Modernization of a High Precision, Heavy Payload Centrifuge

Henry A. Stoffel, Lawrence P. Fallon, Bradley A. Blanchard and Christopher V. Trainor

Abstract:	With the anticipated reduction of missile flight-testing and the continued need for dynamic G-load testing of inertial guidance systems, ground based replacements for flight test dynamics become extremely attractive from cost, performance and repeatability standpoints. Draper Laboratory of Cambridge Massachusetts has recently completed significant technological enhancements to its 28-ton, 57-foot long centrifuge. The Centrifuge is located in a DSS approved secure facility adjunct to Hanscom Air Force Base in Concord, Massachusetts. The original system, designed in the early 1950’s, was a 35 G hydraulic drive centrifuge. The main 65-inch spindle mounted bullgear drove the 28-ton arm. In addition to the hydraulic main axis, a hydraulically driven counter rotating platform (CRP) was also available to “unwind” the main axis rotation for angular rate sensitive test articles. The system was modified for limited special testing in 1962 to provide 100 G’s of acceleration by adding additional motors and pumps. By the early 90’s, the hydraulics were showing their aging and reliability limited usage to very short tests. In 1996, Draper decided to upgrade the system to an all-electric servo motor drive system. Carco Electronics (Pittsburgh, PA) was selected to redesign and upgrade the system from hydraulic to electric. The redesign system drive specified a 25 G minimum capability (firmware limited), under acceleration controlled ramps of 1 G/min from 0-25 G. Servo position readout was specified to 1.2 arc sec, rate accuracy of 25 ppm (per rev basis) with a rate stability of 0.1% peak. In addition to Draper revamping the drive system several other upgrades were incorporated in the overall plan. These upgrades included an improved CRP, a laser interferometer, 389 slip rings, and a dynamic monitoring system with state-of-the-art sensors for real-time measurement of arm stretch, shaft/spindle deflection, and main axis wobble. The original intent for the centrifuge was to test inertial guidance systems for ballistic missiles. With the recent enhancements and versatility, the centrifuge can easily be adapted to handle numerous other military and commercial applications. Payloads of 5000 pounds are reasonable. If required, modifications to the counterweight side of the arm will allow for heavier load balancing. This paper details the technological refurbishment effort for the C. S. Draper Laboratory high precision, heavy payload centrifuge and describes the dynamic environments and capabilities of this unique test facility.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	116 - 125
Cite this article:	Stoffel, Henry A., Fallon, Lawrence P., Blanchard, Bradley A., Trainor, Christopher V., "Modernization of a High Precision, Heavy Payload Centrifuge," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 116-125.
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