M24 Chaffee
During much of World War II, the U.S. Army relied on the M3/M5 Stuart series of light tanks for reconnaissance missions. While it was a mechanically reliable vehicle, and fairly fast and maneuverable, the Stuart‘s design dated back to the 1930s, and it was obsolete by late 1942 as its thin armor, high silhouette, and light 45 mm main gun made it a liability to its crew. In 1943, the Army began developing a new light tank to replace the Stuart. The result was the M24 Chaffee, which entered service in late 1944.
Initially production began in April 1944 at Cadillac, then at Massey-Harris in July of 1944. Cadillac and Massey-Harris managed to produce 4,731 tanks, with Cadillac producing 60% or 2,838 vehicles.
Production Data:
Cadillac - 2,838 total, 177 per month; 16 months
Massy-Harris - 1,892 total, 145 per month ; 13 months
M24 Chaffee
The M24 Light Tank :
Dimensions
Length : 16 ft, 6 in
Width : 9 ft, 10 in
Height : 9 ft , 1 in
Crew : 5 (Commander, Driver, Gunner, Loader, Machine Gunner)
The main weapon of the M24 was a 75 millimeter, 50 calibre, M6 tank gun, capable of firing Armor Piercing (AP) and High Explosive (HE) shells. The shells were attached to a 14 inch brass case. The gun could be reloaded in 8 seconds for ready-use ammunition, and 10 seconds for non-ready ammunition.
The ammunition consisted of the 14 lb M72 AP, the 22 lb M61 APCBC, the 15 lb M48 HE, and the M64 smoke.
Ballistics (M6 Cannon, L/50)
M72 AP - Top Speed : 620 m/s Armor Penetration : 90 mm (3")
M61 APCBC - Top Speed : 650 m/s Armor Penetration : 135 mm (4.5")
M48 HE - Top Speed : 460 m/s The M48 HE shell stored 1.5 pounds of TNP explosive. (Trinitrophenol)
M45 APCR - Top Speed : 900 m/s The M45 APCR Shell used a 45 mm Tungsten Carbide core to penetrate armor. Armor Penetration : 165 mm (5.5")
Ballistics (IMI-77, L/70)
M-300 APDS-FS - Length : 330 mm (11 inches) Width : 36 mm (1.2 inches) Top Speed : 1,620 m/s used a 36 mm Tungsten Nickel Chromate core to penetrate armor. Armor Penetration : 300 mm (10 inches)
The M48 HE Shell measured 13 inches long.
The M61 APCBC Shell measured 13 inches long.
The M72 AP Shell measured 11 inches long.
The M45 APCR Shell measured 10 inches long.
The secondary armory was composed of 2 7.5 millimeter light machine guns and a single 15 millimeter heavy machine gun. These were suited for engaging infantry dugouts, bunkers, trenches, and machine gun nests. One was mounted in the front glacis, while the other one was mounted in the turret, to the left of the main gun. In the case of the M2, It was mounted on the right side of the turret roof, behind the loader's hatch. (This meant the loader or commander would have to climb out of the turret and stand on the engine deck to operate the machine gun.)
Powerplant : Cadillac 346
The powerplant of the M24 tank was two Cadillac 346, V shaped engines. The 346 was an 8 cylinder, 4 stroke, gasoline powered engine of 5.7 liters, developing 110 hp @ 1,600 RPM. (The M24 used two of them, giving a displacement of 11.4 L in total, and 220 horsepower at 3,200 RPM.) the firing order for each engine was 1-8-7-3-6-5-4-2.
Final Drive
8 speed, Manual Transmission with 13 tooth drive sprockets
6 Speeds Forward, 2 Reverse
1st gear : 9.3 km/h
2nd gear : 18.6 km/h
3rd gear : 28 km/h
4th gear : 37 km/h
5th gear : 46 km/h
6th gear : 58 km/h
Reverse
Gear 1 : 18.6 km/h
Gear 2 :24.0 km/h
11 hp/t
Suspension:
Torsion Bar
The Suspension was improved over the M3 Stuarts; most notably in using Torsion Bars. The suspension consists of 10 torsion bars, with 5 per side, each housing a pair of road wheels. It also used 3 sets of return rollers mounted above the road wheels per side to support the tracks. Shock absorbers were installed on the 1st, 2nd, 4th, and 5th road wheels pairs per side. Each road wheel pair had coiled spring bump stops to limit travel on the road wheel arms.
Tracks :
The M24 used the T72 16" steel track. it measures 16 feet long to support the 20 ton light tank. Each track had 75 links. It also used a variant called T185. T185 was 16.5", providing better weight displacement.
Weight : 11 psi (T72 Track)
Weight : 10.8 psi (T185 Track)
Ammunition stowage
The M24 Light tank carried 48 rounds of ammunition; all of which were located on the floor of the hull under the turret in 6 stowage bins, storing 8 rounds. A driveshaft ran from the engine in the rear to the transmission in the front, forcing the ammunition bins to be placed on the left and right sides of the shaft, with 3 bins per side.
The turret of the M24 Chaffee measured 60 inches in width and length, giving an internal displacement of 3,600 square inches. The Gunner and Commander sat on the left side, each having 900 square inches. The loader, who sat to the right, had 1,800 square inches. The Gunner, Commander and Loader sat on adjustable seats attached to a pedestal; The Commander and Gunner's attached to the turret basket floor; the Loaders attached to the turret side. The Gunner was stationed in the front left of the turret, with the Commander above and behind him. To his direct front was the telescopic gunsight; to his 10 o'clock was the geared traverse control; to his 12 o'clock foward of his stomach was the grip for the hydraulic drive. control. To his 1 o'clock, below the hydraulic drive was the geared elevation drive.
The powered traverse system consisted of an electric motor driving a hydraulic gear system that was controlled through a spade shaped grip located to front of the gunner's stomach. It was very simple to operate; the gunner turned the grip to the direction of engagement dictated by the Commander. A left hand turn would traverse the turret left and a right hand turn would traverse the turret right. The hydraulic system could allow for various turret speeds based on the position of the grip.
The speeds ranged from 10 d/s to 20 d/s, meaning the turret would take between 36 - 18 seconds to traverse a full 360 degrees. If the gunner so desired, a manual backup was available; this was signifcantly reduced the turret's speed to 5 d/s.
The gun could elevate or depress at 2 d/s, elevating to 15 degrees in 7.5 s and depressing to 10 degrees in 5 seconds. It would take 12.5 seconds to switch from elevation to depression and vice versa.
The tank uses an open, partial turret basket; this means that the Commander and Gunner have a rotatable floor to rest their feet upon. The loader can either stand on the ammunition bins or sit on his seat. If he is standing on the ammunition bins, he must keep an eye out for the turret floor; if he isn't watching, the turret floor will come around and break his ankle.
Rangefinding
The gunner's main sight was the M71 telescope. This was coaxially mounted, with magnification of 5 times and 13 degrees field of view.
Fuel capacity
110 U.S. gallons (2 fuel tanks were in the engine compartment; the left tank was next to the left engine and the right tank was next to the right engine. Either tank could supply either engine with fuel. Each fuel tank stored 55 gallons.
Driver's section
The driver was stationed in the front left of the hull; to his 12 o' clock was the instrument panel. To his 5 o' clock is the master power switch. this provides main electrical power from the 3 24 volt batteries to run the electrical systems. His instrument panel from left to right reads as follows. The top left is the panel light switch; next to the panel light switch is the Left engine temperature gauge. Below the Left engine temperature gauge is the Left engine Tachometer. Next to the left engine tachometer is the Ammetre gauge. Above the Ammetre gauge is the speedometer. next to the speedometer is the right engine temperature gauge; below the right engine temperature gauge is the right engine tachometer. In the bottom right corner is the ignition switch for the left and right engines. Above the ignition switch is the starter.
To steer the tank, the driver will pull back on the (brake) steering levers on either side of him. The left brake works the left track; the right works the right track. To engage the parking brake, both levers must be pulled back to a 2 o' clock position; then press down the plunger button on the top of the handle. Depending on how far back he pulled the handle would determine how much brake he applied to the track, and therefore increase or decrease the turning radius.
In the middle between the Driver and Machine gunner positions was the fuel tank selector switch. On the floor under the instrument panel was two pedals. The left one was the clutch; the right was the throttle.
Operational range
110 mi (177 km)
Maximum speed 36 mph (58 km/h) on road, 18 mph (29 km/h) offroad
Featured a commander's override control. could allow commander to traverse the turret in case the gunner was incapacitated.
Variants
M24A1 - This was a 1980 modernization of the existing M24. The Cadillac 346 was removed and replaced with a 5.2 L, Detroit Diesel 6V-53ST. It was a 6 cylinder, twin turbocharged, diesel engine. Produced 460 hp @ 2,600 RPM. the firing order was 1,6,3,4,5,2.A brand new 70 calibre, IMI 77, 60 mm gun was used. Could fire APDS-FS.
Armor
M24 (Chaffee) - Lower Glacis : 60 mm. Upper Glacis : 84 mm. Side/Rear : 30 mm. Turret Face : 60 mm. Side/Rear : 45 mm. Roof : 30 mm.
M24A1 (Super Chaffee- Lower Glacis : 68 mm. Upper Glacis : 84 mm. Side/Rear : 30 mm. Turret Face : 60 mm. Side/Rear : 45 mm. Roof : 30 mm.