GKN Aerospace

Technicians at Westland Aircraft's Isle of Wight site working on the first stage of a Black Arrow vehicle c.1968.

While the complex negotiations surrounding Blue Streak and ELDO had been going on, Britain's RAE had proposed two new launch-vehicle designs. The first of these would extend the Black Knight programme. Already, the RAE and industry had produced two-stage versions of the original single-stage Black Knight vehicles. The second stages of these rockets were arranged so that they accelerated the warheads downwards as they re-entered the atmosphere. The RAE's proposed extension of this programme would use an enlarged and still more powerful Black Knight to launch a re-entry physics programme, code-named Crusade.

used as much Black Knight technology as possible in the production of a small satellite-launch vehicle. This vehicle would be far smaller than Black Prince, but still aimed to provide Britain with an independent satellite-launching capability. It would launch satellites of approximately 317lb (144 kg) into low Earth orbits. These satellites would enable scientists to test prototype power, orientation, telemetry and other systems in the harsh space environment, rather than under the standard simulated conditions on the ground.

The proposal suggested that this chance to try out new space technologies on real satellites might help British satellite-manufacturing companies to compete more effectively for foreign orders.

	High-test peroxide (HTP)
	A rocket engine burns fuel in a supply of oxygen, just as a jet engine does. Both engines move forward in the direction opposite to their exhaust. But a rocket engine's exhaust is far stronger than a jet's, so it is said to produce a greater thrust. To achieve this greater thrust, oxygen must be fed into the combustion chamber of the rocket engine as a pressurised liquid, rather than at natural atmospheric pressure. A rocket engine must also burn its fuel at a far higher temperature and pressure. Oxygen can be carried chemically into a rocket engine in a number of different liquid forms, including nitric acid, liquid oxygen and high-test peroxide (HTP) itself. Concentrated nitric acid propellant is a highly corrosive, hazardous substance, whilst liquid oxygen is difficult to use because it evaporates easily and has to be kept at a temperature of -183ºC. Blue Streak's liquid oxygen propellant would have had to have been pumped in immediately before launch. This process takes seven minutes, by which time any incoming Soviet missile would have struck. HTP on the other hand is relatively easy to handle and stays liquid at room temperature and pressure. Despite this, HTP must still be kept in scrupulously clean containers, as impurities will cause it to decompose into oxygen and water. The most critical impurities, such as silver and certain permanganate salts, will cause HTP to decompose in an explosion. But it is this ease of decomposition that makes HTP such a useful rocket-engine propellant.

The RAE did not have sufficient funds to proceed with both proposals. The extended Black Knight programme was considered, but eventually rejected because military strategists now judged it unnecessary. That decision left the option of the satellite launch vehicle, and in autumn 1964 the new minister of aviation, Julian Amery, announced the start of its development. Britain was at least embarking upon its own space launcher programme. But, within weeks, the new programme was encountering difficulties.

Economic crisis
Conservative Prime Minister Harold Macmillan had retired on health grounds in 1963, and his successor, Sir Alec Douglas-Home, called a General Election in October 1964. The Labour party led by Harold Wilson won a narrow victory, but the new government immediately faced a growing economic crisis. Anxious to cut spending, ministers applied the brakes to the satellite-launch vehicle project. They drew back from giving it the go-ahead, and instead would only grant it funds in a series of three-monthly holding contracts. There the situation rested for the entire lifetime of the Wilson government. The project was nearly cancelled because Wilson's Cabinet was unclear whether Britain needed it. In 1966, there was another general election, and the Labour government was returned to power with an increased majority. Towards the end of that year, the launch vehicle project, now publicly known as Black Arrow, was finally given the go-ahead. Its programme would be trimmed however--the number of proposed test launches was reduced from five in order to three to save money. Development would now proceed, and the first launch was planned for 1968.

Black Arrow had survived, in part because its design was not too ambitious. Almost all the technology required for its development was already there. It was very similar to Black Knight, a vehicle that had been launched 22 times without a single major failure. The systems that Black Arrow would use were known, and their performance was predictable. Black Arrow would make maximum use of the existing Black Knight facilities, and the amount of new work required would be kept to an absolute minimum. As a result, the Wilson government was attracted by the project and saw it as a cost-effective way of developing a national satellite-launch vehicle.

Black Arrow's engines were an example of the practicality of the rocket's design. They were variants of Black Knight's engines, which themselves drew on ten years of British rocketry research for defence purposes. The engines' propellant was concentrated (85 percent) hydrogen peroxide, otherwise known as high-test peroxide. Britain had become a world leader in the use of this substance as a rocket propellant, and this rocket-engine knowledge was the key technological factor that allowed Britain to contemplate building a satellite launch vehicle.