SpudFiles

I made a diagram of how I would build a hybrid with an on-board fuel supply and integrated pump, it seems like it's feasible but the thought of getting cartridges to work reliably sounds more appealing now

Why not use a wood nailer/tacker as a base?
That would give you fuelcells, the right mixture etc.

hmm... there is a detent, but why it isn't the main valve ??

ohh consider loading ammo from behind

POLAND_SPUD wrote:hmm... there is a detent, but why it isn't the main valve?

Adding the piston reduces stress on the magazine, something you avoid by adding a separate bolt.

POLAND_SPUD wrote:from behind

My usual choice

As I said though, I probably won't be trying to make this. Just wanted to sketch out what's needed to see if it would be practical.

Adding the piston reduces stress on the magazine, something you avoid by adding a separate bolt.

Not if the gun is loaded

from behind

Basically this with the blowgun replaced by fuel+air+spark?

yeah
and it might work well with this idea ->
http://www.spudfiles.com/forums/viewtop ... tml#310498

POLAND_SPUD wrote:yeah
and it might work well with this idea

Flooding the chamber with fuel and filling to a fixed air pressure certainly makes charging simpler, but you're going to need to add an on-board precisely regulated HPA tank for multiple shots as well as the fuel reservoir, so in short the final result will be at least the size of an assault rifle.

What I was after with this design was something small and compact that could be refilled with a single stroke, certainly it won't be the most powerful launcher. Changing the geometry and upping the calibre could give you more muzzle energu on a pump-action shotgun style package.

but you're going to need to add an on-board precisely regulated HPA tank for multiple shots as well as the fuel reservoir

not necessarily... a typical lighter should be able to provide enough fuel for at least 15 shots, maybe more

who said you need a HPA setup ? put a pump on teh gun and check how many strokes you need to reach the ideal mix

not what I am after but it is certainly an option

Looks tricky, but build-able, I like it, especially the double-pump-metering-system.
But I see two problems and one idea for improvement:

- Due to the fact, that one pump-piston will have a much larger surface, there will be a torsional moment at the point where the (larger-) pump-shaft meets the pump-handle. The whole construction would have to be very rigid...

-You would most probably have to add a little chute in the barrel, to avoid the balls from being pushed in the wrong direction (leading to multi-feeding...)

I would recommend furthermore, that you change the position of the fuel-line to the pump and add a check-valve , because otherwise you would have to seal the shaft of the smaller pump.

I added my thoughts to the diagram:
Edit: Don't ask me why there is a small red arrow on the right. I don't know.

I'd like to describe your solution as simply elegant.

Different piston/tube diameters for calibrated propane/air flow rates is about the best idea I've seen for repeater hybrid fueling so far. If you can get this to work it'll put the pump-action combustion I'm building to shame, even if it is about 50 times smaller.

@mark.f

...the funny thing is, IMO building a pump action hybrid, would be easier to build as a regular 1x combustion, because you would not have to vent the chamber between shots, what I find the most complicated part, and if you already build the metering system for a combustion, you would only have to pressurize the (rich) mix for a hybrid.

I have a little something planned out (that I posted here as well). Not too terribly complicated but slightly tricky to build.

POLAND_SPUD wrote:a typical lighter should be able to provide enough fuel for at least 15 shots, maybe more

Exactly what I had in mind as a fuel source

who said you need a HPA setup ? put a pump on teh gun and check how many strokes you need to reach the ideal mix

I'd rather have *click-click* bang as opposed to *click-click-click-click-click-click-click-click* bang

Due to the fact, that one pump-piston will have a much larger surface, there will be a torsional moment at the point where the (larger-) pump-shaft meets the pump-handle. The whole construction would have to be very rigid...

Moar epoxy

You would most probably have to add a little chute in the barrel, to avoid the balls from being pushed in the wrong direction (leading to multi-feeding...)

I didn't include it in the diagram but in practice a smaller diameter insert would be there to prevent backward feeding.

I would recommend furthermore, that you change the position of the fuel-line to the pump and add a check-valve , because otherwise you would have to seal the shaft of the smaller pump.

The problem with your solution is that the dual piston mixing relies on the fuel being at atmospheric pressure, but it's stored at higher pressure in the reservoir.

I'd like to describe your solution as simply elegant.

Not as simple as I'd like do we get to see your pump action in progress?

I would recommend furthermore, that you change the position of the fuel-line to the pump and add a check-valve , because otherwise you would have to seal the shaft of the smaller pump

right, but there is nothing to block the flow of fuel to the chamber...

though if you think of it you might as well get rid of the fuel pump