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.
An alignment tool is used for aligning an air data sensing probe relative to an aircraft axis has an alignment tool mounting plate that fits over the air data sensing probe base plate and is doweled in position on the air data sensing probe base plate. The alignment tool has a level and incline indicator positioned at a known relation to an axis of the air data sensing probe. The probe base plate and alignment tool are mounted on the aircraft, and the level and incline indicator is used to determine when an aligned position of the air data sensing probe is reached by rotating the alignment tool and probe base plate. The probe base plate of the probe is then fixed in position, and the alignment tool is removed. Bores are formed in the aircraft wall for holding dowel pins extending between the aircraft wall and the probe base plate.
An air data module is provided that is relatively small, lightweight, low cost, uses relatively low power, and is relatively easy to install, test, and maintain. The air data module includes a housing that is adapted to be mounted to an external surface of an aircraft, and includes at least a sensor compartment and an interface electronics compartment formed therein. A pitot-static probe is coupled to the housing and extends therefrom, and has a static pressure passageway that is in fluid communication with the sensor compartment. A plurality of static pressure ports are formed in the pitot-static probe and are in fluid communication with the static pressure passageway. A pitot pressure inlet port is formed in a distal end of the pitot-static probe. A static pressure sensor and a differential impact or absolute pitot pressure sensor, for example, may be mounted within the module and used to sense static pressure and impact or pitot pressure, respectively. The disclosed configuration makes the module less sensitive to a relatively high pressure pulse.
The invention provides a probe for an aircraft including a strut having an interior passage accommodating a plurality of pneumatic lines, a probe head extending from the strut and having at least one inlet opening communicating with the pneumatic lines, a baseplate situated below the strut for attaching the probe to the aircraft, and a manifold situated below the baseplate for communicating with the pneumatic lines, wherein the baseplate is adapted and configured so that the pneumatic lines communicating with the manifold are thermally isolated from the baseplate. The invention also provides a method of thermally isolating at least one pneumatic line in an aircraft probe.
An air data sensing probe or MFP includes a barrel having multiple pressure sensing ports for sensing multiple pressures. Instrumentation coupled to the pressure sensing ports provides electrical signals related to the multiple pressures. A neural network, coupled to the instrumentation, receives as inputs the electrical signals related to the multiple pressures, and in response, the neural network provides, as an output, electrical signals indicative of at least one local air data parameter for the air data sensing probe.
A method providing fault isolation, in an air data system which uses artificial intelligence to generate an air data parameter, includes generating the air data parameter as a function of a plurality of measured values such as static pressures. Then, estimates of each of the plurality of measured values is generated as a function of the generated air data parameter. Each measured value can then be compared to its corresponding estimate to determine if a difference between the measured value and its corresponding estimate exceeds a threshold and therefore indicates a fault in a device which provides the measured value.
