T22 (rocket)

M8
M8 rockets being launched from a "Calliope" multiple launcher mounted on a Sherman tank.
Type	Air-to-surface and surface-to-surface rocket
Place of origin	United States
Service history
Used by	United States Army, United States Navy
Production history
Designer	Picatinny Arsenal
Designed	1941
Manufacturer	Chrysler Corporation, Highland Park Plant (328,327);Hercules Powder Company Radford Ordnance Works and Sunflower Ordnance Works (solvent powder)
Produced	1941-1944
No. built	2,537,000
Specifications
Weight	38 lb (17 kg)
Length	33 in (840 mm)
Diameter	4.5 in (110 mm)
Warhead weight	4.3 lb (2.0 kg)
Engine	Solid-fuel rocket 4.75 lb (2.15 kg) fuel
Operational range	4,600 yd (4.2 km)
Speed	600 mph (970 km/h) 880 ft/s (270 m/s)
Guidance system	None

The M8 was a 4.5-inch (110 mm) rocket developed and used by the United States military during World War II. Produced in the millions, it was fired from both air- and ground-based launchers; it was replaced by the M16 rocket in 1945.

The first modern research into military solid-propellant rockets in the United States was conducted by Colonel Leslie Skinner at the Aberdeen Proving Ground in 1932. Little interest was shown by the US Armed Forces however, until the introduction of a British anti-aircraft rocket; both nations exchanged their research data before the United States entered World War II. The M8 rocket was developed by the National Defense Research Committee and the Army Ordnance Department in the early 1940s; at Picatinny Arsenal. The specifications were agreed in the summer of 1941 after examining equivalent British rockets. Skinner produced the first prototypes which were tested at Aberdeen that fall, improvised from old fire extinguisher tanks for rocket casings, thereby determining the 4.5 inch diameter. It was fin stabilized, a system that proved less than satisfactory for low velocity, ground launched rockets.

Original priority was given to an air-to-ground version, confidence in the initial results was so high that the USAAF had ordered 3,500 rockets before any had been actually fitted to an aircraft and it was hoped to have them operational in time for Operation Torch, the invasion of North Africa, in October 1942. The successful launch of an M8 from a Curtiss P-40E fighter on July 6, 1942 resulted in a procurement order for 600,000 units. Development began on a reloadable launcher that could be fitted in the bomb bay of an Douglas A-20 bomber, but this never became operational. There were considerable problems with the propellant, the fuzes and the underwing launching tubes, all of which considerably delayed operational deployment.