alternative McCready theory and variometers

On Monday, October 27, 2014 9:24:05 AM UTC-4, Martin Gregorie wrote:
On Mon, 27 Oct 2014 00:55:20 -0700, Tibor Arpas wrote:

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?

Not quite. 'Netto' mode tells you what the air mass is doing by
subtracting the glider's polar from the vario indication. When My SDI C4
vario is in cruise mode it bases its STF indication (both display and
sounds) on what it thinks the air mass is doing. I imagine that the 302
and Clearnav do much the same.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

302 audio and pointer give "relative netto" (I dislike this term, it should be "relative vario", but I've lost that battle) which is "the climb rate that you would achieve if you slowed to thermaling speed and adopted a 45 degree bank". Roughly speaking, it is netto - 2 knots, but the calculated value depends on polar, density altitude, wing loading & bugs. ClearNav CNv offers three cruise modes for audio, two for the pointer. Audio choices are relative netto, netto or STF. Pointer choices are relative netto or netto.

STF audio provides useful information, but I tire of the "chatter". I find I prefer relative netto modes, with sink tones off. It does mean that I need to scan the panel a little more often in cruise.

Evan Ludeman (on behalf of CNi)

On Monday, October 27, 2014 10:03:35 AM UTC-4, Evan Ludeman wrote:
On Monday, October 27, 2014 9:24:05 AM UTC-4, Martin Gregorie wrote:
On Mon, 27 Oct 2014 00:55:20 -0700, Tibor Arpas wrote:

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?

Not quite. 'Netto' mode tells you what the air mass is doing by
subtracting the glider's polar from the vario indication. When My SDI C4
vario is in cruise mode it bases its STF indication (both display and
sounds) on what it thinks the air mass is doing. I imagine that the 302
and Clearnav do much the same.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

302 audio and pointer give "relative netto" (I dislike this term, it should be "relative vario", but I've lost that battle) which is "the climb rate that you would achieve if you slowed to thermaling speed and adopted a 45 degree bank". Roughly speaking, it is netto - 2 knots, but the calculated value depends on polar, density altitude, wing loading & bugs. ClearNav CNv offers three cruise modes for audio, two for the pointer. Audio choices are relative netto, netto or STF. Pointer choices are relative netto or netto.

STF audio provides useful information, but I tire of the "chatter". I find I prefer relative netto modes, with sink tones off. It does mean that I need to scan the panel a little more often in cruise.

Evan Ludeman (on behalf of CNi)

I mis-wrote about the C-302. One can select TE or Netto modes for cruise in the PC/PDA configuration program, but I suggest that you probably won't like the results. I found these modes buggy and prone to indicating thermals that didn't exist. In relative netto mode, the 302 is a decent vario, and I still use one for backup.

-Evan