[1] Built by McDonnell, each vehicle was launched on a suborbital trajectory from Cape Canaveral's Pad 17B at speeds of up to 6000 m/s before making a water landing in the South Atlantic near Ascension Island.

Originally, a Scout launch vehicle had been planned for the tests, but this was changed after a large surplus of Thor and Thor-Delta missiles (returned from deployment in the United Kingdom) became available.

[2] Of the six vehicles built, only one was successfully recovered and is currently on display at the National Museum of the United States Air Force in Dayton, Ohio.

[2] In the mid-1960s, McDonnell proposed a variant of the Gemini capsule that retained the original spacecraft's internal subsystems and crew compartment, but dispensed with the tail-first ballistic reentry, parachute recovery and water landing.

According to Mark Wade's Encyclopedia Astronautica, the intent seems to have been to field a crewed military spaceplane at a minimal cost following the cancellation of the Dyna-Soar program.