Thanks for the notes. Don't get me wrong, I think an artificial horizon is a very great thing to have. But, just as a point of conversation, I'd be really be surprised if these things were instant-on in the sense that I was talking about. Surely the guts of the system--the AHRS sensors and processors-- have to be up and running for at least a few tens of seconds before the artificial horizon is needed. And I doubt that those few tens of seconds can take place during a spiral dive. I'd love to be proven wrong-- it would make for a very interesting in-flight video.

Seriously, how long would it take to bring the whole system up from a cold start to accurate functioning during

a) reasonably straight-line flight
b) a spiral dive

I submit that there's some advantage offered to having a self-contained turn rate indicator unit that can be powered up quickly regardless of the glider's flight attitude, as a supplement to whatever AHRS-based artificial horizon may or may not be present.

Sure, it's all a question of how far you want to go. But maybe a vario-incorporated artificial horizon plus a stand-alone instant-on (or rapid-on) turn rate indicator with independent self-contained battery power is a reasonable alternative to a purpose-built artificial horizon instrument, at least for the purpose of strictly emergency use.

Food for thought...

S