This material is mainly from research done by the late Michael Rosen of San Leandro, California.
THE AFV ASSOCIATION
In spite of the significance of his contributions, J. Walter Christie probably remains the most obscure and ambiguous figure to be found in the history of the development of tanks.
From the early 1900's until his death in 1944, Christie devoted himself to the construction of armored fighting vehicles in the USA. Underlying and providing continuity to his work during this period was the attempt to design a chassis possessing superior mobility. While such emphasis is open to conflicting opinions, it should be pointed out that Christie was one of the few who had recognized the full implications of the the concept of mechanized warfare. In aiming for cross-country speeds of 30 to 40mph, and tank transport by air, he sought to create a fighting vehicle which was capable of simply devouring great distances.
FUEL RANGE: 35 miles on tracks, 75 miles on wheels.
FUEL CAPACITY: 59 gallons.
SPECIAL FEATURES: Tracks carried above the wheels when driving on wheels. Small pyramidal lugs on inside of plates for driving and guiding tracks. Center bogies raised when running on wheels. About 15 minutes to change from wheels to tracks or vice versa. The M1919 chassis was originally planned for use as either a truck or a tank. Haste in construction resulted in mechanical unreliability, inaccessibility of engine and transmission, and poorly designed tracks. Capable of equal speeds in forward and reverse.
M1921
Rebuilt from the 1919 tank in 1921 by THE FRONT DRIVE MOTOR COMPANY. Total production = 1.
CREW: 4
ARMAMENT: One 6pdr (57mm) gun in front and one cal. 30 MG on each side.
ARMOR: 0.25" to 0.75".
MAXIMUM SPEED: 7 mph on tracks, 14 mph on wheels.
SUSPENSION: Wheels with double rubber tires; front wheels sprung with coil springs, center wheels on pivoted bogies.
TRACKS: Removable, flat steel plates with grousers and driving lugs; 15" wide, pitch 9.75".
GENERAL ARRANGEMENT: Gunners in front; commander and driver in center (driver at left); engine & final drive in rear.
FUEL RANGE: 60 miles on tracks, 100 miles on wheels.
FUEL CAPACITY: 67 gallons.
SPECIAL FEATURES: Drive wheels unsprung; small crew compartment; poor maneuverability; underpowered.
The CHRISTIE M1921 by Robert J. Icks from the Sept/74 AFV News
WWI on the Western Front, except for the first few and last few weeks, consisted of trench warfare and its influence continued for many years afterward. Because of low track life, medium and heavy tanks had travelled as little as possible outside of combat, while light tanks were carried on trucks. The Westerveldt or Caliber Board, recommended the direction that future weapons development whould take, including a recommendation that only a medium tank be developed.
The US Tank Corps in 1919 urged negotiations with Walter J. Christie, whose self-propelled guns represented a different approach, designed to conserve track life. This was done, and the Christie M1919 tank resulted, but it had been hastily built and assembled. It had poor suspension and the engine and transmission were difficult to get at. Changeover from tracks to wheels required 15 minutes. The center wheels were raised when running on roads.
This tank was armed with a 6pdr(57mm) gun in the main turret and one MG in the cupola. It had 1/4" to 1" armor, steel tracks 15" wide, and 9-3/4" pitch. The road wheels were rubber tired and only the center wheels were sprung. After generally unsatisfactory performance, the tank was returned to Christie, who rebuilt it into the M1921. The appearance was changed by eliminating the turret and placing the 6pdr in the nose, and lowering the height to 7'1". Another MG was added and one was placed on either side of the main weapon. The suspension was similar, but the front wheels in this model were sprung with long recoil springs.
At first this tank performed so well that Army TO&E were rearranged on the premise that eventual rearmament with this type of tank would take place. However, manoeuverability was poor, the crew compartment was cramped, and more and more defects appeared. After testing by Ordnance, it was turned over to the Infantry, who dropped it in 1924.
Christie came back with a new vehicle with a more advanced suspension in 1928 and this evolved into the T3 Convertible. The later T4 finally was also dropped. Christie built 15 vehicles between 1916 and 1924 at a cost to the Ordnance Dept. of $739,240 plus $100,000 for all current and future suspension patent rights. When Congress began cutting funds to the military in 1921, there was little money for experimental designs.
Many of Christie's designs were ingenious, but they were mechanically unreliable. In addition there were other factors during this period. A surplus of tanks was left over from WWI, and the National Defense Act of 1920 assigned tanks to the infantry but the War Dept. made no policy statement on tanks until 1922. At that time they were classified as light, medium and heavy, to be few in number and possessed of slow speed so as to accompany infantry under conditions of trench warfare. Ordnance designed a Medium A tank in 1921 and rebuilt it into the M1922 the following year. It was turreted, armed as the Christie M1919 and was rugged and dependable, and had a longer track life. Interest swung to it and away from Christie.
M1928
Produced in 1928 by U.S. WHEEL TRACK LAYER CORPORATION. Total production = 1.
CREW: Undetermined
ARMAMENT: One 37mm gun and one cal. 30 MG in upper turret.
ARMOR: 0.5".
MAXIMUM SPEED: 42.5 mph on tracks, 70 mph on wheels.
SUSPENSION: "Christie Suspension" (individually suspended bogie wheels, each mounted on a coil sprung bell crank).
TRACKS: Forged steel plates with U-shaped driving lugs attached to each alterate plate, 10" wide, pitch 10".
GENERAL ARRANGEMENT: Crew compartment in front; driver in left rear part of crew compartment; engine & final drive in rear.
DIMENSIONS: Length: 17 ft.; Width: 7 ft.; Height: 6 ft.
WEIGHT: 8.6 tons.
ENGINE: Liberty, 12 cylinder, V-type, 338 HP, forced water cooling.
HORSEPOWER Per Ton: 39.3.
TRANSMISSION: Sliding gear, 4 speeds forward, 1 reverse. First equipped with 5 separate gear shift levers; later replaced with standard gear shift.
OBSTACLE ABILITY: Trench 7 ft.; stream 5 ft.; slope 37 degrees; vertical wall 28 in.
FUEL RANGE: 75 miles on tracks, 115 miles on wheels.
FUEL CAPACITY: 35 gallons; 50 gallons on rebuild.
SPECIAL FEATURES: This was the forerunner of the 1931 tank and although lighter in weight was similar as a vehicle to the later tank in all essential features. The U.S. Army wished to buy the chassis but Christie refused to sell since he felt it could be improved upon. Rebuilt, tested and then sold for junk. The "Christie Suspension" developed for the M1928 was employed in the M1931 and all subsequent Christie tanks.
Apart from the independent suspension, Christie also pioneered two other tank suspension features which were generally applicable: large diameter road wheels and rubber tires. Christie's introduction of both was rather fortuitous, for it was essentially a by-product of his aim to design tanks so that they could operate without tracks as well as with them.
M1931
Produced in 1931 by U.S. WHEEL TRACK LAYER CORPORATION Total production = 9.
CREW: 2
ARMAMENT: One 37mm) gun in main turret and cal. 30 MG in one mount (T-3 Medium); and one cal. 50 MG and cal. 30 MG in coaxial mounting (T-1 Combat Car).
ARMOR: 0.25" to 0.625", exclusive of 0.188 inner hull of nickel steel.
MAXIMUM SPEED: 40 mph on tracks, 70 mph on wheels.
SUSPENSION: "Christie Suspension". Four large weight-bearing wheels each side, each with dual runner tires; long vertically placed, adjustable coil springs. The liberal compression amplitude gave each wheel an independent maximum vertical movement of about 14 inches .
TRACKS: Forged steel plates, each alternate plate having a driving lug integral therewith; 10.25" wide, pitch 10". When on wheels the tracks were carried on shelves at the sides of the tank.
GENERAL ARRANGEMENT: Driver in front; gunner in center; engine & final drive in rear.
DIMENSIONS: Length: 17' 10"; Width: 7' 4"; Height: 7' 3". (The height varied slightly with adjustment of suspension springs.)
WEIGHT: 10.5 tons.
ENGINE: Liberty, 12 cylinder, V-type, 338 HP, forced water cooling.
FUEL RANGE: 170 miles on tracks, 250 miles on wheels.
FUEL CAPACITY: 89 gallons.
SPECIAL FEATURES: Five tanks were originally ordered (chain driven) and later two more (gear driven) were acquired after the Polish government, which had contracted for them was turned down by Christie. Starting in September 1931, delivery of these vehicles (minus armor, armament, engine, guns, and radio) was made at a cost of $34,500 per tank. Armor, armament and engine were installed by the Ordnance Department. Two additional chassis of this type were purchased by Russia. Thirty minutes was required to change from tracks to wheels or vice versa.
COMMENT: There has always been a dispute over exactly which chassis eventually went to England for their Cruiser Tank development, and it appears as though it was a 1930 transitional version of the above. It also appears to be the same chassis that the Polish government tried unsuccessfully to buy, and after being impounded for six years by U.S. Customs during the dispute, it was finally released to the British and purchased by Lord Nuffield for their A13 project. The Poles meanwhile had adopted some of the ideas developed by Christie and started work on their own version, the 10TP cruiser tank.
M1932
Produced in 1932 by U.S. WHEEL TRACK LAYER CORPORATION Total production = 1.
CREW: 3
ARMAMENT: Could carry one cannon and one or more machine guns.
ARMOR: 0.375" to 0.5". (Thicker armor could be installed).
MAXIMUM SPEED: 60 mph on tracks, 120 mph on wheels.
SUSPENSION: Similar to 1931 model but with a maximum vertical movement of 24 inches; wheels of duraluminum with Firestone pneumatic tires. The two rear wheels had a slightly greater diameter than the front pairs.
GENERAL ARRANGEMENT: Cannon in front; crew in front center; engine & final drive in rear.
DIMENSIONS: Length: about 22 ft.; Width: about 7 ft; Height: about 5' 8".
WEIGHT: about 5 tons.
ENGINE: Hispano-Suize, 12 cylinder, V-type, 750 HP, forced water cooling.
HORSEPOWER Per Ton: 150.
TRANSMISSION: Sliding gear, 3 speeds forward, 1 reverse. It had a power take-off for the flying propeller. One modification provided for a transfer gear case to propel a helicopter roter above the vehicle for lift purposes.
OBSTACLE ABILITY: Could jump across a 20 foot trench from a 45 degree slope.
FUEL RANGE: unknown.
FUEL CAPACITY: 89 gallons.
SPECIAL FEATURES: Of very light construction throughout for airborne role. Chassis consisted of a double hull which enclosed the suspension springs. The inner hull was made of welded duraluminum plates, and the outer hull of welded steel plates. Rear ground wheels were driven through a knee-armed gear box when the tracks were off.
Originally it had been proposed that the chassis be equipped with a disposable biplane and propeller assembly. Using this arrangement the vehicle would become airborne by taxiing along the ground on its tracks to gain momentum and then transferring power to the propeller. Later plans contemplated carrying the tank by a special aircraft and releasing it close to the ground. In this case dual air-speed indicators would enable the tanks driver, before being dropped, to accelerate his tracks to a speed equaling that of the aircraft. Adaptation of these concepts and designs in the form of permanently installed, high speed track-laying airplane undercarriages would permit the operation of large aircraft from unimproved fields. Erratic and undependable, the M1932 was modified twice and then sold to Russia, who had a keen interest in the flying tanks idea.
M1935/A
Produced in 1935 (?). Total production = 1.
CREW: 2
ARMAMENT: Dummy gun only. Intended to house any gun up to 75mm.
ARMOR: 0.5".
MAXIMUM SPEED: 60 mph on tracks, 90 mph on wheels.
GENERAL ARRANGEMENT: Cannon in front; crew in center; engine & final drive in rear.
DIMENSIONS: Length: about 21 ft.; Width: about 7 ft.; Height: about 5.5 ft.
WEIGHT: Probably 5.5 tons.
ENGINE: Believed to be Hispano-Suisa, 12 cylinder, 750 HP, forced water cooling.
HORSEPOWER Per Ton: (?)
TRANSMISSION: Selective.
FUEL RANGE: (?)
FUEL CAPACITY: (?)
SPECIAL FEATURES: Airborne convertible wheel-track vehicle. Twin cupolas toward the rear of chassis. Rebuilt M1935/A(?).
M1936
Produced in 1936 by THE CHRISTIE CHASSIS, Inc. Total production = 1.
CREW: 2
ARMAMENT: Dummy cannon.
ARMOR: (?)
MAXIMUM SPEED: (?)
SUSPENSION: "Christie Suspension". Coil springs housed in horizontally placed tubes.
TRACKS: High grade forged nickel steel having no bolted parts.
GENERAL ARRANGEMENT: Cannon in front; crew in center; engine & final drive in rear.
DIMENSIONS: Length: 17.5 ft.; Width: 6.5 ft.; Height: 5.5 ft.
WEIGHT: 6 tons.
ENGINE: Curtiss D-12, 300 HP.
HORSEPOWER Per Ton: (?)
TRANSMISSION: Christie synchro-mesh with aluminum case.
OBSTACLE ABILITY: Could jump 15 foot trench.
FUEL RANGE: (?)
FUEL CAPACITY: (?)
SPECIAL FEATURES: An airborne type vehicle capable of being released from moving aircraft. No provision to be driven with tracks removed. Its gear ratio permitted acceleration to 60mph in 100 feet.
M1937
Produced in 1937 by U.S. CONVERTIBLE SYSTEM, Inc. Total production = 1.
CREW: 2
ARMAMENT: None
ARMOR: Maximum 11/16 in.
MAXIMUM SPEED: (?)
SUSPENSION: "Christie Suspension". As on M1936. Maximum vertical movement of 16".
TRACKS: (?)
GENERAL ARRANGEMENT: Crew in center; engine & final drive in rear.
DIMENSIONS: Length: 17.5 ft.; Width: 6.5 ft.; Height: about 5 ft.
WEIGHT: 6 tons.
ENGINE: Curtiss Wright aviation engine, 430 HP.
HORSEPOWER Per Ton: (?)
TRANSMISSION: 3 speeds forward, 1 reverse.
FUEL RANGE: (?)
FUEL CAPACITY: (?)
SPECIAL FEATURES: Airborne type vehicle similar to M1936. Christie took this tank with him when he traveled to England in 1937 to assist Morris Company in designing the Cruiser Tank Mk.III. During a demonstration for Gen. Le Q. Martel at the Aldershot Proving Grounds a speed of 64 mph was achieved over moderately rough ground.
M1938 (T-12)
Produced in 1938 by U.S. CONVERTIBLE SYSTEM, Inc. Total production = 1.
CREW: 2
ARMAMENT: None
ARMOR: Maximum 5/8 in.
MAXIMUM SPEED: 80 mph.
SUSPENSION: Similar to M1936
TRACKS: Forged steel; weight of both tracks and connecting pins only 1600 lbs; pitch 5 in.
GENERAL ARRANGEMENT: Crew in center; engine & final drive in rear.
DIMENSIONS: Length: about 17.5 ft.; Width: 7.5 ft.; Height: about 5 ft.
SPECIAL FEATURES: Airborne type vehicle similar to M1936-37 models. It may have been a rebuilt M1937. Extensive use of aluminum (e.g. transmission box, fuel tanks, etc.) and flexible tube hosing (e.g. fuel and oil feed lines, etc.) permitted operation at extremely high speeds over rough terrain. Improved brake and clutch system. Its high speed and low silhouette suited it for the role of tank destroyer.
M1941 (Bigley GMC)
Produced in 1937 by U.S. CONVERTIBLE SYSTEM, Inc. Total production = 1.
GENERAL ARRANGEMENT: Crew in center; engine & final drive in rear.
DIMENSIONS: Length: about 18 ft.; Width: about 7 ft.; Height: about 5 ft.
WEIGHT: (?)
ENGINE: (?)
HORSEPOWER Per Ton: (?)
TRANSMISSION: (?)
FUEL RANGE: (?)
FUEL CAPACITY: (?)
SPECIAL FEATURES: Rebuilt T-12 (?). Airborne type to be employed as a high speed tank destroyer. Modified and used as a tracked truck for a number of years and then junked. Christie's AFVs, especially the later airborne models, have been criticised on the following grounds:
Calculations based upon the employment of simulated armor in the prototypes produced an overloaded vehicle, and components incapable of standing the additional strain when actual armor and armament were added.
Exclusive employment of dummy armament resulted in ignoring problems which would be raised when installing real guns.
High horsepower-to-weight ratios made for "flash performances" which could not be expected under conditions of actual combat.
A tendency to throw tracks on turns at high speeds and undue wear caused by too great a track pitch.
Inadequate fighting compartment.
M1942
Produced in 1942. Total production = 1.
CREW: Undetermined.
ARMAMENT: Dummy: six machine guns, one small calibre cannon.
ARMOR: (?)
MAXIMUM SPEED: (?)
SUSPENSION: Similar to M1936.
TRACKS: (?)
GENERAL ARRANGEMENT: Cannon and one MG in front, two MGs on either side; engine & final drive in rear.
DIMENSIONS: (?)
WEIGHT: (?)
ENGINE: (?)
HORSEPOWER Per Ton: (?)
TRANSMISSION: (?)
FUEL RANGE: (?)
FUEL CAPACITY: (?)
SPECIAL FEATURES: Mockup on M1941 chassis. A high-speed light tank with no means for release from moving aircraft..
