Flush Airdata Sensing (FADS) System Calibration Procedures and Results for Blunt Forebodies

Cobleigh, Brent R. and Whitmore, Stephen A. and Haering Jr., Edward A. and Borrer, Jerry and Roback, V. Eric (1999) Flush Airdata Sensing (FADS) System Calibration Procedures and Results for Blunt Forebodies. Technical Report NASA/TP-1999-209012, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

Blunt-forebody pressure data are used to study the behavior of the NASA Dryden Flight Research Center flush airdata sensing (FADS) pressure model and solution algorithm. The model relates surface pressure measurements to the airdata state. Spliced from the potential flow solution for uniform flow over a sphere and the modified Newtonian impact theory, the model was shown to apply to a wide range of blunt-forebody shapes and Mach numbers. Calibrations of a sphere, spherical cones, a Rankine half body, and the F-14, F/A-18, X-33, X-34, and X-38 configurations are shown. The three calibration parameters are well-behaved from Mach 0.25 to Mach 5.0, an angle-of-attack range extending to greater than 30°, and an angle-of-sideslip range extending to greater than 15°. Contrary to the sharp calibration changes found on traditional pitot-static systems at transonic speeds, the FADS calibrations are smooth, monotonic functions of Mach number and effective angles of attack and sideslip. Because the FADS calibration is sensitive to pressure port location, detailed measurements of the actual pressure port locations on the flight vehicle are required and the wind-tunnel calibration model should have pressure ports in similar locations. The procedure for calibrating a FADS system is outlined.

EPrint Type:	NASA Technical Publication
Keywords:	Airdata calibration, Blunt forebody, FADS, Flush airdata sensing, Sphere, X-33, X-34, X-38
Subjects:	Aircraft/Project: X-34 (01 - 09) Aeronautics: (06) Avionics And Aircraft Instrumentation Aircraft/Project: X-38 Aircraft/Project: X-33
ID Code:	102
Deposited On:	03 June 2004
Additional Information:	32 pages. Presented at the 9th International Space Planes and Hypersonic Systems and Technologies Conference, November 1-5, 1999, Norfolk, VA, AIAA 99-4816. Brent R. Cobleigh, Stephen A. Whitmore, and Edward A. Haering, Jr., NASA Dryden, Edwards, California; Jerry Borrer, NASA Johnson, Houston, Texas; and V. Eric Roback, NASA Langley, Hampton, Virginia. A patent has been filed on this NASA invention. Equations (10)–(16) are included in this patent.