Unconventional, Contrary, and Ugly: The Lunar Landing Research Vehicle, NASA History Division, 2005

Background

When the United States began considering a piloted voyage to the moon, an enormous number of unknowns about strategies, techniques, and equipment existed. Some people began wondering how a landing maneuver might be performed on the lunar surface. From the beginning of the age of flight, landing has been among the most challenging of flight maneuvers. Touching down smoothly has been the aim of pilots throughout the first century of flight. Designers have sought the optimum aircraft configuration for landing. Engineers have sought the optimum sensors and instruments for best providing the pilot with the information needed to perform the maneuver efficiently and safely. Pilots also have sought the optimum trajectory and control techniques to complete the approach and touchdown reliably and repeatably. Landing a craft on the moon was, in a number of ways, quite different from landing on Earth. The lunar gravitational field is much weaker than Earth’s.

There were no runways, lights, radio beacons, or navigational aids of any kind. The moon had no atmosphere. Airplane wings or helicopter rotors would not support the craft. The type of controls used conventionally on Earth-based aircraft could not be used. The lack of an atmosphere also meant that conventional flying instrumentation reflecting airspeed and altitude, and rate of climb and descent, would be useless because it relied on static and dynamic air pressure to measure changes, something lacking on the moon’s surface. Lift could be provided by a rocket engine, and small rocket engines could be arranged to control the attitude of the craft. But what trajectories should be selected? What type of steering, speed, and rate-of-descent controls should be provided? What kind of sensors could be used? What kind of instruments would provide helpful information to the pilot? Should the landing be performed horizontally on wheels or skids, or vertically? How accurately would the craft need to be positioned for landing? What visibility would the pilot need, and how could it be provided? Some flight-test engineers at NASA’s Flight Research Center were convinced that the best way to gain insight regarding these unknowns would be the use of a free-flying test vehicle.

Aircraft designers at the Bell Aircraft (Aerosystems) Company believed they could build a craft that would duplicate lunar flying conditions. The two groups collaborated to build the machine. It was unlike any flying ma-chine ever built before or since. The Lunar Landing Research Vehicle (LLRV) was unconventional, sometimes contrary, and always ugly. Many who have seen video clips of the LLRV in flight believe it was designed and built to permit astronauts to practice landing the Apollo Lunar Module (LM). Actually, the LLRV project was begun before NASA had selected the strategy that would use the Lunar Module! Fortunately, when the Lunar Module was designed somewhat later, its characteristics were sufficiently similar to the LLRV that the LLRV could be used for LM simulation. A later version of the LLRV, the Lunar Landing Training Vehicle (LLTV), provided an even more accurate simulation following considerable modification to better represent the final descent stage. Unconventional, Contrary, & Ugly: The Lunar Landing Research Vehicle tells the complete story of this remarkable machine, the Lunar Landing Research Vehicle, including its difficulties, its successes, and its substantial contribution to the Apollo program. The authors are engineers who were at the heart of the effort. They tell the tale that they alone know and can describe.