Methods and systems for calculating atmospheric vehicle air data

Abstract

Methods and systems for calculating atmospheric vehicle air data are disclosed. In one embodiment, a method of calculating air data includes acquiring one or more pressure measurements at locations on an outer surface of the aircraft; acquiring one or more measurements using an alternate navigation device; computing an indicated air data solution using the one or more measurements obtained using the alternate navigation device and an atmospheric model; computing corrections to the indicated air data solution using one or more other measured parameters, wherein the one or more other measured parameters include at least one of the one or more pressure measurements and the one or more measurements obtained using the alternate navigation device; determining a corrected air data solution using the indicated air data solution and the corrections; and providing the corrected air data solution for use in controlling the aircraft.

Description

STATEMENT OF GOVERNMENT INTEREST[0001]This invention was made with government support under contract number F30602-03-C-2005 awarded by the United States Air Force. The U.S. Government has certain rights in this invention.FIELD OF THE INVENTION[0002]This invention relates generally to control of flight vehicles, and more specifically, to methods of calculating atmospheric vehicle air data.BACKGROUND OF THE INVENTION[0003]Flight control and guidance of a vehicle through the atmosphere requires knowledge of the vehicle's motion and attitude relative to the earth's air mass. This knowledge, commonly referred to as “air data,” is generally measured using instruments that either protrude into the surrounding airstream, or are flush mounted with an outer surface of the vehicle. Alternately, other instruments may use inertial navigation system (INS) derived values.[0004]Although desirable results have been achieved using such prior art air data systems, there is room for improvement. For e...

AI Technical Summary

Benefits of technology

The present invention provides methods and systems for calculating atmospheric vehicle air data using both inertial measurements and pressure measurements. This eliminates the need for expensive, bulky, and mechanically deployable air data probes. The methods and systems allow for flexibility in the location of pressure taps, redundancy management of the measurements, and the ability to operate in the absence of pressure measurements. The invention also includes a data acquisition component and a processing component for computing an indicated air data solution and corrections to the solution using pressure measurements and other measured parameters. The corrected air data solution is then provided for use in controlling the aircraft. The technical effects of the invention include improved accuracy and reliability of air data for controlling the aircraft, reduced cost and complexity, and increased flexibility and redundancy management.

Problems solved by technology

For example, for high-speed reentry aircraft, the use of instruments that protrude into the airstream is problematic because of the heating that occurs due to the high velocity of the air.

Deployable probes generally require a considerable amount of calibration, are costly, and require valuable space in the aircraft near the surface to be deployed.

Air data systems that rely on flush-mounted instruments and INS-derived data also have drawbacks.

For a smaller aircraft, however, the stagnation point is typically one of the highest heating points on the aircraft, and the temperatures may be so high that flush-mounted instrumentation is impractical because the instrument materials cannot support the heating rate.

Air data systems that use INS-derived data are typically too inaccurate for proper control of the reentry aircraft.

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