Lightweights

BLACK ARROW

In 1955 the Royal Air Force awarded a contract to de Havilland Aircraft to develop the Blue Streak single-stage missile powered by a pair of two-chamber Rolls Royce engines using kerosene and oxygen. Despite performing well in tests, and on schedule for service by 1965, it was cancelled in April I960 when the British government decided to buy the Skybolt air-launched ballistic missile that was under development for the US Air Force. When the Skybolt was cancelled, the British transferred their interest to the submarine-launched Polaris. The European Space Research Organisation was established in 1962 to pursue collaborative projects. When the European Launcher Development Organisation was formed in 1964 to develop the Europa launch vehicle, the Blue Streak was selected as the first stage because it was by far the most powerful liquid rocket available, and work began to develop a French second stage and a German third stage. Unfortunately, this project was plagued with difficulties, and eventually cancelled. In parallel, the Royal Aircraft Establishment was given the go-ahead to develop a small launcher named Black Arrow as a derivative of the Black Knight, the two-stage rocket built to test materials for the re-entry vehicle of the Blue Streak, which had flown 22 times without a failure.1 The rationale was that this project would keep Britain in the launcher business at a low level. The budget was so tight - only £9 million - that the engines were refined in ground trials rather than by development flights.2

The first test from the Woomera rocket range in Australia was on 28 June 1968, and was to be a sub-orbital test of the first two stages. Within seconds it started to twist and corkscrew. Although the dummy third stage sheared off, the vehicle continued its tortuous climb. At an altitude of 8 kilometres it toppled over and started to tumble, so it was destroyed by the range safety officer. The telemetry indicated that one of the four engine pairs had been repeatedly slewing from one end of its movement range to the other. The investigators ran a computer simulation that indicated that this violent movement had almost certainly been caused by a loss of

On 28 October 1971 a Black Arrow lifts off on its transparent plume carrying the Prospero satellite.

signal, which suggested a broken wire.3 On 4 March 1969 another two-stage vehicle flew this sub-orbital test flawlessly, clearing the way for a three-stage vehicle to attempt to place a demonstration satellite in low orbit on 2 September 1970. Unfortunately, telemetry and tracking indicated that the second stage's engine was losing thrust. It shut down almost 30 seconds ahead of schedule. The Waxwing motor of the third stage ignited successfully, but was unable to compensate for the inherited shortfall in velocity, and fell into the ocean. The enquiry determined that a fractured pipe in the second stage had allowed the nitrogen pressurant to vent.

Starved of oxidiser, the combustion had declined, and eventually shut down the engine. In the spring of 1971 a Parliamentary Select Committee met to assess the future of British space efforts. On 29 July 1971, before the Select Committee could report, the government cancelled the Black Arrow.4 Nevertheless, the next launch was allowed to proceed, and on 28 October this put into a near-polar orbit the 66-kilogram Prospero satellite built by the British Aircraft Corporation.5 That same year, following the advice of the Select Committee, Britain withdrew from the European Launcher Development Organisation (which in 1975 merged with the European Space Research Organisation to become the European Space Agency). This, then, is an example of a purely political failure of a launch vehicle. It was arguably one of the most aesthetically pleasing launchers - tiny, proportioned like a rifle-bullet and rising on a crystal clear oxygen-rich exhaust. The last remaining Black Arrow was put on display in the Science Museum in London.

On 28 October 1971 a Black Arrow lifts off on its transparent plume carrying the Prospero satellite.

SCOUT

The Scout four-stage solid-propellant launcher was designed by the Langley Research Center as a relatively inexpensive multi-stage solid-propellant rocket using off-the-shelf hardware to insert a 60-kilogram satellite into a circular orbit at an altitude of some 500 kilometres. The Algol first stage motor was developed from

Navy's Polaris; the Castor second stage was derived from the Army's Sergeant; and the Antares and Altair upper stages were adapted by Langley from the Navy's Vanguard. Chance Vought Aircraft of Dallas, Texas, was made prime contractor in March 1959. The vehicle was assembled in a horizontal configuration and hoisted upright for launch. The first Scout was fired from Wallops Island in Virgina on 1 July I960 on a vertical trajectory as a sounding rocket.6 The first attempt to launch a satellite was the third mission. To the eye, it appeared to be a good launch, but ground radar indicated a problem after 136 seconds.7,8,9 The Antares developed a rolling moment which, although it soon disappeared, confused the tracking radar, which indicated on the plot board that the vehicle was some 50 degrees off course. The range safety officer was obliged to activate the auto destruct system (an innovation at the time). In reality, having recovered from the roll, the vehicle was performing well. The next flight on 16 February 1961 was successful. On 30 June, on the fifth launch, the third stage malfunctioned. The first launch from Vandenberg Air Force Base in California on 26 April 1962, the 10th of the series, failed. These early failures prompted a recertification of the launcher. Significantly, the in-depth investigations of the rocket's subsystems made during this review revealed that each Scout failure had been caused by a different problem. Institutional factors also played a role - the Langley engineers, the contractors, and their Air Force partners had not been acting as an integrated team. However, the principal cause of the mishaps was the need to make everything happen so fast - parts had been 'borrowed' from vehicles in stock to fix problems on those about to launch. However, after this recertification, the Scout suffered only occasional failures of a 'random' nature. The 22nd mission caused spectacular damage at the Wallops facility. A flame appeared above the fins at the base of the first stage 2.5 seconds after lift-off. Two seconds later, this stage was engulfed by fire. The burn-through caused the vehicle to execute wild gyrations. ''It got about 300 feet high and broke into three parts: the first stage went in one direction; the second stage went in another; and the third and fourth stages fell more or less back on the launch pad and burned. It was a disaster.''10

The Scout was repeatedly upgraded to increase the payloads to 200 kilograms, with the variants designated alphabetically. Nevertheless, the final version was very similar in appearance to the original. In 1967 launches began from Italy's San Marco platform in the sea off the coast of Kenya in Africa, this equatorial launch site maximally exploiting the rotation rate of the Earth to further increase the payload to 270 kilograms. In January 1991 management of the Scout programme was reassigned to the Goddard Space Flight Center, but by then the flight rate had fallen to about one per year. The final launch was on 8 May 1994, with a satellite for the Ballistic Missile Defense Organisation. By then, a number of new lightweight vehicles had either been introduced or were in development to launch commercial satellites. Over a total of 118 launches, the Scout had achieved the enviable success rate of 96 per cent, with its success rate since 1976 being 100 per cent. This stemmed from its simple technology and from standardised procedures and configuration control.11

The launch of the 5th Scout on 30 June 1961.
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