member of the Research Airplane Committee which underwrote the North American X-15. The committee, headed by Hugh Dryden, evaluated the proposed Mach 7 hypersonic aircraft design which aimed to reach altitudes of 300,000 ft. On the committee, Kelsey was sole representative for the Air Force, Dryden represented NACA, and two rear admirals represented the Navy. Dryden convinced the committee to move ahead with the project even though it was not clear there would be any military value gained from it. Kelsey brought to the project the extensive support of the Air Force Flight Test Center, and began to shop the proposal around the industry. He invited 12 aviation contractors with prior fighter aircraft experience to bid on the project: Bell, Boeing, Chance-Vought, Consolidated (Convair), Douglas, Grumman, Lockheed, Martin, McDonnell, NAA, Northrop and Republic. Nine of these showed up to Kelsey's bidder conference in January 1955 where they were informed of late-1954 NACA wind tunnel research data collected at Langley Research Center. Five more companies dropped out before the May 9, 1955 submission deadline, but Bell, Douglas, North American and Republic responded with designs. The Douglas and NAA designs were ranked the highest, with slightly more interest expressed in the more expensive NAA concept which did not use standard alloys and thus would provide additional research information if implemented. Kelsey, Dryden and the committee awarded NAA the contract on September 30, 1955 even though the company was at capacity designing the XB-70 Valkyrie and F-107. Kelsey reverted to his permanent rank of colonel December 30, 1955 and retired from active duty the following day. Personal life Kelsey married Caryl Rathje and they had three sons: Benjamin Jr., Peter and David. Kelsey continued to fly after retirement. He owned a Cessna 190 and worked to restore a Pitts Special. Kelsey wrote about aeronautical subjects and gave lectures. In 1959, he was honored by MIT with the Jerome C. Hunsaker Visiting Professor of Aerospace Systems award. In carrying out the duties of the award, Kelsey appeared in March 1960 at MIT, the University of Maryland, College Park and in Los Angeles to give a talk about the factors which determine the optimum size of aircraft. The engineering lecture was published in 1960. In September 1977, Kelsey was invited to participate in a 50th anniversary symposium celebrating the P-38 Lightning, organized by Lockheed veterans. Tony LeVier, Kelly Johnson and some Lightning aces shared a