- Yes
- No
At the time the two T86 prototypes were approved, a third prototype was authorised. However, its construction was delayed until November 1944 to wait for the test results of the T86. This prototype was designated as the 105 mm Amphibian Howitzer Motor Carriage T87.
The T87’s hull was mostly based off that of the T86, as it was found that the track propulsion used was superior to the propellor propulsion on the T86E1. The length was shorter at about 325 in (8.26 m), the width was the same and the height increased slightly to 117 in (2.97 m; Hunnicutt claims the height to be 125 in). The assistant driver was situated on the right and slightly behind the driver. Dual controls allowed both drivers to control the vehicle on land, but only the assistant driver could control the rudders.
The turret was the same one from the 105mm Howitzer Motor Carriage T88, and hence had some differences from the turret of the T86 and the standard M18. The most obvious change was the use of a 105 mm M4 howitzer as the main gun, which was also fitted with a vertical stabiliser to help aiming. The gunner and loader positions were swapped and the commander was moved to the right rear (essentially a mirror image of the M18). The M2HB machine gun was moved to a pedestal mount at the front of the turret, and metal sheet covers were added to protect the crew from water.
While designed to have essentially identical performance to the T86, initial testing at Aberdeen found that the T87 could only reach 4.4 mph in water, as opposed to the designed 5.4 mph. Canvas grousers increased the speed by 0.25 mph, but 42 of the 78 grousers tore off during testing. It was recommended that LVT-like grousers be welded onto the tracks in the future. When the war ended, further development of the T87 was cancelled.
Specifications
Number built: 1 prototype
Crew: 5
Dimensions:
- Length: 325 in (8.26 m)
- Width: 122 in (3.10 m)
- Height: 117 in (2.97 m)
Mass: 45000 lbs (20.4 t) fully loaded
Armour:
- Turret: same as M18
- Hull:
- Front: 1/4 in
- Sides: 1/4 in above sponson, 1/2 in below sponson
- Rear: 1/8 in
Armament:
- 105 mm M4 howitzer, vertical stabiliser, 50 rounds
- .50 M2HB pintle mounted
Turret traverse rate: not mentioned, but based off M18 and described as power operated, so should be comparable to M18 turret traverse at 24°/s
Engine: Continental R-975-C4 engine, 460 hp gross at 2400 rpm. (Hunnicut and “Amphibian…”; comparing data between sources shows that “Amphibian…” is using net horsepower values)
Speed: 45 mph (72.4 km/h) or 43 mph (69.2 km/h) on land, 5.4 mph (8.7 km/h) in water
More pictures
T87 with .50 MG and turret covers fitted
Rudders deployed and retracted
Top view schematic showing the two driver positions
In game
While the Hellcat-like mobility and vertical stabiliser sounds great, the 105 mm M4 howitzer will be a big letdown with its slow reload and the poor M67 HEAT round. It would be natural to pair the T87 with the M4A3 (105) like the pairing of the M18 with the M4A3 (76) W, but the gun handling of the T87 is superior to the M4A3 (105) with the stabiliser and powered turret. Therefore, the T87 will probably be placed higher in BR, possibly even to 4.0. The US isn’t short on light tanks around this BR, but the T87 will make for a unique experience with practically the only stabilised howitzer in game, along with the powered turret and dual driver controls.
Sources
- Amphibian based on 76mm gun motor carriage M-18
- Pacific Area Material, July 1945
- “Stuart: A History of the American Light Tank” by R. P. Hunnicutt
Many thanks to @R_nminbiY_n and @Conraire for sources!