Dynamic Hydroplaning Type
Dynamic hydroplaning is a relatively high speed that occurs when a film of water on the runway that is at least one tenth inch deep. As the aircraft speed and depth of water increased, the layer of water builds up an increasing resistance to dislocation, resulting in the formation of a wedge of water under the tire.
At a certain speed, called the hydroplaning speed (VP), the upward force generated by water pressure equals the weight of the aircraft and the tire is removed from the surface of the channel. In this condition, the tires no longer contribute to the directional control and braking action is nothing.
Dynamic hydroplaning is related to the inflation pressure of the tire. The data obtained during hydroplaning tests have shown the minimum dynamic hydroplaning speed (VP) of a tire to be 8.6 times the square root of the tire pressure in pounds per square inch (PSI). For an airplane with a head pressure of 24 PSI tire, the calculated hydroplaning speed would be about 42 knots. It is important to note that the rate referenced above is calculated for the beginning of dynamic hydroplaning. Once hydroplaning has begun, may persist to a significantly reduced rate depending on which is experienced.