HUP Pylon Air Inlets

A second pair of air inlets was added to leading edge of the HUP's aft pylon at its intersection with the fuselage after it first entered service in order to increase cooling air to its hard working radial engine mounted in the fuselage. The opening looks like a rounded rectangle from the side but because of the airfoil shape of the pylon cross section and the pylon's interface with the fuselage, it looks very different when viewed from other angles.

For more on the HUP from a modeler's standpoint, see https://tailhooktopics.blogspot.com/2016/04/piasecki-hup-interior.html