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 loft 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.^[1]

The engine has no direct connection to the NK-33, which was developed by a different bureau (Kuznetzov) nearly a decade earlier.

2014 availability concerns

Doubts about the reliability of the supply chain for the RD-180 arose following the Ukraine crisis in March 2014. For over thirteen years since the engine was first used in the Atlas III launch vehicle in 2000, there was never any serious jeopardy to the engine supply, despite an uneven record of US-Russian relations since the Cold War. But worsening relations between the West and Russia after March have led to several blockages, including a short-lived judicial injunction from the US courts that were unclear on the scope of the US sanctions on importing the Russian engine.^[2]

On May 13, 2014, Russian Deputy Prime Minister Dmitry Rogozin announced that "Russia will ban the United States from using Russian-made rocket engines for military launches"^[3]—a frequent payload of the ULA Atlas V launch vehicle which powers its first stage with a single RD-180 engine that is expended after each flight.^[4] In response, the US Air Force has asked the Aerospace Corporation to begin evaluating alternatives for powering the Atlas 5 booster stage with non-RD-180 engines. Early estimates are that it would require five or more years to replace the RD-180 on the Atlas V.^[5]

Even if the Russian government does not cut off the supply to ULA of imported RD-180 engines, the US Congress, with emerging support from the Air Force, has come around to a view that it would not be advantageous to the US government to start up a US production line to produce the RD-180. However, the US Congress is advocating for the initiation of a new US hydrocarbon rocket engine program, to field a new engine by 2022.^[6]

In June 2014, Aerojet Rocketdyne proposed that the US Federal government "fund an all-new, U.S.-sourced rocket propulsion system," the 2,200-kilonewton-class (500,000 lbf) thrust kerosene/LOX AR-1 rocket engine. as of June 2014 Aerojet's early projection was that the cost of the each engine would be under US$25 million per pair of engines—not including the up to US$1 billion estimated development cost to be funded by the US Government. Aerojet believed that the AR-1 could replace the RD-180 in the US Evolved Expendable Launch Vehicle fleet, and that it would be more affordable.^[7]

On 21 August 2014, the U.S. Air Force released an official request for information (RFI) for a replacement for the Russian RD-180 rocket engine. The RFI seeks information on "booster propulsion and/or launch system materiel options that could deliver cost-effective, commercially-viable solutions for current and future National Security Space (NSS) launch requirements. Air Force Space Command (AFSPC) is considering an acquisition strategy to stimulate the commercial development of booster propulsion systems and/or launch systems for Evolved Expendable Launch Vehicle (EELV)-class spacelift applications." The day before, the United Launch Alliance had taken delivery of two RD-180s, the first since the Russian annexation of Crimea. It is not clear when the replacement of the RD-180 would start, and the RFI asked input for several options including similarity to the Russian engine, whether it would come in a new configuration, and the use of "alternative launch vehicles" for the EELV mission.^[8]

In January 2015 Orbital Sciences Corporation have received all the necessary permissions from government bodies for the delivery of 60 engines from NPO Energomash.^[9]

US production of the RD-180

United Launch Alliance announced in February 2015 that they are considering undertaking US production of the Russian RD-180 engine at the Decatur, Alabama rocket stage manufacturing facility. The US-manufactured engines would be used only for government civil (NASA) or commercial launches, and would not be used for US military launches. This potential project is a backup plan to the new engine development work that ULA is undertaking with Blue Origin on the BE-4.^[10]

Replacement for the RD-180 engine on US Atlas launch vehicle

As a result of the geopolitical and US political considerations as 2014 progressed, United Launch Alliance (ULA) initiated an effort to consider the possible replacement of the Russian-supplied RD-180 engine used on the first stage booster of the ULA Atlas V. Formal study contracts were issued in June 2014 to a number of US rocket engine suppliers.^[11]

In September 2014, ULA announced that it has entered into a partnership with Blue Origin to develop the BE-4 LOX/methane engine to replace the RD-180 on a new first stage booster that would succeed the Atlas V. At the time, the engine was already in its third year of development by Blue Origin, and ULA expects the new stage and engine to start flying no earlier than 2019. Two of the 2,400-kilonewton (550,000 lbf)-thrust BE-4 engines will be used on the new launch vehicle booster.^[11]

Dynetics and Aerojet Rocketdyne (AJR) have also offered their AR-1 hydrocarbon-fueled rocket engine as replacement of the RD-180.^[12][13] ULA CEO Tory Bruno has said in early 2015 that both the AR-1 option, and the US manufacture of the RD-180 by ULA under license, are backup options to the primary option ULA is pursuing with the Blue Origin BE-4 engine.^[10]

RD-181 engine on the US Antares launch vehicle

In December 2014, Orbital Sciences announced that they would use the Energomash RD-181 on the version 2 Antares launch vehicle. Two engines will be used on the first stage of each Antares, which is currently used to carry cargo to the International Space Station under contract to NASA.^[14]

The two RD-181s will have 440 kilonewtons (100,000 lbf) more thrust than the dual-AJ-26 engines used on the version 1 Antares. Orbital plans to modify the core stage to accommodate the increased performance, and then to finish up its cargo contract commitment to NASA for delivering a total of 20,000 kilograms (44,000 lb) of cargo in only four additional flights, rather than the five more that would have been required with the AJ-26/Antares I combination. The first engines are scheduled to arrive from Energomash in summer 2015, where an on-pad 29-second static fire test is projected to occur in fall 2015.^[14]

Design and specifications

The combustion chambers of the RD-180 share a single turbopump unit, much like in its predecessor, the four-chambered RD-170. The RD-180 is fueled by a RP-1/liquid oxygen mixture and uses an extremely efficient, high-pressure staged combustion cycle. The engine runs with an oxidizer to fuel ratio of 2.72 and employs an oxygen-rich preburner, unlike typical fuel-rich US designs. The thermodynamics of the cycle allow an oxygen-rich preburner to give a greater power-to-weight ratio, but with the drawback that high pressure, high temperature gaseous oxygen must be transported throughout the engine. The movements of the engine nozzles are controlled by four hydraulic actuators. The engine can be throttled from 40% to 100% of rated thrust.

The RD-181 is a new engine in 2014 and will be manufactured in the same Khimki factory where the RD-180 is built. It is similar to the RD-191 used on the new Russian Angara as well as the RD-151 used on the South Korean Naro-1 launch vehicle.^[14]

The RD-181 uses RP-1/LOX propellants, and has a specific impulse (I_sp) of 312 seconds.^[14]

Applications

During the early 1990s General Dynamics Space Systems Division (later purchased by Lockheed Martin) acquired the rights to use the RD-180 in the Evolved Expendable Launch Vehicle (EELV) and the Atlas program. As these programs were conceived to support United States government launches as well as commercial launches, it was also arranged for the RD-180 to be co-produced by Pratt & Whitney. However all production to date has taken place in Russia. The engine is currently sold by a joint venture between the Russian developer and producer of the engine NPO Energomash and Pratt & Whitney, called RD AMROSS.

The RD-180 was first deployed on the Atlas IIA-R vehicle, which was the Atlas IIA vehicle with the Russian (hence the R) engine replacing the previous main engine. This vehicle was later renamed the Atlas III. An additional development program was undertaken to certify the engine for use on the modular Common Core Booster primary stage of the Atlas V rocket.

Prospective uses

RD-180 was proposed to be used with a new family of Rus-M Russian space launch vehicles, proposed by Roskosmos contractors,^[15][16] but the program was canceled by the Russian Space Agency in October 2011.^[17]

Jerry Grey, a consultant to the American Institute of Aeronautics and Astronautics and Universities Space Research Association and a former professor of aerospace engineering at Princeton University, suggested using the RD-180 for a prospective NASA heavy-lift launch vehicle. For those who might be concerned about too much reliance on Russia, he pointed out that RD Amross was "very close to producing a U.S.-built version of the RD-180, and with some infusion of NASA funding could be manufacturing that engine (and perhaps even a 1,700,000 lbf or 7.6 MN thrust equivalent of the RD-170) in a few years."^[18]

Despite the availability of necessary documentation and legal rights for producing RD-180 in the United States, NASA is considering development of an indigenous core stage engine that would be "capable of generating high levels of thrust approximately equal to or exceeding the performance of the Russian-built engine." NASA considered in 2010 to produce a fully operational engine by 2020 or sooner, depending оn partnership with the U.S. Defense Department.^[19]

See also

• Comparison of orbital rocket engines
• Staged combustion cycle used in engine
• RD-191 derivative engine being developed for the Angara rocket
• RD-0124 used in the Soyuz-2.1b
• RD-107 used in the R-7 Semyorka missiles and Soyuz FG
• RD-58 upper stage RP-1/LOX engine used in the N-1 rocket, derivatives used in the Proton and Zenit rockets
• RD-8 used in the Zenit rocket

References

External links

• Astronautix.com page on RD-180
• RD-180 page (in Russian) at NPO Energomash
• RD-180 specifications and design (in Russian)
• The Engines That Came In From The Cold!, Equinox, Channel Four Television Corporation, 2000. Documentary video on Russian rocket engine development of the NK-33 and its predecessors for the N1 rocket, the development of the staged combustion cycle, and the eventual 1990s resurgence that led to the RD-180 engine sold to the US launch provider Lockheed Martin for the Atlas III. (NK-33 story starts at 24:15–26:00 (program was shuttered in 1974); the 1990s resurgence and eventual sale of the remaining engines from storage starts at 27:25; first use as RD-180 on a US rocket launch in May 2000.)

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RD-170 rocket engine family Derivatives RD-171 RD-180 RD-191 RD-151 Technologies Bipropellant LOX RP-1 Staged combustion cycle Historic rockets Atlas III (RD-180) Energia (RD-170) Naro-1 (RD-151) Current rockets Atlas V (RD-180) Zenit (RD-171) Angara (RD-191) Rockets under development Antares (200-series) (RD-181) Cancelled proposals GX (RD-180) Rus-M (RD-180)