Blue Streak (missile) - Development

Development

De Havilland won the contract to build the missile, which was to be powered by an uprated liquid-fuelled Rocketdyne S3D engine, developed by Rolls-Royce, called RZ2. Two variants of this engine were developed: the first provided a static thrust of 137,000 lb (62,100 kg) and the second (intended for the three stage satellite launch vehicle) 150,000 lb (68,000 kg). The engines were unique at that time in that they could be vectored by seven degrees in flight and could therefore be used to guide the vehicle. This configuration, however, put considerable pressure on the autopilot which had to cope with the problem of a vehicle whose weight was diminishing rapidly and that was steered by large engines whose thrust remained more or less constant. The vibration was also a problem, particularly at engine cut-off, and the later development of the autopilot for the satellite launcher was, in itself, a considerable achievement.

Subcontractors included the Sperry Gyroscope Company who produced the guidance system whilst the nuclear warhead itself was designed by the Atomic Weapons Research Establishment at Aldermaston.

The missiles used liquid oxygen and kerosene propellants. Whilst the vehicle could be left fully laden with 20+ tonnes of kerosene, the 60 tonnes of liquid oxygen had to be loaded immediately before launch or icing became a problem. Due to this, fuelling the rocket took 4.5 minutes, which would have made it useless as a rapid response to an attack. The missile was vulnerable to a pre-emptive strike, launched without warning or in the absence of any heightening of tension sufficient to warrant readying the missile. To negate this problem DeHavilland created a stand-by feature. A missile could be held at 30 seconds' notice to launch for ten hours. As the missiles were to be deployed in pairs and it took ten hours for one missile to be prepared for stand-by, one of the two missiles could always be ready for rapid launch.

To protect the missiles against a pre-emptive strike while being fuelled, the idea of siting the missiles in underground silos was developed. These would have been designed to withstand a one megaton blast at a distance of half a mile (800 m) and were a British innovation, subsequently exported to the US. However, finding sites for these silos proved extremely difficult and RAF Spadeadam in Cumbria was the only site where construction was undertaken. This was also the site where the RZ2 rocket engines and also the complete Blue Streak missile were tested. The best sites for silo construction were the more stable rock strata in parts of southern England, but the construction of many underground silos in the countryside carried enormous economic, social, and political cost.

As no site in Britain provided enough space for test flights, a test site was established at Woomera, South Australia.