Extreme Range Breguet Range eq. best values based on current technology: p = 0.9 c p = 0.4 (piston engine gives the best sfc) L/D = f (A, e, C D0 ) C D0 = f (S wetted, BL state, S)
Extreme Range Structural limits to max allowable A Aerodynamic limits to C D0 Powered airplanes: (L/D) max = 25 very good value ! Transports W i / W f = 2.0 R max = 14,621 n. mi. Nonstop, unrefueled flight around the world R = 28,000 n.mi. ! This range requires a W i / W f = 3.8 Nothing you can do in a short time to overcome technology limitations! The only thing you can do is be creative in your design!
Extreme Range Rutan achieved W i / W f = 4.5 in the Voyager with: A = 33.8 Composites Special airfoils in the lifting surfaces and the propellers Place fuel outboard on the wing: Reduce wing root bending moment Improve W i / W f Experimental regulations instead of civil or military airworthiness constraints, resulting in W savings
Rutan Voyager
Extreme Endurance Breguet Endurance eq. Same tradeoff between L / D and W as in the case of extreme range
Extreme L / D High-performance gliders: Schleicher AS W22 B
Extreme L / D Need to maximize A and minimize C D0 Solutions: Very high A wings (Schleicher AS W22 has A = 38.3) Laminar flow wings Min size fuselage (pilot in reclined position) Advanced composite structures