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A strut or boom mounted probe having separate pressure sensing ports or sets of ports axially spaced at three locations on the probe. The ports are normally located on the probe so that at 0° angle of attack, the pressure difference is zero between a set of opposite ports at the most rear location.

A strut or boom mounted probe having separate pressure sensing ports or sets of ports axially spaced at three locations on the probe. The ports are normally located on the probe so that at 0° angle of attack, the pressure difference is zero between a set of opposite ports at the most rear location. As the angle of attack varies from zero angle, the pressure difference at the aft measuring ports increases, in a positive sense with increasing angle of attack (alpha), and, in a negative sense with increasing opposite (negative) alpha angle. Pressure difference between the rear ports is also proportional to the impact pressure, q c, where q c =pitot pressure minus static pressure=p t -p. The sensor normally has a pitot pressure opening in its forward extremity and static ports located along the forward cylindrical barrel section of the unit. The pressure difference at the rear ports is divided by the pressure difference of the forward ports. A unique ratio of pressure is developed which is a function of angle of attack or flow direction and pitot pressure and this alternate ratio may be utilized using pitot and alpha (angle of attack) pressure only. The sensor is particularly useful at high angles of attack and provides readings at angles of attack in the range of±50°. Angles of side slip (beta) and other flow angles in an established measuring plane may be sensed as well.

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1. An air data sensing probe for sensing the angle of relative movement between the probe and a fluid stream, comprising a barrel having a longitudinal axis and including: a leading end and a trailing end, a first generally cylindrical section, a second generally cylindrical section spaced rearwa

1. An air data sensing probe for sensing the angle of relative movement between the probe and a fluid stream, comprising a barrel having a longitudinal axis and including: a leading end and a trailing end, a first generally cylindrical section, a second generally cylindrical section spaced rearwardly from the first generally cylindrical section, the second section being larger diameter than the first generally cylindrical section, and an increasing diameter surface section generated about the longitudinal axis and joining the first and second sections the increasing diameter surface section forming an included angle of between in the range of 5° and 25° with respect to the longitudinal axis; a pair of pressure sensing port means on said increasing diameter section, said port means having axes which together with the barrel longitudinal axis define a plane in which an angle to be sensed is to be measured with respect to a reference position of the longitudinal axis; means to subtract the pressure at one of said port means from the other; and means providing a signal representing a ratio of the difference between the pressures sensed at the respective port means and a pressure quantity including a pitot pressure function which provides a ratio value which is nonlinear with increasing angles of above about twenty degrees with respect to the reference position of the longitudinal axis. 2. The apparatus of claim 1 wherein the means to determine the difference and the means to divide provide the ratio (p α1 -p α2 )/(p tm -p m ), wherein p α1 and p α2 are the pressures measured at the respective ports, p tm is the measured pitot pressure at the leading end of the probe, and p m is the measured static pressure adjacent the probe. 3. A probe having a longitudinal axis, a leading end section and a trailing end section, the trailing end section being a larger cross sectional size than the leading end section, and an expanding surface section joining said leading and trailing end sections and having a pair of oppositely facing ports defined therein, which ports have axes lying in a plane passing through the lontitudinal axis of said probe the pressure of fluid at the leading end of the probe comprising a pitot pressure; means to individually sense the pressures at each of said ports and to determine the difference between said pressures when there is fluid motion relative to said probe, and means to divide the difference obtained by a quantity comprising (p tm -p α1 )+(p α1 -p α2 ) wherein p α1 and p α2 are pressures measured at said ports, and p tm represents the pitot pressure at the leading end said probe for determining the angle of attack of the longitudinal axis of said probe relative to the fluid with respect to a reference position such that the quantity obtained after division has a progressively greater increase for each degree of increase of angle of attack when the angle of attack exceeds a known amount. 4. The apparatus of claim 3 wherein the trailing section of said probe has a strut mounted thereon for mounting the probe to an aircraft. 5. The apparatus of claim 3 wherein the leading and trailing sections of the probe are generally cylindrical, and said expanding surface section is generally conical, the cone angle being in the range of five to twenty five degrees with respect to the longitudinal axis of the probe. 6. The apparatus of claim 3 wherein said probe has a pitot pressure sensing opening at the leading end thereof to provide the quantity p tm . 7. The apparatus of claim 6 wherein the leading cylindrical section is elongated and has static pressure sensing port means thereon, said static pressure sensing port means providing a pressure quantity p m, and the means to divide dividing by a signal representing the quantity (p tm -p m ). 8. An air data sensor for determining the angle of attack of the sensor relative to the direction of fluid moving relative to the sensor comprising a probe having an elongated probe barrel with a longitudinal axis, said barrel having first and second barrel sections of substantially similar cross sectional shape, but of different cross sectional dimensions, said second barrel section being of larger dimension than the first barrel section and trailing the first section with respect to the direction of relative fluid motion, and a barrel transition section defining an exterior surface joining said first and second barrel sections and increasing in size from the first barrel section to the second barrel section, first and second port means open through the barrel and symmetrically formed about a common central axis and facing in opposite directions, said common axis intersecting the longitudinal axis to thereby define a plane, means to individually sense the pressures at each of said first and second port means and provide signals representative of the sensed pressures as p α1 -p α2 at the first and second ports, respectively, means to provide a signal representative of the pitot pressure at the leading end of the barrel as p t, means for providing the difference between the signals representing the pressures at the first and second port means and for dividing said difference by a signal representing a pressure function including the signal representing the pitot pressure and pressure at the probe related to measured static pressure for thereby providing a ratio signal which varies as a function of the angle of attack and which ratio signal increases in output per degree of change of angle of attack as the angle of attack increases above a known amount. 9. The sensor as specified in claim 8 wherein the plot of the provided ratio relative to the angle of attack of the barrel with respect to the direction of the fluid stream substantially comprises one of the curve shapes substantially as plotted in FIG. 6 of the drawings. 10. The apparatus of claim 8 wherein the means to provide and divide comprises means to supply a signal representing a quantity selected from a group consisting of the following quantities: ##EQU##(p α1 -p α2 )/(p tm -p m ) (a) and ##EQU## where p α1 and p α2 comprise signals representing the pressures at the port means, respectively; p tm is a signal representing pitot pressure; and p m is a signal representing static pressure of the fluid adjacent the probe. 11. A pitot-static probe of elongated, slender form for sensing pitot and static air-pressures and for sensing angle of flow of the probe relative to a fluid stream comprising an elongated forward portion having a forward-facing port for sensing pitot pressure, said forward portion being cylindrical throughout a substantial part of its length, an elongated main-body portion axially aligned with, and aft of, said forward portion, said main-body portion at least at its forward end being of larger cross-section than said forward portion, and an intermediate portion interconnecting said forward and main-body portions, said intermediate portion being of increasing section in the aft direction from said forward portion to the main-body portion, port means for sensing static pressure positioned on said forward portion, and first and second port means positioned on said intermediate portion for sensing angle of flow, said first and second port means facing in opposite directions and being centered on a diametrical line, said intermediate portion having a surface forming an angle of between five degrees and twenty five degrees with respect to the central longitudinal axis of the probe, and means to provide a ratio of pressure sensed on the probe which increases in sensitivity to flow angle as the flow angle exceeds a known angle. 12. The probe of claim 11 wherein the means to provide provides a ratio selected from one of the group of ratios comprising: ##EQU##(p α1 -p α2 )/(p tm -p m ) (a) ##EQU## where p α1 and p α2 represent the pressures at the first and second angle of attack sensing port means, respectively, p tm represents the pressure measured at the forward facing port, and p m represents the pressure sensed at the static pressure sensing port means. 13. The method of determining the angle of flow of a probe having a longitudinal axis with respect to the direction of relative fluid movement past the probe, said probe having a first leading end section of generally cylindrical configuration, and an expanding size conical section downstream from and joining the leading end section, and a second generally cylindrical section of larger size than the first generally cylindrical section joining the conical section at its downstream end, comprising the steps of providing a pitot pressure signal representing the pressure at the leading end of the probe and a signal representing the static fluid pressure adjacent to the probe; providing on the conical section first and second oppositely facing port means each being centered on the same plane passing through the longitudinal axis of the probe; individually sensing the pressures at each of said first and second port means; and correlating the pressures at the first and second port means and selected other sensed pressures for providing a signal representing a ratio selected in accordance with one of the ratios formed in the following group of (a) and (b): ##EQU##(p α1 -p α2 )/(p tm -p m ) (a) ##EQU## when p α1 and p α2 represent the pressure at the first and second port means, respectively, p tm represents pitot pressure at the leading end of the probe, and p m represents static pressure adjacent to the probe, to provide a ratio which increases in sensitivity to angles of flow when the angles of flow being measured range upward from about twenty degrees.