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Light Armored Cars
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Design, Development, Engineering and Production Of Armored Cars (1940-1944) |
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This edition, edited, annotated and illustrated by David R. Haugh |
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A series of 37mm gun motor carriages had been developed during 1941-42 to provide light, self-propelled mounts for 37mm anti-tank weapons. Developments showed that a much heavier weapon than the 37mm gun was needed for anti-tank purposes. With the termination of the program for medium and heavy armored cars, these 37mm gun motor carriages were transferred from anti-tank to reconnaissance vehicles.
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From the experimental models tested, the light armored cars T21, T22, T22E1, T22E2, T23, and T23E1; the T22E2 was standardized as the Army’s present reconnaissance vehicle, the light armored car M8.
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These vehicles will be considered in the order given above.
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The light armored car T21 was previously classified as the 37mm gun motor carriage T43, the designation being changed in March 1942. Development of the 37mm gun motor carriages T22 and T23 had been begun in October 1941 and pilot models were being built by Ford Motor Company and the Fargo Division of the Chrysler Corporation. The Studebaker Corporation desired to build a vehicle in accordance with the characteristics set up for the T22 and T23 and agreed to furnish a pilot model at no cost to the Government.
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The vehicle was a 6x4 car weighing 17,200 pounds (7809kgs) with load. It was armed with a 37mm gun and a caliber .30 machine gun mounted coaxially in a turret with a traverse of 360 degrees and an elevation of minus 12 degrees to plus 25 degrees. Frontal armor was .875 inch (22.3mm), side, top, and rear armor was .375 inch (9.5mm) and turret armor was from .875 to 1.125 inches (22.3 to 28.6mm). The car was powered by a Hercules 6-cylinder engine of 112 horsepower, and carried a crew of four men.
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The report of the Special Armored Vehicle Board stated that this car was satisfactory as an armored reconnaissance vehicle but had defects of design and was not, in December of 1942, ready for production. The using arms were accepting the armored car M8 and had no use for a vehicle of almost the same characteristics. The report of the Board noted that a good feature of the car was the suspension. All six wheels were individually suspended, using the parallelogram type suspension, with longitudinal torsion bars. No further development was recommended, and the project was ended.
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The development of light armored cars T22, T22E1, T23, and T23E1 began in October 1941 in accordance with requirements of the General Staff. The requirement was a 37mm self-propelled mount, to be a light, highly mobile, fast, lightly armored, cross-country vehicle with a low silhouette and capable of mass production at a minimum of cost.
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The military characteristics of this proposed “tank destroyer” were outlined in a memorandum from G-3 to G-4 of 30 July 1941 forwarded to the Chief of Ordnance on 5 August. The vehicle was to weigh about 10,000 pounds (4540kgs), be about 176 inches (4470mm) long, 72 inches (1829mm) high, and 82 inches (2083mm) wide and be designed to carry a crew of four men.
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It was to be protected, turret and front, against caliber .50 A.P. ammunition [A.P. = Armor Piercing] at 250 yards (228.5m) and on the sides against caliber .30 ammunition at 100 years (91.4m). No top or bottom armor was contemplated. The armament was to be one 37mm gun, in a combination mount with a caliber .30 machine gun in a 360 degree traverse turret, the elevation of the gun to be from minus 10 degrees to plus 20 degrees. Additional armament was to be one caliber .30 machine gun in a bow mount, and four caliber .45 submachine guns.
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The power plant was to be designed to give a sustained speed of 15 miles an hour (24.2km/h) on a 10 percent grade, with a speed of 55 miles an hour (88.5km/h) on paved roads and a cross-country speed of 35 miles an hour (56.3km/h). The car was to be able to cross a vertical obstacle 12 inches (304.8mm) high, and to be able to ford water to 24 inches (609.6mm) deep. The ground clearance was to be 12 inches (304.8mm). The car was to drive on six wheels and steer on four, and to have radio installation.
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It was considered desirable that the basic vehicle be adaptable for use also as a mobile mount for ground machine guns in dual or quadruple mount, for caliber .50 machine guns, for dual 20mm anti-aircraft cannon, for the 81mm mortar, or for use as a cargo carrier for battlefield ammunition supply.
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The construction of two pilot models by two different manufacturers was approved. These models were designated the 37mm Gun Motor Carriages, T22 and T23. Leading automotive companies were asked to submit designs based on the above requirement, and from the designs submitted, the Ford Motor Company was selected to build the 37mm gun motor carriage T22, and the Fargo Division of Chrysler Corporation was selected to build the 37mm gun motor carriage T23. Contracts were let in November 1941.
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To speed the development process, and to determine the comparative merits of the four-wheeled and six-wheeled vehicle, it was decided to build four-wheeled versions of the T22 and T23, to be designated the T22E1 and T23E1 respectively, and also to build two pilot models each of the four vehicles.
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Decisions were reached early in 1942 that antitank self-propelled mounts demanded greater firepower than that furnished by the 37mm gun. Since the tables of organization of the tank destroyer battalions included requirements for several types of light armored cars, and since the Cavalry also had such a requirement, it was recommended and approved in March 1942 that the designation of these vehicles be changed to “light armored cars”. On 21 April 1942, in view of the contemplated standardization of the T22 model, the development projects on the remaining three models were canceled. Since two models of each type were nearly completed, it was directed that they be completed for use as proof facilities. |
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The pilot models had been completed in March 1942. The T22 built by the Ford Motor Company was a 6x6 vehicle having a tank-type hull but no frame, a Hercules JXD 110-horsepower engine in the rear, conventional leaf-spring suspension, conventional split type Timken axles, Warner Gear 4-speed transmission, and a 2-speed transfer case. The T22E1 was a 4x4 vehicle of similar construction. [A design study, no pilots of the four-wheeled T22E1 were actually built].
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The T23 built by the Chrysler Corporation was a 6x6 vehicle with a conventional truck-type frame covered by an armored body, a Dodge 105 horsepower engine in the rear, conventional leaf-spring suspension, conventional banjo-type axles, Clark 5-speed transmission, and New Process 2-speed transfer case. The T23E1 was a 4x4 vehicle of similar construction. [A 4x4 vehicle based on a truck type chassis, no pilot T23E1s were completed].
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After completion of tests at Aberdeen Proving Ground the light armored car T22 was driven to Fort Knox, Kentucky for test by the Armored Force Board. Several major redesigns were made, including redesign of the hull around the driver’s compartment hatches, the addition of an armored sponson on each side of the hull between the front and intermediate wheels to provide space for two large radio sets, the addition of sand shields, and refinements in the gun mount, traversing mechanism, and turret roller design. The redesigned vehicle was redesignated Light Armored Car, T22E2.
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The vehicles as redesigned were found acceptable as a reconnaissance vehicle for the Cavalry, Armored Force, and the Tank Destroyer Command, and was standardized at the Light Armored Car M8 in June 1942.
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Tests of the original pilot T22 at General Motors Proving Ground showed that the transmission and transfer case gears required strengthening, the front axle required strengthening, a vacuum booster was required for the brake system, and improvements were needed in the engine cooling system.
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Further changes made as the result of tests of pilot and early production models are here summarized. The gasoline tank was changed to the bullet-sealing type. The armor plate with periscopes for commander and gunner, covering the front half of the turret top was eliminated. Before the beginning of production, and as a result of the recommendations of the Special Armored Vehicle Board, the traversing mechanism was redesigned to include two speed ratios; bullet-splash protection was improved; an interphone system was added; and a change was made from hand-firing of the turret guns to foot-firing. The front spring was strengthened. An armor floor plate of .25-inch (6.35mm) thickness was designed for the driver’s compartment for protection against antitank mines. A folding pedestal type caliber .50 machine gun mount was installed on the turret for antiaircraft protection.
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The Ford Motor Company was selected to build the light armored car M8 at their Chicago and Kansas City branches. With cancellation of the armored car T17, the program intended for the Kansas City factory was transferred to the St. Paul facility.
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A production of 5,000 vehicles was planned; a total later raised to cover 6,000 vehicles. A production order was issued 1 May 1942 for that number of cars. A second production order covering 5,070 additional vehicles was issued 17 July 1942. This quantity was later reduced to 2,460 vehicles, making a total of 8,460 vehicles under firm procurement.
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Delay in acceptance of contract by Ford Motor Company, since the terms prohibited the inclusion of any sum for rehabilitation at the end of contract, and consequent delay in placing orders for machine tools, tooling, and components resulted in no production of vehicles in 1942.
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The Miller Printing Company of Pittsburgh, Pennsylvania was set up to manufacture 37mm mounts. Warner Gear Division of Borg Warner was chosen to provide transmissions and transfer cases. This facility had been expanded under the armored car T17 project and this expansion provided capacity for the M8 program as well. Engines were had from the Hercules Motor Company, Canton, Ohio. |
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Production began in March 1943, and peak production of 1,000 vehicles per month was reached in November 1943, with a total of 4,229 vehicles accepted during 1943.
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The production rate for 1944 was set at approximately 560 cars per month to provide a total production of 6,672 vehicles in that calendar year. By the Army Supply Program of 1 February 1944, the total authorization for 1944 was reduced to 3,383 cars, with a total authorization for 1945 of 2,401 cars. Procurement was adjusted to the new requirement. Spare parts canceled by readjustment were picked up by requisition from Stock Control Division to apply on all-time buy.
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Letter-Purchase Order W374-ORD-1744, Supplement No. 1, covering $15,000,000.00 was accepted by Ford Motor Company on 23 July 1942. Supplement No. 2, covering $4,500,000.00 on Letter-Purchase Order for 5,070 additional vehicles was accepted 27 July 1942.
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By Amendment No. 1 to Production Order T-3809 of 29 September 1942, covering production of 6,000 vehicles, additional funds of $126,480,000.00 were authorized for finalization of contract. The estimated cost per vehicle was $18,000.00 plus a fixed fee of $1,080.00 per vehicle [This amount did not include the costs of weapons and radios]; this to be renegotiated after 3,000 cars had been accepted.
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On reduction of Production Order T-4175 by amendment No. 1 to 2,460 vehicles, funds were allotted for completion of the contract. The armored utility car M20 was developed from the light armored car M8 as a companion vehicle. The Tank Destroyer Command recommended that, for use of the M8 as a command car, the 37mm gun mount be removed and a caliber .50 machine gun be mounted in a ring mount on top of the turret, and that the turret and top plate of the be removed and the interior be rearranged. For use of the basic M8 as personnel, ammunition, and cargo carrier, the same changes were recommended. For use as an antiaircraft vehicle, it was recommended that a Maxson multiple machine gun turret be used, employing the original turret ring with a special Maxson type turret mount.
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Recommendation was made that pilot models of each of these variations from the original vehicle be constructed, and that the antiaircraft vehicle be designated Multiple Gun Motor Carriage, T69, that the command vehicle be designated Armored Command Car, T26 and that the personnel and cargo vehicle be designated Personnel-Cargo Carrier, T20. |
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It was later found possible to meet the requirements indicated for personnel carrier T20 and armored car T26 in one vehicle and the designation of this design, fulfilling both needs, was changed to Armored Utility Car T26. This was standardized in May 1943 as Armored Utility Car M10. To avoid confusion with the 3-inch gun motor carriage M10 the designation of this car was then changed to Armored Utility Car M20.
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The chassis, running gear, and lower hull of the armored utility car M20 were identical with those of the light armored car M8. The turret on the upper hull of the M8 was removed and the sidewalls extended upward about 15 inches (381mm) to form a rectangular crew compartment. Above the crew compartment was mounted the Caliber .50 Ring Mount, M49. Provision was made for carrying a crew of from five to seven men. Crew compartment seats and a bulkhead between driving and crew compartment may be removed, providing space to carry about 3,000 pounds (1362kgs) of cargo.
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All improvements found needed on the M8 were incorporated simultaneously on the M10/20. Production of the armored utility car, M20 was begun in July 1943 at the Chicago branch of the Ford Motor Company.
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The Army Supply Program of 1 August 1943 revised requirements for this vehicle from 4,000 in 1943 to 3505, and from 2,622 in 1944 to 567. Procurement was adjusted in accordance with these changes. A total of 1,624 cars were accepted in 1943 the difference between this quantity and the requirements being carried forward and added to the requirements for 1944.
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Production for 1944 was scheduled at about 215 vehicles per month. The Army Supply Program of 1 February 1944 reduced the total requirement for that year to 766 vehicles, and authorized procurement of 785 vehicles in 1945. Procurement was again adjusted in accordance.
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A change in the Army Supply Program of 18 July 1944 increased the procurement authorized for 1944 from 766 vehicles to 1337, and increased the procurement authorized for 1945 from 785 vehicles to 806. Remarks were made, and procurement was once again adjusted to conform to these requirements.
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The project for this vehicle [the M20] is still in existence early in 1946 and present schedules are being maintained. |
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The Multiple Gun Motor Carriage T69 was developed at the request of the Tank Destroyer Command, using the chassis of the Light Armored Car M8.
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Engineering studies made by the Ordnance Department indicated the possibility of mounting four caliber .50 machine guns in a power operated turret capable of 360 degree traverse and elevations from minus ten degrees to plus 85 degrees. The power control mechanism used in the M45 mount, in production, was found to be adequate for the proposed turret. In November 1942 the W.L. Maxson Corporation, of New York City, began design and construction of a pilot caliber .50 machine gun turret. A modified armored car M8 chassis, with the electrical system changed from 12 to 24 volts, and with the addition of an auxiliary motor-generator capable of supplying 50 amperes at 24 volts, was furnished by the Ford Motor Company for incorporation of the new turret.
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By direction of Army Ground Forces, responsibility for service testing of the pilot T69 was placed with the Antiaircraft Command rather than with the Tank Destroyer Command.
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The pilot T69 was tested at Aberdeen Proving Ground and was returned to the W.L. Maxson Corporation for incorporation of new power feed assist for feeding the two outboard guns, improved disposition of empty cases, strengthening of the sight mounting, and improving the gunner's seat.
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With modifications, the T69 was returned to Aberdeen Proving Ground for additional firing tests, and was tested by the Antiaircraft Artillery Board at Camp Davis, North Carolina, in comparison with the standard multiple gun motor carriage M16. The report of this Board indicated that the T69 was inferior to the M16 in weight-carrying capacity, mobility, space provisions, centering of fire of the mount, and effectiveness of fire.
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The Office, Chief of Ordnance-Detroit believes, however, that the T69 is superior to the M16 in its greater armor protection for the crew, vehicle, and components, in reduction of crew personnel from five to three men, and the fact that the T69 has a manual control which could permit effective fire against ground targets. Further advantages are ability to engage enemy aircraft with at least two guns firing continuously for a longer time, and greater flexibility of electric power available for operation of the turret by provision of a generator on the vehicle engine in supplement of the auxiliary generator unit.
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The Antiaircraft Artillery Board recommended no further consideration of the T69 and the project was closed. |
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There are several US vehicles that were either produced or under consideration that were missed in the original history. Below are photos and a brief description of some of those vehicles.
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Copyright: David Haugh - August 2006 |
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