Martlet 2G1

The Martlet 2G-1 was the absolute minimum gun-launched satellite vehicle. Conceived when the HARP project was under threat, it was a seven-inch diameter, two-stage solid propellnat vehicle that would be sabot-launched from the HARP 16 inch gun. Its total payload in orbit would have been just two kilogrammes - ideal for today's planned nano-satellites. Unfortunately even this minimum orbital launch vehicle could not be demonstrated before the program was shut down.

During the last year of the HARP program, when it became clear that further funding was not forthcoming, and that the goals of the Martlet 4 program were not to be realised, full efforts were diverted to developing a Martlet 2G-1 orbital vehicle (GLO-1A). It was felt that if a satellite - any satellite, no matter now small - could be successfully gun-launched, that it then would be possible to encourage further funding, either public or private, which would permit the orbital goals of the HARP program to be realised. Unfortunately time and fate were against HARP and the project was closed down on June 30 1967, only a few months before an orbital 2G-1 could be flown.

Manufacturer: Bull. LEO Payload: 2.00 kg (4.40 lb). to: 185 km Orbit. at: 13.00 degrees. Total Mass: 500 kg (1,100 lb). Core Diameter: 0.30 m (0.98 ft). Total Length: 4.29 m (14.07 ft).

• Stage Number: 0. 1 x Stage: HARP Gun. Gross Mass: 450 kg (990 lb). Empty Mass: 1.00 kg (2.20 lb). Thrust (vac): 127,000.000 kN (28,550,000 lbf). Isp: 365 sec. Burn time: 0.0100 sec. Isp(sl): 43 sec. Diameter: 0.42 m (1.37 ft). Span: 0.42 m (1.37 ft). Length: 36.59 m (120.04 ft). Propellants: Guncotton. No Engines: 1. Engine: 16 in gun. Status: Development ended 1966. 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.

• Stage Number: 1. 1 x Stage: Martlet 2G1-1. Gross Mass: 130 kg (280 lb). Empty Mass: 21 kg (46 lb). Diameter: 0.29 m (0.95 ft). Span: 0.45 m (1.47 ft). Length: 3.21 m (10.53 ft). Propellants: Solid. Status: Development 1966.

• Stage Number: 2. 1 x Stage: Martlet 2G1-2. Gross Mass: 41 kg (90 lb). Empty Mass: 7.00 kg (15.40 lb). Diameter: 0.29 m (0.95 ft). Span: 0.29 m (0.95 ft). Length: 0.53 m (1.73 ft). Propellants: Solid. Status: Development 1966.

• HARP project closed down Nation: Canada. The cancellation came only a few months before an orbital 2G-1 could be flown. Martlet 2's were used to conduct extensive research at altitudes of up to 180 km with some 200 flights being conducted between 1963 and 1967. The very low cost per flight, about $3,000, made it ideal for a wide variety of applications.. Typical mission payloads included chemical ejection to produce an observable atmospheric trail and assorted sensors with multi-channel telemetry.

• Goebel, Greg, Space Guns, . Accessed at: http://www.geocities.com/CapeCanaveral/Launchpad/6000/v1998_05.html#m2.