RTV-A-2 Hiroc

The RTV-A-2 Hiroc, short for high-altitude rocket, was a research rocket that Convair flew in 1947 at White Sands Proving Ground. It came out of the MX-774 project, the first United States effort to develop an intercontinental ballistic missile, which the Army cancelled in 1947; Convair used leftover funds to build and launch three of the planned ten research vehicles. The rocket was 9.6 m long and 760 mm in diameter, with an empty weight of 547 kg including payload and a gross liftoff weight of 1,860 kg, and it burned liquid oxygen and alcohol in an XLR35-RM-1 engine with four gimballed thrust chambers. All three flights, on 13 July, 27 September and 2 December 1947, partly failed through premature closure of the liquid oxygen valve, yet they proved gimballed engine guidance, a pressure-supported airframe and a separable nose cone, concepts later used on the Atlas missile.