The LR87 was an American liquid-propellant

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 on the first stages of

Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...

intercontinental ballistic missile An intercontinental ballistic missile (ICBM) is a ballistic missile with a range (aeronautics), range greater than , primarily designed for nuclear weapons delivery (delivering one or more Thermonuclear weapon, thermonuclear warheads). Conven ...

s and

launch vehicles A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistag ...

. Composed of twin motors with separate combustion chambers and

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 ...

machinery, it is considered a single unit and was never flown as a single combustion chamber engine or designed for this. The LR87 first flew in 1959. The LR87 was developed in the late 1950s by

Aerojet Aerojet was an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California, with divisions in Redmond, Washington, Orange and Gainesville in Virginia, and Camden, Arkansas. Aerojet was owned by GenCorp, ...

. It was the first production rocket engine capable (in its various models) of burning the three most common liquid rocket propellant combinations:

liquid oxygen Liquid oxygen, sometimes abbreviated as LOX or LOXygen, is a clear cyan liquid form of dioxygen . It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an application which is ongoing. Physical ...

RP-1 RP-1 (Rocket Propellant-1 or Refined Petroleum-1) and similar fuels like RG-1 and T-1 are highly refined kerosene formulations used as rocket fuel. Liquid-fueled rockets that use RP-1 as fuel are known as kerolox rockets. In their engines, RP- ...

nitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russian rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

(NTO)/

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 ...

(a 50:50 mixture by mass of

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...

and

UDMH Unsymmetrical dimethylhydrazine (abbreviated as UDMH; also known as 1,1-dimethylhydrazine, heptyl or Geptil) is a chemical compound with the formula H2NN(CH3)2 that is primarily used as a rocket propellant. At room temperature, UDMH is a colorle ...

), and liquid oxygen/

liquid hydrogen Liquid hydrogen () is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecule, molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point (thermodynamics), critical point of 33 Kelvins, ...

. The engine operated on an open gas-generator cycle and utilized a regeneratively cooled combustion chamber. For each thrust chamber assembly, a single high-speed turbine drove the lower-speed centrifugal fuel and oxidizer pumps through gearing, a configuration designed for high turbopump efficiency. This lowered fuel use in the gas generator and improved specific impulse. The LR87 served as a template for the

LR-91 The LR91 was an American liquid-propellant rocket engine, which was used on the second stages of Titan intercontinental ballistic missiles and launch vehicles. While the original version - the LR91-3 - ran on RP-1/LOX (as did the companion LR87 ...

, which was used in the second stage of the Titan missile. The LR87 was a fixed-thrust engine, which could not be throttled or restarted in flight. The LR87 delivered approximately 1,900 kilonewtons (430,000 pounds) of thrust in its

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 ...

configuration. Early LR87 engines used on the

Titan I The Martin Marietta SM-68A/HGM-25A Titan I was the United States' first multistage intercontinental ballistic missile (ICBM), in use from 1959 until 1962. Though the SM-68A was operational for only three years, it spawned numerous follow-on mode ...

burned RP-1 and liquid oxygen. Because liquid oxygen is

cryogenic In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held in Washington, DC in 1971) endorsed a univers ...

, it could not be stored in the missile for long periods of time, and had to be loaded before the missile could be launched. For the

Titan II The Titan II was an intercontinental ballistic missile (ICBM) developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later adapted as a medium-lift space ...

, the engine was converted to use Aerozine 50 and nitrogen tetroxide, which are

and storable at room temperature. This allowed Titan II missiles to be kept fully fueled and ready to launch on short notice. For the

Titan III Titan was a family of United States expendable rockets used between 1959 and 2005. The Titan I and Titan II were part of the US Air Force's intercontinental ballistic missile (ICBM) fleet until 1987. The space launch vehicle versions contribu ...

and IV, which were larger, more capable space launch vehicles, the LR87 was modified further. Thrust and nozzle area ratio were progressively increased, requiring heavier turbopumps, pipes, and other parts.

Variants

LR87-3

Used on the

, the LR87-3 burned liquid oxygen and RP-1. Following the retirement of the Titan missile program, these engines saw no further use. The LR87-3 was also operated with NTO/Aerozine 50 and ground tested with LOX/H2 (with a new fuel pump), making it one of very few engines to have been run on three different propellant combinations. File:Titan I XLR87 Rocket Engine.jpg, Titan I LR87-3 (

Steven F. Udvar-Hazy Center The Steven F. Udvar-Hazy Center, also called the Udvar-Hazy Center, is the Smithsonian National Air and Space Museum (NASM)'s annex at Dulles International Airport in the Chantilly area of Fairfax County, Virginia. It holds numerous exhibits, ...

) File:Titan I engine.jpg, Titan I LR87-3 ( Cordele, GA) File:LR87-3 at the Evergreen Aviation & Space Museum 1580 (6586630307).jpg, Titan I LR87-3 (

Evergreen Aviation & Space Museum The Evergreen Aviation & Space Museum is an independent, 501(c)(3) non-profit, aviation museum in McMinnville, Oregon. Its exhibits include the Hughes H-4 Hercules (''Spruce Goose'') and more than fifty military and civilian aircraft, unmanned ...

)

LR87-5

Instead of liquid oxygen and RP-1, the

used

and

. This change was done for storability at the request of the US Air Force. The LR87-5 engine was generally lighter and simpler than its predecessor, partly due to the use of

propellants, which do not need an independent ignition system. The engines also had simpler controls, solid-propellant cartridges to start the turbopumps, simplified injectors, and autogenous pressurization, replacing the heavy tanks of cold helium gas. Instead, the fuel tank was pressurized with fuel-rich gas-generator exhaust, and the oxidizer tank with NTO evaporated in a heat exchanger using turbine exhaust. Beginning in 1984,

missiles were decommissioned and became available as launch vehicles. Their engines were modified for this use. File:TitanMissileStage1 LR87 Engine.jpg, Titan II LR87-5 ( Titan Missile Museum) File:Aerojet LR87-02.jpg, Titan II LR87-5 (

Kansas Cosmosphere and Space Center Cosmosphere is an international science education center and space museum in Hutchinson, Kansas, United States, located on the northeast corner of Plum Street and 11th Avenue, next to the Hutchinson Community College. It was previously known ...

) File:Titan II Missile LRAFB 1985.jpg, Titan II LR87-5 ( LRAFB)

LR87-7

The LR87-5 was adapted to the needs of the

Gemini program Project Gemini () was the second United States human spaceflight program to fly. Conducted after the first American crewed space program, Project Mercury, while the Apollo program was still in early development, Gemini was conceived in 1961 and ...

. The LR87-7 had added redundancies and safety features for

human-rating certification Human-rating certification, also known as man-rating or crew-rating, is the certification of a spacecraft or launch vehicle as capable of safely transporting humans. There is no one particular standard for human-rating a spacecraft or launch veh ...

. The performance was similar to the previous version, only reducing the chamber pressure and nozzle thrust to meet human-rating requirements. This version was only used on the Titan II GLV. File:Kennedy Space Center Titan II with LR87 engine (2).jpg, Titan II GLV LR87-7 (

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the NASA, National Aeronautics and Space Administration's (NASA) ten NASA facilities#List of field c ...

) File:LR87 on Titan missile stage 1.jpg, Titan II GLV LR87-7 (

)

LR87-9

The LR87-9 was first flown in 1966 and used on the

Titan IIIA The Titan IIIA or Titan 3A was an American expendable launch system, launched four times in 1964 and 1965, to test the Transtage upper stage which was intended for use on the larger Titan IIIC. The Transtage was mounted atop two core stages deriv ...

, IIIB, and IIIC.

LR87-11/11A

The LR87-11 was first flown in 1968 and used on Titan 24B, 34B, IIIBS, IIID, 34D, 34D7, IIIE. It had a higher trust than previous versions. The LR87-11A was used on the

Titan IV Titan IV was a family of heavy-lift space launch vehicles developed by Martin Marietta and operated by the United States Air Force from 1989 to 2005. Launches were conducted from Cape Canaveral Air Force Station, Florida and Vandenberg Air Forc ...

A/B. File:Rocket engine at the Wings Over the Rockies Air and Space Museum (4282675983).jpg, LR-87-11A (

Wings Over the Rockies Air and Space Museum The Wings Over the Rockies Air and Space Museum (WOTR) is located on the former Lowry Air Force Base in Denver, Colorado, United States. The museum preserves the history of Lowry AFB's operations from 1938 to 1994 in its collections, archives, an ...

) File:Titan IVB at the Evergreen Aviation & Space Museum 1599 (6586636607).jpg, LR-87-11A (

) File:2014 08 140829-F-IO108-012.jpg, LR-87-11A (

National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is ...

)

LR87 LH2

The LR87 LH" was an engine modified to burn liquid oxygen and liquid hydrogen. The development coincided with other variants of the late 1950s. Compared to the -3, it had a number of changes associated with the use of lighter and colder liquid hydrogen. The fuel injectors were greatly modified, and the RP-1 pump was replaced with a purpose-designed single-stage hydrogen pump. Developed 1958–1961, a total of 52 static tests were performed without serious issue.

took part in the selection process for a new engine for the second stage of the

Saturn IB The Saturn IB (also known as the uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage (, 43,3 ...

and

Saturn V The Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, had multistage rocket, three stages, and was powered by liquid-propel ...

. Though LR87 LH2 was the best in 10 out of 11 criteria,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

selected Rocketdyne's J-2. Lessons learned were used during development of the Aerojet M-1. It was only built with 1 chamber.

LR87 / Alumazine

The LR87 was also tested with a gelled

Dinitrogen Tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russian rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

/ Alumizine fuel. Though the earlier tests with the LR87 were terminated due to combustion instabilities and funding restraints development of gelled fuel and oxidizers continued to produce fuels for engines currently used in space.

Engine comparison

References

External links

Encyclopedia Astronautica

National Museum of the USAF, Ohio

{{Rocket engines Rocket engines using kerosene propellant Rocket engines using hypergolic propellant Rocket engines using hydrogen propellant Rocket engines using the gas-generator cycle Rocket engines of the United States