Miles per hour
COMMAND AND RECONNAISSANCE VEHICLES
As originally proposed, the three man Lockheed XM800W was a six wheel vehicle weighing 16,972 pounds. Based upon the earlier XM808 Twister, it was a two body vehicle with roll articulation between the two bodies. The front body mounted the two wheel steerable front suspension and it contained the fuel tank, drive line, and front differential.
The driver's station, turret, engine, transmission, drive lines, rear differential, and walking beam suspension with four wheels were installed in the rear body. The lightweight two man turret was armed with the 20mm gun M139. An M60D 7.62mm machine gun was carried on an external mount. The hull was assembled from aluminum alloy armor with dual hardness steel and aluminum applique.
The turret was cast aluminum and dual hardness steel. The vehicle was driven by the 6V53T diesel engine with an aluminum block and it developed 300 horsepower at 2,800 rpm. This was the engine used in the M551 Sheridan. The Allison MT650 transmission had five speeds forward and two in reverse.
The maximum road speed was estimated as 65 miles per hour and the 90 gallon fuel tank provided a cruising range of approximately 450 miles. The Aerojet water-jet propulsion unit was expected to drive the vehicle at a maximum speed of 5 miles per hour in water.
The FMC XM800T also was a three man vehicle with the driver located in the center front hull. It had an estimated weight of 18,188 pounds. The hull and turret were assembled from 5083, 7039, and Kalshield dual hardness aluminum armor. As on the Lockheed vehicle, the two man turret was armed with the M139 20mm gun and an externally mounted M60D 7.62mm machine gun. The XM800T also was powered by the Sheridan engine although it was derated to 285 horsepower to improve reliability.
It drove the vehicle through the Allison X200 transmission with hydrostatic steering. The sprockets were at the rear of the 19 inch wide, double pin, tracks. The torsion bar suspension supported the vehicle on four dual road wheels per side. The estimated performance included a maximum road speed of 52 miles per hour with a cruising range of 450 miles. In water, track propulsion was expected to drive the vehicle at 4.5 miles per hour.
From June through August 1974, the XM800T and the XM800W were compared with and without their turrets against several other vehicles during the force development test and evaluation (FDTE). The other vehicles in the comparison test included the M113A1 armored personnel carrier which was used to provide a baseline, the M113A1 AIFV, the Canadian Lynx, the PI M113A11/2 with the turbocharged engine and the tube-over-bar suspension, a British Scimitar reconnaissance vehicle, a modified M551 Sheridan, an XR-311 Dune Buggy four wheel drive vehicle, and a V-150 armored car.
In comparing the two XM800 vehicles with the baseline M113A1, the test report concluded that the XM800T was superior to both the M113A1 and the XM800W in overall performance as an ARSV. The XM800W performed well on roads and its quiet operation and high road speed were goals to be achieved for future scout vehicles. However, its limited crosscountry capability and safety hazards associated with lateral instability and directional control made it less effective than the M113A1.
As frequently happens during a development program, the final version of the XM800T was heavier and its performance somewhat different from the original estimates. The combat weight had increased to 19,600 pounds decreasing the freeboard to about 8 inches when afloat. The maximum road speed was 55 miles per hour and the maximum water speed was 4.2 miles per hour. The cruising range remained at about 450 miles (U.S. Army).
Despite its successful performance, the ARSV did not go into production. Budget limitations required the cavalry scout vehicle program to be merged with that for the new infantry fighting vehicle. Thus the new scout eventually emerged as the M3 cavalry fighting vehicle.
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