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 byRocketdyne, 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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