In 1942, U.S. Army Colonel Leslie Skinner received the M10 shaped-charge grenade which was capable of stopping German tanks. He tasked Lieutenant Edward Uhl with creating a delivery system for the grenade. Uhl created a small rocket, but needed to protect the firer from the rocket exhaust and aim the weapon. According to Uhl,
"I was walking by this scrap pile, and there was a tube that ... happened to be the same size as the grenade that we were turning into a rocket. I said, That's the answer! Put the tube on a soldier's shoulder with the rocket inside, and away it goes."[1]
Uhl developed the rocket launcher and is known as father of the Bazooka.[1] Development of the M1 prototype took place in Corcoran Hall at The George Washington University in Washington, D.C. with the help of Clarence Hickman who had worked for Goddard. The M1 consisted of a sheet metal tube with a simple wooden stock, hand grips, and sights (replaced by metal in production models), into which the 60.07 mm-diameter (officially designated "M6, 2.36-inch" to avoid confusion with rounds for the 60 mm mortar) rocket grenades were inserted at the rear with trailing electrical leads. The cast steel warhead contained 1.6 lb of Pentolite high explosive. A two-cell dry battery in the wood shoulder rest provided a charge to ignite the rocket when the trigger was pulled; the wires sticking out the back of the round having been connected to two contacts by the assisting loader.
Although the weapon had some reliability and accuracy problems, Ordnance officials were greatly pleased with the penetrative effect of the new M1, which blew the turret off a tank during field trials.[4] The weapon's M6 rocket warhead was capable of penetrating roughly 4.5 inches (112 mm) of armor plate.[6] As a result, the War Department cancelled all plans for anti-tank rifles and in 1942 adopted the M1 rocket launcher and its M6 rocket as standard. The M1 rocket launcher was the first type to see combat use.[7]
The M1 Bazooka
By late 1942, the improved Rocket Launcher, M1A1 was introduced. The forward hand grip was deleted, and the design simplified. The production M1A1 was 54 inches (1.37 m) long and weighed only 12.75 pounds (5.8 kg).
The ammunition for the original M1 launcher was the M6, which was notoriously unreliable. The M6 was improved and designated M6A1, and the new ammunition was issued with the improved M1A1 launcher. After the M6, several alternative warheads were introduced. The 2.36-Inch Smoke Rocket M10 and its improved subvariants (M10A1, M10A2, M10A4) used the rocket motor and fin assembly of the M6A1, but replaced the anti-tank warhead with a white phosphorus (WP) smoke head. WP smoke not only acts as a visible screen, but its burning particles can cause burns on human skin. The M10 was therefore used to mark targets, to blind enemy gunners or vehicle drivers, or to drive troops out of bunkers and dugouts.[8] The 2.36-Inch Incendiary Rocket T31 was an M10 variant with an incendiary warhead designed to ignite fires in enemy-held structures and unarmored vehicles, or to destroy combustible supplies, ammunition, and materiel.
The original M1A1 rocket launcher was equipped with a simple hinged rear sight and fixed front sights, and used a launch tube without reinforcements. During the war, the M1A1 received a number of running modifications. The battery specification was changed to a larger, standard battery cell size, resulting in complaints of batteries getting stuck in the wood shoulder rest (the compartment was later reamed out to accommodate the larger cells).[9] This was followed by a new aperture rear sight and a front rectangular "frame" sight positioned at the muzzle. The vertical sides of the frame sight were inscribed with graduations of 100, 200, and 300 yards. On later models, the iron sights were at first replaced by a plastic optical ring sight, which proved unsatisfactory in service, frequently turning opaque after a few days' exposure to sunlight.[10] Later iron sights were hinged to fold against the tube when not in use, and were protected by a cover. The launcher also had an adjustable range scale that provided graduations from 50 to 700 yards (46 to 640 meters) in 50-yard (46 m) increments. An additional strap iron shoulder brace was fitted to the launcher, along with various types of blast deflectors.
The bazooka required special care when used in tropical or arctic climates or in severe dust or sand conditions. Rockets were not to be fired at temperatures below zero F or above 120 F.[11]
[edit] Field experience induced changes
In 1943, field reports of rockets sticking and prematurely detonating in M1A1 launch tubes were received by Army Ordnance at Ogden Arsenal and other production facilities. At the U.S. Army's Aberdeen Testing Grounds, various metal collars and wire wrapping were used on the sheet metal launch tube in an effort to reinforce it. However, reports of premature detonation continued until the development of bore slug test gauges to ensure that the rocket did not catch inside the launch tube.[12]
The original M6 and M6A1 rockets used in the M1 and M1A1 launchers had a pointed nose, which was found to cause deflection from the target at low impact angles. In late 1943, another 2.36-in rocket type was adopted, the M6A3, for use with the newly standardized M9 rocket launcher.[6] The M6A3 was 19.4 inches (493 mm) long, and weighed 3.38 lb (1.53 kg). It had a blunted nose to improve target effect at low angles, and a new circular fin assembly to improve flight stability. The M6A3 was capable of penetrating five inches (125 mm) of armor plate.
Battery problems in the early bazookas eventually resulted in replacement of the battery-powered ignition system with a magneto sparker system operated through the trigger. A trigger safety was incorporated into the design that isolated the magneto, preventing misfires that could occur when the trigger was released and the stored charge prematurely fired the rocket. The final major change was the division of the launch tube into two discrete sections, with bayonet-joint attachments. This was done to make the weapon more convenient to carry, particularly for use by airborne forces. The final two-piece launcher was standardized as the M9A1. However, the long list of incorporated modifications increased the launcher's tube length to 61 inches (1.55 m), with an overall empty weight of 14.3 lb (6.5 kg). From its original conception as a relatively light, handy, and disposable weapon, the final M9A1 launcher had become a heavy, clumsy, and relatively complex piece of equipment.[9]
In October 1944, after receiving reports of inadequate combat effect of the M1A1 and M9 launchers and their M6A1 rockets, and after examining captured examples of the German 8.8 cm RPzB 43 and RPzB 54 Panzerschreck, the U.S. Ordnance Corps began development on a new, more powerful anti-tank rocket launcher, the 3.5-inch M20. However, the weapon's design was not completed until after the war.[13]
In 1945, the U.S. Army's Chemical Warfare Service standardized improved chemical warfare rockets intended for the new M9 and M9A1 launchers, adopting the M26 Gas Rocket, a cyanogen chloride (CK)-filled warhead for the 2.36-in rocket launcher.[14] CK, a deadly blood agent, was capable of breaking down the protective chemical barriers in some gas masks, and was seen as an effective agent against Japanese forces (particularly those hiding in caves or bunkers), whose gas masks lacked the impregnants that would provide protection against the chemical reaction of CK.[14][15][16] While stockpiled in U.S. inventory, the CK rocket was never deployed or issued to combat personnel.[14]
Even though in late 1942 the general American public became aware of the bazooka in small articles in the monthly magazines Popular Mechanics and Popular Science it was not until early 1945 that they learned in a very large and detailed article in Popular Science the true secret of the bazooka's warhead. The US War Department had decided that it was only a matter of time before both Germany and Japan were defeated and the secrets of shape charges were already well known by its enemies.[17]
