Nitpicking: the image of the guy is labled wrong. He's not holding a speed ring, but a crossection of a wing spar https://en.wikipedia.org/wiki/Paul_MacCready#

Nitpicking: the image of the guy is labled wrong. He's not holding a speed ring, but a crossection of a wing spar https://en.wikipedia.org/wiki/Paul_MacCready#/media/File:Paul_maccready.jpg https://en.wikipedia.org/wiki/Paul_MacCready#/media/File:Pau...