HARP Gun

Guncotton propellant rocket stage. The HARP gun, a converted 16 inch naval gun, was used during the 1960's to launch the Martlet series of rocket-launched space probes.

Using 450 kg of M8M propellant, with optimum web size, and a maximum muzzle pressure of 4100 atmospheres, the gun had the following performance:

• 250 kg projectile accelerated at 13,000 peak G's to 2,300 m/s muzzle velocity
• 500 kg projectile accelerated at 9,000 peak G's to 1,900 m/s muzzle velocity
• 750 kg projectile accelerated at 6,500 peak G's to 1,680 m/s muzzle velocity
• 1,000 kg projectile accelerated at 5,000 peak G's to 1,550 m/s muzzle velocity

'Specific impulse' indicated here is effective specific impulse for a 750 kg projectile. Due to muzzle dynamics, value differs for other masses of projectile. Diameter and length are that for the gun bore.

Release velocity: 1,072 m/s (3,517 ft/sec). Release altitude: 27 m (87 ft). Release conditions: 298 m/s losses from muzzle exit velocity..