Improving the river crossing capability of an amphibious vehicle

A study of an Amphibious Armored Personnel Carrier (AAPC) was conducted to enhance its amphibious capability by considering floatability, stability and resistance/propulsion characteristics and its performance during a river crossing operation. Existing data for an Armoured Personnel Carrier including the geometry, weight distribution and speed range were utilized in this study. Initial resistance and flow visualization tests showed that water enters into the driver compartment and that there is a need for a head plate in order to prevent water build-up at the front of the driver's periscope.The river crossing capability of AAPC was examined by utilizing heading angles to simulate the effect of the current of a river. Resistance as well as side force acting on the vehicle were measured and presented through the speed range. The underwater flow visualization tests were carried out in order to investigate the flow around bow and aft of the vehicle, including the propulsion system inlet regions. The selection procedure of the propulsion system is briefly summarized and powering estimates were conducted.

► Most important feature of AAPC concept is the low freeboard, which causes several problems including poor longitudinal and transverse stability as well as low visibility over the driver's periscope.
► It was observed during resistance test that there is need for head plate since the vehicle does not have ship-like bow form.
► When the speed increases in water the height of the head plate should also be increased accordingly.
► Correct propeller design is vital to obtain ceiling propulsive efficiency and minimum power necessity using flow image tests.