How do I rig a netto variometer

On Feb 15, 10:39*pm, Scott Alexander
wrote:
This is going to be much more productive if you tell us what make,
model, type (mechanical? Electric? Pellet?) vario you're talking
about.
John Cochrane

Thanks JC appreciate you chiming in.

It is mechanical, has two ports on the back, one says static, other
capacity. *Emblem on front has a A W written on it. *I know it's more
complicated than just plugging in the static line and the capacity
line. *Not wanting to use it as a simple vario. *I like the netto
idea.

It sounds like you have a regular mechanical vario (Winter perhaps?).
Netto behavior is obtained by putting a calibrated leak from your
capacity to the static line, or a TE netto by leaking to the TE line.
Reichmann describes setting up a netto in Cross Country Soaring.

I'll try some ascii art:

+----------+
| vario |
| +----------+--- TE probe
| | |
| +-----+---X
+----------| |
|
capacity

I hope that comes out OK. The X in the line from the capacity bottle
to the TE line has to have a capillary tube in it. Start with a
longer
tube and cut it down until the vario reads 0 in still air. Remember
also
to greatly separate this vario from others on the same TE line; you
will get cross talk between the varios so that none of them read right
otherwise.

What is simpler is to have one of the modern fancy varios that
will give you netto readings if you want. My LX160 (not very
modern, really) will display netto during cruise if it's configured
properly. The various speed to fly varios (B50, C302, VW1020, LX,
etc.)
give you readings of what the air is doing compared to your
polar.

-- Matt

On Feb 15, 8:58*pm, mattm wrote:
On Feb 15, 10:39*pm, Scott Alexander
wrote:

This is going to be much more productive if you tell us what make,
model, type (mechanical? Electric? Pellet?) vario you're talking
about.
John Cochrane

Thanks JC appreciate you chiming in.

It is mechanical, has two ports on the back, one says static, other
capacity. *Emblem on front has a A W written on it. *I know it's more
complicated than just plugging in the static line and the capacity
line. *Not wanting to use it as a simple vario. *I like the netto
idea.

It sounds like you have a regular mechanical vario (Winter perhaps?).
Netto behavior is obtained by putting a calibrated leak from your
capacity to the static line, or a TE netto by leaking to the TE line.
Reichmann describes setting up a netto in Cross Country Soaring.

I'll try some ascii art:

+----------+
| *vario * |
| * * * * * +----------+--- * TE probe
| * * * * * | * * * * * *|
| * * * * * +-----+---X
+----------| * * *|
* * * * * * * * * *|
* * * * * * * *capacity

I hope that comes out OK. *The X in the line from the capacity bottle
to the TE line has to have a capillary tube in it. *Start with a
longer
tube and cut it down until the vario reads 0 in still air. *Remember
also
to greatly separate this vario from others on the same TE line; *you
will get cross talk between the varios so that none of them read right
otherwise.

What is simpler is to have one of the modern fancy varios that
will give you netto readings if you want. *My LX160 (not very
modern, really) will display netto during cruise if it's configured
properly. *The various speed to fly varios (B50, C302, VW1020, LX,
etc.)
give you readings of what the air is doing compared to your
polar.

-- Matt

Dick Ball wrote an article about calibrating varios a number of years
ago that has a very nice section on hooking up netto systems. I have
a PDF copy if you want to contact me by email.

Thanks,
Craig