Project HARP - Martlet Projectiles

Martlet Projectiles

There were several models of test projectile fired or designed during Project HARP.

Martlet 1

The first test projectile. 16-inch (410 mm) gun bore, projectile weighed 450 lb (200 kg), was 6.6 inches (170 mm) in diameter and 70 inches (1,800 mm) long. Only four manufactured. Two were fired on January 21 and February 1, 1962.

Martlet 2

Primary 16-inch (410 mm) test projectiles. Around 200 fired, of various weights and configurations. Most carried research payloads studying upper atmosphere and near space conditions. About half the weight of the typical Martlet 2 series projectile was in the pusher plate and centering sabot.

Martlet 2G

A more advanced projectile, which had nearly all of its total 350 lb (160 kg) weight in the projectile. The Martlet 2G utilized a sabot system very similar to modern antitank kinetic energy penetrators.

Martlet 2G-1

A proposed space launch vehicle variant of Martlet 2G, which had a solid rocket motor in the projectile. The follow-on 2G-2 would have had a second rocket motor and been able to place the second stage in orbit, though with little or no payload.

Martlet 3

A series of more advanced rocket propelled projectiles in the HARP project.

Martlet 3A

Intended to be a 16-inch (410 mm) diameter, gun fired rocket projectile able to reach 500 km altitude. The rocket motors' solid propellant deformed during firing and the design was never successful, despite several test firings.

Martlet 3B

Similar to the Martlet 3A, using steel casings and attempting to solve some of the 3A model's problems. Unsuccessful.

Martlet 3D

This model was going to be a suborbital test rocket, using the first stage of the Martlet 4 solid rocket version. As Martlet 4 was never built, no Martlet 3Ds were produced either.

Martlet 3E

A suborbital solid rocket designed to be fired from a smaller, 7-inch (180 mm) cannon used in the HARP project.

Martlet 4

Two versions of full scale orbital launch vehicle projectiles were proposed in the Martlet 4 series. The first used three solid rocket motor stages and was planned to orbit about 50 pounds of payload. The second used liquid rocket motors and was planned to have orbited 200 pounds of payload. Both were about 28 feet (8.5 m) long and 16 inches (410 mm) in diameter, weighing about 2,900 pounds (1,300 kg) at launch. No Martlet 4 vehicles were built; the project halted before the design was completed.