This is the largest remaining hardware from Project Orion. Project Orion was to test the nuclear pulse concept of successive explosions of small nuclear bombs for extremely fast and powerful propulsion for deep space missions, although this test model, known as "Hot Rod," used conventional high explosives to test the feasibility of the pulse concept. It was designed and built by the General Atomics Division of the General Dynamics Corporation.
The test was conducted in 1959 at Point Loma, California. The vehicle's five rapid successive explosions sent shock waves against a well-protected pusher plate, driving the vehicle forward. "Hot Rod" was then recovered by parachute. Project Orion was cancelled in 1965. This object was donated to the Smithsonian in 1972 by the Gulf General Atomic Co.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.