Relative is airmass less glider sink in a typical thermalling turn.
About 2 knots is right for most modern gliders. Varies with wing
loading and altitude(density) which is computed in properly designed
modern varios.
In summary:
total energy compensates for rate of change of airspeed due to pilot
commanded attitude changes (unfortunately also rates of change of
airspeed due to horizontal gusts)
netto(airmass) adds the glider sink rate at any speed to this reading
so what you see is just the airmass vertical speed. Makes it easier
to pick the best path through the air but when you encounter a
thermal you might like to climb in, the vario reading must have
around 2 knots subtracted to figure your likely rate of climb while circling.
Relative just offsets the netto downwards by that 2 knots or so, so
at all times in the cruise the vario will read the rate of climb you
would get if you circled now. You can still pick the best path
through the air easily using this but we help by having a green light
that lights up when the airmass is going up in the B500/B600/B800.
All of these things are designed to reduce the mental processing
required to pick the best path through the air which gives you more
time and attention span to looking further out to assess the total situation.
More under articles on our website www.borgeltinstruments.com
The above mentioned horizontal gust problem is THE major problem in
total energy varios. Fortunately I've figured out how to do total
energy without running in to this. Sensor testing continues.
Mike
At 06:34 PM 18/03/2013, you wrote:
Dear Tom and others,
Sort of related ....
Do you operators at/near the top in Nationals favour using while
cruising a vario set to relative mode, ie showing all the time what
happens if the glider were slowed below 60 knots, in effect airmass
less glider rate of sink at 60 kts?
Cheers
Roger Druce
On 18/03/2013 6:12 PM, tom claffey wrote:
For myself, I am not interested in any variometer cruise modes so
am content with my B400 and B40 in our second glider. Interestingly
both Bruce Taylor and myself seem to muddle along OK with sink tone disabled!
;) Tom
From: Mike Borgelt
<mailto:mborg...@borgeltinstruments.com><mborg...@borgeltinstruments.com>;
To: Discussion of issues relating to Soaring in Australia.
<mailto:aus-soaring@lists.internode.on.net><aus-soaring@lists.internode.on.net>;
Subject: Re: [Aus-soaring] Intermediate/short term goals
Sent: Sun, Mar 17, 2013 10:25:08 PM
Mark,
The idea is to fly in air that's going up. You should not be
hearing the sink sound much. If you are it is time to go somewhere
else and be in cruise mode while doing this when you won't hear the sink sound.
Mike
At 12:37 AM 18/03/2013, you wrote:
On 17/03/2013, at 11:08 AM, Mike Borgelt
<mailto:mborg...@borgeltinstruments.com><mborg...@borgeltinstruments.com>
wrote:
> Yes, staying out of sink is very important. Most of us do it
poorly. It is extremely important when trying to center weak and
broken thermals which is why I like a vario with a sink sound as
it provides full information on the bad air as well as the good
air while doing this.
And on that note, I'd like to congratulate you for the B50, which,
as installed in AUGC's H205
Club Libelle, had the most inspiringly depressing sink sound I've
ever had the misfortune to
hear.
Excellent work, well done :-)
- mark
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mob: 042835 5784 : int+61-42835 5784
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To check or change subscription details, visit:
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Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
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