It is interesting to note the split in the green activists over wind-generated electrical power ("Wind power splits greens," Culture, et cetera.; Wednesday). The main cause of the split appears to be the harm caused to wildlife by the current design of wind generators. I agree that the current design of wind generators, with their open propellers flailing unprotected in the open air, do represent a danger to local and migratory birds and bats. In addition, I also find them not just aesthetically unpleasing, but downright ugly.

This brings in to question why this design was even selected at all. In the early part of the 20th century (1926) a man named Anton Flettner developed a wind-driven electrical drive system for ships known as the Flettner Rotor. He actually converted one ship, the Baden-Baden, as a test bed to utilize his drive system. The Baden- Baden appeared like any late-design, full-rigged sailing vessel, except that the masts were removed and replaced with two tall cylindrical towers resembling large steamship funnels. These towers were the housings for the Flettner Rotors. The rotors themselves were large columnar wind turbines that provided the energy to drive electrical dynamos, which, in turn, supplied the power to the ships' motors.

The system was tested successfully, but building a vessel utilizing the Flettner system versus building a vessel with either motor propulsion or a conventional marine steam engine was not cost- effective.

The advantages of the Flettner design, beyond the utilization of free wind, are that the design is cylindrical and can take wind from any angle without provision for a pivoting generator head, and it is fully encased in a visible housing that, if need be, can even have screens installed to prevent entry of birds and airborne debris. The housings can also be designed to be more pleasing in appearance than the current wind generators. In addition, Flettner designed his system to make use of a phenomenon called the "Magnus Effect." Flettner equipped his rotors with a small electric motor that drew current off the ships' generator system.

These motors initially imparted motion to the turbines and allowed them to spin freely, creating an effect not unlike the lift effect of an airplane wing. Air flowing around the rotor was split, and the air flowing in the direction of the turbine rotation accelerated, giving the turbine extra torque and increasing output.

Given the potential advantages of the Flettner system, I question why it appears that no one has looked in to the possibility of using the Flettner Rotor as the basis for a wind generator design.

KEN WILLIS

Ashburn, Va.