811 Fins

[GM]

........W.E. did have fins in sectoral horns that pre-dated the 811.

Actually, the few I've seen were true sectoral horns, i.e. the 'vanes' extended all the way back to the throat to create a cast multi-cell whereas the later 311/511/811 appear to be a manufacturing compromise to at least get some of the earlier design's HF gain, though over a narrower arc.

GM