Air Cushion Vehicle Ground Contact Directional Control Devices.

• Main Authors: Abele,Gunars, Liston,Ronald A
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER N H
• Format: Text
• Language: English
• Published: 1976
• Subjects: Surface Effect Vehicles & Amphibious Vehicles; *AIR CUSHION VEHICLES; *GROUND EFFECT MACHINES; MANEUVERABILITY; STEERING; AUXILIARY; CONTROL SYSTEMS; YAW; TEST METHODS; MOMENTS; WHEELS; AERODYNAMIC CHARACTERISTICS; SKIRTS; ECOLOGY; RETRACTABLE; TUNDRA; Ground contact devices; AS91D; PE61101A; WU194; Tundra
• Online Access: http://www.dtic.mil/docs/citations/ADA034825; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA034825

The maneuverability of air cushion vehicles can become a serious operational problem when the vehicle's travel route is restricted by obstacles, slopes or cross-wind conditions, or when close-quarter turns are required. While improvement and perfection of aerodynamic methods may be a more desirable approach, there is a practical limit to these methods, and the use of ground contact devices requires consideration for providing more positive directional control. Wheels deserve special attention, and therefore are analyzed in more detail because of their obvious application on a variety of land terrains. Brake rods and harrows are more suitable on water, ice and snow. The saucer-shaped ground contact device would cause the least ecological impact on fragile organic terrains such as tundra. Relative directional stability is evaluated in terms of the total yawing moments produced by wheel arrangements (single, dual, tandem), location on the vehicle, and operational modes (free-rolling, braked, or a combination of the two). The available moments are plotted against the yaw angle of the vehicle to determine the most effective operational mode with a particular wheel arrangement for any yaw condition. The analysis is limited to retractable devices which act as moment producing brakes or rollers and do not serve as either propulsion or load support aids. Controlled ground contract with skirt sections having special wearing surfaces may provide a suitable control method and would require the least significant change to the basic design of the vehicle or its components. The concept involves the use of an air flow control mechanism for deflating specific skirt sections.