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

Version 2 (29 August 2026). Changes from version 1: the cruise lift-to-drag method has been corrected — version 1 used the maximum-L/D expression while specifying a different cruise speed, which overstated range by about 6 %. Lift-to-drag is now evaluated at the cruise point (light design 1695 → 1598 km, heavy design 1868 → 1814 km). A new Section 6.6 reports independent vortex-lattice and strip calculations that bound — but deliberately do not replace — the two assumed aerodynamic coefficients, and shows the assumed zero-lift drag coefficient to lie above the whole of the computed range. An internal-volume closure shows the configuration is mass-limited rather than volume-limited. Section 8.6 now reports that the transition result survives an 18 % error in the lift-curve slope it rests on. --- 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, its drag when exposed in cruise, and a power system sized by a condition holding for roughly two percent of the flight — and every known 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 has no control surfaces, no tilting or retraction mechanism and no dedicated lift system. Two reference designs are sized twenty times apart in mass, at 50 kg and 1000 kg, from identical equations, with the governing fractions preserved across that range. Two findings changed the study: the tip frames must be faired, and transition altitude loss falls with rotation time rather than rising with it. The study is analytical, with no wind-tunnel or flight validation, and the mass budget is a target. The two aerodynamic coefficients that carry the most weight are not replaced by computation but bounded by it.