The Lunar Landing Research Vehicle (LLRV) flies in the skies above Dryden in 1967. NASA Photo
LLRV Paved Way to Moon Landing
By Gray Creech
Dryden Public Affairs
After making the 240,000- mile journey to the moon, cruising through open space, the last 300 feet represented the most difficult and dangerous part of the Apollo moon missions.
The Apollo astronauts needed a way to practice that final descent and landing before Apollo 11 astronauts Neil Armstrong and Edwin "Buzz" Aldrin made the first historic moon landing in their lunar lander Eagle on July 20, 1969.
On the 35th anniversary of the first moon landing, a look back at the development of one type of the lander simulators, the Lunar Landing Research Vehicle, or LLRV, serves as a reminder of the ingenuity that fueled America's space program.
At the start of the Apollo program in 1960, there were no simulators on which would-be moonwalkers might practice the art and finesse of lunar surface landings. So, as the program got under way, NASA began planning for such simulators. Three types were developed: an electronic simulator, a tethered lander, and the ambitious Flight Research Center (now Dryden) contribution, a free-flying vehicle. The three types evolved into serious projects, and all contributed greatly to the Apollo mission's success.
The LLRVs, dubbed "flying bedsteads" by those who worked with them for the crafts' ungainly appearance, were used by the Flight Research Center to study piloting techniques needed to fly and land the Apollo Lunar Module in the moon's airless environment.
Success with the two LLRVs led to the building of three Lunar Landing Training Vehicles (LLTVs) used by Apollo astronauts at the Manned Spacecraft Center in Houston, Texas, predecessor of Johnson Space Center.
Neil Armstrong, the first human to step onto the moon's surface, said the mission would not have been successful without the type of simulation provided by the LLRVs and LLTVs.
Built of aluminum alloy trusses, the vehicles were powered by a 4,200-pound thrust General Electric CF-700-2V turbofan engine mounted vertically in a gimbal. The engine lifted the vehicle to test altitude and was then throttled back to support five-sixths of the vehicle's weight, simulating the reduced gravity of the moon. Two hydrogen peroxide lift rockets with thrust that could be varied from 100 to 500 pounds handled the vehicle's rate of descent and horizontal movement. Sixteen smaller hydrogen peroxide thrusters, mounted in pairs, gave the pilot control in pitch, yaw and roll. As safety backups, six 500-pound thrust rockets could take over the lift function and stabilize the craft for a moment if the jet engine failed. The pilot had an ejection seat that would then push him to safety.
After testing at the Flight Research Center, the LLRVs were sent to Houston, where research pilots used them in learning to become LLTV instructor pilots. In December 1967, the first of the LLTVs joined the LLRVs to eventually make up the five-vehicle training and simulator fleet.
Modifications to some of the vehicles gave astronauts a three-axis side control stick and a more restrictive cockpit view, both features of the actual lunar module they would later fly down to the moon's surface.
During the Houston training flights, three of the five vehicles were destroyed in crashes, LLRV No. 1 in May 1968 and two LLTVs in December 1968 and January 1971. Neil Armstrong was one of the pilots who ejected safely following an engine failure.
Donald K. "Deke" Slayton, then NASA's chief astronaut, later said there was no way to simulate a moon landing other than by flying the LLTV.
The final 300-foot descent to the lunar surface was the last major step in the journey to the moon, leading to Armstrong's incredible first step there 35 years ago this month. A monograph detailing the history and development of the LLRVs, written by project engineers Gene Matranga, Wayne Ottinger and Calvin Jarvis, is due to be published by Dryden.