| Abstract | In order to investigate ground effect on a fan-in-wing configuration, a test rig was built. A 1-ft. diameter fan was buried in a 3-ft. by 5-ft. wing section. A movable ground board permitted operation at ground to fan-exit distances between 6 and 1/2 fan diameters. For one series, a symmetry wall was attached to one end of the aerofoil. Tip speeds ranged from 425 to 625 f.p.s.
At 1 fan diameter above the ground, the loss in net thrust was 18 percent. This net thrust consisted of the computed momentum thrust which was modified by the forces acting on the underside of the wing, the fan base, and the fan annulus. Because of reduced mass flow, the momentum thrust at 1 diameter height was found to be 78 percent of that in "free air". |
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