Subsonic Tests of an All-Flush-Pressure-Orifice Air Data System

Larson, Terry J. and Siemers III, Paul M. (1981) Subsonic Tests of an All-Flush-Pressure-Orifice Air Data System. Technical Report NASA TP-1871, Research Engineering, NASA Dryden Flight Research Center.

Full text available as: PDF - Requires Adobe Acrobat Reader or other PDF viewer.

Abstract

The use of an all-flush-pressure-orifice array as a subsonic air data system was evaluated in flight and wind-tunnel tests. Two orifice configurations were investigated. Both used orifices arranged in a cruciform pattern on the airplane nose. One configuration also used orifices on the sides of the fuselage for a source of static pressure. The all-nose-orifice configuration was similar to the shuttle entry air data system (SEADS). The flight data were obtained with a KC-135A airplane. The wind-tunnel data were acquired with a 0.035-scale model of the KC-135A airplane. With proper calibration, several orifices on the vertical centerline of the vehicle's nose were found to be satisfactory for the determination of total pressure and angle of attack. Angle of sideslip could be accurately determined from pressure measurements made on the horizontal centerline of the aircraft. Orifice pairs were also found that provided pressure ratio relationships suitable for the determination of Mach number. The comparisons in the study indicated the accuracy that can be expected for the air data determined with SEADS during subsonic orbiter flight.

EPrint Type:	NASA Technical Publication
Keywords:	Air data, Airspeed and altitude measurements, Flow angularity measurements, Flush air data system, Flush pressure orifices
Subjects:	(01 - 09) Aeronautics: (06) Avionics And Aircraft Instrumentation Aircraft/Project: KC-135 Aircraft/Project: Space Shuttle Orbiter
ID Code:	666
Deposited On:	07 Febuary 2006
Additional Information:	50 pages. This paper is a revised and expanded version of "Subsonic Investigation of an All Flush Orifice Air Data System," a paper presented by the authors at the 1980 Air Data Systems Conference (Colorado Springs, Colo.) in May 1980.