reducing dependence on bridges. They use their tracks, sometimes with added propeller or water jets for propulsion. As long as the banks have a shallow enough slopes to enter or leave the water they can cross rivers and water obstacles. Some heavy tanks can operate amphibiously with a fabric skirt to add buoyancy. The Sherman DD tank used in the Normandy landings had this setup. When in water the waterproof float screen was raised and propellers deployed. Some modern vehicles use a similar skirt. Airborne vehicles Lightweight armoured fighting vehicles designed or modified to be carried by aircraft and delivered by air drop, helicopter lift, glider, or air landing with infantry to provide heavier tactical firepower and mobility. The air-equivalent to amphibious vehicles, the main advantage of airborne forces is their ability to be deployed into combat zones without land passage, as long as the airspace is accessible. Airborne vehicles are limited only by the tonnage capacity of their transport aircraft. Airborne vehicles typically lack the armour and supplies necessary for prolonged combat, so they are utilized for establishing an airhead to bring in larger forces before carrying out other combat objectives. One modern example is the German Wiesel AWC. The USA also created the M22 Locust as a way to aid paratroopers/ being paradropped in as it was very lightly armored and very small. Armoured engineering vehicle Modern engineering AFV's utilize chassis based on main battle tank platforms: these vehicles are as well armoured and protected as tanks, designed to keep up with tanks, breach obstacles to help tanks get to wherever it needs to be, perform utility functions necessary to expedite mission objectives of tanks, and to conduct other earth-moving and engineering work on the battlefield. These vehicles go by different names depending upon the country of use or manufacture. In the United States the term "combat engineer vehicle (CEV)" is used, in the United Kingdom the term "Armoured Vehicle Royal Engineers (AVRE)" is used, while in Canada and other commonwealth nations the term "armoured engineer vehicle (AEV)" is used. There is no set template for what such a vehicle will look like, yet likely features include a large dozer blade or mine ploughs, a large calibre demolition cannon, augers, winches, excavator arms and cranes, or lifting booms. Although the term "armoured engineer vehicle" is used specifically to describe these multi-purpose tank-based engineering vehicles, that term is also