| 7.2-inch Multiple Rocket Launcher T40/M17 | |
| Origin: | United States |
| Type: | Tank mounted Multiple Rocket Launcher |
| Is Ranged: | yes |
| Is Artillery: | yes |
| Service: | 1944–1945 |
| Used By: | United States |
| Wars: | World War II |
| Weight: | 4615lb (Empty) |
| Length: | 105inches |
| Width: | 105inches |
| Part Length: | 90inches |
| Cartridge: | HE Rocket T37 Chemical Rocket T21 |
| Cartridge Weight: | T37: 61lb T21: 51.8lb |
| Caliber: | 7.2inches |
| Barrels: | 20 |
| Velocity: | T37: 160ft/s T21: 680ft/s |
| Max Range: | T37: 230yd |
| Carriage: | M4 Sherman |
| Elevation: | -5° to 25° |
| Traverse: | 360° |
The 7.2-inch Multiple Rocket Launcher T40/M17 Whizbang (sometimes spelled Whiz-Bang or Whiz Bang) was a tank-mounted multiple rocket launcher used by the United States Army during World War II. The launcher was mounted atop 75mm variants of the M4 Sherman, and fired a barrage of 7.2inches rockets from 20 launch tubes. It was developed and used in the late stages of the war, and saw limited combat in 1944–45.
The T40/M17 Whizbang could hold twenty 7.2-inch rockets in two racks of ten rockets each, housed in a box-like frame protected by hydraulically operated doors. These doors protected the rockets from enemy fire, reflecting that it was designed to be used at a close range. The launcher could be aimed by elevating the tank's main gun, and had two firing modes, enabling the operator to fire a single rocket, or a salvo of rockets at a selected rate of fire. After expending all the rockets, the operator could easily jettison the empty launcher by turning the turret towards the side of the tank, fully elevating the gun, disconnecting the cables, and then pulling two handles.
The Whizbang was originally intended for use in the allied invasion of France, where it would be used to breach shoreline defenses. No T40s were ultimately deployed during the landings, despite some tanks already being fitted with the mounting brackets. Later the U.S. Army planned to equip a total of 30 Shermans, belonging to the 743rd Tank Battalion, with the system, to be used in a planned operation in Belgium in December 1944. This operation was eventually cancelled due to the German counter-offensive in the Ardennes on December 16, prompting the U.S. Army to remove the T40s from the battlefield. The launcher ended up not being reinstalled on their intended Shermans, instead, 8 of the launchers were sent to Italy, to be used for artillery fire support. In Italy, the Whizbang's range proved dissatisfactory, prompting the 760th Tank Battalion to rearm at least one of theirs with 54 4.5-inch M10 aircraft rocket launch tubes.
The Marine Corps examined the Whizbang for possible use in the Marianas Campaign in 1944, but ultimately it was not used in the Pacific.