The Martin Marietta Model 845 was a remotely piloted aircraft developed in the United States in the late 1960s and early 1970s for use as a communications relay in the Vietnam War.
Two prototypes were built as part of the United States Air Force's Compass Dwell program, these machines also being based on a Schweizer SGS 1-34 sailplane and similar in configuration to the competing XQM-93 design by Ling-Temco-Vought.
It continued flying as SPTVAR (Special Purpose Test Vehicle for Atmospheric Research) until the late 1990s.
Its missions included flights over the Langmuir Laboratory facility in south-central New Mexico, flying through thunderstorms and making measurements of the electric field inside clouds.
Related development Aircraft of comparable role, configuration, and era