M3 Medium Tank

Ennen sotaa USA valmisti vain 94 M2 Medium panssarivaunua. Näiden aseistuksena
oli 37 mm tykki.
WW-2 alkaessa huomattiin tykin kaliiberin olevan heikko-tehoinen taistelussa muita panssarivaunuja vastaan.

1940 valmistettiin suurella kiirellä uusi vaunu, joka valmistui M2 (long chassis or long pottom plate) vaunun alustalle. Tämä nopeasti kehitetty vaunu sai nimen M3 Medium.
Se oli varustettu 75 mm tykillä joka oli asennettu rungon vasemmalle puolelle ja toimi
kuten rynnäkkötykki, pienellä suuntaus alueella. Myös panssarointi oli vahvistettu.

Chrysler autotehdas rakensi uudet tuotantolinjat tämän vaunun valmistuamiseen.
Rakennuksen pinta ala oli 46 hehtaaria (46.000 m2)

100 x 100 m = Hehtaari = 10.000 m2 (1 x hehtaari = 2,471 053 815 acre).

M3 Medium sarjavalmistus alkoi elokuu 1941, jatkui vuosi 1942 loppuun. 
Yhteensä valmistettiin 6258 kpl M3 Medium tankkia. Pieni määrä vaunuja valmistui vielä 1944, vuoden loppuun mennessä. 

Chrysler tehdas valmisti yhteensä 3352 M3 vaunua. Neljässä muussa (4) tehtaassa valmistettin loput 2906 M3 Medium vaunuista.

Medium perusmallin lisäksi valmistettiin tyypit; M3A1, M3A23, M3A3, M3A4, M3A5.
Britit antoi vaunulle nimeksi Lee tai General Lee, vaunujen sarjanumerot I - VI.

Näistä panssarivaunuista puuttui vaunun johtajan kupu. Englannissa lisättin tähystys torni muutamiin eri vaunu malliin ja tällä lisätornilla varustetut saivat Grant nimen.

M3 Medium muistutti hieman ensimmäisiä,ww-I ajan panssarivaunuja. Se oli korkea ja tämän johdosta taistelussa hyvin erottuva ja helppo maalitaulu. Rauhan aikaiset vaunujen kehityksen laimin lyönnit kostautui, ja sen haitat näkyivät tässä vaunussa.
Kun vaunua verrataan Neuvostoliiton valmistamiin panssarivaunuihin Medium M3 oli
hyvin alkeellinen ja heikko.

Vaunun päätykki oli asennettu rungon oikealle puolelle ja sen liike-vara oli vastaava kuin ensimmäisen maailmansodan aikaisissa panssarivaunuissa. Kuljettaja edessä oleva 50 mm panssari oli kallistettu, kaikki muut panssaroidut pinnat olivat suoria.
Vaunun torni ja runko oli koottu joko niittaamalla ja hitsaamalla. Pienet tornit tehtiin valamalla, panssarointi 12 mm - 88 mm, paino 28 - 29 tonnia, mallista riippuen.

Telapyörät olivat yksi-osaiset, jousitus pyörä-pareittain, pystysuorin kierrejousin.
Vaunuissa oli radio, Grant mallissa 6 miestä, Lee mallissa oli 7 miestä.
M3 Medium vaunu runkoa käytettiin myös; hinaus, kuljetus, liekinheitin, valonheitin 
ja kenttätykkien valmistukseen.


Rungon oikella puolella olevan 75 mm tykin putken pituus-kaliberi oli 31. 
Panssarikranaatti läpäisi 90 asteen kulmalla 76 mm panssarin 500 metrin etäisyydeltä
1000 metrin etäisyys 70 mm. Nämä arvot oli lähellä T-34 / 76mm tykin arvoja.
Pyörivässä pienessä tornissa oli 37 mm tykki, lisäksi Lee, 3 konekivääriä, Grant 4.

Moottori, monta vaihto-ehtoa: 
M3 Yleisin,  Continental tähtimoottori, 9 sylinteriä, bensiini, teho 340 hv / 259 kw.
M3A2; 1x Guibertson diesel, M3A3 / M3A5; 2 x GMC linja auton diesel moottoria.
M3A4: 5 x 85 hv / 62,5 kw Chrysler auton moottoria, teho yhteensä 425 hv / 313 kw.

Teho - paino suhde 12, 7 hv/tonni ja Telapaine 094 kp/cm2.
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Wikipedia

M3 (M3 Medium Tank) oli yhdysvaltalainen keskiraskas panssarivaunu, jota liittoutuneet käyttivät toisessa maailmansodassa. Britit antoivat vaunuilleen nimen "Lee" kenraali Robert E. Leen mukaan, ja myöhempi matalammalla tornilla britti spesifikaation mukaan valmistettu malli sai nimekseen "Grant" kenraali Ulysses S. Grantin mukaan.

M3 kehitettiin vuonna 1939 tuotantoon tulleen M2-panssarivaunun pohjalta, joka oli Yhdysvaltojen liittyessä toiseen maailmansotaan vuonna 1941 jo aseistukselta ja panssaroinnilta vanhentunut. Yhdysvaltain armeija halusi 75 mm tykillä varustetun uuden panssarivaunumallin, mutta vaatimukset täyttävä M4 Sherman ei kuitenkaan ollut vielä valmis sarjatuotantoon.

Korvikkeeksi suunniteltiin M2:n alustalle vahvemmin panssaroitu ja rungon oikeaan laitaan sijoitetulla 75 mm tykillä aseistettu M3, lisäksi vaunussa oli myös pieni 37 mm tykillä varustettu tykkitorni. Vaunun huonoja puolia olivat muun muassa sen korkea profiili, runkoon sijoitetun tykin pieni kääntymäsektori ja niitit, joilla panssarilevyt niitattiin paikoilleen. Se kuitenkin tarjosi tärkeissä taisteluissa Pohjois-Afrikassa vastuksen Panzerkampfwagen III:lle ennen Shermanin tuloa rintamalle.

M3-vaunuja käytettiin Kauko-idässä sodan loppuun asti. Yli 1 200 dieselmoottorista M3A3 ja M3A5-vaunua toimitettiin Neuvostoliittoon 1942–1943. 
Vaunu ei ollut suosittu Neuvostoliitossa. 

Sitä pidettiin suuresta siluetistaan huolimatta alitehoisena, nirso polttoaineen ja öljyjen suhteen ja liikkumiskyky heikko. Vaunu soveltui huonosti Venäjän teille ja jäi helposti jumiin telaketjujen mennessä rikki.

M3:n alustalle rakennettiin 3 490 kappaletta 105 mm M1/M2 haupitsilla aseistettua M7 Priest-panssarihaupitsia, sata 155 mm tykillä aseistettua M12-panssarihaupitsia ja erilaisia huolto- ja kuljetusvaunuja. Kanadassa M3:n alustalle suunniteltiin Ram-vaunu.

Tekniset tiedot
Aseistus: 75 mm M3 tykki, 37 mm M6 ilmatorjuntatykki, 3 x .30–06 (7,62 mm) kaliiperinen Browning M1919 konekivääri
Panssarointi: edessä 51 mm, kyljissä 38 mm
Paino: 27,9 tonnia
Moottori: Wright (Continental) R975 EC2, 400 hv
Huippunopeus: 34 km/h
Kokonaispituus: 6,12 m
Leveys: 2,72 m
Korkeus: 3,12 m
Miehistö: 6
Valmistuksessa: 1941-1942
Valmistusmäärä: Chrysler 3352 kpl + Muut 4 tehdasta 2906. Yhteensä 6528 kpl
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Wikipedia

Medium Tank M3 / 1942
Type: Medium tank
Place of origin: United States
Service history: World War II
Production: August 1941–December 1942
Number built: 6,258
Variants: Numerous see text
Weight: 30 short tons (27 t)
Length: 18 ft 6 in (5.64 m)
Width: 8 ft 11 in (2.72 m)
Height: 10 ft 3 in (3.12 m) - Lee
Crew: 7 (Lee) or 6 (Grant)
Armor: up to 51 mm Steel
Armament: 1 × 75 mm Gun M2/M3 in hull, 46 rounds
1 × 37mm Gun M5/M6 in turret, 178 rounds, 3–4 × .30-06 mg 9,200 rounds
Engine: Wright (Continental) R975 EC2 400 hp (300 kW)/340 hp (250 kW)
Transmission: Synchromesh, 5 speeds forward, 1 reverse
Suspension: Vertical volute spring
Ground clearance: 18 in (0.46 m)
Fuel capacity: 662 liters (175 US gallons)
Range: 193 km (119 mi)
Speed: 26 mph (42 km/h) (road) 16 mph (26 km/h) (off-road)

Steering: Controlled differential

The Medium Tank M3 was an American tank used during World War II. In Britain the tank was called by two names based on the turret configuration. Tanks employing US pattern turrets were called the "General Lee", named after Confederate General Robert E. Lee. Variants using British pattern turrets were known as "General Grant", named after U.S. General Ulysses S. Grant.

                      
Design commenced in July 1940, and the first M3s were operational in late 1941
The U.S. Army needed a good tank and coupled with the United Kingdom's demand for 3,650 medium tanks immediately, the Lee began production by late 1940. The design was a compromise to produce a tank as soon as possible. The M3 was well armed and armoured for the period, but due to design flaws (high silhouette, archaic sponson mounting of the main gun, riveted construction, below-average off-road performance) it was not satisfactory and was withdrawn from front line duty as soon as the M4 Sherman became available in large numbers.

n 1939, the U.S. Army possessed approximately 400 tanks, mostly M2 Light Tanks, with less than a hundred of the discontinued M2 Medium Tanks. The U.S. funded tank development poorly during the interwar years, and had no infrastructure for production, little experience in design, and poor doctrine to guide design efforts.

M3 Lee being manufactured
The M2 series medium tank was typical of armored fighting vehicles (AFVs) many nations produced in 1939. When the U.S. entered the war, the M2 design was obsolete with a 37 mm gun, 32 mm frontal armor, excessive machine gun secondary armament and a very high silhouette. The Panzer III and Panzer IV's success in the French campaign led the U.S. Army to immediately order a new medium tank armed with a 75 mm gun in a turret. This would be the M4 Sherman. However, until the Sherman was in production, an interim design with a 75 mm gun was urgently needed.

The M3 was the solution. The design was unusual because the main weapon — a larger caliber, low-velocity 75 mm gun — was in an offset sponson mounted in the hull with limited traverse. (The sponson mount was necessary because at the time American tank plants were incapable of casting a turret big enough to take the 75mm main gun.) A small turret with a lighter, high-velocity 37 mm gun sat on the tall hull. A small cupola on top of the turret held a machine gun. The use of two main guns was seen on the French Char B, the Soviet T-35, and the Mark I version of the British Churchill tank. 

In each case, two weapons were mounted to give the tanks adequate capability in firing both anti-personnel high explosive ammunition and armor-piercing ammunition for anti-tank combat. The M3 differed slightly from this pattern having a main gun which could fire an armor-piercing projectile at a velocity high enough for efficiently piercing armor, as well as deliver a high-explosive shell that was large enough to be effective. Using a hull mounted gun, the M3 design was produced quicker than if a turret mounted gun design had been manufactured. It was understood that the M3 design was flawed, but Britain urgently needed tanks.

The M3 was tall and roomy: the power transmission ran through the crew compartment under the turret cage to the gearbox driving the front sprockets. Steering was by differential braking, with a turning circle of 37 ft (11 m). The vertical volute suspension units included a return roller made with self-contained and readily replaced units bolted to the chassis. The turret was power-traversed by an electro-hydraulic system — an electric motor providing the pressure for the hydraulic motor. This fully rotated the turret in 15 seconds. Control was from a spade grip on the gun. The same motor provided pressure for the gun stabilizing system.

The 75-mm was operated by a gunner and a loader. Sighting the 75-mm gun used an M1 periscope — with an integral telescope — on the top of the sponson. The periscope rotated with the gun. The sight was marked from zero to 3,000 yd (2,700 m) with vertical markings to aid deflection shooting at a moving target. The gunner laid the gun on target through geared handwheels for traverse and elevation.

The 37-mm was aimed through the M2 periscope, though this was mounted in the mantlet to the side of the gun. It also sighted the coaxial machine gun. Two range scales were provided: 0-1,500 yd (1,400 m) for the 37-mm and 0-1,000 yd (910 m) for the machine gun.

British M3 Grant (left) and Lee (right) in the Western Desert, 1942, showing differences between the British turret and the original design.
Though not at war, the U.S. was willing to produce, sell and ship armoured vehicles to Britain. The British had requested that their Matilda and Crusader tank designs be made by American factories, but this request was declined. With much of their equipment left on the beaches near Dunkirk, the equipment needs of the British were acute. Though not entirely satisfied with the design, they ordered the M3 in large numbers. British experts had viewed the mock-up in 1940 and identified features which they considered flaws — the high profile, the hull mounted main gun, the lack of a radio in the turret (though the tank did have a radio down in the hull), the riveted armour plating (whose rivets tended to pop off inside the interior in a deadly ricochet when the tank was hit by a non-penetrating round), the smooth track design, insufficient armour plating and lack of splash-proofing of the joints.

The British desired a number of modifications be made for the tank they were purchasing, including the turret being cast rather than riveted. A bustle was to be made at the back of the turret to house the Wireless Set No. 19 radio. The tank was to be given thicker armour plate than the original U.S. design, and the machine gun cupola was to be replaced with a simple hatch. With these modifications accepted the British ordered 1,250 M3s. The order was subsequently increased with the expectation that when the M4 Sherman was available it could replace part of the order. Contracts were arranged with three U.S. companies. The total cost of the order was approximately 240 million US dollars. This equaled the sum of all British funds in the US. It took the Lend-Lease act to solve the United Kingdom's shortfall.

The prototype was completed in March 1941 and production models followed with the first British specification tanks produced in July. Both U.S. and British tanks had thicker armour than first planned. The British design required one fewer crew member than the US version due to the radio in the turret. The U.S. eventually eliminated the full-time radio operator, assigning the task to the driver. After extensive losses in Africa and Greece the British realized that to meet their needs for tanks both the Lee and the Grant types would need to be accepted.

The U.S. military used the "M" (Model) letter to designate nearly all of their equipment. When the British Army received their new M3 medium tanks from the US, confusion immediately set in, as the M3 medium tank and the M3 light tank were identically named. The British army began naming their American tanks, although the U.S. Army never used those terms until after the war. M3 tanks with the cast turret and radio setup received the name "General Grant", while the original M3s were called "General Lee", or more usually just "Grant" and "Lee". The M3 brought much-needed firepower to British forces in the African desert campaign.

The chassis and running gear of the M3 design was adapted by the Canadians for their Ram tank. The hull of the M3 was also used for self-propelled artillery and recovery vehicles.