Accession Number : ADA018563

Title :   Hull Modifications of Air-Sea Craft to Reduce Motions at Zero Speed in a Seaway.

Descriptive Note : Final rept.,


Personal Author(s) : Mercier,John A.

Report Date : OCT 1974

Pagination or Media Count : 46

Abstract : Methods for reducing the motions response of floating air/sea craft in waves will enhance their effectiveness for certain kinds of missions, such as rescue or surveillance operations. Great improvements can be accomplished with relatively small craft by lifting them above the ocean's surface on vertical flotation elements, but such systems entail complex design, installation and operational features and some weight and space penalty. This research considered alternative, simpler, modifications to air/sea craft to improve the sea-keeping behavior. The relatively minor changes to hull shape and/or weight distribution which can reasonably be made and still satisfy aerodynamic and take-off and landing performance requirements do not produce significant modifications. Various appendages connected to a typical air/sea craft hull, such as flat plates extended below the hull's underbody, were found to reduce significant pitch motions in typical irregular waves to about 40% of the motions for the basic craft: vertical floats supports might reduce motions to as little as 10% in similar waves. Heave motions are nearly the same for the three alternative systems in these waves. An alternative inflatable, water-filled appendage is proposed which is capable of substantially attenuating wave-induced forces and motions. (Author)

Descriptors :   *Flying boats, *Flying boat hulls, Modification, Ocean waves, Motion, Reduction, Floats, Vertical orientation, Takeoff, Aircraft landings, Heaving, Inflatable structures, Water, Bags, Force(Mechanics), Missions, Sea rescues, Ocean surveillance, Pitch(Motion), Plates, Attachment, Weight, Distribution, Space environments, Trade off analyses, Flaps(Control surfaces), Feasibility studies, Stabilization

Subject Categories : Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE