Engineering topics

Hammond, J. C.

Publications and source records attributed to Hammond, J. C..

2 records

NASA NTRS1983

A broadbased actuator concept for spaceflight application

An electromechanical actuator is applicable to a variety of spaceflight requirements. Characterized by high torque and a small output step angle, the device is comprised of a coaxial, symmetrical arrangement in which a cup type harmonic drive is directly coupled to a pancake configuration drive motor. The motor, with its dual stator driving a common rotor, is one illustration of the concept of selective redundacy. Selective redundancy promotes the idea that redundancy, to be effective, must not compromise inherent design simplicity nor introduce new failure modes. The usefulness of the actuator is exemplified by its selection for a broad range of positioning and driving applications including TDRSS gimbal drives, Space Telescope deployment and latching machanisms, and Space Telescope secondary mirror drive, as well as others.

Hammond, J. C.↗

NASA NTRS1975

Fluid infusion system

Development of a fluid infusion system was undertaken in response to a need for an intravenous infusion device operable under conditions of zero-g. The initial design approach, pursued in the construction of the first breadboard instrument, was to regulate the pressure of the motive gas to produce a similar regulated pressure in the infusion liquid. This scheme was not workable because of the varying bag contact area, and a major design iteration was made. A floating sensor plate in the center of the bag pressure plate was made to operate a pressure regulator built into the bellows assembly, effectively making liquid pressure the directly controlled variable. Other design changes were made as experience was gained with the breadboard. Extensive performance tests were conducted on both the breadboard and the prototype device; accurately regulated flows from 6 m1/min to 100 m1/min were achieved. All system functions were shown to operate satisfactorily.

Hammond, J. C.↗