I am not sure what your question is here.
For small wind power there is not much incentive to work at constant speed. For the earlier asynchronous generators of grid tie machines they were confined to constant speed or two speeds ( both constant).
The need was to extract good power over the working wind speed and to reduce blade power drastically above full rating. Blade design has a large influence on the performance in the working range and during stall limiting above rating.
The normal small machine should be designed for the rotational speed to track wind speed and conditions are very different. If you get things right a fixed pitch blade will run at fixed tsr if the alternator loading follows the cube of wind speed.
The aim is to work the blades at best lift/drag ratio over the useful range. What you do beyond the full power point is a different issue. With suitable blades you may be able to induce stall with a monster alternator but it is unlikely so you need other power limiting.
Designing small alternators to be efficient and cost effective is a serious problem if you limit yourself to constant speed operation. The cost of an alternator drops drastically with speed for the same efficiency. That and the poor blade operation makes anything other than tracking prop speed with wind speed a poor starting point.
Unfortunately the conventional direct loading scheme approximates to constant speed with a very efficient alternator and a compromise between the two with a less efficient electrical system.
What works best for the blade profile must depend on the loading method as much as any other factor.
Even the stall limited constant speed machines can't handle no load and back up schemes such as tip flaps are always used to catch things if load is lost.
Bergey seem able to get their machines to survive off load but with a lot of noise and speed. Changing the blade profile may result in loss of this facility and would also almost certainly need a furling redesign so the choice of blade profile may have been based on a combination of factors.
Flux
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