The XR-10 transport helicopter, still without national insignia, at the Kellett factory site in North Wales, near Lansdale. Standing by the nose are test pilots Al Bayer and his older colleague Dave Driskoll, in suit, who got killed in the XR-10 in 1949. Photo courtesy of CW Bayer, author of the online book Flying Without Instruction about his late father's work.

The XR-10, which was to carry ten troops, was said to be the largest helicopter in the world. It first flew on 24 April 1946. This photo was probably taken during a press demonstration on 25 September. Powered by two Wright R-975 Whirlwind engines in nacelles on the sides, the beast was dangerous to fly and the prototype crashed on 3 October 1949, killing test pilot Dave Driskill. Photo by: Howard Levy / Nederlands Instituut voor Militaire Historie