Engineering topics

Mehmed, O.

Publications and source records attributed to Mehmed, O..

22 records · Page 2

NASA NTRS1980

Single-stage electrohydraulic servosystem for actuating on airflow valve with frequencies to 500 hertz

An airflow valve and its electrohydraulic actuation servosystem are described. The servosystem uses a high-power, single-stage servovalve to obtain a dynamic response beyond that of systems designed with conventional two-stage servovalves. The electrohydraulic servosystem is analyzed and the limitations imposed on system performance by such nonlinearities as signal saturations and power limitations are discussed. Descriptions of the mechanical design concepts and developmental considerations are included. Dynamic data, in the form of sweep-frequency test results, are presented and comparison with analytical results obtained with an analog computer model is made.

Webb, J. A., Jr.↗

NASA NTRS1976

Pressure tube instrumentation

Set of standards in the form of drawings provides detailed information about materials fastening techniques, surface finishes, critical dimensions, quality control specifications, and installation methods for variety of static and total pressure tube instrumentation.

Foerster, G.↗

NASA NTRS1974

Mechanical coupling for high cyclic loading

One-piece cylindrical coupling with ""necked-down'' regions at each end form flexures allowing small misalignments between actuator and load. Coupling has zero backlash, low mass, close spacing between actuator and load, high stiffness in direction of motion, and allowance for misalignments and deflections without causing high side loading on components.

Dustin, M. O.↗

NASA NTRS1973

Improved design of a high response slotted plate overboard bypass valve for supersonic inlets

The electrohydraulically actuated slotted-plate bypass valve used to control the position of the normal shock during wind-tunnel investigations of supersonic inlets also has proven to be a valuable device for determining inlet dynamics and creating airflow disturbances. Operation of previous valves at high frequencies (to 100 Hz) for extended testing has resulted in numerous failures. An improved bypass-valve design is presented which increases the cyclic tolerance of the device considerably over past designs. The use of dynamic limit criteria to obtain an optimum actuator-piston size results in a frequency response which is flat within + or - 3 decibels to 120 Hz for a peak-to-peak variation of 20 percent of full area.

Webb, J. A., Jr.↗