The RP-3 (from Rocket Projectile 3 inch) was a British air-to-ground rocket projectile introduced during the Second World War. The "3 inch" designation referred to the nominal diameter of the rocket motor tube. The use of a 60 lb (27 kg) warhead gave rise to the alternative name of the "60-pound rocket". Though an air-to-ground weapon, it saw limited use in other roles. They were generally used by British fighter-bomber aircraft against targets such as tanks, trains, motor transport and buildings, as well as by Coastal Command and Royal Navy aircraft against U-boats and ships

[](https://en.wikipedia.org/wiki/RP-3)