On Wed, 16 Jul 2008 14:35:28 -0700, Ian wrote:

On 16 Jul, 20:37, Bruce wrote:

So why install mechanical varios in a new high tech glide? Convince me.

How well do electric ones react to nearby lightning bolts? Apart from
that, isn't it an awful lot easier to fit a mechanical vario than it
is to fit a complete second electrical system?

Depends on which type you pick for your backup vario.

I have a single electric system fitted. I use an SDI C4 as my main
vario and a Borgelt B.40 as backup. Normally the electrical system drives
both varios, but the B.40 has its factory-supplied backup system. A 9v PP3
strapped to it and it has a three position power switch (Ext-Off-Int) to
select its power source. As the B.40 is said to run for about 24 hours on
a PP3, its as likely to get me home as a mechanical unit. I swap the PP3
annually.

The B.40 was no harder to install than a mechanical backup, eliminates
capacity vs pressure sensor problems and is safer in backup mode than a
mechanical because it is an audio vario.


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martin@ | Martin Gregorie
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org | Zappa fan & glider pilot