On Friday, April 8, 2016 at 1:17:10 PM UTC-7, son_of_flubber wrote:
WRT OP's question. I'd guess that Butterfly has the sensor input to compute AOA. I don't know if they have the computation resources to complete the calculation in the real time constraints (but they will in the future generation of chips). I don't think that offering this functionality would increase their revenue. It would increase their costs, in particular their liability costs. Has anyone ever been sued for an inaccurate vario reading?


The video raises other questions:

At :30 in the video "he steepens the bank, stalls and spins, even though the aircraft was well above the published stall speed".

I understand that steeper bank increases load factor and that increases the speed at which critical AOA is reached. What I don't understand is why do power pilots use such low Va (such that an increase in bank commonly causes a stall/spin!).

Is it because the stall speeds are so much higher in a power plane relative to the lengths of the runways? So a power pilot needs to fly slow, close to stall speed, to have an acceptable runout?

I also notice in power flying forums that the notion of increasing Va proportional to wind/gust conditions gets little attention.

I noticed power planes fly slow Va (a low multiple of their stall speed), shallow glide slopes and shallow bank turns. Gliders do the opposite. Why?

I'm curious because I'm planning to take some lessons in a tailwheel power Kitfox, and I'd rather not pay to argue these points with my CFI.

Please research the V-G diagram, it describes the concept of Va, which is not what I think you're referring to. The Va speed is not selected by the "pilot" it is a construct of load factor, the angle of attack for a stall(both positive and negative), and the speed at which it occurs. It is often described as the speed at which a full control deflection (usually with regard to pitch) will result in a stall occurring before the load factor reaches a value that will damage the aircraft. Recent studies have shown that the other controls (for Yaw and Roll) may in fact cause damage below the Va speed.

Here's a pretty good Video:
https://www.youtube.com/watch?v=ZjBXAosfcco