In theory adds little mechanical complexity, but as the Falcon 9 has shown additional control systems may need to be added). Weight penalty is that of reserve fuel, not of engines, and is fairly small. 4: propulsive landing (effectively zero vertical speed and horizontal on landing. Wings are very heavy and add a lot of drag during ascent, but offer excellent cross-range capability). Harder to make redundant.) 3: wings (effectively zero vertical speed on landing, but very high horizontal speed. Any long skinny object like a rocket would have to land on its side, making landing gear design and parafoil suspension a bit interesting. Slight cross-range capability, hopefully allowing a runway to be targeted. 2: parafoils (low vertical speed, some horizontal speed on touchdown. 1: parachutes (highest vertical speed on touchdown, very poor accuracy, but easy redundancy by using a cluster of parachutes. So, I consider there to be four main ways of landing a stage. Therefore it will be assumed that both stages will use metholox engines. In addition, it reduces residue in engines compared to kerosene, making reuse easier, and as a gaseous fuel any leaks or spills are inherently less hazardous. Methane may offer the best of both worlds, offering reasonable density and insulation requirements (boosting mass ratio compared to hydrolox) as well as decent specific impulse and TWR. For upper stages, it may not be the best option either due to boiloff. Hydrolox is very efficient, but a bad choice for lower stages because hydrolox engines have a poor TWR and atmospheric ISP. Kerosene's low specific impulse makes it decidedly suboptimal for upper stages. Some type of "kick stage" will be used for high-energy orbits this may be a cheap hypergolic or solid-fueled stage, or a pricier cryogenic stage where maximum performance is required.Ĭhoice of fuels: First of all, hypergolics shouldn't be fueling the main engines of a launch vehicle, because they're toxic, corrosive, and otherwise a pain in the ass to deal with. The upper stage will only deliver its payload to trajectories of similar energy to GTO - this is because a reusable stage will naturally have a poor mass ratio making it inneficient to send payloads directly to high-energy orbits, and you're throwing away a reusable vehicle if you put out on an Earth escape trajectory. Strap-on boosters may be used to boost payload capacity as high as 20 tons to LEO. The basic design will be 2STO - the second stage of a 3STO design would have a very high burnout velocity, leaving it on a very difficult reentry trajectory. We'll assume the design is a multi-stage rocket, capable of lifting at least 10 metric tons into LEO - enough for a manned spacecraft, a space station resupply, and some GSO, Molniya, or other high-energy satellite launches. I know reusability on the Falcon 9's second stage has been shelved in favor of development of the MCT, and nobody else is even considering it.īut let's say I was given the task of designing a fully reusable (aside from a few minor components like payload fairings) launcher. So, there are currently attempts to make the first stages of launch vehicles reusable.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |