The De Havilland Red Top was an infra-red guided air-to-air missile and was the successor to the earlier Firestreak. Often viewed as merely an upgraded Firestreak the Red Top is in fact a far more potent and mature weapon.
Development of Red Top began under the codename Blue Jay Mk.4 before being re-designated Firestreak IV for operational use. However, De Havilland argued that the changes to the weapon were so dramatic that a new name should be selected and therefore it was named Red Top to distinguish it from its forebear. Whereas the Firestreak looked like something out of a 1930s Flash Gordon serial the new missile was more modern yet menacing to look at. It was certainly larger being a noticeable 13cm longer and weighing an extra 40lbs and having redesigned wings of greater span but it was inside the weapon that made the greatest difference.
In developing Red Top the De Havilland team completely reassessed the layout of the Firestreak. One of the more unusual decisions taken in building the original weapon was to place the warhead in the tail of the missile around the motor. Not only did this limit the size of the warhead but it also limited its effectiveness upon impact. In Red Top the warhead was placed behind the seeker assembly in the nose and consisted of 68lbs (compared to Firestreak’s 50lbs) of explosive triggered by a proximity detonator. Like Firestreak the new weapon was controlled by four guidance fins at the rear that gave it excellent agility.
Guidance for the weapon was provided by the Violet Banner infra-red seeker. For the early 1960s this was a very sophisticated scanner and was one of the first infra-red missiles to introduce a cooling system in the seeker head to improve the infra-red image of the target. In all infra-red guided missiles (and even infra-red cameras) background heat from inside the sensor such as that generated by the hot electronic equipment or the heat built up on the seeker’s window as a result of friction as the missile flies though the air can overpower the comparatively weak signal of the target. Cooling the seeker head therefore clears up the infra-red image of the target and dramatically increases sensitivity.
This led to a general belief that Red Top was the world’s first all-aspect infra-red air-to-air missile however this is not entirely true. Red Top could only engage targets from the front that were travelling at supersonic speeds thanks to the target developing a rather large heat plume from its engines and the friction-heating of the fuselage at high speeds. For targets travelling at subsonic speed then a more traditional rear-hemisphere attack was required. An often cited problem with the seeker however was that cloud inhibited its effectiveness in tracking a target but it is important to note that this was a common problem with all infra-red weapons of the day. While this would potentially be a drawback fighting tactical aircraft at low to medium altitude it remained a very effective weapon intercepting high altitude bombers where there was little cloud. The seeker was aided by the launch aircraft’s own radar which can transmit the location of the target to the missile while its on the rail so that the seeker is looking directly at the target upon launch.
Red Top was cleared for service in 1964 and armed the RAF’s English Electric Lightning F.3/6 and the Royal Navy’s De Havilland Sea Vixen FAW.2 (right). While the Gloster Javelin was armed with the earlier Firestreak plans to equip it with Red Top were shelved due to the aircraft’s impending retirement. Of the two aircraft that carried Red Top operationally the Sea Vixen was arguably the better platform for the weapon having a second crewman who could plot and prosecute the target more efficiently without having to fly the aircraft as well. The Sea Vixen could carry up to four weapons whereas the Lightning could only carry two (theoretically the Lightning could carry four weapons but plans for additional weapons to be carried under the wing pylons for export aircraft never materialised).
However the Lightning’s own performance actually increased the performance envelope of the missile. When flying at speeds in excess of Mach.1 at the Lightning’s service ceiling of 54,000ft the Red Top could generate enough energy to reach an altitude in excess of 70,000ft. The Lightning’s supersonic speed also increased range and reports from testing claim the weapon flying out to a head-on target range of 7-8 miles (when in the chase position this range will decrease as the target is moving away and so the weapon has to overtake it). Carrying the quite heavy weapon did impose restrictions on the light and aerodynamically pure Lightning and pilot notes for the Lightning F.6 model dictated that whilst armed the aircraft should not fly passed Mach 1.75 so as to not overstress the airframe.
Any infra-red air-to-air missile developed in the 1960s will ultimately be compared to the US AIM-9 Sidewinder family. Compared to the AIM-9B Sidewinder, Red Top was a far superior weapon with a more sophisticated seeker, longer range, greater agility and a substantially more powerful warhead. The AIM-9B also had a very limiting launch load factor of just 2.6G whereas Red Top could be fired at up to 4G making Red Top the better weapon in a dogfight. The only real advantage the AIM-9B had was that it was much lighter weighing just 180lbs compared to Red Top which weighed in at nearly 340lbs and could be more easily integrated on to a wider array of aircraft. This latter fact was the key to its export success compared to most other air-to-air weapons of the era including Firestreak and Red Top. When you consider that the primary Soviet close-in air-to-air missile for the 1960s and 70s was the AA-2 “Atoll”, a reverse engineered AIM-9B, then it can be claimed that Red Top was better than this weapon also.
The AIM-9B’s extremely poor showing over Vietnam forced rapid development of an improved model, the AIM-9D Sidewinder and this had advantages and disadvantages when compared to Red Top. The AIM-9D had a marginally longer head-on range compared to Red Top again dependant on the conditions at launch. Red Top still had the more sensitive seeker and its larger window gave it a better view of the world outside. Also Red Top’s larger warhead meant that it was more likely to destroy whatever it hit or inflict fatal damage with a proximity hit. It’s interesting to note however that when the Royal Navy selected McDonnell Douglas’ F-4 Phantom II in its Anglicized F-4K Phantom FG.1 form both Red Top and AIM-9D were tested against each other. The Admiralty decided to keep the AIM-9D as the aircraft’s primary close-in weapon despite Red Top already being supported in service with the Sea Vixen. The main reason cited for this was to simplify the introduction of the already overly complex British Phantom to squadron service.
Consequently, Red Top was withdrawn from Royal Navy service in 1972 when the Sea Vixens were retired leaving the Sidewinder armed Phantoms as the Fleet Air Arm’s primary fighter. Red Top continued to arm the RAF’s Lightnings until 1988 and in July of that year the very last live round was fired over Cardigan Bay, South Wales (see top image).
- Wingspan : 0.91 metres (2.95ft)
- Length : 3.32 metres (10.89ft)
- Body Diameter : 0.23 metres (0.75ft)
- Weight : 154 kilograms (340lbs)
- Warhead : 31 kg (68.3 lb)
- Speed : Mach 3.2 (2436 mph)
- Range : 7.5 miles
- Service Ceiling : 70,000+
- Launch Load Factor : 4G