The X-15 Design Proposals

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	Models of competing X-15 designs surrounding the earlier Bell X-1A

Bell Aircraft

Douglas Aircraft

North American Aviation

Republic Aircraft

Technical direction of the X-15 program had been assigned to the National Advisory Committy for Aeronautics (NACA, the predecessor of NASA). Design and construction of the research aircraft had been assigned to the Air Force. The Air Force sent invitation-to-bid letters to 12 Aerospace companies on December 30, 1954. Nine of these companies participated in a bidders' conference on January 18, 1955. One day before that conference the Air Force notified NACA that this would be Air Force Project 1226, and that the aircraft designation would be X-15.

Several of the remaining contractors dropped out in the following months, leaving Bell, Douglas, North American, and Republic as those who submitted proposals for the May 9th deadline to the Air Force at Wright Field (Wright Patterson Air Force Base). On May 11th the Air Force sent technical data for the proposals to evaluation groups at the Wright Air Development Center (WADC), Air Research and Development Command (ARDC), NACA, and Navy, requesting responses by June 22nd.

Part of the package for evaluation of the proposals was a set of 9 8x10 photographs of design models for all of the proposals. The photo above compares all four proposed designs and a similarly scaled model of the Bell X-1A design, which also had been manufactured as the X-1B and the X-1D.

Here are other photographs in this set, with two for each of the competing design submissions.