F-1 rocket engine (The kind used by the Saturn V.)
A bipropellant rocket is a rocket that uses separate fuel and oxidizerpropellants. Bipropellant systems are more efficient than monopropellant systems, but they tend to be more complicated because of the extra hardware components needed to make sure the right amount of fuel gets mixed with the right amount of oxidizer (this is known as the mixture ratio.)
Thousands of combinations of fuels and oxidizers have been tried over the years. Some of the more common and practical ones are:
T-Stoff (80% Hydrogen Peroxide, H2O2) and C_Stoff (methanol, CH3OH, and hydrazine hydrate, N2H4.n(H2O) _ Walter Werke HWK 109_509 engine used on Messerschmitt Me 163B Komet a rocket fighterplane of (WW2)
The best mixture oxygen and hydrogen suffers from the deep temperature (20 K (−253 °C)) which is needed to store the fuel. Also the low density (70 kg/m3), which makes the need for large and heavy tanks, is a disadvantage. The use of lightweight foam, to insulate the cryogenic tank, proved to be dangerous as seen in the Columbia (STS-107) accident. For storable ICBMs or interplanetary spacecraft, the cooling is an unsolvable problem. Because of this the mixtures of hydrazine and its derivatives in combination with nitrogenoxides are used for these rockets.
Small scale rocket engines
XCOR Aerospace (http://www.xcor.com), a California based company, is developing small scale rocket engines to power small airplanes for suborbital flights. They have tested various combination of propellants including nitrous oxide/propane, nitrous oxide/alcohol, LOX/alcohol, LOX/kerosene with success.
A bipropellant gas generating system in which water is injected through slotted inlets along the combustion chamber wall to provide an unstable boundary layer and stripping of the water from the wall for efficient steam generation is disclosed in U.S. Pat.
The bipropellant gas generator has a chamber wherein a fuel and an oxidant are mixed, ignited, and combusted yielding flooding agents at elevated temperatures and pressures.
The exhaust gases formed in the bipropellant generator 20, which include steam resulting from the water formed during combustion along with the steam generated by evaporation of the cooling fluid, is fed through line 30 toward the well bore 22.
Because bipropellant systems permit precise mixture control, they are often more efficient than solid or hybrid rockets, but are normally more complex and expensive, particularly when turbopumps are used to pump the propellants into the chamber to save weight.
Bipropellantrocket engines are extremely powerful rockets- they can provide the highest specific impulse of all current Earth launchable rocket engines whilst at the same time as providing thrust to weight ratios of 70-100+, and permitting extraordinarily lightweight tankage and vehicle structure.
The highest ISP bipropellantrocket engine in existence is the hydrogen/oxgen fuelled SSME which gives very high performance; but in terms of overall performance the dense-fuelled NK-33 is comparable due to better mass ratios; in spite of lower specific impulse.
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