Nerdy analysis 
That is very good. Thanks for posting it.
I know this sounds “smart ar*se” but one doesn’t need to do analysis to see that a go-pro thus mounted is going to be totally terrible aerodynamically, as well as suffering from flutter (visible as “jello” in the footage) because its “stick” mount is so flimsy (it is probably ok for ski movies etc).
This is why I went for the X3000 which has much better aerodynamics. It still needs to be firmly mounted to prevent flutter.
Quite a lot of people have been around this “jello” loop and very few have solved it with the go-pro type cameras and the go-pro mounting hardware – even when screwing the camera firmly to the wing strut of a Cessna.
Here is a short screen capture of a video I made of one of my trips. Made with a Go-Pro (Hero8), mounted underneath the (foot)step of a DA40. No editing done, just the raw cut. No “jello” and a very stable recording.
what are the latest recommendations for actions cams to mount externally?
looking for high frame rate (60fps or 120 fps), good mountability, good battery life, ideally some ability to remotely turn on and off.
I researched the GoPro Session, but it seems there hasn’t been a new release in some years now…
This youtube (two) may be a good intro. Actually more of an in cockpit photography primer so apologies off topic.
The original GoPro Session is a nice camera for outdoor mounting, because it has a relatively small frontal area, so a super-rigid mount is not as essential as it is with all the other GoPro style cams. I know a guy who has one on a Jetprop and it shoots just fine at 270kt TAS
The action cam business has ground to a halt. Sony have dropped it (the X3000 seems to be the last one), GoPro nearly went bust, the upper end is covered by appropriately pricey high perf models (used a lot on drones), and the others (Garmin etc) seem to have given up. IMHO too many people jumped onto the “do movies of everything” bandwagon and as Youtube filled up with mostly awful material, people got bored.
