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An XR311 with six-tube recoilless rifle cluster
Manufacturer FMC Technologies/Chrysler
Production Limited Production (at least one pre-production batch)
Body and chassis
Class Attack Vehicle
Related Humvee
Engine 5.2L (318 ci) LA, 190 hp
Transmission 3-speed Chrysler Torqueflite A727 automatic
Wheelbase 3,070 mm (121 in)
Length 4,340 mm (171 in)
Width 1,930 mm (76 in)
Height 1,600 mm (63 in)
Successor None

The XR311 was a prototype military vehicle of US origin that was procured in limited numbers. It had the nickname G.I. Hotrod.


Development of the XR311 commenced as a private venture in 1969 with the first of two prototypes being completed in 1970. As a result of the trials of these 2 prototypes the US Army purchased 10 improved or second generation models in 1971. Of these 10 vehicles, 4 had TOW missile installation for use in the anti-tank role, 3 had an M2HB machine-gun for use in the reconnaissance role and 3 had 7.62mm M60 machine guns and the crew armor kit for use in the escort/security role. These trials were completed in 1972. They were then tested by the 2nd Armored Division. In 1974 they were also tested in the 2nd Armored Reconnaissance Scout Vehicle competition along with a number of vehicles including the original FMC Technologies and Lockheed Martin[citation needed] designs. It has been stated[by whom?] that an XR311 with TOW missile installation costs around $50,000. The XR311 has been designed to carry out a wide variety of roles including anti-tank, recce, convoy escort, command and control, medivac, military police, mortar carrier, internal security and forward air defense communications vehicle.


Detail of the six-tube recoilless rifle cluster

There are 2 models of the XR311:

  1. A recoilless 106 mm rifle mounted above the crew compartment and a total of six rounds of ammunition,
  2. TOW installation with a total of 10 TOW missiles

Reconnaissance: Fitted with a ring-mounted .50cal M2HB machine guns with a 360 degree traverse

Convoy Escort/ Security Vehicle: This can be provided with a pintle-mount 5.56mm/7.62 mmCal GPMG's, XM174 automatic grenade launchers and various other similar weapons. These weapons can also be mounted on the reconnaissance model on the ring mount.

The following kits are available for the basic vehicle: Crew compartment armor kit, consisting of a high-hardness steel doors, side body panels, toe panel, firewall, bulletproof windshield and bulletproof side windows. Armored radiator, Armored fuel tank, Top and door kit (waterproof fabric with plastic windows and hinged doors) Various communications installations, High output alternators, 100 and 180 Amp, Litter-carrying kit, Jump seat for two additional passengers, Explosion resistant reticulated foam fuel-tank filler, Radial ply tires or bulletproof foam-filled tires, Extreme climate kits for winterization or desert temperatures, Tool kit and portable fire extinguisher.


The XR311 is built around a tubular-steel frame safety roll-cage which protects the passenger compartment if the vehicle turns over. This cage is covered by a heavy-gauge sheet metal. An electrical winch with a capacity of 5,000 kg (11,023 lb) can be mounted at the front of the vehicle if required, and the windshield can be removed. The passenger compartment is in the center of the vehicle with the driver on the left and two passenger seats to his right. There is space for 0.93 cubic metres (33 cu ft) of cargo behind the passenger seats. The engine and transmission are at the rear of the hull and there is a load-carrying space above this which can take a maximum load of 386 kg (851 lb). A full length skid pan protects the hull and allows the vehicle to slide over obstacles. The transmission is a Chrysler A-727 fully automatic with a torque converter, there are 3F and 1R gears - the XR311 is in 4 x 4 drive all the time. Limited-slip clutches, in front and rear, and inter-axle differentials automatically distribute more torque to those wheels with the most grip. The independent suspension is of a double 'A' design with a torsion-bar spring and hydraulic telescopic shock absorber at each station. A stabilizer bar is provided for the rear suspension.

The steering is power-assisted and the tubeless tires have a high-pressure tube inner tire which provides a built-in spare for each tube as well as eliminating rim leaks during high speed cornering. The tires are self-cleaning and disc brakes are fitted on all four wheels. The electrical system is 24V DC and two batteries with a capacity of 45 Amp/Hr are provided. The alternator is of the integral rectifier and regulator type. The XR311 is provided with a heavy duty towing pintle as well as a trailer wiring harness receptacle. It is air-transportable and can be air-dropped.

See also[edit]