I like your point about moving upwind, but think it rather relies on conservation of momentum as that insists the wheels must result in thrust in the opposite d

I like your point about moving upwind, but think it rather relies on conservation of momentum as that insists the wheels must result in thrust in the opposite direction to the props thrust in order to change the momentum of the earth as much as the momentum of the atmosphere is changed. They must each be reduced, in order to transduce energy. If you have stored energy you can propel mass from rest, but forces can only be applied equal and opposite. It is extremely enigmatic and curious that the engine can work to synergistically blow air into the atmosphere in one direction and resist the inertia of the earth in the other direction with the same force, without expending any energy reserves in the engine. Ive not seen a model or comment or article which fully illuminates the situation, although it is well demonstrated. Perhaps there is not language or a familiar concept which yet suffices. A sane and experienced physicist lost 10k bet on its plausibility.