Doesn't RL-10 run fine on LOX/CH4?
Is a sort of "Diesel" style rocket engine possible? I'm not talking of a motor that uses compression to achieve ignition, (although that WOULD be a neat trick!) but more along the lines of being able to use multiple types of liquid fuels and oxidizers in a standardized motorto achieve thrust, while still making the engine reusable? Jason
I can think of one potential application, far in the future: a lander engine capable of running on both LOX/methane and LOX/silane.For moon applications this could be useful in combination with ISRU for the silicon and oxygen. Importing the required hydrogen (only useful if the reported ice deposits turn out not to be practical) could be done in the denser form of methane. During descent the engine would run on methane. Once on the ground the cargo of methane and any remaining propellant could be processed into silane using lunar silicon. The resulting carbon could then be used on the surface for things like plastics.It could also be useful to have an engine capable of using both silane (possible with moon ISRU) and methane (easier on Mars, though silane would still remain possible).All very speculative, and far, far in the future.
I can think of one potential application, far in the future: a lander engine capable of running on both LOX/methane and LOX/silane.
If you can synthesize something like silane, surely you could synthesize something simpler like ethane.
Then go with a propellant that is a known hypergol with liquid oxygen and is itself a liquid: tri-ethyl aluminum.
Quote from: TyMoore on 03/16/2010 02:32 pmIf you can synthesize something like silane, surely you could synthesize something simpler like ethane.The potential advantage of silane would be that you could get the silicon from ISRU. The methane conversion is just for finding a denser way to import hydrogen. You could also use ammonia or hydrazine.Quote Then go with a propellant that is a known hypergol with liquid oxygen and is itself a liquid: tri-ethyl aluminum. The aluminium is a nice twist since that can also be sourced from ISRU. You could also consider metal-loaded gelled propellants.
Not to derail this, but I've seen you mention silane a few times.
Isn't it a problem that half of the combustion product (by weight) is silicon dioxide or silicon monoxide?
But is it worth it? You must weigh the costs plus any potential gains or penalties of using diesel.
I just wanted to add: I once looked at the possibility of using a liquid parafin wax/aluminum emulsion burning with liquid oxygen as a very high-impulse density propellant. Trouble with this is that again, you have to insulate both tanks very well, and tens of thousands of gallons of hot wax and aluminum are going to radiate a heck of a lot of heat and couple it to 60,000 gallons or so of liquid oxygen. Refrigeration and heating in very close proximity is really complicated!Also pressure drop in pintel injector is ferocious, not to mention the pumping power needed for moving a thick, dense slurry. And the need for an auxiliary jet pump to keep the fuel emulsion stirred up so the aluminum doesn't settle out.Way too complicated.I even had the crazy idea for painting the resulting booster a garish color to look like a big crayon! (Inspiration for kids, and all...)
Quote from: FinalFrontier on 03/16/2010 03:48 pmBut is it worth it? You must weigh the costs plus any potential gains or penalties of using diesel.Oh, I was just thinking about how engines that can run on more than one fuel might be useful one day, not about diesel as a fuel. I guess we're getting off topic.
Your best best for a multi propellant rocket that can essentially be a goat and run off any volatile you can find might be a gas core nuclear thermo rocket.Solid core NTRs also may have some level of flexibility as well you could in theory make one able to use CO2 or water for example. A VASIMR engine depending on it's design also could have some level of flexibility.