On Saturday, September 29, 2012 10:49:36 AM UTC-4, kirk.stant wrote:
Evan,



I wonder if there has been a study done on tradeoffs between sink rate and circle size. Of course, the problem is that thermals are not very consistent...



And just to make things clear, I also vary my speed and bank angle until I find what I think is the best climb.



But I disagree that the best speed cannot be somewhat quantified. Stall is obviously the slowest - and that speed changes based on at least two variables. How far above stall - up to CL max, or perhaps even faster in a tight, turbulent thermal at 60 degrees of bank) is optimum? Without knowing what stall speed or min sink is, you are guessing or relying on experience or glider feedback. If you are not experienced, or your glide does not give much feedback, you are left with guessing - probably on the high side because of all the "stall spin" stories you have read here on RAS.



So if it is easy to display, in real time, what stall/min sink/Cl max is at your current flight condition, that data helps calibrate your "experience" quicker.



I find it amusing that we are raving about new technology varios and debating the relative merits of PNA thermal centering displays, while the airspeed cue we display in the cockpit to use all the new info is still just a mechanical airspeed indicator. Some gliders talk a lot, so that monitoring the airspeed is not very necessary. Others, like my ls6, have very little change in feel from the stall up to ridiculously high thermalling speeds - only the nose position relative to the horizon is a givaway to how fast I'm flying, once trimmed up. So the technique of pulling till you feel the stall buffet and easing off doesn't work very well!



Anyway- interesting discussion.



Cheers - gotta go give a glider ride.



Kirk

66

The LS-6 is a much loved glider, what gives? My 20 gives plenty of feedback. Here's how I train T8's pilot: instrument covers. Climb to top of convection, cover everything but altimeter and averager, no audio. Great for back to basics.

As far as calculating the optimum way to climb, we do trade studies several times a year. We call 'em "contests" :-). I find them effective.

Seriously, given an accurate mathematical description of any given thermal, any given sailplane, you could of course, find an optimum. That's been hashed out for simple cases in Reichmann, other places. It's probably all valid, but it puts me to sleep.

As far as Nav instruments and all the rest... well, I've tried a bunch. On the ClearNav team since June (end user and part time associate, just to be clear). Like that a lot. I've tried the thermal assistants in various devices to see what they do. I found one of them useful for a while a couple of years ago (WinPilot) until I discovered my real problem was a buggy, jumpy electric vario (with smooth nmea output so the thermal assistant worked fine). With the vario problem solved I no longer have any use for that stuff.

What I like about the CN is speed of info acquisition. Glance, and done. It doesn't try to tell me how to fly, I'm not going to have to hassle with anyone about an AHRS disabled mode, it doesn't show me pictures of off field landing sites, it doesn't have the amazing in flight statistical analysis of thermals and wind that some other devices do. While I found the statistics useful (or thought I did)... the statistic I really like is that is that I fly one helluva lot better in competition on CN than I do on anything else. I don't think that was a fluke. It was simply figuring out a Nav setup that doesn't get in my way.

-Evan Ludeman / T8

PS Cheers, got to go to a birthday party (it's raining, no loss :-))