Reducing the High Cost of Flight Research

Research aircraft are designed to explore advanced technologies and new fight regimes. Consequently, they are often relatively expensive to build and operate, and inherently risky to fly. Flight research from the earliest days of aviation well into the mid-20th century resulted in a staggering loss of life and valuable, often one-of-a-kind, aircraft.

This was tragically illustrated during experimental testing of advanced aircraft concepts, early jet-powered aircraft, and supersonic rocket planes of the 1940s and 1950s at Muroc Army Air Field in the Mojave Desert. Between 1943 and 1959, more than two-dozen research airplanes and prototypes were lost in accidents, more than half of them fatal. Among these were several of Northrop’s flying wing designs, including the N9M-1, XP-56, and both YB-49 prototypes. Early variants of Lockheed P-80 and F-104 jet fighters were lost, along with the two Martin XB-51 bomber pro­totypes. A rocket-powered Bell X-1 and its second-generation stablemates, the X-1A and X-1D, were lost to explosions—all fortunately nonfatal—and Capt. Milburn Apt died in the Bell X-2 after becoming the first human to fly more than three times the speed of sound.

By the 1960s, researchers began to recognize the value of using remotely piloted vehicles (RPVs) to mitigate the risks associated with flight-testing. During World War I and World War II, remotely controlled aircraft had been developed as weapons. In the postwar era, drones served as targets for missile tests and for such tasks as flying through clouds of radioactive fallout from nuclear explosions to collect particu­late samples without endangering aircrews. By the 1950s, cruise-missile prototypes, such as the Regulus and X-10, were taking off and landing under radio control. Several of these vehicles crashed, but without a crew on board, there was no risk of losing a valuable test pilot.[881] Over the

years, advances in electronics greatly increased the reliability of control systems, rendering development of RPRVs more practical. Early efforts focused on guidance and navigation, stabilization, and remote control. Eventually, designers worked to improve technologies to support these capabilities through the integration of improved avionics, micropro­cessors, and computers. The RPRV concept was attractive to research­ers because it built confidence in new technology through demonstration under actual flight conditions, at relatively low cost, in quick response to demand, and at no risk to the pilot.

Taking the pilot out of the airplane provided additional savings in terms of development and fabrication. The cost and complexity of robotic and remotely piloted vehicles are generally less than those of com­parable aircraft that require an onboard crew, because there is no need for life-support systems, escape and survival equipment, or hygiene facil­ities. Hazardous testing can be accomplished with a vehicle that may be considered expendable or semiexpendable.

Quick response to customer requirements and reduced program costs resulted from the elimination of redundant systems (usually added for crew safety) and man-rating tests, and through the use of less com­plex structures and systems. Subscale test vehicles generally cost less than full-size airplanes while providing usable aerodynamic and systems data. The use of programmable ground-based control systems provides additional flexibility and eliminates downtime resulting from the need for extensive aircraft modifications.[882]