Kenneth P. Spreemann
An investigation has been made to study the effects of propeller diameter on the ability of a flapped wing, with and without boundary-layer control, to deflect propeller slipstpeams downward for vertical take-off. The results of the investigation indicate that without boundary-layer control an increase in the ratio of flap chord to propeller diameter increases the turning angle but decreases the ratio of resultant force to thrust, either in or out of the region of ground effects. It appears that the ratios of flap chord to propeller diameter used in the investigation (0.25 to 0.375) were too low to provide the turning angles normally required for vertical take-off without boundary-layer control. The results also indicate that the increment of turning angle and the increment of the ratio of resultant force to thrust due to boundary-layer control are, in general, independent of the ratio of flap chord to propeller diameter.
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