M8 (rocket)

The M8 was a 4.5 inch 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.

Development
The M8 rocket was developed by the National Defense Research Committee and the Army Ordnance Department in the early 1940s; at Picatinny Arsenal. Ground tests began in 1941, while the first air launch of the system was conducted in 1942, from a Curtiss P-40 pursuit aircraft. It was fin stabilized, and had a diameter of 4.5 inch.

The initial production model was given the Army designation of M8; improvements resulted in the M8A3, with a more powerful rocket engine and enlarged fins, and the T22, which had improved reliability and modifications to make the rocket safer.

Operational history
Entering service in 1943, the M8 family of rockets saw service with the United States Army, which classified the M8 as a "barrage rocket". The rocket was also widely used by the United States Army Air Forces. Over 2,500,000 of the M8 type rocket had been produced by the end of the war.

Operational service showed some drawbacks in the M8's performance; ground launch resulted in the rockets' fin stabilizers proving ineffective, reducing the accuracy of the rocket; despite this, it was considered an effective barrage weapon. Due to the lack of accuracy, when ground-launched, it was being launched from large multiple launchers; the most commonly used being eight- and 60-tube launchers, called "xylophones" and "calliopes" respectively. The "calliope", given the official designation T34, was mounted on top of a M4 Sherman tank; once fired, the launcher could be detached and discarded, allowing the tank to be used in conventional combat, while the "xylophone", officially the T27, was carried on a 2½-ton truck's cargo bed. A 120-round launcher, designated T44, and a 144-round T45 launcher were also developed; these were intended for use by the United States Navy, being mounted on DUKW amphibious vehicles and LST amphibious warfare vessels. Single- and twin-14-round launchers were also developed.

The M8 showed poor effectiveness against hardened targets; this resulted in the development of the Super M8, which had larger fins, a more powerful rocket and a more powerful warhead. The Super M8 underwent testing in late 1944, but failed to see combat. The M8 was replaced by the improved spin-stabilized M16 rocket during 1945.