Andy Blackburn wrote on 9/5/2018 9:44 AM:
On Wednesday, September 5, 2018 at 9:20:53 AM UTC-5, krasw wrote:
keskiviikko 5. syyskuuta 2018 8.22.14 UTC+3 2G kirjoitti:
What I know is I don't have a Kalman filter going in my head: but I do have a butt which feels vertical acceleration. If it doesn't tell me I am going up, I discount the screaming vario.
Tom
The wing transforms horizontal gust into vertical, and your butt gets it wrong.
That's true if you only use your butt and not you're inner ear to sense the pitch rotation. A horizontal gust on the nose excites the phugoid (dCm/dV) and pitches the nose up. Vertical air movement excites the short period (dCm/dalpha) and pitches the nose down. A thermal you can climb in is likely to produce a more prolonged surge than a vertical gust. The exact magnitude of these effects depend on the specific aircraft aerodynamics and things like cg location.
Tom, you may not have a Kalman filter in your head, but you are a neural network - kind of by definition since your brain is made of connected neurons.. Pattern recognition is how we all interpret the "feel" of thermals. It helps a little if you can decompose some of the bigger dynamic effects, but there's a lot going on with lift, gusts and aircraft dynamics - as UH points out. I think a smart vario ought to be able to sort out some of these dynamic interactions better than simple total energy compensation. I figure with cheap gyros and accelerometers they would be doing a lot of this already, but I don't know how far it's gotten.
Again, apologies if I didn't completely accurately describe the engineering of aircraft dynamics. I think this is roughly correct.
I'm thinking a horizontal gust on the nose is similar to a higher airspeed, and
with the glider elevator set for the lower airspeed, a pitch-up would occur.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm
http://soaringsafety.org/prevention/...anes-2014A.pdf