Engineers at NASA's John C. Stennis Space Center recently installed an Aerojet AJ26 rocket engine for qualification testing as part of a partnership that highlights the space agency's commitment to work with commercial companies to provide space transportation. Stennis has partnered with Orbital Sciences Corporation to test the AJ26 engines that will power the first stage of the company's Taurus II space launch vehicle. Orbital is working in partnership with NASA under the agency's Commercial Orbital Transportation Services (COTS) joint research and development project. The company is under contract with NASA through the Commercial Resupply Services program to provide eight cargo missions to the International Space Station through 2015. Stennis operators have been modifying their E-1 test facility since April 2009 to test the AJ26 engines for Orbital. Work has included construction of a 27-foot-deep flame deflector trench. The latest step in the project involved delivery and installation of an AJ26 engine for testing. In upcoming days, operators will perform a series of "chilldown" test, which involves running sub-cooled rocket propellants through the engine, just as will occur during an actual "hotfire" ignition test. The chilldown tests are used to verify proper temperature conditioning of the engine systems and elapse time required to properly chill the engine, and to measure the quantity of liquid oxygen required to perform the operation. Once the installed engine passes the chilldown and other qualification tests, it will be removed from the Stennis E-1 test facility. The first actual flight engine then will be delivered and installed for hotfire testing. The AJ-26 engine is a modified Russian NK-33 providing 338,000 pounds of thrust at sea level. The NK-33 is a kerosene/liquid oxygen staged combustion rocket engine designed and built in the late 1960s by the Soviet Union's Kuznetsov Design Bureau. The NK-33 was intended for the ill-fated Soviet N-1 rocket moon shot. The staged combustion cycle, which is used in all Russian liquid fuel engines, provides high efficiency (high specific impulse, or Isp), but leads to combustion instability in larger configurations. As a result, the Russians never built large engines equivalent to the Saturn V's F-1, which provided 1.5 million pounds of thrust. The Russian RD-170, developed in the early 1980s, provides 1.7 million pounds of thrust but uses four combustion chambers to do so, making the RD-170 effectively four rocket engines sharing common turbo pumps. In the late 1960s, the Soviet solution to the combustion instability problem was to use a large number of smaller engines. The first state of the N-1 moon rocket was powered by thirty NK-33 engines arranged in two rings. Complex plumbing was needed to feed fuel and oxidizer into the clustered arrangement of rocket engines. This proved to be extremely fragile, and was a major factor in the design's launch failures. All four N-1 test launches ended in failure, each before first-stage separation. The longest flight lasted 107 seconds, just before 1st stage separation. Two test launches occurred in 1969, one in 1971 and the final one in 1972. The second flight, in 1969, resulted in the largest rocket explosion in history. At liftoff, a loose bolt was ingested into a fuel pump, which failed. After detecting the inoperative fuel pump, the automatic engine control shut off 29 of 30 engines, which caused the rocket to stall. The rocket exploded 23 seconds after shutting off the engines, destroying the rocket and launch tower. The explosion of 2,600 tons of fuel had the power of a small nuclear bomb. The destroyed complex was photographed by American satellites, disclosing that the Soviet Union was building a Moon rocket After the fourth failure in 1972, the remaining N-1 boosters were deliberately broken up in an effort to cover up the USSR's failed moon attempts. However, the NK-33 engines escaped destruction. Although the spacecraft as a whole was unreliable, the NK-33 engine is considered rugged and reliable when used as a standalone unit. The NK-33 engine achieves the highest thrust-to-weight ratio of any Earth-launched rocket engine, while achieving a very high specific impulse. NK-33 is by many measures the highest performance LOX/Kerosene rocket engine ever created. About 150 engines survived, and in the mid-1990s, Russia sold 36 engines to Aerojet for $1.1 million each. Aerojet also acquired a license for the production of new engines. Supplied through Aerojet, three of the NK-33 engines were incorporated into Japanese rockets J-1 and J-2. The US company Kistler Aerospace (later Rocketplane Kistler) worked on incorporating these engines into a new rocket design before declaring bankruptcy. The current design of Orbital Science's Taurus II launch vehicle includes two NK-33s as the first stage engines. The Aerojet AJ26 implements several modifications to the NK-33. Most of these modifications are specific to the Taurus II. However, an industry source quoted by Space News said that Russia is interested in a new gimbal and a number of modern actuators that Aerojet designed for its Americanized NK-33. The Taurus II is an expendable launch system being developed by Orbital Sciences Corporation. The Taurus II is a two stage vehicle designed to launch payloads weighing up to 15,000 lb into low-Earth orbit. The Taurus II is scheduled to make its first flight in March 2011. NASA awarded a Commercial Orbital Transportation Services (COTS) contract to Orbital to demonstrate delivery of cargo to the International Space Station. For these COTS missions, Orbital intends to use Taurus II to launch its Cygnus spacecraft. In addition, Taurus II will compete for small-to-medium missions. The first stage of the Taurus II uses RP-1 (kerosene) and liquid oxygen (LOX) as propellants, powering two AJ26 engines. Orbital's previous launch vehicles are solid fueled, so Orbital has little experience with liquid propulsion and has contracted some of the Taurus II first stage work to the Ukrainian company Yuzhnoye, designer of the Zenit launch vehicles. The second stage of the Taurus II uses the solid-fuel Castor 30, which is being developed by ATK as a derivative of the Castor 120 solid stage. The Castor 120 is a derivative of the first-stage motor of the MX Peacekeeper missile. The Castor 120 was first used as the first-stage motor of Lockheed Martin's Athena I in 1995, and later the first and second stages of the Athena II. -- July 20, 2010 In other news...