Two RD-181 engines in 2015 are being integrated with the Antares first stage air frame at the Wallops Island, Virginia Horizontal Integration Facility (HIF). Credit NASA
The RD-181 is based on the NPO Energomash RD-191 and is adapted for integration on the Antares rocket. On December 17, 2014, Orbital Sciences announced that it would use the NPO Energomash RD-181 on the Antares 200 series launch vehicle and had contracted directly with NPO Energomash for up to 20 RD-181 engines.
NPO Energomash “V. P. Glushko”, Energomash for short, is a major Russian rocket engine manufacturer which primarily develops and produces liquid propellant rocket engines. Energomash originates from the Soviet design bureau OKB-456. NPO Energomash acquired its current name on May 15, 1991, in honor of its former chief designer Valentin Glushko.
Two engines are used on the first stage of each Antares, which is currently used to carry cargo to the International Space Station under the NASA CRS contract. Russian press had stated that the contract was valued at US$ 1 billion with options, Orbital ATK stated on 26 January 2015 that even when exercising all the options the contract was less than that amount.
The old age of the engines started to cause issues. A catastrophic failure of an AJ26 during testing at Stennis Space Center in May 2014 and the Orb-3 launch failure in October 2014 were indicators that the Antares needed a newer engine. Due to concerns over corrosion, aging, and the limited supply of AJ26 engines a new deal to purchase Russian engines was struck.
The new first stage engines was the NPO Energomash RD-181 and leveraged to bid on a second major long-term contract for cargo resupply of the ISS. The RD-181 is a modified version of the RD-191 and replaced the AJ26 on the Antares 200-series. The first successful flight with the RD-181 engines in leu of the AJ26 engines was October 17, 2016, carrying the Cygnus CRS OA-5 cargo to the ISS.
The two NPO Energomash RD-181 engines provide 440 kilonewtons (100,000 lbf) which was more thrust than the dual AJ26 engines used on the Antares 100. The changes to the Antares increased performance in the 200 Series, allowing Antares to deliver up to 6,500 kg (14,300 lb) to low Earth orbit. The increased performance, and then to finish up its CRS-1 cargo contract commitment to NASA for delivering a total of 20,000 kg (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.
