Lunar Landing Research Vehicle

https://en.wikipedia.org/wiki/Lunar_...search_Vehicle

The Bell Aerosystems Lunar Landing Research Vehicle (LLRV) was an Project Apollo
era program to build a simulator for the Moon landings. The LLRVs were used by
the FRC, now known as the NASA Armstrong Flight Research Center, at Edwards Air
Force Base, California, to study and analyze piloting techniques needed to fly
and land the Apollo Lunar Module in the Moon's low gravity environment.

The research vehicles were vertical take-off vehicles that used a single jet
engine mounted on a gimbal so that it always pointed vertically. It was adjusted
to cancel 5/6 of the vehicle's weight, and the vehicle used hydrogen peroxide
rockets which could fairly accurately simulate the behaviour of a lunar lander.

Success of the two LLRVs led to the building of three Lunar Landing Training
Vehicles (LLTVs) an improved version of the LLRV, for use by Apollo astronauts
at the Manned Spacecraft Center in Houston, Texas, predecessor of NASA's Johnson
Space Center. One LLRV and two LLTVs were destroyed in crashes, but the rocket
ejection seat system recovered the pilot safely in all cases.

The final phase of every Apollo landing was manually piloted by the mission
commander. Because of landing site selection problems, Neil Armstrong, Apollo 11
commander, said his mission would not have been successful without extensive
training on the LLTVs. Selection for LLTV training was preceded by helicopter
training. In a 2009 interview, Apollo astronaut Curt Michel stated, ”For
airborne craft, the helicopter was the closest in terms of characteristics to
the lunar lander. So if you didn’t get helicopter training, you knew you weren’t
going. That sort of gave it away.” Even Tom Stafford and Gene Cernan did not get
LLTV training for their Apollo 10 mission which was the first flight of the
Lunar Module to the Moon, because NASA "didn't have plans to land on Apollo 10"
so "there wasn't any point in ... training in the LLTV." Cernan only got this
training after being assigned as backup commander for Apollo 14, and in 1972 was
the last to fly the LLTV while training as commander for Apollo 17, the final
landing mission.

Built of aluminum alloy trusses, the LLRVs were powered by a General Electric
CF700-2V turbofan engine with a thrust of 4,200 lbf (19 kN), mounted vertically
in a gimbal. The engine lifted the vehicle 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 lbf (440 to 2,200 N) 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.

The pilot had an ejection seat. On activation, it propelled the pilot upward
from the vehicle with an acceleration of roughly 14 times the force of gravity
for about a half second. From the ground, it was sufficient to propel the seat
and pilot to an altitude of about 250 feet (80 m) where the pilot’s parachute
could be automatically and successfully deployed. Manufactured by Weber Aircraft
LLC, it was one of the first zero-zero ejection seats, capable of saving the
operator even if the aircraft was stationary on the ground, a necessity given
the LLRV's low and slow flight envelope.


Role
Experimental VTOL aircraft

Manufacturer
Bell Aerosystems

First flight
30 October 1964

Primary user
NASA

Number built
2 LLRVs
3 LLTVs

Unit cost

$2.5 million


There were two distinct modes of flight for the LLRV and LLTV. The basic mode
was with the gimbaled engine fixed to the body so that it always pointed
downward in relation to the body. But in the gimbaled "Lunar Sim Mode", the
engine was allowed to swivel and was kept pointing downward to the earth. This
allowed the vehicle to tilt at the far greater angles that would be typical of
hovering and maneuvering above the lunar surface. Despite its ungainly
appearance, the LLRV was equipped with an astonishingly sophisticated array of
early sensor and computational hardware. The system had no specific name, but
the effect it produced was called "Lunar Sim Mode". This was the highest degree
of hardware-based simulation, and was the purpose of the whole project. This was
not a system to unburden the pilot, such as an autopilot does, nor was it meant
to introduce any sort of safety or economy. The system's sole intention was to
project the illusion of piloting the Lunar Module. So, Lunar Sim Mode can be
thought of as a mixture of stability augmentation, recalculation of vertical
acceleration according to the lunar gravity constant, all followed by
accompanied instantaneous corrective action. The LLRV's Lunar Sim Mode even was
able to counter-correct wind gusts within milliseconds, as they definitely would
have disturbed the impression of a missing atmosphere. Sensor input for the
Lunar Sim Mode was the Doppler radar. The visually significant sign of an
engaged Lunar Sim Mode was the free-gimbaled turbofan, always strictly pointing
downward toward the ground, regardless the LLRV's current attitude. This unique
aircraft represents one of the few hardware simulators that ever became
airborne.

Specifications (LLRV)

General characteristics
Crew: one, pilot
Length: 22.5 ft (6.85 m)
Wingspan: 15.08 ft (4.6 m)
Height: 10.0 ft (3.05 m)
Empty weight: 2,510 lb (1,138 kg)
Loaded weight: 3,775 lb (1,712 kg)
Max. takeoff weight: 3,925 lb (1,780 kg)
Powerplant: 1 × General Electric CF-700-2V jet, 4,200 lbf (19 kN)

Performance
Maximum speed: 40 mph (64 km/h; 35 kn)
Service ceiling: 6,000 ft (1,800 m)
Rate of climb: 3,600 ft/min (17.9 m/s)
Thrust/weight: 1.07
Secondary Engine: 2 x hydrogen peroxide lift rockets with 500 lbf (2,200 N) each
Endurance: 10 minutes




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