These are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.These folks are going places!
Quote from: TyMoore on 03/16/2010 08:10 pmThese are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.These folks are going places!I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane. A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.
Quote from: HMXHMX on 03/17/2010 02:23 amQuote from: TyMoore on 03/16/2010 08:10 pmThese are the folks that use a novel pneumatic pumping system using pressurized gas in a set of 4 small run tanks. As one tank is pneumatically filled at low pressure from the main tank, the other uses pneumatic pressure to pump the propellant into to the rocket engine at higher pressure. By sequencing valves to alternate the fill/expell cycles you get a pump. One pump for each propellent: 4 run tanks total. It gives the advantage of the simplicity of a piston pump, the power of a higher performance turbopump (to a limited extend) and the lightness of the main tanks because they aren't pressurized to the full injector pressure pluss pressure drop.It reminds me of an idea that I had when I was a kid, but I never did anything with it. And they've got the patents.These folks are going places!I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane. A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.It appears to be a remarkably simple yet effective technology. (Although the devil is probably in the details). IIRC, a few years ago Armadillo built some working test pumps, with and without free pistons, over a weekend.One interesting technique is to use heat from the rocket engine to heat up the pump pressurant gas. This can substantially decrease the mass of pressurant, and/or mass of the pressurant tank.Another idea is to use a gas generator to produce the pressurant gas in flight.Both these have parallels to existing turbo-pump cycles. Which is to be expected since a turbo-pump is just a different approach to the same task of using high pressure gas to push propellants into a combustion chamber at high pressure.
Another excellent feature of pistonless pumps, is that you can leave one chamber of each pump filled at shutdown. This allows zero-g restarts without settling the tanks.
A few years ago, I did a rough design and simulation of a sub-orbital (100km), lox/methanol vehicle using pistonless pumps. Pump pressurant gas (He) was about 1.1% of GLOW, of which half was used to maintain propellant tank pressure and do RCS, the rest exhausted overboard. Propellant tank masses were quite low.
Quote from: kkattula on 03/17/2010 07:13 amAnother excellent feature of pistonless pumps, is that you can leave one chamber of each pump filled at shutdown. This allows zero-g restarts without settling the tanks.Using cryo-fuels how would you handle boil off? I guess you could bury the pump inside the tank...
Pistonless pumps are pretty cool--does anyone know what the crossover threshold would be between turbopumps and pistonless pumps? I'd WAG maybe 10 lbs/s flow rate at 1000 psia...
Whatever happened to these guys? Any idea of the performance of their rocket engine in terms of ISP?
I first saw the basic concept of displacement pumps of this type in 1960, in Felix Goodwin's "Exploration of the Solar System" but his idea used a membrane. A number of others, including John Whitehead at LLNL, have built and tested piston pumps, and John even flew one about fifteen years ago. Steve has added to the technology base by demonstrated pumping without a membrane or pistons.
