High Quality Content by WIKIPEDIA articles! The RP-3 (from Rocket Projectile 3 inch), was a British rocket used in the Second World War. Though primarily an air-to-ground weapon, it saw limited use in other roles. Its 60 lb (27 kg) warhead gave rise to the alternative name of the "60 lb rocket"; the 25 lb (11.3 kg) solid-shot armour piercing variant was referred to as the "25 lb rocket". They were generally used by British fighter-bomber aircraft against targets such as tanks, trains, motor transport and buildings, and by Coastal Command and Royal Navy aircraft against U-Boats and shipping.