Directory of U.S. Military Rockets and Missiles
Appendix 4: Undesignated Vehicles
Copyright © 2004-2024 Andreas Parsch

4.5 inch HE Rocket M8

The 4.5 inch aircraft rocket was among the first air-launched rockets developed for the U.S. military in World War II. The program was conducted primarily by the National Defense Research Committee (NDRC) and Army Ordnance. The first ground tests of the solid-propellant rocket motors occurred in May 1941, and in July 1942, the rocket was air-launched for the first time from a P-40 fighter.

The initial and most common model of 4.5-inch rocket was the M8. It was stabilized by four tail fins, which were fixed on initial M8s and folding on later ones. The M8A1 variant had a strengthened motor tube. The M8A2 was a variant of the M8A1 with a smaller, heavier-walled shell, and a slightly higher velocity. The M8A3 was an M8A2 with a modified fin assembly. The M9, M9A1, M9A2 and M9A3 were inert practice rockets to simulate the M8, M8A1, M8A2 and M8A3, respectively. The T22 HE rocket and T46 practice rocket were further improved M8A2/M9A2, which were safer and more reliable than the M8/M9. All these rockets flew at high subsonic speed and had an effective range of about 1600-3200 m (1-2 miles). M8-type rockets were also used as ground-launched 4.5-inch barrage rockets.

Photo: via Ordway/Wakeford
4.5 inch Rocket M8

The USAAF used the 4.5-in. rockets with good results, especially in the 1943/44 winter against Japanese forces in Burma. However, the rockets were ineffective against many of the sturdier ground targets, and therefore the so-called "Super M8" was developed. It had four fixed fins and a larger and improved rocket motor, giving higher speed, range and destructive power. Its 18 kg (40 lb) warhead section was either a solid armour-piercing type or contained 3.9 kg (8.5 lb) of high-explosive. The "Super M8" was ready by December 1944, but was not used in combat.

4.5 inch Fixed-Fin Rockets

A different type of air-launched 4.5 inch rockets was the fixed-fin type. Variants were the T78 with a SAP (Semi Armour Piercing) warhead, the T86 practice round for the T78, the T83 with a HE (High Explosive) warhead, and the T87 practice round for the T83.


Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for M8, T22, "Super M8":

 M8T22"Super M8"
Length91 cm (36 in)84 cm (33 in)1.78 m (5 ft 10 in)
Diameter11.4 cm (4.5 in)
Weight17 kg (38 lb)47 kg (104 lb)
Speed960 km/h (600 mph)1450 km/h (900 mph)
Range3.2 km (2 miles)6.4 km (4 miles)
Propulsion4.5-inch solid-fueled rocket

Main Sources

[1] Norman J. Bowman: "The Handbook of Rockets and Guided Missiles", Perastadion Press, 1963
[2] Frederick I. Ordway III, Ronald C. Wakeford: "International Missile and Spacecraft Guide", McGraw-Hill, 1960
[3] War Department: "Technical Manual TM9-1950, Rockets", July 1945
[4] Department of the Army: "Technical Manual TM9-1950, Rockets", June 1950

Back to Directory of U.S. Military Rockets and Missiles, Appendix 4

Last Updated: 8 June 2024