Orbital to Replace Old Russian Engines With New Russian Engines on Antares

An Orbital Sciences Corporation Antares rocket is seen as it launches from Pad-0A at NASA's Wallops Flight Facility, Thursday, January 9, 2014, Wallops Island, VA. Antares is carrying the Cygnus spacecraft on a cargo resupply mission to the International Space Station. The Orbital-1 mission is Orbital Sciences' first contracted cargo delivery flight to the space station for NASA. Cygnus is carrying science experiments, crew provisions, spare parts and other hardware to the space station. Photo Credit: (NASA/Bill Ingalls)
An Orbital Sciences Corporation Antares rocket is seen as it launches from Pad-0A at NASA’s Wallops Flight Facility, Thursday, January 9, 2014, Wallops Island, VA. Antares is carrying the Cygnus spacecraft on a cargo resupply mission to the International Space Station. The Orbital-1 mission is Orbital Sciences’ first contracted cargo delivery flight to the space station for NASA. Cygnus is carrying science experiments, crew provisions, spare parts and other hardware to the space station. (Credit: NASA/Bill Ingalls)

I guess Orbital Sciences Corporation can kiss any defense launches goodbye for its Antares launch vehicle. The company plans to replace the rocket’s Russian surplus AJ-26 engines with new Russian engines they hope won’t blow up during flight or be banned from export at some point in the future.

Designated the RD-181, the new engine will be used on Antares in shipsets of two to accommodate as closely as possible the two-engine configuration built around the AJ-26 engines supplied by Aerojet Rocketdyne, Orbital Sciences managers said Dec. 16.

A descendant of the RD-171 that powers the Ukrainian-built Zenit launch vehicle, the RD-181 will be manufactured in the same Khimki factory that builds the RD-180 used on the United Launch Alliance Atlas V. It closely resembles the RD-191 on Russia’s new Angara launcher and the RD-151 that powers South Korea’s Naro-1 launch vehicle.

In testing at Energomash, “the RD-181s have seen more than two times the Antares flight duration to date, and if you take a look at some of the heritage of this engine, the RD-151 and the RD-191 combined have over 10 hr. of test time for their configuration testing,” said Mark Pieczynski, Orbital’s vice president for space launch strategic development.

Like the AJ-26, the single-thrust-chamber, single-nozzle RD-181 uses liquid oxygen and refined petroleum (RP) as propellants, generating a sea-level performance in the two-engine configuration of 864,000 lb. thrust with a specific impulse of 311.9 sec. That is equivalent to the twin-nozzle RD-180, but the two engines are a better fit with the Antares main stage, built for Orbital by Ukraine’s Yuzhmash.

Congress has just voted to prohibit ULA from using Russian RD-180 engines in its Atlas V booster due to deteriorating relations with that country. That would seem to limit Orbital’s ability to bid for defense launch contracts unless there is a change in policy.

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