Search Results

A methodology and software to automatically define airplane configurations is presented. The general airplane configuration has wing, fuselage, vertical tail, horizontal tail, canard, pylon, and engine nacelle components. The wing, tail, canard, and pylon components are manifested by solving a fourth order partial differential equation subject to Dirichlet and Neumann boundary conditions. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage and nacelles are described with analytic equations. The methodology is called Rapid Airplane Parametric Input Design (RAPID), and both batch and interactive software based on the technique are described. Examples of high-speed civil transport configurations and subsonic transport configurations are presented.

The addition of four wheel steering to a vehicle improves transitional stability at highway speeds. This is accomplished by allowing additional control of the lateral forces generated by the rear tires. The strategies used to control the rear steer angle are classified as open loop or closed loop. The open loop control measures inputs to the vehicle including the steering wheel angle and the vehicle forward velocity to determine the rear steer angle. Closed loop control uses these inputs and also measures the resultant vehicle response. The error between a desired and actual vehicle response determines the rear steer angle. The closed loop strategies give reductions of undesirable responses to external inputs, such as wind gusts or rough roads. This paper details the design and testing of a 4WS concept vehicle with both open loop and closed loop control. The vehicle used a computer controlled servo actuator with a self contained hydraulic circuit to steer the rear wheels.

A two part digital computer program is being used to evaluate dynamic responses and internal frame forces and moments to assist the design engineer in the design of agricultural equipment. The designs can be optimized for actual field operating environments at a savings of development costs and time.

An estimate of the major simulation requirements for high-altitude tests of rocket engines is presented. The design criteria for such facilities are examined in terms of the exhaust gas handling requirements, including both the pumping and cooling systems. Some requirements for the test cell and specialized installation and instrumentation equipment are discussed. Where appropriate, the characteristics of the test units in operation in the Rocket Test Facility at the Arnold Center are cited as examples. A forecast of future test requirements is also included.