The TR-201 or TR201 is a

hypergolic A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. The ...

pressure-fed

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 ...

used to propel the upper stage of the

Delta rocket The Delta rocket family was a versatile range of American rocket-powered expendable launch systems that provided space launch capability in the United States from 1960 to 2024. Japan also launched license-built derivatives (N-I (rocket), N-I, N ...

, referred to as

Delta-P The Delta-P is an American rocket upper stage, stage, developed by McDonnell Douglas and TRW, first used on November 10, 1972 as the second stage for the Delta 1000 series. It continued to serve as the second stage for subsequent Delta 2000 and ...

, from 1972 to 1988. The

uses

Aerozine 50 __NOTOC__ Aerozine 50 is a 50:50 mix by weight of hydrazine and unsymmetrical dimethylhydrazine (UDMH), developed in the late 1950s by Aerojet General Corporation as a storable, high-energy, hypergolic fuel for the Titan II ICBM rocket engines ...

as fuel, and as oxidizer. It was developed in the early 1970s by TRW as a derivative of the lunar module descent engine (LMDE). This engine used a

pintle injector The pintle injector is a type of propellant injector for a bipropellant rocket engine. Like any other injector, its purpose is to ensure appropriate flow rate and intermixing of the propellants as they are forcibly injected under high pressure into ...

first invented by Gerard W. Elverum Jr. and developed by TRW in the late 1950s and received US Patent in 1972. This injector technology and design is also used on SpaceX

Merlin The Multi-Element Radio Linked Interferometer Network (MERLIN) is an interferometer array of radio telescopes spread across England. The array is run from Jodrell Bank Observatory in Cheshire by the University of Manchester on behalf of UK Re ...

engines. The thrust chamber was initially developed for the

Apollo Lunar Module The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed sp ...

and was subsequently adopted for the Delta expendable launch vehicle 2nd stage. The engine made 10 flights during the Apollo program and 77 during its Delta career between 1974 and 1988. The TRW TR-201 was re-configured as a fixed-thrust version of the LMDE for Delta's stage 2. Multi-start operation is adjustable up to 55.6 kN and propellant throughput up to 7,711 kg; and the engine can be adapted to optional expansion ratio nozzles. Development of the innovative thrust chamber and pintle design is credited to TRW Aerospace Engineer Gerard W. Elverum Jr. The combustion chamber consists of an ablative-lined

titanium alloy Titanium alloys are alloys that contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness (even at extreme temperatures). They are light in weight, have extraordinary corrosion resistance ...

case to the 16:1 area ratio. Fabrication of the

Ti6Al4V Ti-6Al-4V (UNS designation R56400), also sometimes called TC4, Ti64, or ASTM Grade 5, is an alpha-beta titanium alloy with a high specific strength and excellent corrosion resistance. It is one of the most commonly used titanium alloys and is appli ...

alloy titanium case was accomplished by machining the chamber portion and the exit cone portion from forgings and welding them into one unit at the throat centerline. The ablative liner is fabricated in two segments and installed from either end. The shape of the nozzle extension is such that the ablative liner is retained in the exit cone during transportation, launch and boost. During engine firing, thrust loads force the exit cone liner against the case. The titanium head end assembly which contains the Pintle Injector and propellant valve subcomponents is attached with 36 A-286 steel bolts. In order to keep the maximum operating temperatures of the titanium case in the vicinity of , the ablative liner was designed as a composite material providing the maximum heat sink and minimum weight. The selected configuration consisted of a high density, erosion-resistant silica cloth/phenolic material surrounded by a lightweight needle-felted silica mat/phenolic insulation. The installed pintle injector, unique to TRW-designed liquid-propulsion systems, provides improved reliability and less costly method of fuel–oxidizer impingement in the thrust chamber than conventional coaxial distributed-element injectors typically used on liquid bipropellant rocket engines.

Specifications

* Number flown: 77 (Delta 2000 configuration) * Dry mass: with columbium (

niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

)

nozzle extension A nozzle extension is an extension of the nozzle of a reaction/rocket engine. The application of nozzle extensions improves the efficiency of rocket engines in vacuum by increasing the nozzle expansion ratio. As a rule, their modern design assume ...

installed * Length: – gimbal attachment to nozzle tip (minus nozzle extension) * Maximum diameter: (minus nozzle extension) * Mounting: gimbal attachment above injector * Engine cycle: pressure fed (15.5 atm reservoir) * Fuel: 50:50 NO/UDMH (

) at 8.92 kg/s * Oxidizer: dinitrogen tetroxide at 5.62 kg/s * Oxidizer:fuel ratio: 1.60 * Thrust, vacuum: 42.923 kN * Specific impulse, vacuum: 303s * Expansion ratio: 16:1 without nozzle extension; 43:1 with nozzle extension * Cooling, upper thrust chamber: film * Cooling, lower thrust chamber: ablative quartz phenolic; * Cooling, nozzle extension: radiative * Chamber pressure: 7.1atm * Ignition: hypergolic, started by 28V electrical signal to on/off solenoid valves * Burn time: 500s for total of 5 starts; 10 × 350-s single burn

Delta usage

The TR-201 engine was used as the second stage for 77

Delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...

launches between 1972 and 1988. The engine had a 100% reliability record during this 15 year operational period.

References

{{Orbital spacecraft rocket engines Rocket engines using hypergolic propellant Rocket engines using the pressure-fed cycle Rocket engines of the United States