Eric Drexler's solar-sail patent was the only actually-educational patent I've ever seen, myself. https://patents.google.com/patent/US4614319 https://patents.go

Eric Drexler's solar-sail patent was the only actually-educational patent I've ever seen, myself. https://patents.google.com/patent/US4614319 https://patents.google.com/patent/US4614319 (Hm, I remember it as more detailed -- maybe I was remembering a tech report instead. But still this looks like reasonable English.)