The expander cycle is a power cycle of a bipropellant rocket engine. In this cycle, the fuel is used to cool the engine's combustion chamber, picking up heat and changing phase. The heated, now gaseous, fuel then powers the turbine that drives the engine's fuel and oxidizer pumps before being injected into the combustion chamber and burned.
RP-1 (alternately, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 has a lower specific impulse than liquid hydrogen (LH2), but is cheaper, stable at room temperature, far less of an explosion hazard, and far denser. RP-1 is significantly more powerful than LH2 by volume. RP-1 also has a fraction of the toxicity and carcinogenic hazards of hydrazine, another room-temperature liquid fuel.
A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. Liquids are desirable because their reasonably high density allows the volume of the propellant tanks to be relatively low, and it is possible to use lightweight centrifugal turbopumps to pump the propellant from the tanks into the combustion chamber, which means that the propellants can be kept under low pressure. This permits the use of low-mass propellant tanks, resulting in a high mass ratio for the rocket.
The J-2 was a liquid-fuel cryogenic rocket engine used on NASA's Saturn IB and Saturn V launch vehicles. Built in the U.S. by Rocketdyne, the J-2 burned cryogenic liquid hydrogen (LH2) and liquid oxygen (LOX) propellants, with each engine producing 1,033.1 kN (232,250 lbf) of thrust in vacuum. The engine's preliminary design dates back to recommendations of the 1959 Silverstein Committee. Rocketdyne won approval to develop the J-2 in June 1960 and the first flight, AS-201, occurred on 26 February 1966. The J-2 underwent several minor upgrades over its operational history to improve the engine's performance, with two major upgrade programs, the de Laval nozzle-type J-2S and aerospike-type J-2T, which were cancelled after the conclusion of the Apollo program.
The staged combustion cycle is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is thus combusted in stages. The main advantage relative to other rocket engine power cycles is high fuel efficiency, measured through specific impulse, while its main disadvantage is engineering complexity.
The pressure-fed engine is a class of rocket engine designs. A separate gas supply, usually helium, pressurizes the propellant tanks to force fuel and oxidizer to the combustion chamber. To maintain adequate flow, the tank pressures must exceed the combustion chamber pressure.
The gas-generator cycle is a power cycle of a bipropellant rocket engine. Some of the propellant is burned in a gas generator and the resulting hot gas is used to power the engine's pumps. The gas is then exhausted. Because something is "thrown away" this type of engine is also known as open cycle.
The YF-73 was China's first successful cryogenic liquid hydrogen fuel and liquid oxygen oxidizer gimballed engine. It was used on the Long March 3 H8 third stage, running on the simple gas generator cycle and with a thrust of 44.15 kilonewtons (9,930 lbf). It had four hinge mounted nozzles that gimbaled each on one axis to supply thrust vector control and was restart capable. It used cavitating flow venturis to regulate propellant flows. The gas generator also incorporated dual heat exchangers that heated hydrogen gas, and supplied helium from separate systems to pressurize the hydrogen and oxygen tanks. The engine was relatively underpowered for its task and the start up and restart procedures were unreliable. Thus, it was quickly replaced by the YF-75.
The YF-77 is China's first cryogenic rocket engine developed for booster applications. It burns liquid hydrogen fuel and liquid oxygen oxidizer using a gas generator cycle. A pair of these engines will power the LM-5 core stage. Each engine can independently gimbal in two planes. Although the YF-77 is ignited prior to liftoff, the LM-5's four strap-on boosters will provide most of the initial thrust in an arrangement similar to the European Vulcain on the Ariane 5 or the Japanese LE-7 on the H-II. Like the Vulcain, the YF-77 uses the less efficient gas generator cycle and even for that application it has less performance than the European engine.
The YF-100 is a Chinese liquid rocket engine burning LOX and kerosene in an oxidizer-rich staged combustion cycle.
The LE-7 and its succeeding upgrade model the LE-7A are staged combustion cycle LH2/LOX liquid rocket engines produced in Japan for the H-II series of launch vehicles. Design and production work was all done domestically in Japan, the first major (main/first-stage) liquid rocket engine with that claim, in a collaborative effort from the National Space Development Agency (NASDA), Aerospace Engineering Laboratory (NAL), Mitsubishi Heavy Industries, and Ishikawajima-Harima. NASDA and NAL have since been integrated into JAXA. However, a large part of the work was contracted to Mitsubishi, with Ishikawajima-Harima providing turbomachinery, and the engine is often referred to as the Mitsubishi LE-7(A).
The LE-5 liquid rocket engine and its derivative models were developed in Japan to meet the need for an upper stage propulsion system for the H-I and H-II series of launch vehicles. It is a bipropellant design, using LH2 and LOX. Primary design and production work was carried out by Mitsubishi Heavy Industries. In terms of liquid rockets, it is a fairly small engine, both in size and thrust output, being in the 89 kN (20,000 lbf) and the more recent models the 130 kN (30,000 lbf) thrust class. The motor is capable of multiple restarts, due to a spark ignition system as opposed to the single use pyrotechnic or hypergolic igniters commonly used on some contemporary engines. Though rated for up to 16 starts and 40+ minutes of firing time, on the H-II the engine is considered expendable, being used for one flight and jettisoned. It is sometimes started only once for a nine-minute burn, but in missions to GTO the engine is often fired a second time to inject the payload into the higher orbit after a temporary low Earth orbit has been established.
The LR87 was an American liquid-propellant rocket engine, which was used on the first stages of Titan intercontinental ballistic missiles and launch vehicles. Composed of twin motors with separate combustion chambers and turbopump machinery, it is considered a single unit. The LR87 first flew in 1959.
Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines.
TM65 is a rocket engine developed by Copenhagen Suborbitals. TM65 uses Ethanol and liquid oxygen as propellants in a pressure-fed power cycle.
The RD-0110R is a rocket engine burning liquid oxygen and kerosene in a gas generator combustion cycle. It has four nozzles that can gimbal up to 45 degrees in a single axis and is used as the vernier thruster on the Soyuz-2-1v first stage. It also has heat exchangers that heat oxygen and helium to pressurize the LOX and RG-1 tanks of the Soyuz-2.1v first stage, respectively. The oxygen is supplied from the same LOX tank in liquid form, while the helium is supplied from separate high pressure bottles.
The Bell Aerosystems Company XLR81 was an American liquid-propellant rocket engine, which was used on the Agena upper stage. It burned UDMH and RFNA fed by a turbopump in a fuel rich gas generator cycle. The turbopump had a single turbine with a gearbox to transmit power to the oxidizer and fuel pumps. The thrust chamber was all-aluminum, and regeneratively cooled by oxidizer flowing through gun-drilled passages in the combustion chamber and throat walls. The nozzle was a titanium radiatively cooled extension. The engine was mounted on an hydraulic actuated gimbal which enabled thrust vectoring to control pitch and yaw. Engine thrust and mixture ratio were controlled by cavitating flow venturis on the gas generator flow circuit. Engine start was achieved by solid propellant start cartridge.
