Country of origin | United States |
---|---|
Date | 1958 |
Designer | Rocketdyne |
Manufacturer | Rocketdyne |
Application | Vernier Thruster |
Status | Retired |
Liquid-fuel engine | |
Propellant | LOX / RP-1 |
Cycle | Gas Generator / Pressure-fed |
Configuration | |
Chamber | 1 |
Performance | |
Thrust, vacuum | (Pressure-fed) 830 pounds-force (3,700 N) |
Thrust, sea-level |
|
Chamber pressure |
|
Specific impulse, sea-level |
|
Burn time | Rated for 184 Sec |
Used in | |
Thor, Atlas, Delta |
The LR-101 is a fixed thrust, single start vernier thruster developed by Rocketdyne in the mid-to-late fifties and used in the Atlas, Thor and Delta launch vehicles until 1990.
Each of these rockets used two LR-101 secondary engines to provide yaw, pitch and roll control during their ascent to space. The pair of LR-101 vernier thrusters would receive their propellant flow from the turbopumps of the sustainer engine until it was shut off. After sustainer burnout, this pair of thrusters would switch to feed off the remaining propellant, effectively becoming a Pressure-fed engine. The remaining fuel would then be spent for the last trajectory corrections and stabilization of the rocket before separating the payload.
Due to several modifications the LR-101 underwent over the years, there are many different variants of this engine (LR101-NA-3, [1] LR101-NA-7, [2] [3] LR101-NA-9, [4] LR101-NA-11, [5] [3] LR101-NA-13, [1] etc).
One of the first changes was the downrating of the engine to a lower thrust level, both because the engine provided far more thrust than required to steer the rocket and to save fuel for the main engines. Another major change was the replacement of the original pyrotechnical ignition system with an igniter using a hypergolic fuel mixture composed of Triethylaluminum and Triethylborane. [6]
Additionally, the Atlas, Thor and Delta Rockets each possessed unique aerodynamically shielded gimbal mounts in the vicinity of their primary engines to provide large arcs for the vernier thrusters. While the pair of LR-101s on the Atlas was mounted radially above the booster engines of the vehicle, on the Thor they were placed at the base of the vehicle. [7]
The LR-101 is one of the most common vernier thrusters utilized in American rocketry and has become a sought-after object for item collectors and builders of amateur rockets. Rocket engineer Robert C. Truax, who had led the initial design studies for the PGM-17 Thor missile had planned on propelling his 'X-3 Volksrocket' with four Rocketdyne LR-101 engines, but despite many test firings the rocket never left the ground. [8]
On the 'Galactic Aztec', the engine used RP-2 (Kerosene) as a propellant instead of RP-1, which was utilized in the SM-65 Atlas and PGM-17 Thor ballistic missiles as well as the later commercial Delta rockets.
The SM-65 Atlas was the first operational intercontinental ballistic missile (ICBM) developed by the United States and the first member of the Atlas rocket family. It was built for the U.S. Air Force by the Convair Division of General Dynamics at an assembly plant located in Kearny Mesa, San Diego.
Rocketdyne is an American rocket engine design and production company headquartered in Canoga Park, in the western San Fernando Valley of suburban Los Angeles, in southern California.
The PGM-17A Thor was the first operative ballistic missile of the United States Air Force (USAF). It was named after the Norse god of thunder. It was deployed in the United Kingdom between 1959 and September 1963 as an intermediate-range ballistic missile (IRBM) with thermonuclear warheads. Thor was 65 feet (20 m) in height and 8 feet (2.4 m) in diameter.
Delta II was an expendable launch system, originally designed and built by McDonnell Douglas, and sometimes known as the Thorad Delta 1. Delta II was part of the Delta rocket family, derived directly from the Delta 3000, and entered service in 1989. There were two main variants, the Delta 6000 and Delta 7000, with the latter also having "Light" and "Heavy" subvariants. During its career, Delta II flew several notable payloads, including 24 Global Positioning System (GPS) Block II satellites, several dozen NASA payloads, and 60 Iridium communication satellites. The rocket flew its final mission, ICESat-2, on 15 September 2018, earning the launch vehicle a streak of 100 successful missions in a row, with the last failure being GPS IIR-1 in 1997. In the late 1990s, Delta II was developed further into the unsuccessful Delta III, which was in turn developed into the more capable and successful Delta IV, though the latter shares little heritage with the original Thor and Delta rockets.
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 from 1975 to 1992. More than 300 Delta rockets were launched with a 95% success rate. The series was phased out in favor of the Vulcan Centaur, with the Delta IV Heavy rocket's last launch occurring on April 9, 2024.
The Rocketdyne H-1 was a 205,000 lbf (910 kN) thrust liquid-propellant rocket engine burning LOX and RP-1. The H-1 was developed for use in the S-I and S-IB first stages of the Saturn I and Saturn IB rockets, respectively, where it was used in clusters of eight engines. After the Apollo program, surplus H-1 engines were rebranded and reworked as the Rocketdyne RS-27 engine with first usage on the Delta 2000 series in 1974. RS-27 engines continued to be used up until 1992 when the first version of the Delta II, Delta 6000, was retired. The RS-27A variant, boasting slightly upgraded performance, was also used on the later Delta II and Delta III rockets, with the former flying until 2018.
The RL10 is a liquid-fuel cryogenic rocket engine built in the United States by Aerojet Rocketdyne that burns cryogenic liquid hydrogen and liquid oxygen propellants. Modern versions produce up to 110 kN (24,729 lbf) of thrust per engine in vacuum. Three RL10 versions are in production for the Centaur upper stage of the Atlas V and the DCSS of the Delta IV. Three more versions are in development for the Exploration Upper Stage of the Space Launch System and the Centaur V of the Vulcan rocket.
Atlas II was a member of the Atlas family of launch vehicles, which evolved from the successful Atlas missile program of the 1950s. The Atlas II was a direct evolution of the Atlas I, featuring longer first-stage tanks, higher-performing engines, and the option for strap-on solid rocket boosters. It was designed to launch payloads into low Earth orbit, geosynchronous transfer orbit or geosynchronous orbit. Sixty-three launches of the Atlas II, IIA and IIAS models were carried out between 1991 and 2004; all sixty-three launches were successes, making the Atlas II a highly reliable space launch system. The Atlas line was continued by the Atlas III, used between 2000 and 2005, and the Atlas V, which is still in use as of 2024.
Aerojet Rocketdyne is a subsidiary of American defense company L3Harris that manufactures rocket, hypersonic, and electric propulsive systems for space, defense, civil and commercial applications. Aerojet traces its origins to the General Tire and Rubber Company established in 1915, while Rocketdyne was created as a division of North American Aviation in 1955. Aerojet Rocketdyne was formed in 2013 when Aerojet and Pratt & Whitney Rocketdyne were merged, following the latter's acquisition by GenCorp, Inc. from Pratt & Whitney. Aerojet Rocketdyne was acquired by L3Harris in July 2023 for $4.7 billion.
Delta III was an expendable launch vehicle made by McDonnell Douglas. Development was canceled before the vehicle became operational. The vehicle is the third generation of the Delta rocket family, developed from the highly successful Delta II to help meet the launch demand of larger satellites. While the Delta III never had a successful launch, some of the technologies developed were used in its successor, the Delta IV.
A liquid rocket booster (LRB) uses liquid fuel and oxidizer to give a liquid-propellant or hybrid rocket an extra boost at take-off, and/or increase the total payload that can be carried. It is attached to the side of a rocket. Unlike solid rocket boosters, LRBs can be throttled down if the engines are designed to allow it, and can be shut down safely in an emergency for additional escape options in human spaceflight.
A vernier thruster is a rocket engine used on a spacecraft or launch vehicle for fine adjustments to the attitude or velocity. Depending on the design of a craft's maneuvering and stability systems, it may simply be a smaller thruster complementing the main propulsion system, or it may complement larger attitude control thrusters, or may be a part of the reaction control system. The name is derived from vernier calipers which have a primary scale for gross measurements, and a secondary scale for fine measurements.
Thor was a US space launch vehicle derived from the PGM-17 Thor intermediate-range ballistic missile. The Thor rocket was the first member of the Delta rocket family of space launch vehicles. The last launch of a direct derivative of the Thor missile occurred in 2018 as the first stage of the final Delta II.
The Thor-Burner was an American expendable launch system, a member of the Thor rocket family. It consisted of a Thor missile, with one or two Burner upper stages. It was used between 1965 and 1976 to orbit a number of satellites, most commonly Defense Meteorological Satellite Program (DMSP) weather satellites. Twenty-four were launched, of which two failed. It weighed 51,810 kg and was 24 metres tall.
The SM-65C Atlas, or Atlas C was a prototype of the Atlas missile. First flown on 24 December 1958, the Atlas C was the final development version of the Atlas rocket, prior to the operational Atlas D. It was originally planned to be used as the first stage of the Atlas-Able rocket, but following an explosion during a static test on 24 September 1959, this was abandoned in favor of the Atlas D. Atlas C was similar to Atlas B, but had a larger LOX tank and smaller RP-1 tank due to technical changes to the Rocketdyne engines. Improvements in materials and manufacturing processes also resulted in lighter-weight components than the Atlas A and B. Booster burn time was much longer than the A/B series, up to 151 seconds. All launches took place from LC-12 at CCAS.
The Altair was a solid-fuel rocket with a fiberglass casing, initially developed for use as the third stage of Vanguard rockets in 1959. It was manufactured by Allegany Ballistics Laboratory (ABL) as the X-248. It was also sometimes called the Burner 1.
The LR87 was an American liquid-propellant rocket engine 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 and was never flown as a single combustion chamber engine or designed for this. The LR87 first flew in 1959.
The RS-27 was a liquid-propellant rocket engine developed in 1974 by Rocketdyne to replace the aging MB-3 in the Delta. Incorporating components of the venerable MB-3 and the H-1 designs, the RS-27 was a modernized version of the basic design used for two decades. It was used to power the first stage of the Delta 2000, 3000, 5000, and the first model of the Delta II, the Delta 6000.
The LR105 is a liquid-fuel rocket engine that served as the sustainer engine for the Atlas rocket family. Developed by Rocketdyne in 1957 as the S-4, it is called a sustainer engine because it continues firing after the LR89 booster engines have been jettisoned, providing thrust during the ascent phase.
The Rocketdyne LR89 was a liquid-fueled rocket engine developed in the 1950s by Rocketdyne, a division of North American Aviation. It was designed to serve as a booster engine the Atlas rocket family. The LR89 was a liquid oxygen (LOX) and RP-1 (kerosene) engine.