Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
2000-09-13
2002-01-01
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C701S001000, C244S177000, C244S180000, C073S147000, C073S183000, C702S045000
Reexamination Certificate
active
06336060
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an arithmetic processing algorithm for flight velocity vector measurement of a wide velocity range that extends from low velocities to supersonic velocities and to a system using said algorithm.
2. Description of the Related Art
The present applicant previously invented and obtained a patent for (U.S. Pat. No. 5,423,209; Japanese Patent No. 2913005) a flight velocity vector measurement system using a square truncated pyramid-shape five-hole Pitot probe as in FIG.
6
. FIG. A is a front view. FIG. B is a partial side sectional view. As in FIG. A, a group of pressure holes having a total pressure hole in the center thereof is provided on each of the four slanted sides of the pyramid shape. The patented invention is a flight velocity vector detection system using a multi-side truncated pyramid shape Pitot probe wherein an extreme end portion has a multi-side truncated pyramid shape, a shield hole is provided at the apex thereof, a total pressure tube of a smaller diameter than that of the shield hole is secured at a position by a predetermined length determined by a relationship with the diameter of the shield hole from the extreme end of the shield hole; wherein pressure information detected by said multi-side truncated pyramid shape Pitot probe on each side thereof are positioned pressure holes is input to a velocity vector arithmetic processor to convert said information into electronic signals, which are processed using pressure coefficients of the pressure holes of said probe with respect to velocity vector, said pressure coefficients being stored in advance in a memory, to calculate flight velocity vector (V, &agr;, &bgr;) with respect to the probe axis from the pressure information and air density; wherein an output of an attitude azimuth reference device is input to said velocity vector arithmetic processor and information from the attitude azimuth reference device is connected with flight velocity vector information with respect to said airframe axis to calculate flight velocity vector. Adoption of such a configuration enables a single square truncated pyramid shape Pitot probe and an arithmetic processor to perform the respective functions of a conventional airspeed indicator, altimeter, rate of climb indicator, Mach meter, and yaw meter, thereby making it possible to reduce the number of detection devices; to connect the various information and output and display said information; and to provide a pilot with highly reliable atmospheric information. Furthermore, a limited effect of pressure coefficients caused by variation in velocity eliminates the need to perform complex correction, making it possible to obtain velocity vector information with good accuracy and over a wide angular range and facilitating installation, without the need for an advanced computer, in a wide range of aircraft, from ordinary aircraft, including helicopters and other vertical takeoff and landing aircraft, to supersonic aircraft that are accompanied by shock waves. In addition, [the patented invention] is a groundbreaking invention offering many superior effects, namely, being less influenced by the pressure coefficients caused by variation of velocity of those pressure holes that detect wind direction, requiring no complicated correction, being able to obtain velocity vector information with good accuracy and over a wide angular range, and posing no likelihood of defective measurement due to clogging, vibrations and the like.
Arithmetic processing method's concerning Mach number M (or velocity V) stored in ROM form and used in an arithmetic processor for a flight velocity vector measurement system that uses a square truncated pyramid-shape five-hole Pitot probe comprise (1.) those in which said five-hole probe is not subjected to compression and which are suitable for low-velocity ranges not requiring high-speed arithmetic processing and (2.) those suitable for a wide range of velocities that extends from low velocities to supersonic velocities accompanied by shock waves. The former, namely (1.) arithmetic processing for low-velocity ranges in which said five-hole probe is not subjected to compression, is a processing technology wherein the Newton-Raphson method (“N-R method”) is used and wherein three parameters comprising attack angle &agr;, sideslip angle &bgr;, and velocity (dynamic pressure q) are determined, by repeated calculation, using pressure calibration coefficients concerning attack angle, sideslip angle, and velocity calculated in advance. Said technology is disclosed in the Specifications of the said patented invention and has been implemented in the HOPE Automatic Landing Flight Experiment (ALFLEX) demonstration vehicle and in NAL experimental vehicles.
Regarding the latter, namely (2.) arithmetic processing methods for a wide range of velocities that extends from low-velocity flight to supersonic-velocity flight in which said five-hole probe is subjected to shock waves, flight velocity vector arithmetic processing equations that were also developed by the present applicant and in which five items of pressure information are used as basic data and Mach number M is first determined by some processing method and then used determine angle have been presented (U.S. Pat. No. 2884502, “Wide Velocity Range Flight Velocity Vector Measurement System Using a Square Truncated Pyramid-Shape Five-Hole Probe”). This technology has been used in airflow measurement in supersonic wind tunnels.
The flight velocity vector calculation methods for the aforesaid (2.) comprise two methods. One is a system wherein a Mach number equation and angle equations are solved directly in third-order polynomial approximation equations for each segmented velocity range; the other, a lookup table system that omits the solution of a third-order equation for intermediate calculation of the Mach number and wherein Mach number is read directly from a Mach number table created in advance by calculating Mach number M from airflow angle pressure coefficient and Mach pressure coefficients determined in advance. Within the former system for solving Mach number M and angles with third-order equations, Mach number calculation, wherein angle to airflow pressure coefficient C&ggr; is obtained in advance by further processing Mach pressure coefficient CM, which is obtained by making a pressure difference between a total pressure and average pressure of four holes in the square truncated pyramid surfaces obtained by processing the five items of pressure information detected by said five-hole probe nondimensional according to said total pressure, and wherein pressure coefficients C&agr; and C&bgr; are also obtained in advance by making a vertical pressure difference and transverse pressure difference among the four holes in the square truncated pyramid surfaces nondimensional according to total pressure, is specified using pressure calibration coefficients determined in advance for each velocity range in conjunction with determination of segmented velocity ranges, said velocity ranges being determined from the aforesaid pressure coefficient CM, and the aforesaid angle to airflow pressure coefficient C&ggr;. Mach number M is arrived at by solving said third-order equations for each velocity region to determine an appropriate root. Angles are arrived at by similarly solving a third-order arithmetic processing equation concerning angle &agr; and angle &bgr; using aforesaid pressure coefficients C&agr; and C&bgr; and the pressure calibration coefficient corresponding to the angle. The arithmetic processing equation used to calculate Mach number, angle &agr;, and angle &bgr; are all third-order equations, each having three roots (with said roots comprising either three real roots or one real root and two imaginary roots), and so selection of an appropriate root entails using complicated determination methods.
The other method, namely the lookup table method, is a method wherein, without using a third-order equation in Mach number d
Nakaya Teruomi
Ohnuki Takeshi
Shigemi Masashi
Shindo Shigemi
Takizawa Minoru
Armstrong Westerman Hattori McLeland & Naughton LLP
Cuchlinski Jr. William A.
Hernandez Olga
National Aerospace Laboratory of Science and Technology Agency
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