#llrv

Test pilot Joe Walker flying Lunar Landing Research Vehicle

Today Marks The Anniversary Of Neil Armstrong’s Near-Fatal Lunar Landing Vehicle Crash

“First man to walk on the moon... That’d be something.”

LLRV - Take Off and Flight

-One of the LLRVs in flight over Edwards, with a TB-47B and B-57A 55-0665, nicknamed “Snoopy” (which was modified to house a test version of the AN/ASG-18 radar for the F-108 and F-12 programs) in the background. | Photo: NASA / Dryden Flight Research Center

Edwards AFB, 1 January 1965

Built by Bell Aerosystems, the 2 Lunar Lander Research Vehicles and 3 Lunar Lander Training Vehicles (collectively nicknamed Flying Bedsteads) were used to develop controls for the Lunar Landers used by the Apollo program, as well as train the pilots for the Landers.

NASA selected Bell as the contractor for the LLRV program based on the company’s experience with VTOL aircraft, and issued a study contract in 1961 to develop a system to simulate landing on the Moon. Bell had also been studying the idea independently, and by February of 1963 the company was awarded a contract worth $3.6 million ($30.5 million today) to produce the LLRVs, with the first two craft expected at Edwards for flight testing within 14 months.

-Line drawing of the LLRV, showing the simplicity of its construction as well as its dimensions. | Illustration: NASA

“Aircraft” only in the most general sense, the LLRVs and LLTVs were a series of truss sections built from aluminum tube. A single GE CF700/TF34 was placed in the center of the vehicle, oriented vertically downward and mounted on a gimbal to keep the axis of thrust centered. The turbofan would lift the LLRV to an appropriate altitude (500 feet or less) , at which point it would be throttled back to simulate the 1/6th gravity of the Moon. two rockets, powered by hydrogen peroxide and throttleable between 100lbf and 500lbf, would be used to slow the craft’s descent rate and provide horizontal movement. Sixteen smaller RCS motors, also powered by H2O2,were mounted in pairs and controlled pitch, roll and yaw. In an emergency, six solid fuel rockets could be used to maintain the 5/6th support if the turbofan failed, allowing a safe landing. Finally, one of the first zero/zero ejection seats was fitted, which could catapult the pilot to safety even from zero altitude and zero speed (hence the name).

-Engine test of LLRV #1 in late 1964. | Photo: NASA/DFRC

Both LLRVs were shipped from Bell’s plant to Edwards in April of 1964, though #2 was shipped in pieces and assembled there to keep costs down. After initial tests on a tilt table, the vehicles were moved to the South Base area of Edwards and flight testing began in October. Test flights were carried out by FRC pilots Joe Walker and Con Mallick, as well as Army helicopter test pilot Jack Kleuver and NASA pilots Joe Algranti and H. E. Ream. After the test series at Edwards, the LLRVs were modified, adding the three-axis hand controllers and throttles of the future LM, as well as a cockpit enclosure (made from Styrofoam to keep weight down) to simulate the view from the LM.

LLRV #2, after modifications. Also note the landing pegs instead of the casters present on the preceding picture. | Photo: NASA/DFRC

-Picture of a preserved LLTV, showing the instruments in the cockpit. | Photo: NASA

In December of 1966, LLRV #1 was transported to NASA Houston, followed by #2 in January of ‘67, and NASA’s flights began on 27 March 1967, with Neil Armstrong piloting #1 at Ellington AFB. Armstrong, as well as other pilots of the craft, were quick to point out that given the LLRV’s operations envelope, use of the ejection seat was their only option if something went wrong, which was proven on 6 May 1968, when a control failure forced Armstrong to eject at 200 feet.

A review board found that the fuel for the RCS thrusters had run out, aggravated by high winds on the day of the flight. NASA decided to terminate further flights of the LLRV at this point, as the improved LLTV were due to be shipped to Ellington from Bell. At the time of the accident, LLRV #1 had completed 198 flights accident-free, with #2 completing 6 flights.

In March of 1967, Bell Aerosystems was granted a contract worth $5.9 million ($45.7 M today) to produce three Lunar Lander Training Vehicles, an advanced version of the LLRV used to train the LM pilots. The first vehicle arrived at Ellington in June of 1968, with first flight carried out by JSC’s Aircraft Operations Division (AOD) head Joe Algranti in August. Tests lasted until 8 December, when Algranti lost control of the vehicle and ejected just 3/5th of a second before impact.

The accident review found that, due to the decision to not test the LLTV in a wind tunnel prior to flight tests, the full capabilities and limitation of the RCS were unknown. The decision was then made to fly LLTV #3 to NASA Langley in a Super Guppy for wind tunnel testing.

-LLTV #3 being loaded into the Super Guppy. | Photo: NASA

-LLTV #3 inside the 30x60 foot wind tunnel at NASA Langley. | Photo: NASA

Testing on the vehicle lasted from 7 January to 7 February 1968, and determined that the Styrofoam cabin was inducing a yaw at sideslip angles exceeding -2°, which quickly exceeded the RCS’ ability to counteract. NASA took the simple expedient of removing the top of the cabin, which eliminated the yaw. Data from the tests also allowed NASA to build a preliminary flight envelope, though this would have to be checked with test flights, as the LLTV’s engine could not be run in the tunnel. A Flight Readiness Review Board was convened in March of 1969 to review the findings of the accident board, as well as the data from the tunnel tests, and on 30 March approved a resumption of flight tests, which were completed in March of 1969, leaving Neil Armstrong a month to complete his LLTV training prior to the Apollo 11 launch.

After the successful landing of Apollo 11, the remaining LM pilots each took their turn in the LLTV, though #3 was destroyed on 29 January ‘71 after an electrical failure at 200 feet.

The LLRV and LLTV were invaluable tools in the Moon landing, and were some of the few hardware simulators to get get airborne. Then Chief Astronaut of NASA Deke Slayton said simply: “[There was] no other way to simulate moon landings except by flying the LLRV.”

Unsurprisingly, only two of the craft survived the program:

LLRV #2 is on display at the Armstrong Flight Research Center (FKA NASA Dryden), which is apparently Fort Knox as I cannot find a pic anywhere.

LLTV #2, also known as NASA 952, is hanging in the lobby of the NASA Johnson Space Center: