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The combustion tap-off cycle is a power cycle of a
Blue Origin, 10 August 2018, accessed 15 August 2018]. The Reaver 1 engine in
The combustion tap-off cycle is a power cycle of a bipropellant rocket
A liquid-propellant rocket or liquid rocket uses a rocket engine burning liquid propellants. (Alternate approaches use gaseous or solid propellants.) Liquids are desirable propellants because they have reasonably high density and their combusti ...
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...
. The cycle takes a small portion of hot exhaust gas from the rocket engine's combustion chamber
A combustion chamber is part of an internal combustion engine in which the air–fuel ratio, fuel/air mix is burned. For steam engines, the term has also been used for an extension of the Firebox (steam engine), firebox which is used to allow a mo ...
and routes it through turbopump
A turbopump is a fluid pump with two main components: a rotodynamic pump and a driving gas turbine, usually both mounted on the same shaft, or sometimes geared together. They were initially developed in Germany in the early 1940s. The most co ...
turbines to pump fuel before being exhausted (similar to the gas-generator cycle
The gas-generator cycle, also referred to as the GG cycle or colloquially as an open cycle, is one of the most commonly used power cycles in bipropellant liquid rocket engines.
Propellant is burned in a gas generator (analogous to, but distinct ...
). Since fuel is exhausted, the tap-off cycle is considered an open-cycle engine. The cycle is comparable to a gas-generator cycle engine with turbines driven by main combustion chamber exhaust rather than a separate gas generator or preburner.
The J-2S rocket engine, a cancelled engine developed by NASA, used the combustion tap-off cycle and was first successfully tested in 1969.
By 2013, Blue Origin
Blue Origin Enterprises, L.P. is an American space technology company headquartered in Kent, Washington. The company operates the suborbital New Shepard rocket and the heavy-lift New Glenn rocket. In addition to producing engines for its own ...
, with their New Shepard
New Shepard is a Reusable launch vehicle, fully reusable Sub-orbital spaceflight, sub-orbital launch vehicle developed for space tourism by Blue Origin. The vehicle is named after Alan Shepard, who became the List of space travelers by nationali ...
launch vehicle, had successfully flight-tested the BE-3 engine using a tap-off cycle. According to Blue Origin, the cycle is particularly suited to human spaceflight due to its simplicity, with only one combustion chamber and a less stressful engine shutdown process. However, engine startup is more complicated, and due to the hot gas fed from the main combustion chamber into the turbopumps, the turbine must be built to withstand higher-than-normal temperatures. In contrast, the upper-stage variant of the BE-3, the BE-3U, uses an expander cycle
Expander may refer to:
*Dynamic range compression operated in reverse
*Part of the process of signal compression
*Part of the process of companding
*A component used to connect Serial Attached SCSI#SAS expanders, SCSI computer data storage, device ...
to power the turbopump, and will be used on the upper stage of the New Glenn
New Glenn is a heavy-lift launch vehicle developed and operated by the American company Blue Origin. The rocket is designed to have a Reusable launch vehicle, partially reusable, two-stage design with a diameter of . The first stage is powered ...
launch vehicle.BE-3 test updateBlue Origin, 10 August 2018, accessed 15 August 2018]. The Reaver 1 engine in
Firefly Alpha
Firefly Alpha (Firefly α) is a two-stage orbital expendable small lift launch vehicle developed by the American company Firefly Aerospace to compete in the commercial small satellite launch market. Alpha is intended to provide launch o ...
uses a tap-off cycle. It first flew in September 2021 then made it to orbit on its second attempt in October 2022.
See also
*Expander cycle
Expander may refer to:
*Dynamic range compression operated in reverse
*Part of the process of signal compression
*Part of the process of companding
*A component used to connect Serial Attached SCSI#SAS expanders, SCSI computer data storage, device ...
* Pressure-fed engine
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 th ...
* Rocket engine
A rocket engine is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed Jet (fluid), jet of high-temperature gas produced by the combustion of rocket propellants stor ...
* Staged combustion cycle
The staged combustion cycle (sometimes known as topping cycle, preburner cycle, or closed cycle) is a power cycle of a bipropellant rocket engine. In the staged combustion cycle, propellant flows through multiple combustion chambers, and is th ...
* Gas-generator cycle
The gas-generator cycle, also referred to as the GG cycle or colloquially as an open cycle, is one of the most commonly used power cycles in bipropellant liquid rocket engines.
Propellant is burned in a gas generator (analogous to, but distinct ...
* Electric-pump-fed engine
References
{{Thermodynamic cycles Combustion Rocket engines Spacecraft propulsion Thermodynamic cycles