Energy

[[email protected]]

Hi
I am looking for a text on total energy, netto and relative netto.
Specifically on why use one in particular in climb or cruise on my vario?
Which setting gives a better picture of the condition you are in?
Thank you
Gilles

[Dan Marotta]

I haven't read it on over 30 years, but check _Cross Country Soaring_ by
Helmut Reichman.

On 8/1/2017 7:28 AM, wrote:
> Hi
> I am looking for a text on total energy, netto and relative netto.
> Specifically on why use one in particular in climb or cruise on my vario?
> Which setting gives a better picture of the condition you are in?
> Thank you
> Gilles

--
Dan, 5J

[Bruce Hoult]

On Tuesday, August 1, 2017 at 4:28:47 PM UTC+3, wrote:
> Hi
> I am looking for a text on total energy, netto and relative netto.
> Specifically on why use one in particular in climb or cruise on my vario?
> Which setting gives a better picture of the condition you are in?
> Thank you

It's just a theoretical progression of making the vario easier to interpret.

The question each vario answers:

basic: how fast are are we climbing or descending? (static pressure)
TE: how fast are we gaining or losing energy? (add in airspeed)
netto: how fast is the air mass rising or sinking? (add in the glider's polar)
rel netto: how fast would we climb if we circled? (add in circling polar)

[Scott Williams]

On Tuesday, August 1, 2017 at 8:28:47 AM UTC-5, wrote:
> Hi
> I am looking for a text on total energy, netto and relative netto.
> Specifically on why use one in particular in climb or cruise on my vario?
> Which setting gives a better picture of the condition you are in?
> Thank you
> Gilles

I agree with Dan,
Herr Reichman,
Secrets of the Universe!
Good Lift,
Scott.

[Alex[_6_]]

Use total energy for climb and relative netto for cruise. Here is why:

A total energy vario is difficult to interpret at high speeds. If you go fast it will show plenty of sink because your polar sink increases with speed.. If you pass through a weak thermal it will be masked by all the polar sink in your vario reading.

The netto vario will solve the issue by removing your polar sink for speed you are currently flying. In dead air the Netto vario should read zero, no matter how fast you fly. A netto vario can be a bit awkward because a positive reading does not necessarily mean you are climbing - it just means the air is going up.

A relative netto solves exactly this problem. It takes the netto value and inserts your polar sink for your thermalling polar. In dead air it should be reading around minus 0,6m/s for your average high performance glider.

While thermalling, relative and total energy should be reading the same value. The whole point of netto and relative netto is getting good indicator of climb and sink at cruising speeds.

Whether you prefer netto or relative netto is a matter of taste. A netto vario will make it easier to read minute energy lines at a glance whereas relative netto is closer to what you are accustomed to.

[[email protected]]

Le mardi 1 août 2017 09:28:47 UTC-4, a écritÂ*:
> Hi
> I am looking for a text on total energy, netto and relative netto.
> Specifically on why use one in particular in climb or cruise on my vario?
> Which setting gives a better picture of the condition you are in?
> Thank you
> Gilles

Thank you all
Gilles