On Friday, September 28, 2012 8:55:30 AM UTC-4, kirk.stant wrote:
On Thursday, September 27, 2012 3:50:35 PM UTC-6, Tim Taylor wrote:



1. Most pilots don't/can't thermal steep enough and can't tell what



bank they are flying even when told how to look at the panel or look



outside the glider.







2. You already have an instrument to tell you optimum speed and bank



to fly, it is the variometer. There is no magic perfect speed to fly



that you can predict ahead of time. Depending on the thermal itself,



I may fly slower or faster than optimum for some equation. All those



factors come down to one number, maximum climb rate! I adjust bank



angle, speed, flap setting, slip, etc until I get the best rate of



climb for each thermal.



Tim, I totally agree about bank angle - steep is good! And I mostly agree on your second point, about varying a bunch of parameters to find what works best in any particular thermal. Where I disagree, probably due to less experience, is that there isn't room for better instumentation to tell the pilot what exactly his glider is doing. Min sink is min sink - it only happens at one angle of attack. That equates to one unique airspeed for every combination of bank angle and wing loading. Think of it as Mcready speed - a wonderful invention, gives the theoretical optimum cruise speed to fly, made cross country faster, etc.. and all our fancy computers give us a variety of indicators on how fast to fly, when to push or pull, audio tones, etc... Of course, a lot of us just use it as a guide and adjust our speed for the conditions at hand, since the bloody black box isn't looking out the window!



I'm just thinking that the equivalent for thermalling might be useful.



Cheers,



Kirk

66

Best climb isn't achieved at minimum sink. Usually (90%), it pays (in climb) to fly slower than (load factor corrected) minimum sink speed. The optimum is going to be very slippery -- it depends as much on the thermal characteristics, turbulence, etc. as it does on glider performance. It's this sort of abstract, complicated, multivariable, analog "computing" that humans can still do better than machines (with enough practice). Enjoy it while it lasts!

-Evan Ludeman / T8