Case for aircraft with outboard horizontal stabilizers

Abstract

A description is given of what is believed to be an innovative aircraft configuration in which the horizontal stabilizing surfaces are mounted outboard, and downwind, of the tips of the mainplane. It was shown theoretically that the pitch-control effectiveness of such tail surfaces is, due to their location in the mainplane-generated upwash, greater than that of a corresponding conventional horizontal stabilizer subjected to the mainplane downwash. Wind-tunnel and flow visualization tests were carried out that showed that the divided horizontal stabilizer was also usable as an effective lifting surface to augment the lift of the mainplane. It was found experimentally that the liftidrag ratio of the new configuration can be up to about 30% greater than that of an otherwise comparable conventional configuration. The results of flight tests are reported of large, powered, radio-controlled model aircraft featuring the new configuration. These did not reveal any significant problems with flying qualities. A simplified analysis of structural loading showed that provided the design parameters are chosen correctly, wing bending and torsional loads are fairly comparable with those of conventional aircraft.