Martin Marietta Model 845

The Martin Marietta Model 845 was a remotely piloted aircraft developed in the United States in the late 1960s and early 1970s as a communications relay for use in the Vietnam War. Two prototypes were built for the United States Air Force Compass Dwell program, based on a Schweizer SGS 1-34 sailplane, and flight testing began in April 1972. One prototype stayed aloft for almost 28 hours, but the aircraft failed to meet the Air Force requirement for a service ceiling of 40,000 feet, and the Model 845A was cancelled in 1973 together with its competitor, the LTV XQM-93, with Compass Cope replacing the program. Two airframes then passed to the Langmuir Laboratory for Atmospheric Research at New Mexico Tech, where one was converted to a piloted research aircraft and flew through thunderstorms as SPTVAR until the late 1990s.