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Hiroc

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MX-774 Credit: Ronald Wade

AKA: MX-774;RTV-A-2;Upper Air Test Vehicle. Status: Cancelled 1947. First Launch: 1948-07-14. Last Launch: 1948-12-02. Number: 3 . Thrust: 35.00 kN (7,868 lbf). Gross mass: 1,300 kg (2,800 lb). Unfuelled mass: 700 kg (1,540 lb). Height: 9.60 m (31.40 ft). Diameter: 0.76 m (2.49 ft). Apogee: 50 km (31 mi).

In 1945 the U.S. Army Air Force awarded Consolidated-Vultee project MX-774, which was to lead to a long-range ballistic missile. The Air Force contracted for ten MX-774 vehicles, in three phases. Stage A, the Teetotaler, was a sub-sonic, self-guided cruise missile. Stage B, the Old Fashioned, was a test missile using V-2 technology but incorporating new concepts planned for the next phase. Stage C, the Manhattan, was to be an ICBM. The MX-774 was cancelled by the Air Force in June 1947 due to budget restrictions and continued Air Force skepticism. Using residual contract and corporate funds, Bossart was able to launch three stage B test vehicles from White Sands after the cancellation.

A Reaction Motors XLR35-RM-1 four-chamber liquid-propellant rocket motor was fitted to the rocket's cylindrical body. Four fixed stabilizing fins provided stability. New technologies demonstrated gimbaled rocket nozzles, a separable nose cone, and the balloon internal pressure stabilized flight structure. The missile's skin was very thin, and was inflated by internal pressure like a balloon. Three Hiroc's were flown in July to December 1948.

While none of the launches were completely successful, they did demonstrate Bossart's innovative design concepts including pressurized monocoque propellant tanks. Despite the heavy investment of company funds, the Air Force later directed Bossart to sell the MX-774 development package to TRW for a song. TRW in turn delivered it, in total, to Douglas and Martin to assist them in design of their competing Thor and Titan missiles. There were many hard feelings at Convair about that. However the know-how obtained in designing and building the Hiroc would be the starting point for their Atlas ICBM just a few years later.

Atlas The Atlas rocket, originally developed as America's first ICBM, was the basis for most early American space exploration and was that country's most successful medium-lift commercial launch vehicle. It launched America's first astronaut into orbit; the first generations of spy satellites; the first lunar orbiters and landers; the first probes to Venus, Mars, Mercury, Jupiter, and Saturn; and was America's most successful commercial launcher of communications satellites. Its innovative stage-and-a-half and 'balloon tank' design provided the best dry-mass fraction of any launch vehicle ever built. It was retired in 2004 after 576 launches in a 47-year career.

• Strategic Missile Proposals - . Nation: USA.

  Bids were received in response to the USAAF request for proposal of the previous October. Vultee submitted proposals for two types (glide and ballistic) of 8000-km range missiles. North American proposed a three-year development program for a supersonic 800-km range missile, culminating in a production run of 50 missiles.

• MX-774 strategic missile study contract awarded - . Nation: USA. Convair received contract W33-038-AC-14168 for a $1.4 million, one-year study of two missile designs..

• MX-774 Azusa tracking - . Nation: USA. Study report submitted to Air Force on proposed Azusa tracking/guidance system. MX-774 funding cut back..

• MX-774 Azusa tracking tests - . Nation: USA. Tracking tests started with experimental Azusa equipment.

• MX-774 cancelled. - . Nation: USA.

  Contract with Convair for the MX-774 "Upper Air Test Vehicle," predecessor of the Atlas ICBM, was cancelled by the AAF. However the service approves Convair use of unexpended MX-774 funds to launch the MX-774 test vehicles already built. The decision made to move Vultee operations to San Diego.

• First complete MX-774 moved to Pt. Loma for test - . Nation: USA.

• First static firing of MX-774 - . Nation: USA. Unsuccessful, small fire..

• Second MX-774 static firing - . Nation: USA. Successful, at Point Loma..

• MX-774 static firing tests at Pt Loma completed. - . Nation: USA.

• First MX-774 arrives at White Sands Proving Ground - . Nation: USA.

• MX-774 Flight 1 - . Nation: USA. Agency: USAF. Apogee: 1.00 km (0.60 mi). First Convair MX-774 (RTV-A-2) test rocket was successfully launched, first demonstrating use of gimballed engines and design features later incorporated in the Atlas ICBM. This was the first of three Convair-sponsored test flights..

• MX-774 Flight 2 - . Nation: USA. Agency: USAF. Apogee: 47 km (29 mi). Second Corvair MX-774 test rocket fired. Shut down at 15 km; reached 65 km before malfunction of unknown origin caused self-destruction..

• MX-774 Flight 3 - . Nation: USA. Agency: USAF. Apogee: 50 km (31 mi). Third (last) MX-774 launched, WSPG; shut down at 51 seconds attaining an altitude of 48 km. Self-destructed at high altitude..

• All MX-774 work shut off by Air Force - . Nation: USA.

• MX-774 unexpended funds run out in 1950. - . Nation: USA. Convair allocated R&D funds to ICBM studies and marketing, running into 1950.