ESDU 84035:1988

ESDU 84035 provides simple empirical methods for estimating the drag of the excrescences, either wholly or partially immersed in a turbulent boundary layer, for Mach numbers up to 3 but excluding the transonic range from 0.8 to 1.2. The methods allow determination of the drag penalty due to such fittings as blade aerials, mounting struts, and fairings over warning beacons or radar antennae. Simple expressions are given for the drag ratio (drag in the presence of the boundary layer on the mounting plate divided by drag in its absence) involving stub wing or fairing geometry, boundary layer thickness, and the effect of shear in the boundary layer for which data are provided. If not known, the drag in the absence of a boundary layer can be obtained from other ESDU documents in the Series. The stub wings can have any profile but must be straight-tapered; drag coefficient based on frontal area is thought to be predicted to within 0.02 or 0.05 at subsonic or supersonic speeds respectively. The fairings can have semi-circular or non-circular cross-sections and their drag coefficients based on frontal area are predicted to within 0.01 or 0.1 at subsonic or supersonic speeds respectively.