A few manufacturers have been experimenting with high-speed rotor craft. Sikorsky put its efforts into a project called X2. This is a contra-rotating helicopter with a pusher propellor. The contra-rotation of the rotors offsets the retreating blade stall issues that high speeds on helicopters cause. The rear pusher propellor allows the higher speeds to be achieved.

When the programme was completed, the airframe was donated to the National Air a Space Museum which put it on display at the Udvar-Hazy Annex at Dulles. Seeing it in person made it quite clear just how small the vehicle is. Since it is a research airframe, there is no need for payloads to be carried. It is about proving the concepts. That means it can be smaller and smaller also can mean cheaper. Seeing it from the side was also matched by having a good view down on it from one of the stairways. It would have been cool to see it fly, I imagine.