Have any pumps been built that can switch between combustion chambers?
I remember an NPO Energomash paper stating that the RD-170 could (not sure if can) shutoff individual chambers. And then you have cases like the RD-0110 that feeds the main chambers and the vernier chambers from the same TP. But generally speaking the combustion chamber and nozzle are really heavy and duplicating the mass is simply not worth it for the possible increase in isp.
I have an unusual and pointless question.What does a liquid fueled rocket engine sound like? And I don't mean the hypersonic exhaust hitting the atmosphere, the huge roar we are all familiar with (at least second hand).Mullane in 'Riding Rockets' describes the SSMEs ('three Rocketdyne beauties..') as smooth as glass (or similar, it's been a while since I've read it) after the SRBs have separated. Now there's some distance between the flight deck and the engines and probably lots of sound insulation. (I'm not sure he actually describes them as quiet, perhaps only smooth).So.. subtracting anythng from the engine bell, would they sound like a jet engine perhaps?
Quote from: nicp on 07/01/2016 11:58 amI have an unusual and pointless question.What does a liquid fueled rocket engine sound like? And I don't mean the hypersonic exhaust hitting the atmosphere, the huge roar we are all familiar with (at least second hand).Mullane in 'Riding Rockets' describes the SSMEs ('three Rocketdyne beauties..') as smooth as glass (or similar, it's been a while since I've read it) after the SRBs have separated. Now there's some distance between the flight deck and the engines and probably lots of sound insulation. (I'm not sure he actually describes them as quiet, perhaps only smooth).So.. subtracting anythng from the engine bell, would they sound like a jet engine perhaps? Correct--smooth, not quiet. Remember the HPFT is spinning at (36,000?) rpm and HPOT at a good clip too. One cannot have that much compression/impeller force without plenty of sound.
I recall a presentation by Firestar, the company that was behind the NOFBX monopropellant, that said non-hypergolic bi-propellant engines tend to be noisier than hypergols which in turn tend to be noisier than monoprops. I believe the claim was that the smoothness of mixing of fuel and oxidizer was a factor in noisiness.
I guess I'd need to model it to truly convince myself. I was imagining a system where the second stage is smaller; payload smaller; and staging at a much higher speed.And consequently the rocket would spend more time throttled back on two high isp chamber/nozzles on the way up and on the deceleration and re-entry burn.Say, staging at mach 14? then decelerating to mach 5? for re-entry, before a barge landing. With a small cheap pressure-fed disposable upperstage.
Quote from: gin455res on 06/04/2016 10:24 pmI guess I'd need to model it to truly convince myself. I was imagining a system where the second stage is smaller; payload smaller; and staging at a much higher speed.And consequently the rocket would spend more time throttled back on two high isp chamber/nozzles on the way up and on the deceleration and re-entry burn.Say, staging at mach 14? then decelerating to mach 5? for re-entry, before a barge landing. With a small cheap pressure-fed disposable upperstage.Trading thrust for ISP is generally a bad idea on first stages. Every second the 1st stage has to burn is almost 10 m/s of gravity losses. Over 30% of the F9's first stage performance is just fighting gravity losses.And the F9 can't get to Mach 14 at MECO with ANY reserves for boostback, no matter what ISP gains you theorize. It simply doesn't have the mass fraction after gravity losses (and reducing thrust will make those worse).
Little historical question...S1.5400, built in OKB-1 for Molniya launch vehicle, was the first staged combustion engine.But what was the first American staged combustion engine ? SSME ?Thanks !
the Americans needed 21 more years to fly a staged combustion engine than the Russians