Patent ID: 8887486

Claim:
A ram air fan inlet housing for containing a ram air fan rotor, the inlet housing comprising: a flanged surface perpendicular to an axis of the inlet housing, the flanged surface defining a flange plane at an axial end of the inlet housing and; an interior surface symmetric about the axis of the inlet housing, the axisymmetric interior surface comprising: a flange section having a cylindrical shape, the flange section abutting the flanged surface; a transition section having a frustoconical shape, the transition section abutting the flange section opposite the flanged surface and extending away from the flange section and radially inward toward the axis at an angle between 14.50 and 15.50 degrees from the axis; an outlet section having a frustoconical shape, the outlet section abutting the transition section at a plane parallel to, and between 1.150 inches and 1.160 inches (or between 29.21 mm and 29.46 mm) from, the flange plane; and extending away from the transition section and radially inward toward the axis at an angle between 4.00 and 5.00 degrees from the axis; such that a step is formed between the transition section and the outlet section; a rotor section having a cylindrical shape, the rotor section abutting the outlet section opposite the transition section; and an inlet section having a frustoconical shape, the inlet section abutting the rotor section opposite the outlet section and extending away from the outlet section and radially outward from the axis at an angle of between 1.50 and 2.50 degrees from the axis.