I love the question.

Don't forget, though, that "wind chill" as normally understood, is the effect of evaporation of surface moisture. If you didn't sweat you would experience very little wind chill. In fact, you may well have experienced a day when cooling was almost impossible simply because the atmospheric humidity is so high that your sweat can't evaporate. Often, these humid days are actually cooler than dry days, but feel hotter.

There is a fallacy implied in your question: that air friction heats fast moving objects. In fact the heat that burns up whizzing meteors is caused by the compression of air in front of them. They hit the atmosphere at many thousands of kilometres per hour and cause a huge compression of the air in their path, this heats up as a result.

When I first read your question I was trying to imagine a steel pole standing in a field being blasted by wind. If the pole and the wind were both at (say) 20C then there would be no cooling. Wet the pole and it would cool through evaporation. Heat the pole and it would cool through transfer of heat energy into the air (assisted by the wind).

Around trans-sonic speeds.

As an example of the problems this effect can cause, the cannon fitted to high-speed aircraft need very loose tolerances to cope with the -50C or so encountered at altitude and frictional heating which can easily exceed +100C. Differential thermal expansion must be allowed for in the design and contruction of such units. The lubricants used must also be able work effectively at these extremes of temperature.

That's interesting Brian. I'm still not quite convinced, though, that the heating is caused by friction as opposed to air compression. For a moment I wondered if they could be bundled together i.e. air compression happens because of the friction, but this doesn't sit with me.

Say you blew air over a flat surface at near-sonic speeds: would it heat up the surface to +100C? I suspect not, but I'm open to contradiction.