Wind tunnel tests of a wing fitted with a single lifting fan

Abstract

Results are given of wind-tunnel tests of a square wing with a lifting fan of 1/44th the wing area located at 0.354 chord. Forces and pressure distributions were measured both on the bare wing and with plain and split flaps, A loss of flap effectiveness is noted for a very limited combination of plain flap deflection and advance ratio. An analysis is given of the flow through the fan and the total head rise is related to the local conditions at entry and exit. Tests with a cascade in the fan duct at exit to deflect the efflux are described and the results are presented in a form that shows an economy in power requirements up to 20 deg jet deflection. The forward-speed lift characteristics are greatly affected by fitting underfins of a suitable size and disposition, tangential to the duct exit. The loss of lift at low forward speeds can be completely eliminated by these means.