Red Angel, a rainbow code name, was an anti-ship unguided rocket developed for the Royal Navy's Fleet Air Arm as a counter to the Soviet Union's Sverdlov-class cruiser.
A version with a solid armour piercing warhead replacing the large high explosive model was introduced with the goal of puncturing the hull of U-boats and thus forcing them to remain surfaced where they could be easily attacked.
Attacks with this weapon demonstrated an unusual behaviour: a projectile that entered the water short of the target would steer itself upwards on a curving trajectory and travel horizontally.
The most concerning aspect of the new cruiser was the implementation of fully-automated, radar-guided dual-purpose guns, integrated into a fire control system which used the novel 'Sun Visor' and 'Egg Cup' high-frequency targeting radars.
[4] After the Sverdlov was publicly presented in 1953, First Sea Lord Admiral McGrigor was questioning whether or not it was wise to depart from the gun philosophy with regard to warships, since aerial attack had been largely checked and suitable underwater weapons had not yet been developed.
At the same time, development began on "Bootleg", an air-dropped torpedo with a rocket booster that allowed it to be fired from about the same range as Red Angel.
Several problems were found; the rocket motor failed to ignite on occasion, a number broke up on impact with the water, and the folding fins were slow to extend in cold weather, leading to low accuracy in these conditions.
[7] Another issue was that the number of aircraft carriers in RN service was cut back, meaning that the Sverdlovs were going to have to be countered, at least on occasion, by surface ships.
[1] It was first deployed on the Westland Wyvern turboprop, but had always been earmarked for the new jet naval strike aircraft developed in response to the Sverdlov threat, the Blackburn Buccaneer.