amphibia amphibian amphibious vehicle armor armour battle Camouflage car carrier gun history military Poland PT 76 shield swim tank cannon vehicle war weapon amphibious armored personnel BRDM soviet boat bus course ship street tour tour bus tourist tourists tours transport travel water OT-64 armoured tracked ACV aerodynamic aerodynamics air air-cushion air-cushion-vehicle air-pressure craft cushion drive engines fans flexible flexible-skirt flight friction high-air-pressure hovercraft hull hybrid-vessel impeller inflated inflated-skirt low-frictional-force MTV multi-terrain-vehicle multiple-terrain on-board pilot propel propellers rise sightseeing skirt skirted specialised-transport speed stationary surface surfaces thrust tourism transporting travelling 2S1 army artillery Carnation Gvozdika howitzer machine power self-propelled tank wheel