compensating for the increased velocity.)
Im only worried that the energy required for the nesc.force of pull would need such a massive discharge of EM(p) that the batteries needed for the sustained 1 ms.loadphase of current discharge, would make it a stationary gun only, and that everything running on cirquits around you would fry\die because of the magn.radiation:)

The projects would only come to life if iron-rods\moulded rods made of tightly stamped, epoxyresined iron-filings\dust is possible as projectile,though..
I would rather ask u guys then trust the joule-velocity-mass formula blindly.

Follow-up:
I was wondering if the laws of pressurized,dry gas would function to my benefit the meaning of velocity if I could break-load my springer in a Helium-filled compartment as a balloon or a big plastig bag?
Or filled the barrel with thin Helium for easing the resistance of moving air?
Thank u Smile

rsterne · Moderator

Actually, using Helium in a springer would likely reduce the velocity.... The Cardew brothers used Nitrogen and lost a large amount of velocity because there was no Oxygen to support combustion.... The velocity returned as soon as they went back to air.... Apparently there is a very thin film of lubricant spread over the walls of the compression chamber each shot that is burned off on the next shot and adds to the power of the gun.... Since Helium won't support combustion you would lose that power boost....

Helium works to increase the velocity in PCPs because the atoms themselves travel at a much higher speed than air moelcules (N2 & O2).... That allows Helium to expand faster than air in a parallel tube (ie barrel).... In a PCP, however, you are starting with the gas compressed and releasing some of it.... in a springer, you are compressing and releasing the gas during the shot cycle....

Bob

AirGunEric · Site Admin

hardraade · New Member

No, its an emp-accelerator for iron projectiles which contains the needed mass of magn.active iron for the max. force of pull from the eddycurrents generated from the coils.

They need a certain amount of iron in the accelerating body of projectile to function.
Thats why I asked for the max.limit of pellets u guys have ever experienced
so I dont wreck the rifle or some other cruel accident occurs because I didnt ask experienced users:)

*
I hoped that it was an photosensor that triggered the blitz in the tracer..that would be the only useable thing in that thing for me. The surge alone induces an extra 1.2 kJ of electric energy as an accelerating pull and thrust-force because the length of projectile exceedes beyond the magnetic poles wich the coil generates at each side. So any softgun-\barrel for plastic bb \<1.2 joule based springer would change into some outsider art if exposed to the barreltension created when an el.discharge of 1.2 kJ + 20 joule mechanical energy..

hardraade · New Member

I didnt mean gas as in carfuel but as in the state of the element\gaseous form.
Helium alone,since the smaller atoms travels faster than air, I thought the aircussion created would travel down the barrel faster than the airmixture of nitrogen and oxygene would do...?

Helium being inert is very cool due to the forces involved.

kanyon · Silver Status Member

hardraade · New Member

I think the push would get some more time that the champagne-cork didnt get, since the rod being 7 cm or more, until needed iron mass for the coils to interact is reached. I will be using moulded,re-fixated filings as ironbody rather than a machined solid iron-rod because every solid bit of metal get a magn.field\flux-currents on their own. Making the corresponsive pull the magnets give upon eachother as even and all-directional as possible for a smooth accelleration.

Evt.making the projectile hollow at the back for a pressure-seal when pushed.

hardraade · New Member

And further, the coils will get very much effective in the sense of not waisting any energy in the form of heat and poor conductivity-related issues of performance and theoretical limits.
Pressurized light gases will enter the coils and decompress, thus cooling the copperwiring at exactly the one\1.00 mS the loadingphase is inducing the surge , creating the supercooling effect that minimize the resistance of the wiring. Not as in the absolute zero way of supercool, but as in applying a very efficient, mechanically active cooling instead of passive heatsinks in just the right timing of the triggering.

The timing is going to be the imperative factor and the part thats open for tuning, because the window of opportunity\cinema Verite, is the delay between triggering the airrifle and the activiaton of the magn.pull.

rsterne · Moderator

With all due respect... You're not talking about an airgun at all, and this IS an airgun forum.... I can't imagine that anyone here would be able to help you....

Perhaps a physics forum of some kind would be a better place to find information on how to build an electromagnetic rail-gun?....

Bob