Rocket engine

A rocket engine is a type of jet engine that uses only stored rocket propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines, obtaining thrust in accordance with Newton's third law. Most rocket engines are internal combustion engines, although non-combusting forms (such as cold gas thrusters) also exist. Vehicles propelled by rocket engines are commonly called rockets. Since they need no external material to form their jet, rocket engines can perform in a vacuum and thus can be used to propel spacecraft and ballistic missiles.

Compared to other types of jet engines, rocket engines have the highest thrust, are by far the lightest, but are the least propellant efficient (have the lowest specific impulse). The ideal exhaust is hydrogen, the lightest of all gases, but chemical rockets produce a mix of heavier species, reducing the exhaust velocity. Rocket engines become more efficient at high velocities (due to greater propulsive efficiency and Oberth effect). Since they do not require an atmosphere, they are well suited for uses at very high altitude and in space.

RD-180

The RD-180 (РД-180, Ракетный Двигатель-180, Rocket Engine-180) is a rocket engine designed and built in Russia. It features a dual-combustion chamber, dual-nozzle design and is fueled by a kerosene/LOX mixture. Currently RD-180 engines are used for the first stage of the US Atlas V launch vehicle.

The RD-180 is derived from the RD-170/RD-171 line of rocket engines, which were used in the Soviet Energia launch vehicle, and are still in use in the Ukrainian/Russian Zenit launch vehicles.

History

The roots of the RD-180 rocket engine extend back into the Soviet Energia launch vehicle project. The RD-170, a four-chamber engine, was developed for use on the strap-on boosters for this vehicle, which ultimately was used to lift the Buran orbiter. This engine was scaled to a two-chamber version by combining the RD-170's combustion devices with 1/2 size turbomachinery. After successful performance in engine tests on a test stand, and high-level agreements between the US government and the Russian government, the engines were imported to the US for use on the Lockheed Martin Atlas III, with first flight in 2000. The engine is also used on the United Launch Alliance Atlas V, the successor to the Atlas III.

RD-170

The RD-170 (РД-170, Ракетный Двигатель-170, Rocket Engine-170) is the world's most powerful liquid-fuel rocket engine, designed and produced in the Soviet Union by NPO Energomash for use with the Energia launch vehicle. The engine burns the Russian equivalent of RP-1 fuel and LOX oxidizer in four combustion chambers, all supplied by one single-shaft, single-turbine turbo pump rated at 170 MW in a staged combustion cycle.

Shared turbopump

Several Soviet and Russian rocket engines use the approach of clustering small combustion chambers around a single turbine and pump. During the early 1950s, many Soviet engine designers, including Valentin P. Glushko, faced problems of combustion instability while designing bigger thrust chambers. At that time they solved the problem by using a cluster of smaller thrust chambers.

Variants

RD-151

The RD-151 is the RD-191 with thrust reduced from 196 to 170 tonnes. This engine was test-fired on July 30, 2009. The first flight test of this engine was conducted on August 25, 2009 as part of the first launch of South Korean Naro-1 rocket. The first stage of the Naro-1 rocket is made of the Universal Rocket Module (URM) from the Angara rocket.