This is a model of unknown scale of the Improved Delta, a three-stage rocket more commonly known as the Delta E. It was the third in a long series of Delta rockets developed by Douglas Aircraft for the National Aeronautics and Space Administration (NASA), and it used as its first stage a modified first stage from the Thor intermediate-range ballistic missile with three boosters. NASA used the rocket to launch a variety of satellites, lunar probes, and other scientific payloads beginning in 1966.
The model's manufacturer is unknown. John and Cynthia Heyde donated it to the museum.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.