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A method of and apparatus for obtaining angle of attack, local static pressure and local pitot pressure from measured pressure values at ports of a probe having angle measuring ports with angle measuring axes lying in a plane and a pitot port having an axis lying along an axis in the plane bisecting

A method of and apparatus for obtaining angle of attack, local static pressure and local pitot pressure from measured pressure values at ports of a probe having angle measuring ports with angle measuring axes lying in a plane and a pitot port having an axis lying along an axis in the plane bisecting the angle between the measuring ports. A table of known values of angle of attack relative to measured pressure ratio at measured Mach numbers determined by P.sub.1 /P.sub.m is stored in memory and used when P.sub.1 is greater than the pressure sensed at the pitot port (P.sub.t'm), P.sub.1 is the pressure measured at the one of the angle measuring ports that is higher than the pressure measured at the other angle measuring port, and P.sub.m is an average of the pressures at the angle measuring ports. The correlation of the ratio of measured pressures on the probe relative to angle of attack is determined using the known values P.sub.1 /P.sub.m at different angles of attack either in wind tunnel tests or by computer simulation. The known values are stored in a look-up table in an onboard air data computer. The values that have been stored then can be retrieved to solve for the correct angle of attack, using the measured pressures P.sub.1, P.sub.2 and P.sub.t'm. The angle of attack values are used with an algorithm to determine local pitot and static pressure.

대표청구항 ▼

[ What is claimed is:] [1.]1. The method of providing angle of attack of an object using a pressure ratio obtainable from air data sensing ports on the object providing pressures P.sub.1 and P.sub.2 which vary from each other at changing angles of attack and also providing a pitot pressure P.sub.t'm

[ What is claimed is:] [1.]1. The method of providing angle of attack of an object using a pressure ratio obtainable from air data sensing ports on the object providing pressures P.sub.1 and P.sub.2 which vary from each other at changing angles of attack and also providing a pitot pressure P.sub.t'm, comprising providing predetermined values of angle of attack for values of the pressure ratio at Mach numbers related to measured P.sub.1 /P.sub.m, where P.sub.1 is the higher of the pressures P.sub.1 and P.sub.2, and P.sub.m is the average of pressures P.sub.1 and P.sub.2, and using the predetermined values to obtain angle of attack from measured pressure values forming the pressure ratio, when P.sub.1 is greater than P.sub.t'm.