The AQM-35 program began life in 1953 as the Model RP-61 supersonic target drone.

In June 1954 the United States Air Force awarded Northrop a contract for development of the project as the Q-4; the first flight-capable XQ-4 was launched in 1956.

When the mission was completed the XQ-4 would deploy a three-stage parachute system along with four large inflatable airbags to cushion the impact with the ground.

They were never considered entirely successful, with a variety of problems arising during both the development and flight testing phases.

It was also considered that the flight performance of the drone was so high that it was not a realistic test for the missiles being developed––ironic since the whole point of the project was to develop a supersonic target.