Hawker Siddeley Red Top

First, there was Fire Streak, which was succeeded by Red Top; and Red Top was to be succeeded by Tall Dog. Firestreak and Red Top were examples of common requirements between the RAF and the Navy.

Red Top was originally a rationalized, upgraded version of the earlier Firestreak air-to-air missile. In 1956, de Havilland Propellers started work on the Blue Jay Mark 4 (its development codename) and Firestreak Mk. IV.[1] Such were the changes that it was effectively a new missile. It arranged its components in more logical fashion than the Firestreak (which had its warhead in the tail), with an improved "Violet Banner" seeker, "Green Garland" IR fuze, and a more powerful "Linnet" booster rocket. It also had a larger warhead, at 31 kg (68.3 lb) against 22.7 kg (50 lb).

The Red Top was faster, and had greater range and manuverability than the Firestreak, and its more sensitive infrared seeker enabled a wider range of engagement angles. Being more sensitive it could home in on a target that had been warmed by air friction heating, rather than just flying up a hot tail pipe. In the aftermath of the 1957 Defence White Paper, Red Top was initially seen to be a stopgap measure only until the Bloodhound Mk. II SAM came into service. This meant that some of the planned improvements to Red Top were never carried out, including all-aspect capability (as seen on the later AIM-9L/M Sidewinder). Red Top was only "capable of all aspect homing against super-sonic targets. Unlike modern [1990s] missiles, Red Top and Firestreak could only be fired outside cloud, and in winter, skies were rarely clear over the UK."

The Linnet I and Linnet IIA rocket motors were intended to meet the requirements specified for an internally stowed rocket motor for the Red Top air-to-air missile. The arrangement of the missile required the motor body to be placed in the center section to minimise the shift of the centre of gravity of tho missile during boosted flight, the exhaust gases being ducted axially through the rear section by means of a tail-pipe. The internal dimensions of the missile sections therefore determined the maximum motor body and tail-pipe dimensions. In addition, the specification contained two novel requirements. The tail-pipe was to be permanently secured within the rear section of the missile where it would support certain items of equipment; the center and roar sections of the missile were to be joined after alignment by an external locking ring (hence a simple push-fit joint between motor and tail-pipe was essential).

The 7.25-inch diameter motor developed for use in the Red Top air-to-air missile employs a charge of colloidal propellent, as necessitated by the somewhat wide temperature limits demanded by the specification. The performance requirements have been met satisfactorily within the rather limited development time-scale available by the use of a charge composited from three extrusions of different conduit area. The igniter of this motor incorporates an effectivo form of attenuator to give protection against radio frequency hazards to the firing circuit.

During development of the first version of the new motor, designated Linnet I, a chargo cracked during a firing at -40°C, causing failure; since motors were urgently required for the missile flight test programme, the low temperature limit was raised to -25 C. No trouble was experienced in motors fired at this temperature, but a small number fired at 50 C showed excessively high levels of pressure and thrust. Linnet I, therefore, had to be confined to missile research and development flight trials. The second version, designated Linnet IIA, was a development of Linnet I, incorporating charge improvements designed to ensure safe operation over the full temperature range -40 to 50 C, and certain modifications to the hardware which had been requested by the user.

Even in the missile era the UK needed fighters to prevent reconnaissance, to identify and intercept intruding aircraft, and to deter and prevent the jamming of our radar system. For these tasks Fighter Command would be equipped with progressive developments of the Lightning, including the introduction of the collision course weapon Red Top. The Red Top entered service in 1964, arming the RAF's English Electric Lightning and the Navy's de Havilland Sea Vixen.

In the interceptor rôle, the Mark III version of the Lightning all-weather fighter came into service in 1964. This fighter is a great advance on the Mark I and Mark II from the point of view of both speed and range. It is equipped with a highly complex radar system which, in conjunction with Red Top, will gave it a far better attack and interception capability. Red Top was a very advanced [for the time] air-to-air missile that has been developed to match the performance of the Mark III Lightning, and to provide it with an integrated weapon system capable of dealing with supersonic targets on a collision course.

Although the United Kingdom was declared one of the 4 air defence regions in NATO in 1960 and made subordinate to SACEUR in 1961, it was not until 1975 that a dedicated separate air defence command was set up in the UK, the United Kingdom Air Defence Region, (UKADR). Within this new NATO framework, the Command introduced the Lightning, armed with the Firestreak and later the Red Top air-to-air missile, further developed its control and reporting systems, perfected the techniques of air-to-air refuelling. Red Top remained in limited service until the final retirement of the Lightning in 1988. Unusually, the missile that the Red Top was intended to replace – Firestreak – also remained in limited service on the Lightning until 1988.

In 1966 comparative evaluation of Red Top and Sidewinder as secondary armament for Phantom aircraft showed that their performance would be roughly equivalent in this particular rôle.