All company missions begin from a standard low orbit drop using the UD-4L 'CHEYENNE' Utility Dropship and M577 Armored Personnel Carrier
UD-4L 'CHEYENNE' UTILITY DROPSHIP
he UD-4 'Cheyenne' is a versatile Dropship and tactical transport employed in a primary role in the Corps. Derived from an original Department of Defense requirement formulated at the end of the Tientsin conflict for a multi-role light aerospace shuttle capable of lifting heavy payloads up to 16,000 kg, the UD-4 has evolved into the definitive Dropship design, influencing the shape of many derivatives and successors.
The Cheyenne's unique flexibility comes from its ability to lift itself into orbit under its own power from unprepared landing sites with the aid of its vertical take-off (VTOL) capability. In addition to carrying its large payload, the Cheyenne can operate in the close-support gunship role by deploying weapons pods and hardpoints for rockets and missiles, as well as using its own internal gun.
M577 ARMORED PERSONNEL CARRIER
The M577 evolved from the Marine 70 battlefield development strategy, which proposed a requirement for a low cost lightweight APC capable of being transported into combat aboard a Dropship. Designed as a multi-role vehicle within a lightly-equipped rapid-reaction force, the M577 is a mobile and well armed. However, the rigid design restrictions and compromises imposed by the need to be drop-transportable have resulted in a lighter, less capable vehicle than other APC's currently in service.
Because the vehicle weight had to be kept below 15,000 kg, the M577's components were designed to be a lightweight and sturdy as possible. The chassis chosen for the prototype was based on that of the M570 family of wheeled vehicles which, in the late sixties, was being developed for use in a variety of roles, mainly as a prime mover and mortar platform. The APC is built around a 4 x 4 wheeled layout, powered by a 286 kW multi-fuel gas turbine engine which generates a power to weight ratio in the region of 19.7 kW/Kn. Although the wheeled configuration foes not give as rugged a cross country performance as a tracked vehicle, it does offer considerable savings in terms of weight penalties and reliability. Each of the massive 159cm diameter wheels receives power independently form the engine via a fully automatic, electronically-controlled transmission system. The tires are armored against small-arms and splinter, and their pressure is controlled by a central regulation system. This allows the driver to reduce the vehicle ground pressure over soft terrain by deflating the tires, whilst still being able to reinflate them of road travel.
The M577's chassis is made of bonded titanium and incorporates a 5 cm foam-packed floor cavity to protect against forged-fragment mines. Ground clearance is normally only 22cm, but the vehicle employs a hydro-pneumatic, fully active suspension to allow a clean ride over rough terrain. The suspension is capable of boosting ground clearance by a full 30 cm and allows the M577 to comfortably tackle vertical obstacles up to 0.5m. The hull is made from welded light alloys and is latched and bonded (rather than welded) to the chassis in order to prevent fatigue and failure form the piezo-electric effects associated with an alloy-titanium interface. The inside of the hull is lined with boron carbide ceramic ties, each of which has been coated with a polymer resin to prevent cracks or shattering during normal travel; this resin is 2mm thick on the outward-facing surface of the tile and is said to provide limited ablative protection against pulsed lasers. The tiles are backed with a thick layer of woven fore resistant polymer armor to limit spalling in the event of a hull penetration. Because of weight restrictions, the armor protection is very light. It is capable of defeating fragmentation, small arm rounds and low-velocity armor penetrating ammunition such as rifle grenades; however, its ability to stop dedicated tank-killing weaponry is slight.
