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The novel engine concept represents an alternative approach to achieve the benefits ideally associated with so-called Otto-Atkinson engines in which, in earlier experimental units, the induction stroke was effectively shortened, at part load, by early, or late, inlet valve closure. In the new engine the need for variable valve timing is avoided because a specially designed mechanism shortens the induction/compression strokes and lengthens the expansion/exhaust strokes for part-load operation while maintaining constant the engine compression ratio. A concern with such an engine relates to the inherent friction loss. Accordingly, a theoretical study of the mechanical loss due to the new mechanism was conducted using a commercially available code. It was found that the friction loss of the new engine configuration was approximately 10% lower than that of an otherwise comparable conventional four-stroke engine.

A description is given of the outboard horizontal stabilizer (OHS) system in which the horizontal tail surfaces are mounted outboard of the mainplane tips, in the wing upwash, at the extremities of booms projecting downwind from the mainplane tips. The theory of operation of the OHS concept is reviewed together with the current development status. Configurational geometries of OHS and comparable conventional aircraft are defined and first order, comparative, performance analyses are presented for cruise, take-off and landing modes of operation. It is shown that the pitch-mode control of OHS aircraft does not present any problems relative to the control, in pitch, of comparable conventional aircraft. It was also shown that the OHS concept makes possible a reduction of the drag of the wing and tail surfaces of about 20% together with a reduction in planform area of, typically, 13%.