M27 Roosevelt Medium Tank Development History

M27 Roosevelt Medium Tank

T27 – M27 Medium Tank Roosevelt (Nickname: Franklin)

History: (From: http://en.wikipedia.org/wiki/T20_medium_tank#M27)

…On the basis that the M4 was becoming obsolete, the Ordnance Department requested the T23E3 and the T20E3 be standardized as the M27 and M27B1 in July 1943. However, the request was rejected and neither design was ever mass produced.

With standardization of the M27 rejected, the Ordnance Department continued designing improved tanks, this time armed with 90 mm guns. The immediate result of this line of development was the T25 series—basically a slightly enlarged version of the T23—and then the bigger, better protected T26. The T26 would further evolve into the T26E3, and ultimately be standardized as the M26 Pershing and accepted into service at the very end of the war.

Alternate History:

The T23E3 was reconsidered in late 1945 as the M26 Pershing performed well in engaging enemy tanks but proved lacking in crew protection and maneuverability. Critics have used it as a point that the Pershing does not have the armor it is needed to be a heavy tank. At the same time, US Army doctrine was also phasing out the ‘Tank Destroyer Doctrine” at the same time and it was decided to design a tank that is capable of reaching an adequate top speed, fire-power and mobility.

The basis for the Pershing, the T26E3 was reexamined to see if additional armor could be added while increasing mobility of its T23 predecessor. The result is the T27, originally to be named the Pershing II but was renamed in memory of President Franklin D. Roosevelt. Designed to engage the enemy at long distances and support infantry with a large gun, protected by adequate armor and capable of become both the spearhead of an assault, a flanking assault force or a steady defense to hold off against its armored rivals with the heavy armor compared to heavy days of its era. Essentially, the qualities of a Main Battle Tank while still referred to as a medium tank.

Comparison:

In-game stats:Tank:

M27 Roosevelt M26 Pershing (US, Tier 8)

M46 Patton(US, Tier 9)

Panther II (German, Tier 8)

T-54 (USSR, Tier 9)

Crew: 4 5 5 5 4Engine Power

(hp): 810 450 810 810 581

Hull Armor (mm):

127/89/51 (5”/3.5”/2”)

102/76/51* (4”/3”/2”) 102/76/51* 100/60/40* 120/80/45*

Turret Armor (mm):

165/89/76 (6.5”/3.5”/3”)

114/76/76* (4.5”/3”/3”)

102/76/76* 100/45/45* 200/108/65*

Gun: 90-mm T15E1 L/73 90mm Gun M390 mm gun

M3A1 88 mm L/71 KwK100 mm D-

10T* Stats are taken from the World of Tanks wiki and do not represent real-world values due to lack of data.

http://en.wikipedia.org/wiki/T20_medium_tank#M27


Development:

The M27 Medium tank is the final development of the T27 series. Originally canceled with the acceptance of the T26E3/M26 Pershing series, it was designed and rushed into the prototype state at the end of 1945 due to changes in American armored doctrine; changes which would cumulate with reclassification of tanks and introduction of the Main Battle Tank concept.

Classified as one of the first generation Main Battle Tanks, the M27 is still referred to as a medium tank. The origin of the M27, the T20E3 mounted a 76mm gun, which was found to be lacking and while on par with contemporaries like the German Panther, it was found to be lacking in protection. With the change in doctrine removing the Tank Destroyer class of armored vehicles, the US Tank Corps was more ready to accept a 90mm medium tank, especially after the Pershing showed promise

Original design attempted to mount a 105mm gun on the experimental T29 Heavy Tank but mounting such a large gun would require designing an entirely new tank. The T15E1 mounted on the M26E4-1 used single piece ammunition, increasing the firing rate of when compared to the T15E2, which used 2-piece ammunition. The T15E1

was 73 calibers long, making its performance on par with the gun mounted on the Tiger II.

The removal of the hull-machine gunner/assistant driver removed an obvious weak spot in the tank’s frontal armor and also allowed extra ammunition to be stored. The driver’s position was moved to the center as a result. An additional 30cal. Machinegun is mounted on the top of the enlarged turret, next to the Loader’s hatch. The coaxial machinegun remains in its original position and can be used by the gunner if necessary.

Image intensification/ night vision equipment, originally issued as the M1 and M3 “sniperscope” to snipers was redesigned with technology salvaged from destroyed German Panthers (some of which also sported NV-equipment). The result was the M3V Night Vision scope. 2 are built into a tank. An independently mounted one for the Commander and 1 mounted coaxially to the main gun, used by the Gunner.

Crew:4

(Commander, Gunner, Loader, Driver)

Main Armament: 1 x 90mm T15E1 L/73

Secondary Armament:1 x 12.7 (.50cal) MG,

2 x .30cal M1919A4 MG

Radio:SCR-694

Field telephone connected for infantry

Vision:

2 x M3V Night vision (Commander, Gunner)360 ° vision ports on

Commander’s cupola.120 ° vision periscope for

Gunner160 ° bullet-proof vision ports

for DriverLength Gun Forwards: Approx. 10.5m

Length Hull: Approx. 6.2mWidth: Approx. 3.7m

Height to commander's hatch: Approx. 2.8m

Ground clearance: Approx. 0.44mWeight, combat: Approx. 48 - 55tonne

Power-to-weight ratio: 16.76 - 14.73 hp/tonneGround pressure: <1kg/cm2

Engine: Continental AV1790-3 810hpMaximum road speed: 600 - 800 LitersMaximum road range: >48 km/h

Fuel capacity: 600 - 800 Liters

Armor(mm): Hull: 127/89/51Turret: 165/89/76

Armor type: RHA Steel & Spaced Armor


Variants:

T27, T27E1 – Prototype variants.

M27 – First series mass produced tank.

M27A1 – Field telephone mounted onto tank hull to improve combined arms operation.

M26E3 – Refurbished and up armored M26 upgraded to M27. Mostly used for training and arming reserve battalions.

M27A2 – Bore-evacuator, ERA plates, new generation night vision equipment added.

M27A2E1 – Urban Assault Tank, 90mm gun replaced by 105mm Howitzer. Loader and Commander’s machinegun mount can be replaced with Recoilless Gun or Anti-tank rocket launchers.

Status:Production complete, over 2500 units produced.


Recognition and Manufacturing Features:

- Hull – Well slopped glacis plate with driver’s hatch in the center, vertical side and rear hull. Raised engine deck. Very similar to M26 Pershing – Tracks and Hull marginally enlarged. No-hull machine gun.

- Turret – Turret ring size same as M26 Pershing. Turret position center-forward of hull. The turret is a mixture of armor of different qualities. The turret is made of rolled steel backed by cast steel. Rolled-spaced steel gives extra protection against HEAT-projectiles and is more difficult to penetrate than cast steel. The cast-steel center reduces spalling injuring crew. Sloped armor on all sides with stowage rack in the back. Left side of stowage rack has opening for radio access, which can is used to connect to a field telephone if necessary.

- Manufacturing – Current M26s can be upgraded to M27s, saving production time and cost for new tanks. Current equipment used for the manufacturing of M26s can be used with minor changes to produce new M27 units.

- This vehicle is intended to be easy to be mass-produced but powerful, similar in line to the doctrine of current NATO Main Battle Tanks. While doctrine maintains that it is a medium tank, it could theoretically fulfill both roles of medium and heavy tanks in combat. There are no plans for adding amphibious capabilities to it.

(Above): Artist concept of how the M27 would look. Drawing lacks the roof mounted MG posts but sports counter-shadowing on barrel.


Size Comparison of Original M26 Pershing to M27 Roosevelt. M27 at 1:200 Ratio.

M26 and T29 at 1:400 Ratio.










Resources used:

http://www.freeweb.hu/gva/weapons/usa_guns7.html#Tank_Gun_T15E2 – 90mm gun penetration comparison

M26/M46 Pershing Tank 1943-53, By Steven J. Zaloga, Tony Bryan, Jim Laurier - General Reference

T-34-85 Vs M26 Pershing: Korea 1950, By Steven J. Zaloga – General Reference

http://en.wikipedia.org/wiki/M26_Pershing#T25_and_T26 – Historical Reference

http://afvdb.50megs.com/usa/m46patton.html – Comparison Reference

http://afvdb.50megs.com/usa/m26pershing.html – Comparison & Statistical Reference

http://static.hlj.com/images/rym/rymrm339.jpg – Crew Position Reference

http://otvaga2004.narod.ru/publ_w5/pershing/001.gif – Image Reference

http://armor.kiev.ua/Tanks/Modern/Heavy/T29.gif – Image Reference

http://armor.kiev.ua/Tanks/Modern/Heavy/T28_1.gif – Image Reference

http://www.tankinfo.ru/Country/USA/2/main/images/MBT70.jpg – Image Reference

http://www.the-blueprints.com/blueprints-depot/tanks/tanks-m/m1a1-abrams.gif – Image Reference

http://i32.photobucket.com/albums/d23/RRoan/reference%20pics%20olol/gmxm1-2.jpg – Image Reference

http://www.wwiivehicles.com/usa/tanks-heavy/m26-heavy-tank-pershing/m26-heavy-tank-pershing-drawing-01.png – Image Reference

http://www.achtungpanzer.com/german-infrared-night-vision-devices-infrarot-scheinwerfer.htm – Technology Reference

http://en.wikipedia.org/wiki/SCR-694 - Technology Reference

(Left): M27A2E1 – Urban Assault Tank variant concept. Note the 90mm has been replaced with a 105mm Howitzer.

While the Commander’s roof machinegun remains, the Loader’s MG position has been converted to mount a Bazooka to respond to threats that the turret cannot reach in tight urban environments or does not warrant the use of a 105mm shell.

M27 Roosevelt Medium Tank Development History

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