0.22" mini piston hybrid

[Hotwired]

It just means a piston that when opened, shows significantly more surface area than when closed, resulting in the piston opening faster once slightly opened.

[Crna Legija]

its a piston with a big part and a small part, you only need a little bit to get it to move but once it start it open up tonnes more surface area and makes the piston really POP open. you can see it in jsr drawing above look how little the pressure can act on at the start.

edit to late

[Gun Freak]

Ok thanks, makes sense.

[jackssmirkingrevenge]

For the sake of clarity:

[jackssmirkingrevenge]

Thinking of giving this another go, now that I have more experience with materials and machining. The delrin/metal face seal is quite common in the commercial PCP airgun field, the question is how well it can stand up to the heat spike from hybrid ignition.

This would naturally be filled by placing the cartridge inside a filling chamber.

[Labtecpower]

Looks good!

How are you going to force th piston forward? pneumatical or with a spring?

[Moonbogg]

Looks like a fun project. I also wonder how the delrin would do. So many plastics to choose from for piston material.

[qwerty]

How are you going to force th piston forward? pneumatical or with a spring?

Piston goes backward with the pressure spike of the mix igniting.

Shame i don't use my hybrid much anymore, too much fuss cutting out stupid burst disks, might have to try a piston hybrid.

[dewey-1]

Looks like a fun project. I also wonder how the delrin would do. So many plastics to choose from for piston material.

Delrin is so nice to machine compared to some of the other plastics.

[Labtecpower]

Piston goes backward with the pressure spike of the mix igniting.

I know, but how is it held against the barrel?

[jackssmirkingrevenge]

How are you going to force th piston forward? pneumatical or with a spring?

No springs, just the pre ignition pressure. The idea is that it is placed in a fill rig as attached, fuel is injected and the rig is sealed. The rig is taken up to pressure, then the schrader stem is depressed, causing a pressure imbalance which should force the piston shut.

Delrin is so nice to machine compared to some of the other plastics.

So true, it's become my favourite polymer and quite cheap too!

[dewey-1]

JSR;

Use 2 set screws rather than an exposed headed screw!

[jackssmirkingrevenge]

Use 2 set screws rather than an exposed headed screw!

This would be just to fill the cartridges at pressures below 400 psi, so it doesn't to be neat or overengineered.

[dewey-1]

Use 2 set screws rather than an exposed headed screw!

This would be just to fill the cartridges at pressures below 400 psi, so it doesn't to be neat or overengineered.

My apologies then!

I did not realize that was the filling rig.

[Labtecpower]

No springs, just the pre ignition pressure. The idea is that it is placed in a fill rig as attached, fuel is injected and the rig is sealed. The rig is taken up to pressure, then the schrader stem is depressed, causing a pressure imbalance which should force the piston shut.

Why would this work?

If you inject the mix, it will push back the piston.
Why would there go enough mix behind the piston to force it shut when you depress the schrader?

I think it would slam against the back plug while filling, removing the air behind it.