Construction of Airfoil Pressure Models Using the Multiple Plate Method

A research and development program to build wind tunnel pressure models is described. The program is centered on the concept of bonding together plates with pressure channels cut into the bond planes. Photographic “masking” combined with chemical milling is a reliable and cost effective method of providing pressure channels suitable for high density pressure instrumentation with minimum demand on parent model material. Small diameter high quality pressure orifices (i.e., round holes with smooth edges) are economically produced when pre-drilled holes are cut at the model surface by the wire-cut process. With care in the choice of materials and technique, vacuum brazing can be used to produce strong bonds without blocking pressure channels and with no bonding voids between channels. Using multiple plates, a wing with a thickness of 5 percent of chord and having 96 orifices has been constructed and tested in a transonic cryogenic wind tunnel.