The Martlet 3B vehicle was similar in design to the 3A vehicle but sported several design changes intended to improve the system performance. The first major change was to replace the aluminum airframe with a alloy steel airframe in the hopes the stronger material would lead to higher mass fractions. Other improvements included the use of a larger diameter rocket motor (increasing the outer diameter to 8 inches / 20 cm) and the use of six fixed fins instead of the 3A's four fins.
Status: Retired 1965. First Launch: 1964-07-01. Last Launch: 1965-11-17. Number: 25 . Gross mass: 180 kg (390 lb). Diameter: 0.20 m (0.65 ft).
The Martlet 3B was used to test a wide variety of variations in rocket motor types and launch techniques in order to fully explore the dynamics of sub-caliber gun-launched rockets. This included shear loading and hydraulic loading techniques, the use of radial and end burning rocket motor grains, as well as the use of composite and extruded propellants produced by four different agencies. Unfortunately there was no major improvement in the vehicle performance over the Martlet 3A in terms of vehicle mass fraction or the structural performance during the gun launching.
The last test flights of the Martlet 3B were performed in mid-1964 after which no further work was performed by HARP on sub-caliber gun-launched rocket vehicles.
by Richard K Graf
|Project HARP 16 inch|
Used with permission of Stephen E. Mendes - visit his Barbados Photo Gallery
Credit: © Stephen E. Mendes