Data Analysis of Bag/Cushion Heave Forces and Pitch Moments Acting on a 10-Ton SEV While Crossing Isolated Obstacles

• Main Authors: Shank, Jr , Samuel R, Hubbard, James E
• Other Authors: DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER ANNAPOLIS MD PROPULSION AND AUXILIARY SYSTEMS DEPT
• Format: Text
• Language: English
• Published: 1974
• Subjects: Surface Effect Vehicles & Amphibious Vehicles; *SURFACE EFFECT VEHICLES; ACCELERATION; AERODYNAMIC CHARACTERISTICS; ARCTIC REGIONS; BARRIERS; COMPUTATIONS; FLIGHT PATHS; FORCE(MECHANICS); HEAVING; IMPACT; INTENSITY; MOMENTS; PITCH(MOTION); PRESSURE; SLAMMING; VENTING; *SK-5 VEHICLES; BAG EFFECTS; Arctic
• Online Access: http://www.dtic.mil/docs/citations/ADB000524; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADB000524

A method for evaluating the magnitude of the bag effects on the vehicle dynamics of a surface effect vehicle has been developed. The method involves the calculation of bag heave forces and pitch moments from vehicle acceleration and cushion pressure data. The method is applied to an SK-5 crossing discrete obstacles having obstacle height to cushion height ratios of 0.5 and 1.0. For the cases examined, bag effects (as compared to cushion effects) are important in heave but not in pitch. Average bag heave forces on the order of 10% and 25% of vehicle weight are typical for the 0.5 and 1.0 obstacles, respectively. A detailed physical description of the cushion/obstacle interaction has resulted from the data analysis. Three major data trends - impact, venting, and slamming - are identified and related to cushion geometry. Bag effects have been correlated in terms of obstacle size, vehicle speed, and cushion geometry for ease of application as correction factors for analytical vehicle dynamics models based on cushion pressures only. Sponsored in part by DARPA.