Experimental Study of Pylon Cross Sections for a Subsonic Transport Airplane

Pylon cross sections that are intended to reduce the installation drag of an underwing propulsive system were investigated on a ^ scale low-wing transport model in the NASA Langley 16-ft Transonic Tunnel. The design philosophy for the pylons was to alleviate flow acceleration on the lower surface of the wing without introducing severe adverse pressure gradients near the junction of the pylon and wing. This was achieved by means of a gradually diverging pylon with maximum thickness occurring at the wing trailing edge. The pylon closure occurred aft of the wing trailing edge. A hybrid derivative of this pylon, with a more practical thickness distribution for conventionally mounted engines, also achieved the desired effect. The surface static pressure measurements, surface flow visualization data, and force balance data support the design philosophy.