alternative McCready theory and variometers

On Monday, October 27, 2014 3:55:21 AM UTC-4, Tibor Arpas wrote:
On Sunday, October 26, 2014 1:54:55 PM UTC+1, John Cochrane wrote:


The confusion is in the name. It says "speed to fly" mode, which gives off the air of listening to it and doing huge pulls and pushes. Maybe we should rename it "listen to the air in cruise mode" which is how it works.

This setup works best if the vario units remain in vertical knots, i.e. that the sensitivity of the vario is the same in cruise and climb mode. If you hit 2 knots of lift a previously silent vario should always make the same "2 knots" sound. Of my varios, the 302 and clearnav do that. The LX, while otherwise a very nice vario, is much more sensitive to ups and downs in cruise mode than in climb mode, rendering it pretty useless for this sort of flying.


Exactly! I would love to be able to listen to the air in cruise but the LX and ILEC sounds make little sense to me, I agree they are useless.

And If I understand you correctly the 302 and ClearNav then have what I called "relative netto" audio. (relative netto indicates the vertical speed the glider would achieve IF it flies at thermalling speed)
But how much is it skewed with MC settings?

On a given thay after a couple of thermals I have THE SOUND I want to hear in the next thermal in my mind. If in cruise I hear something ressembling that , or better, I'd pull up into the thermal - perfect.

I've had the chance to play around extensively with my ClearNav Vario using audio Speed To Fly vs. Relative Netto. For the reasons stated by others (i.e. moving away from chasing the STF and averaging over a longer period), I've found Relative Netto to be much, much more useful. If I'm flying along at 80 kts and I fly through a real solid core, I want to know that I'd be able to climb at 4kts if I stopped now. That's useful data. I already have a numerical speed to fly indication (e.g. "Fly 80kts") which I glance at to make sure the speed I'm using is "roughly right". That's in many ways similar to the wide STF dead-band that others are using.

I don't remember which of the top US national pilots said this, but his comment was something like: I have two speeds for a given day: Fast and Slow. Those absolute numbers change on any given day (ie. on a booming day, fast might be 90 knots and on a weakish day it might be 70kts), but I don't really worry about a lot of increments in between. Makes sense to me.

P3