The SM-65A Atlas, or Atlas A, also designated X-11 was the first full-scale prototype of the Atlas missile, which first flew on 11 June 1957. Unlike later versions of the Atlas missile, the Atlas A did not feature the stage and a half design. Instead, the booster engines were fixed in place, and the sustainer engine was omitted. The Atlas A conducted eight test flights, of which four were successful. All test flights were conducted from Cape Canaveral Air Force Station, at either Launch Complex 12 or Launch Complex 14.