Sunday, March 12, 2023

Shenanigans with Jimmy

I think this is the first time I mention my friend Jimmy O'Neal on this blog. Jimmy is an Airball early adopter and development partner, has been an absolute joy to work with. He is a stupendous backcountry pilot, outdoors and motorsports enthusiast, and overall great dude, and over the past 6-9 months has really helped get Airball to the next level. He was the one who asked for a mini-display on the glareshield, and in so doing put us on the path to a really awesome product vision.

Last month, I did my longest XC yet, flying from San Jose to Camarillo to hang out with Jimmy, go flying, and try things out on his RANS S-20. Here's are a few interesting workshop photos:

In particular, note that we mounted the Airball probe on a wingtip pole. We were hoping to get even farther out of the propwash, and also into a more convenient location for a "wired-in" installation since most wingtips have some wiring going to them already.

We found out that the airflow about a foot to a foot and a half ahead of his wingtip is moving spanwise outboard a bit, such that the relative wind points outboard by about 5 or 6 degrees. We scratched our heads and could not figure it out....

One go-to explanation is that this is the upstream effect of the wingtip vortices. Which makes sense, right? In a subsonic flow, we expect upstream effects, so why not? Except that we would then expect the magnitude of this effect to change with the amount of circulation produced by the wing, i.e., the angle of attack. And yet Jimmy observes no such effect (or if it's there, it's too small to notice). I am totally weirded out, and the usual "call a scientist" response has yet to yield a comprehensive explanation.

There was a lot of lovely scenery on my XC! I'm hoping to visit again soon and do more aviation experimenting!

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