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Compatibility of the Radio Frequency Mass Gauge with Graphite-Epoxy Composite TanksThe radio frequency mass gauge (RFMG) is a low-gravity propellant quantity gauge being developed at NASA for possible use in long-duration space missions utilizing cryogenic propellants. As part of the RFMG technology development process, we evaluated the compatibility of the RFMG with a graphite-epoxy composite material used to construct propellant tanks. The key material property that can affect compatibility with the RFMG is the electrical conductivity. Using samples of 8552/IM7 graphite-epoxy composite, we characterized the resistivity and reflectivity over a range of frequencies. An RF impedance analyzer was used to characterize the out-of-plane electrical properties (along the sample thickness) in the frequency range 10 to 1800 MHZ. The resistivity value at 500 MHz was 4.8 ohm-cm. Microwave waveguide measurements of samples in the range 1.7 - 2.6 GHz, performed by inserting the samples into a WR-430 waveguide, showed reflectivity values above 98%. Together, these results suggested that a tank constructed from graphite/epoxy composite would produce good quality electromagnetic tank modes, which is needed for the RFMG. This was verified by room-temperature measurements of the electromagnetic modes of a 2.4 m diameter tank constructed by Boeing from similar graphite-epoxy composite material. The quality factor Q of the tank electromagnetic modes, measured via RF reflection measurements from an antenna mounted in the tank, was typically in the range 400 less than Q less than 3000. The good quality modes observed in the tank indicate that the RFMG is compatible with graphite-epoxy tanks, and thus the RFMG could be used as a low-gravity propellant quantity gauge in such tanks filled with cryogenic propellants.
Document ID
20150011071
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Zimmerli, G. A. (NASA Glenn Research Center Cleveland, OH United States)
Mueller, C. H. (Vencore Headquarters Chantilly, VA, United States)
Date Acquired
June 18, 2015
Publication Date
June 1, 2015
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
GRC-E-DAA-TN23088
Meeting Information
Meeting: JANNAF Propulsion Meeting
Location: Nashville, TN
Country: United States
Start Date: June 1, 2015
End Date: June 5, 2015
Sponsors: Department of the Army, Department of the Air Force, Department of the Navy, NASA Headquarters
Funding Number(s)
WBS: WBS 448887.04.03
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Propellant tanks
Electrical properties
Graphite-epoxy composites

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