Maybe I need an ornathologist

[stonemullion]

Perhaps someone can help with a puzzle that's been on my mind for some time:-


I'm at constant altitude and constant airspeed into a strong headwind. My ground speed is zero. As I understand it in this scenario lift equals weight and thrust equals drag.


The thing is I've watched Kestrels doing this many times at Reigate Hill and since even a bird must have some drag I can only conclude that a Kestrel has a hidden means of propulsion.


Am I missing something? (apart from a life that is)

[Mark 1]

The thing you're missing is that the bird needs an updraught to hover without any work input.

It doesn't take much, just the effect of a small ridge, up-slope or building and a steady breeze.

[exuw]

You're also missing a dictionary, mate.

(Sorry - couldn't resist.) :)

[Airbanda]

I think updraught is the answer given OP's observation site. A 'windhover' over flat land is constantly exercising it's wings.

[Intruder]

There can be updrafts over flat land. I've done a lot of soaring over south Texas...