Pressure sensor for determining airspeed altitude and angle of attack

Abstract

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.degree. 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.sub.c, where q.sub.c =pitot pressure minus static pressure=p.sub.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.degree.. Angles of side slip (beta) and other flow angles in an established measuring plane may be sensed as well.