Although initially counter-intuitive, not a perpetuum-mobile; analogies to sailing
Very interesting!
To KiloB & M(Flt)Sc
If the device would be able to keep itself moving without any wind blowing over the ground, using this combination of wheeling, gearing and aerodynamics, then it would be a true perpetuum mobile. This one isn’t and as I understand is not meant to be a perpetuum mobile either.
In wind however, as long as a relative wind is maintained between the vehicle’s aerodynamic components by also mechanically connecting the vehicle to the ground, to provide an “anchor” for the lift to oppose itself against, energy can actually be extracted from the wind.
Sailing vehicles are known to be able to move faster than the absolute wind, when they move so as to increase the relative wind. Typically the relative wind is larger than the vehicle’s motion, which is faster than the absolute wind. Such a vehicle accelerates by the lift force in the sail, thereby accelerating the relative wind, enabling the vehicle to extract more energy from the larger air mass flow over the sail, thus creating more lift accelerating the vehicle further until some equilibrium is reached, with the lowest friction vehicles (ice-skaters ranking top of the list) the highest speeds, faster than the wind, can be reached. Only NOT directly downwind, and NOT directly into wind. Some angle to the wind is required to have an efficient lift producing configuration.
Now when the direct and simple mechanical coupling between the vehicle’s motion and the motion of it’s sails (sails mounted statically to the vehicle’s hull) is substituted by a more complex coupling through wheels “anchoring” the lift forces and using a gearing connecting the vehicle’s linear motion over ground to a rotary motion of its sails (propeller blades now), then actually the oblique-to-the-wind motion of the sails is maintained in a coiled-up movement while the vehicle itself can move directly down-wind. The vehicle being initially propelled by poor aerodynamics of its stalled propeller blades will slowly accelerate, thus accelerating the blades until proper lift is produced, ever more efficient with ever more air passing over the blades, the blades thus being able to extract more energy from the wind until some equilibrium is reached. That may be well above the speed of the absolute wind, thus becoming faster than the wind. Disconnect the gearing and the vehicle will again slow down until (much) slower than the wind.
To ThinAirDesigns,
Any plans for a DUWFTTW device? Any numbers on that? Just curious.
jr