I can't recall the name of the British SSP that never was
Chris.......the other day I offered up one of my old creations but, based on member response, it appears to have been the wrong place to do it: www.gatewaytoairguns.org/GTA/index.php?topic=71647.msg682905#msg682905Have a look at the brief writeup (YF link) as it may well contain specific information you would find useful. That projectwas much larger and more technical than my description would indicate but unfortunately very few people were ableto take advantage and ask questions. The gun continues to be a joy to shoot and I use it frequently.The Webley gun mentioned above had, in my opinion, a couple of serious shortcomings but then, in all fairness, itwas designed for economical production (?) and not maximum performance.
For purposes of illustration and to ensure that we're all on the same page, the Olafsson patent drawings # 6 and 7 work well (shown partway down in the old original post). -- the chamber to the right of the piston is precharged to 925 psi-- air from the pump is introduced at the corner thru passage 40-- once the pump pressure reaches 925+ the piston is forced to the right........ for a 10 inch stroke the final pressure is ~ 1007 (both sides of the piston)-- the valve is opened, air flows directly into the barrelBob.........." the piston is in a precharged chamber, so in fact working like a gas ram?" Not really. It merely separates the precharge from the pump charge. ..........." I'm not sure what the active volume of the valve is" Could you rephrase please? ............" with the pressure staying above 925 psi until the piston completes its travel" Due to the speed of the process (therefore at least "partly" adiabatic) I'd say it drops below that value. Hope this helps. Ron