Gas Spring Hybrid Piston Valve

[kjjohn]

I have heard of people using gas springs for hybrid piston valves (snap valve type), but I was wondering how effective they are. I am talking about the type of gas springs that can be bought from McMaster. There are some that reach up into the 200-300 lb force range, which could be connected to a piston. Has anyone ever experimented with these, and would they be able to take the intense force of the piston flying back?

[deathbyDWV]

I haven't heard of using that type of gas spring. By what most people mean is the piston is in a tube and when it fires the air behind the piston just acts like a gas spring...

[ramses]

That is correct, but you need a perfect seal to be able to adjust the "spring" strength independently from the mix. I also chose to minimize the dead volume behind the piston just to make sure the piston would never bottom out. Essentially, make it with as high of a compression ratio as possible.

This has worked quite well for me. I haven't shot the hybrid much, but it hasn't broken itself yet.

On a sidenote, I am seeing a lot of piston hybrid threads. I like this trend!

[kjjohn]

@deathbyDWV - I don't quite get what you mean. I am talking about a regular gas spring, the same kind you described. Perhaps it was when I said snap valve"; by that I meant the type of hybrid piston valve, not the type of gas spring.

@ramses - Did you make your gas spring yourself, or did you buy one commercially? I was planning on buying one from McMaster, and I would assume that a commercially made gas spring would not have any problems with leaking. And what do you mean by high compression ratio? Chamber ignition pressure to gas spring pressure?

By the way, if this works, you should see my piston hybrid on the site within the next few months.

[ramses]

I was responding to DWV. Essentially, the piston in my valve is air tight. before fueling, I fill pilot area with air to a given pressure. That is my air spring. I reduced the dead volume in the pilot area to have a high compression ratio, so that the piston would never bottom out against the back of the pilot area. I did not use a commercial gas spring.

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