Abstract: A method and apparatus for pressure testing the static pressure orifices and associated connections used in wind tunnels. A cylindrical module, having in one end an open hemispherical calibration pressure chamber separated from and surrounded by an annular vacuum chamber, is placed over the orifice of the system to be tested. O-rings ensure seating and a vacuum seal between the chambered end of the module and the surface around the orifice: one O-ring separates the two chambers and another separates the outer chamber from the outside environment. Ports lead from each of the chambers out the other end of the module to tubes connected to a control box consisting of calibration pressure and vacuum supply lines, bleeder valves, and guages. The calibration pressure supply may be above or below atmospheric pressure.

Abstract: An adjustable geometrical instrument for making interrelated angular and linear measurements comprising an alinement head, a detachably mounted retractable tape measure, and a slidably mounted cooperating angle indicator. Indices of linear measurement are provided on the alinement head for determining the distance between the tape measure and the vertex of the angle being formed by the angle indicator and the alinement head, thus providing for calculation of the total linear distance between a reference point and the desired point of angular measurement. Provision is made for mounting the tape measure at either end of the alinement head in alinement therewith by means of a permanent magnet recessed in the bottom of the tape measure unit and alinement pins which cooperate with corresponding mounting recesses in the alinement head.