Fiets, I'm not arguing that they did or did not produce drag. I'm sharing the fact they were single wire does not mean they were AC or DC. This is simple engineering. It's also quite basic that one kind is not more efficient than the other, save a slight increase in drag with brushes. But if they were DC they SHOULD have had some provision for brush service.

With modern design techniques drag and efficiency should have become greatly improved even for the ancient design concept of an AC machine, but this has to do with engineering and materials science rather than the principles of AC or DC operation.

You can stick to your guns incorrectly for as long as you like, I'm not going to waste a lot of time on it.

You can test AC v. DC with a cheap Radio Shack multimeter. If you can spin the gen and it will only show a measurable DC voltage, it's a DC machine. Period. If you can only read an AC voltage, it's an AC machine. Period. It's the only test that actually makes sense. If you can show a photo if the one that tests as DC and your results you might have a case. But what you've said so far is not correct, both regarding wiring and efficiency.

Glad you like your hub dyno! I like my SON, too. I'm looking for another one for Mrs. Road Fan's bike.