Eliminating the Cruise-Efficiency Penalty of Hybrid VTOL: The meryemAircraft Tail-Sitting Blended-Wing-Body Configuration with Propeller-Only Control

Hybrid vertical take-off and landing (VTOL) aircraft combine runway independence with wing-borne cruise, but purchase that combination at a cost to cruise efficiency. This paper argues the cost is architectural rather than a defect of implementation. It is charged in three currencies — the mass of hover hardware carried through cruise, the drag of hover hardware exposed in cruise, and a power system sized by a condition that holds for roughly two percent of the flight — and every known architectural remedy reduces one currency by increasing another. Stating the cost this way makes its escape condition explicit: it is charged whenever hover and cruise are served by hardware that is not the same hardware, in the same orientation, doing the same job. A configuration satisfying that condition is proposed — an uncrewed tail-sitting blended-wing body in which one coaxial counter-rotating pair at the nose produces all thrust in both regimes, four small coaxial pairs at the wing tips produce attitude moments only, and a deployable strip in the nose-propeller slipstream supplies the rolling moment that body-axis-parallel thrust vectors cannot generate. The aircraft carries no elevons, rudder, tilting mechanism, retraction mechanism or dedicated lift system. Two reference designs are sized twenty times apart in mass, at 50 kg and 1000 kg, from identical equations; disc loading, energy-buffer mass fraction and tip-frame drag fraction are preserved across that range. Two findings changed the study: the tip frames must be faired, as circular tubing would produce nearly as much drag as the rest of the aircraft; and transition altitude loss falls with rotation time rather than rising with it, so entering the rotation while climbing removes it. The study is analytical: no wind-tunnel, computational or flight validation is presented, and the mass budget is a target.