Netto

On 7/31/2011 9:43 AM, John Sinclair wrote:
At 17:19 29 July 2011, bish wrote:
Hi

This question has probably been ask many time!
My new to me LX 7000 offer the choice of Netto or Relative netto for
the vario needle

During cruise with pure Netto selected the needle will be down most of the
time. When you go through a 3 knot thermal your display will go from 600
down to 300 down, hard to realize you are in a 3 knotter. If you select
relative Netto, the display will show the climb rate you will get if you
slow down to thermal speed, or 300 up! Much easier to read and understand.
I never use anything but relative netto.
JJ


Because JJ's description of "netto" apparently conflicts with what I posted
earlier, this may be a good place to define "netto" (as I've learned/used
it...not all soaring descriptions are universal).

To me, "netto" means a vario display indicating the actual vertical air
motion, relative to the earth's surface...i.e. 'net air motion' once the
glider's own speed-dependent sink-rate contribution has been
subtracted/eliminated from the picture. In other words, 'my netto display'
always indicates actual air motion, independent of glider speed (the 'glider
speed' bit being the 'compensation' part). No interpretation needed - that's
the beauty of it, so far as my brain is concerned. And that's also why the
speed ring doesn't require the pilot to iterate in on the speed to
fly...because the glider's increasing sink rate with increasing speed has
already been subtracted out of the display. Hence the vario needle *always*
points to 'absolute air motion,' and in consequence to the whatever speed to
fly your ring setting calls for.

Everything in my earlier post presumed 'my netto definition.'

It's entirely possible the LX 7000 folks use a different definition; if they
do, you're on your own!

Regards,
Bob W.