New answers tagged engine-design
2
The SSME engine uses a bootstrap start sequence which is quite drawn out. On the Raptor the method is not clear but the latest drawing seems to present Helium gas spinup. for sure the engine start sequence is very rapid. but I don't think that Spacex would use a difficult to provide gas. Its much more likely that tank pressure and the respective propellants ...
7
A lot of questions here, let's tackle these two first:
4.And last but not least, what's SpaceX's solution for the oxygen-rich environment at 377bar, 748K injector and 546bar, 811K pre-burner?
2.The Raptor's oxygen pump sits directly on top of the main combustion chamber, while the SSME's two pumps are on the opposite sides of the main combustion ...
15
I wouldn't draw any conclusions based on diagrams alone, SSME is very well-known to the public, so we have a more detailed diagram. That doesn't mean that the actual engine is more or less complex, because many things are omitted from diagrams. To prove my point, here is a newer Raptor diagram drawn by a propulsion engineer Elisei Maslov, who's ...
2
I think the RL10 is a biprop cyro system that was also tested with methane in the 60s, to get you started with something. Generally your isp takes a big hit when switching fuels, along with max thrust and general mass ratio.
In general though, you would have to change your whole prop system assembly to fit a different fuel configuration, not just your ...
4
There is no problem running Kerosene and Oxygen on the same turbopump shaft, at any temperature. provided both are liquid, the density variations are not sufficient to make any practical difference to the feasibility of a turbopump.
From the OP, the densities of Oxygen and Kerosene are 1.18 and 0.8 g/cm3 , a ratio of 1.475. The pressure produced by a single ...
3
As noted in my comment on Organic Marble's answer, the RD170 baffles look very similar to the SSME, but with 6 radial baffles instead of 5.
Using nozzles to make baffles is a win-win. You don't lose any area and the propellant keeps them cool.
According to this the baffles on the Saturn V's F-1 engines were cooled by fuel. At first glance there don't ...
5
Your question specifically asks about "reliable" thrusters, but makes no mention of any other criteria (such as whether it be used for interplanetary missions). I will focus this answer on reliability, since cost is too complicated and mission-dependent. In this case, we should look for simplicity above all else. Simpler may mean more reliable and in that ...
10
In early versions of the Space Shuttle Main Engine (SSME), the main injector was baffled. The baffles were formed by extra-long liquid oxygen posts protruding from the injector face.
Block IA engines and later removed the baffles. (See "Taxonomy of the SSME" in this answer.)
The injectors on the preburners were also baffled in a similar manner. As far as ...
8
Fundamentally, a liquid rocket engine consists of two parts: the combustion chamber / nozzle; and the turbopumps.
Combustion chamber / nozzle
It is easier to scale a combustion chamber down than it is to scale it up. Getting the fuel and oxidizer to mix uniformly in a large engine is more difficult due to the larger distances involved. Large engines suffer ...
0
The F-1 Engine Familiarization Manual tells us, on page 1-8, that the Rocketdyne engineers worked with only 1 pressure in the combustion chamber: the injector end pressure, nominally at 1125 psia (7.757 MPa in SI units, or 76.55 atm). The nominal exit pressure was 9.6 psia (66 kPa in SI units, or 0.65 atm).
0
No, it doesn't. There is always a valve between the purging circuitry and the turbopump, preventing the turbopump from going dry (which, as @GittingGud points out in a comment) is highly undesirable. The valve is closed by the same gas as the one used to purge. For a nice description, see p. 60 of Huzel and Huang, "Design of Liquid-Propellant Rocket Engines" ...
4
This is another example of a perpetual motion machine. Although you may believe it will produce net motion without violation of conservation of momentum:
Any net motion produced would be a violation of conservation of momentum, so it cannot occur
You've not fully accounted for the net center of mass motion throughout your machine's cycle, or how momentum is ...
4
According to the paper from the 64rd International Astronautical Congress, Beijing, China The Development of the LOX/LH2 Engine in China; IAC-13, C4.1, 1x18525, the nozzle was welded from spiral-shaped elements. So the spiral pattern is here by design.
The spirals are "dump-cooled", an old Rocketdyne idea described in this 1966 NASA Technical Note TN D-...
2
I don't know of any RP-1/kerosene fueled engines that used two fluids for film cooling. The only instance of film cooling was of the gas generator exhaust fluid being fed into the nozzle to insulate it from the hot combustion products streaming out of the chamber. This btw was responsible for the F-1 exhaust gases always looking brighter in the center of the ...
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