The RS-27 (Rocket System-27) was a

liquid-propellant rocket A liquid-propellant rocket or liquid rocket uses a rocket engine burning liquid rocket propellant, liquid propellants. (Alternate approaches use gaseous or Solid-propellant rocket , solid propellants.) Liquids are desirable propellants because th ...

engine developed in 1974 by

Rocketdyne Rocketdyne is an American rocket engine design and production company headquartered in Canoga Park, California, Canoga Park, in the western San Fernando Valley of suburban Los Angeles, California, Los Angeles, in southern California. 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 First stage or First Stage may refer to: * First Stage Children's Theater, a professional American children's theater based in Milwaukee, Wisconsin * First stage (rocketry), the first stage of a multistage rocket * the first reading of a bill in t ...

of the

Delta 2000 The Delta 2000 series was an American expendable launch system which was used to conduct forty-four orbital launches between 1974 and 1981. It was a member of the Delta family of rockets, sometimes called Thorad Delta. Several variants existed, ...

3000 3000 or 3000s usually refers to: * 3000 (number), the decimal number * 3000 AD/CE, the first year of the 31st century * 3000 BC(E), a year in the 3rd millennium BC * 3000s AD/CE, a decade, century, millennium in the 4th millennium * 3000s BC(E), ...

5000 5000 or ''variation'', may refer to: In general * A.D. 5000, the last year of the 5th millennium CE * 5000 BCE, a year in the 5th millennium BC * 5000s AD, a decade, century, millennium in the 6th millennium CE * 5000s BCE, a decade, century, mil ...

, and the first model of the

Delta II 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 ...

, the Delta 6000. The RS-27 was a modified

Rocketdyne H-1 The Rocketdyne H-1 was a 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 (rocket), Saturn I and Saturn IB rockets, respectively, where it was used in c ...

built to power the first stage of the

Saturn I The Saturn I was a rocket designed as the United States' first medium lift launch vehicle for up to low Earth orbit Payload (air and space craft), payloads.Terminology has changed since the 1960s; back then, 20,000 pounds was considered "heavy l ...

and

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 replaced the MB-3 engine that had been used on previous versions of the Delta launcher. NASA had a large supply of surplus H-1 engines in the early 1970s, as the Apollo program was ending. In addition to its main engine, the RS-27 included two

vernier Vernier may refer to: *Vernier, Switzerland *Vernier (surname) *Pierre Vernier, French mathematician and inventor of the Vernier scale *Vernier scale, a secondary measuring device *Vernier thruster, a secondary control mechanism on spacecraft *Ve ...

engines to provide vehicle roll control during flight. RS-27 was later developed into the RS-27A and

RS-56 RS-56 (Rocket System-56) was an American liquid-fueled rocket engine, developed by Rocketdyne. RS-56 was derived from the RS-27 engine, which itself is derived from the H-1 engine used in the Saturn I and Saturn IB. Two variants of this engi ...

RS-27A

The RS-27A is a

liquid-fuel 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 combustio ...

engine developed in 1980s by

for use on the

of the

and

Delta III Delta III was an expendable launch vehicle made by McDonnell Douglas (later acquired by Boeing). Development was canceled before the vehicle became operational. The vehicle is the third generation of the Delta rocket family, developed from the ...

launch vehicles. It provides of thrust burning

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- ...

and

LOX Lox is a fillet of brined salmon, which may be smoked. Lox is frequently served on a bagel with cream cheese, and often garnished with tomato, onion, cucumber, and capers. Etymology The American English word ''lox'' is a borrowing of Yiddi ...

in a

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 ...

. The engine is a modified version of its predecessor, the RS-27; its thrust nozzle has been extended to increase its area ratio from 8:1 to 12:1, which provides greater efficiency at altitude. The RS-27A main engine is neither restartable nor throttleable. In addition to its main engine, it includes two

engines to provide vehicle roll control during flight. When used as the main booster propulsion system for the Delta II family of launch vehicles, has an operational duration of 265 seconds. The last RS-27A engine was used for the

ICESat-2 ICESat-2 (Ice, Cloud, and land Elevation Satellite 2), part of NASA's Earth Observing System, is a satellite mission for measuring ice sheet elevation and sea ice thickness, as well as land topography, vegetation characteristics, and clouds. ICES ...

launch on 15 September 2018.

External links

Aerojet Rocketdyne RS-27A Product Page

Pratt and Whitney RS-27A Brochure

References

Rocketdyne engines Rocket engines using the gas-generator cycle Rocket engines using kerosene propellant Rocket engines of the United States {{space-stub