Kestrel

Although not much chop as a photo, here's a shot of 'our' local kestrel, as it was buzzed by another smaller bird who was obviously not impressed at the turf the kestrel had chosen.


I'd been watching it as it hovered, in a stiffish breeze, and for seconds at a time, it didn't flap the wings at all. That's an amazing effort, balancing the four forces* so perfectly. (It's equivalent to a person walking on a medicine ball while it rolls down a bumpy hill - blindfold (you can't 'see' air, remember?).) Despite all the much vaunted capability of modern aircraft, fly-by-wire computers, variable geometry et al, we don't have anything that can do this without a lot of pilot skill or using a lot of energy - a lot more than muscle power for certain.

James

*Lift, Thrust, Weight & Drag - here.