A Christmas question for the Diana experts

[ccdjg]

nope, you've misunderstood... although your definition of peak pressure in a conventional firing cycle is fine; probably my crap explanation to blame ! Nothing to do with pellet fit. If the pistons don't meet correctly in the middle, the pressure that may make reduces exponentially.

In that case I am still a bit puzzled. If the springs are of equal strength and length then the pistons will always eventually come to equilibrium in the centre of the cylinder, with all the air expelled. You can't get a situation where one piston has traveled past the exit hole and the other hasn't reached it, and there is a volume of compressed air permanently trapped in the cylinder. (Though you could if one spring was longer and stronger than the other).

If there is a mismatch with the timing I imagine there would a transfer of energy from one spring to the other from the building-up air pressure as they travel towards each other, in a kind of shuffling process, until they finally end up in contact at the centre with all the air expelled.

But you could be right. I imagine that technically this is a very complicated process (and very interesting) and the only way to sort it out would be to make an example of the pistol and road test it. As a result I have moved it up my priority list of projects!

[Shed tuner]

In that case I am still a bit puzzled. If the springs are of equal strength and length then the pistons will always eventually come to equilibrium in the centre of the cylinder, with all the air expelled.

agreed - eventually - but only if they are 100% balanced will those pistons be stopping in line with the tp, as opposed to a mill or two either way,

You can't get a situation where one piston has traveled past the exit hole and the other hasn't reached it

I think you could... unless something is stopping the pistons going past centre.

If there is a mismatch with the timing I imagine there would a transfer of energy from one spring to the other from the building-up air pressure as they travel towards each other, in a kind of shuffling process, until they finally end up in contact at the centre with all the air expelled

yup, that seems reasonable too

But you could be right. I imagine that technically this is a very complicated process (and very interesting) and the only way to sort it out would be to make an example of the pistol and road test it. As a result I have moved it up my priority list of projects!

Ha, would love to see it. I think a cylinder end wall (in the centre) might be needed if you can't synch them

[dvd]

First of all this is a very interesting thread, thanks to the original poster and subsequent contributers.

To think that mechanical recoilless airguns were being designed and patented 70 years ago, makes me wonder if the single piston recoiling design was already perceived as old hat in the 1950's.

I think that relying on the simultaneous release of two pistons and hoping that they meet at a predetermined point time after time, is not going to happen without mechanically linking the two together.
Perhaps the absence of some sort of synchronizing mechanism in the patent design by Wagria which predated the Diana diverging piston system, rendered the Wagria system much less efficient, which explains why unlike Diana, Wagria never made it to commercial production of recoiless pistols and rifles.

Happy Christmas to all .