AGAINST THE WIND

If this doesn't start an argument nobody's listening. It's among the least explicable phenomena in soaring, yet one that many pilots may have never noticed.

Would you believe that gliding into the wind in lift will net more height than going the opposite direction seconds later in the very same air? Yes, zero sink on a downwind pass can become a gain of height to windward, and zero on a windward pass might yield a loss downwind – all at the same airspeeds! I didn't believe it either at first, but repeated test runs (admittedly non-scientific) over many years leave no doubt. It occurs in soaring conditions that offer consistent – not to say constant – lift accessible in level flight both upwind and downwind. Examples include shearlines of several kinds and angled ridge lift with headwind one way and tailwind the other. Wave too? Maybe, but that's always hard to tell.

This is no hypothesis, mind you, only empirical observation. The hope is, you'll gather some data and hatch a theory of your own. But because I can't resist noodling, here's a little thought grenade for openers. Aerodynamic fundamentalists might wanna look away, I'm about to pull the pin.

Stipulate first that air rising while also drifting in steady wind does so diagonally. Molecules striking an airframe approach that point from an oblique vertical angle, acute while tacking one direction and obtuse the other. (Each molecule has its own inertia, right?) What if, somehow, this distinction imparts a subtle relativity between pitch angle and angle of attack? What if the wing cares about those angles differently from other parts of the aircraft?

And what role might CG play?

Yeah yeah, Einstein on a train, the infamous downwind turn and all those other conundra. Thing is, they've all been analyzed and explained! So far as I know, this one hasn't. You can shake your head and never think of it again, and maybe no one will ever explain it, but the effect will still be REAL whether we understand it or not. It's saved my skin lots of times and I want to know more. So do us a favor. When finally you do learn the secret, please don't keep it.