When Apollo planning was underway in 1960, NASA was looking for a simulator to profile the descent to the moon's surface. Three concepts surfaced: an electronic simulator, a tethered device, and the ambitious Dryden contribution, a free-flying vehicle. All three became serious projects, but eventually the NASA Flight Research Center's (FRC) Landing Research Vehicle (LLRV) became the most significant one. Hubert M. Drake is credited with originating the idea, while Donald Bellman and Gene Matranga were senior engineers on the project, with Bellman, the project manager.

Simultaneously, and independently, Bell Aerosystems Company, Buffalo, N.Y., a company with experience in vertical takeoff and landing (VTOL) aircraft, had conceived a similar free-flying simulator and proposed their concept to NASA headquarters. NASA Headquarters put FRC and Bell together to collaborate. The challenge was; to allow a pilot to make a vertical landing on earth in a simulated moon environment, one sixth of the earth's gravity and with totally transparent aerodynamic forces in a "free flight" vehicle with no tether forces acting on it.

After conceptual planning and meetings with engineers from Bell the NASA FRC Issued Bell a $50,000 study contract in December 1961. Out of this study came the NASA headquarters endorsement of the LLRV concept, resulting in a $3.6 million production contract awarded to Bell Feb. 1, 1963, for delivery of the first of two vehicles for flight studies at the FRC within 14 months. Wayne Ottinger, from FRC Flight Operations, was the NASA resident representative at Bell during this period. He returned to FRC as the LLRV Flight Operations Project Engineer for the first two years of flight testing until he moved to Bell as the Technical Director of the successor program, the Lunar Landing Training Vehicle (LLTV)

Built of tubular aluminum like a giant four-legged bedstead, the vehicle was to simulate a lunar landing profile from around 1500 feet to the moon's surface. To do this, the LLRV had a General Electric CF-700-2V turbofan engine mounted vertically in gimbals, with 4200 pounds of thrust. The engine, using JP-4 fuel, got the vehicle up to the 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 LLRV's rate of descent and horizontal translations. Sixteen smaller hydrogen-peroxide rockets, mounted in pairs, gave the pilot control in pitch, yaw, and roll. On the LLRV, in case of jet engine failure, six-500-pounds-of thrust rockets could be used by the pilot to carefully apply lift thrust during the rapid descent to hopefully achieve a controllable landing. A drogue chute was also to be ballistically deployed for additional stability in this emergency recovery mode.

This emergency recovery technique required precision energy management practice on the fixed base simulator by all LLRV pilots, but fortunately was never required during actual flights. The pilot's platform extended forward between two of the vehicle's legs while an electronics platform, similarly located, extended rearward. The pilot had a zero-zero ejection seat that would then lift him away to safety. Weight and balance design constraints were among the most challenging to meet for all phases of the program (design, development, operations).

The two LLRVs were shipped disassembled from Bell to the FRC in April 1964, with program emphasis placed on vehicle No. 1. Early closed-loop testing of the jet, rocket, and hydraulic systems required modifications to both the structure and the control systems. The LLRV project team had made a decision to avoid any "tethered" flight testing to lessen the risk to the pilots and vehicles. Two test fixtures to provided "hot" closed loop testing of all jet, rocket, hydraulic, and electronic control systems (except for the yaw attitude rocket system). The scene then shifted to the old South Base area of Edwards Air Force Base. On the day of the first flight, Oct. 30, 1964, NASA research pilot Joe Walker flew it three times for a total of just under 60 seconds, to a peak altitude of approximately 10 feet.

Later flights were shared between Walker, another Center pilot named Don Mallick, and the Army's Jack Kluever. By mid-1966 the NASA Flight Research Center had accumulated enough data from the LLRV flight program to give Bell a contract to deliver three Lunar Landing Training Vehicles (LLTVs) at a cost of $2.5 million each. As 1966 ended, the LLRV #1 had flown 198 flights, some by Joseph Algranti and H.E. "Bud" Ream from the NASA Manned Spacecraft Center, Houston, preparing as instructor pilots for training astronauts. During the period of time the number one LLRV was undergoing flight testing the LLRV #2 was being assembled, instrumented and cockpit modifications made at the South Base. Kluever conducted the first flight of the number two LLRV in early January 1967.

The first flight was quickly followed by five more. By the ending of the Flight Research Center phase of the LLRV program, flight times had reached 9-1/2 minutes and altitudes of around 750 feet had been achieved. As a result of the high reliability experienced with the CF-700-2V jet engine and the shift in mission from research to training, the six emergency lift rockets and the emergency drogue chute were removed. Part of the significant weight savings achieved with this action were allocated to upgrading the ejection seat rocket catapult to a new model with 50% more impulse. This decision turned out to have a major positive impact, as the training operations used the ejection seat on three occasions, none related to jet engine problems.

In December 1966 vehicle No. 1 was shipped to Houston, followed by No. 2 in mid January 1967, after a total of six flights at the Flight Research Center. Modifications already made to No. 2 had given the pilot a three-axis side control stick and a more restrictive cockpit view, both features of the real Lunar Module (LM) that would later be flown by the astronauts down to the moon's surface. When the LLRVs arrived at Houston, additional research pilots were trained to become LLTV instructor pilots. In December 1967, the first of the LLTVs joined Dryden's LLRVs to eventually make up the five-vehicle training and simulator fleet.

Three of the five vehicles were later destroyed in crashes at Houston - LLRV No. 1 in May 1968 and two LLTVs, in December 1968 and January 1971. The two accidents in 1968, before the first lunar landing, did not deter Apollo program managers who enthusiastically relied on the vehicles for simulation and training. Donald "Deke' Slayton, then NASA's astronaut chief, said there was no other way to simulate a moon landing except by flying the LLTV.

Lunar Landing Research Vehicle No. 2 was eventually returned to the NASA Dryden Flight Research Center, where it is on public display, a silent artifact of the Center's contribution to the Apollo program.