Key S100 Variometer Settings -

[Mark Morgan]

Hello all - would like to compare my key S100 variometer settings to others who feel they have their variometer working well. 

Vario Parameters

Needle Filter (sec) - 2.0
Sound Filter (sec) - 2.0
Netto Filter (sec) - 4.0
Relative Filter (sec) - 4.0
SC Filter (sec) - 4.0

TE Compensation - 0 (I am setup for pneumatic comp with using the TE probe)

Graphics Parameters

Vario Needle - Relative
SC Needle - Relative

Sound Parameters

Sound Shape - Harmonic
Vario Audio Mode - Digital Pos Only
SC Audio Mode - Relative
Dead Band (kts) - 2.1

By no means do I consider my settings optimized.  Curious to see how others are set up.  Paul Remde was kind enough to send me his settings which are a little different than above.  I will be testing my setup with Paul's setting soon.  

Also on my pneumatic compensation, my TE line is split just before the S100 and one line is feeding a Winter mechanical vario.  Some skilled glider pilots have shared that is a bad idea, since as mechanical vario creates "noise" in the TE line that causes some confusion for the S100.  Would love to hear comments about this as well.  

If I get a good response to this email - I will put a comparison table together and share.  

Thanks, 

Mark Morgan

WK

[christopher behm]

I'm interested in participating, but my glider is 130 miles away and not sure when I'll get to the S100.

I'll try to remember to check my settings when I fly next though. 

I think that my Winter vario also short splits the feed from my TE probe, but I'll have to look also. 

Along that topic, is there an agreed upon length that should be used between the split and the two varios?

My canopy and panel front hinge, and I'm hesitant to try to add another line through the pivot unless I'm going to be doing something there in the future anyway. 

If someone knows about that length, please advise. 

My S100 seems to work good enough for me, although I'm no expert!

Kind regards 

Chris Behm

N304DD

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From: lxnav-us...@googlegroups.com <lxnav-us...@googlegroups.com> on behalf of Mark Morgan <avnm...@gmail.com>
Sent: Sunday, October 5, 2025 1:18:36 PM
To: LXNav Soaring Glider Equipment User Discussion Group <lxnav-us...@googlegroups.com>
Subject: [LXNAV-user-group] Key S100 Variometer Settings -

 

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[Ludovic Launer]

Hi

Needle Filter: 3.0

Sound filter: 2.0

Hawk Wind variance: 0.05

Hawk avg. hor.: 30.0

hawk Wind avg. ver.: 20.0

SC tab: 0.5

Integrator: 20

Auto SC: Off

Smart vario filter: 1

Netto Filter: 3.0

SC Filter: 3.0

Relative Filter:3.0

Graphics:

Vario needle: Vario

SC needle: Relativ

Sounds:

Linear positive

Also on my pneumatic compensation, my TE line is split just before the S100 and one line is feeding a Winter mechanical vario.  Some skilled glider pilots have shared that is a bad idea, since as mechanical vario creates "noise" in the TE line that causes some confusion for the S100.  Would love to hear comments about this as well.  

Never heard of that...and I don't really understand why that would be the case. Curious to hear some explanation on why that would be the case.

 Regards

Ludovic

[Tom Dukerich]

Here are my differences only.  It has been a long time since I set it up and I do not recall how my settings were chosen:

Vario Parameters

Sound Filter (sec) - 1.7
SC Filter (sec) - 2.0

Graphics Parameters

Vario Needle - Vario

Sound Parameters

Sound Shape - Sinus
Vario Audio Mode - Linear Positive
SC Audio Mode - SC Mixed

[jpg...@gmail.com]

If the electronic vario uses pneumatic TE then don't T-piece the TE tube to both that and a mechanical vario close to the instruments.   Avoid it or mitigate it by dividing the TE pneumatics as far aft as possible - or use electronic TE.  A mechanical variometer uses a capacity flask to measure the rate of pressure change. An electronic variometer uses a pressure transducer with a much smaller volume.  Close connecting these two very different systems will cause pneumatic flow between the instruments and pressure interference.

[MH]

How far in tube-length away from the varios should the t-piece be to avoid pneumatic flow between the instruments?

MH

[cdeerinck]

I don't think there is an "agreed distance".

It's important to be aware that a mechanical vario is in effect a controlled leak.

So when air pressure goes up, the mech vario "steals" a little bit of that pressure.

When it goes down, the mech vario "puts back" a little bit of that pressure.

It does this ALWAYS.  The more sensitive the mech vario is, and the larger it's capacity flask, the more  this effect shows up.

So in general, follow these rules:

1) If at all possible, don't put anything else on the same tube as a mechanical vario

2) If #1 is not possible, make the split as far from the mechanical vario as possible, to reduce this effect.

In my personal opinion, the length won't have much effect on reducing the error introduced by the mech vario.

In theory, it should due to resistance of air moving through the tube, but as we know, that resistance is minimal.

A 3rd option is to put a restrictor on the mech Vario, so it behaves more like a smoothed average, as that would reduce the interference.

Assuming that the mech vario is a backup to the primary electronic vario, consider not having the mech vario be a TE vario at all.

Why mess up your primary vario,  to have a good backup that you rarely use?

Anyway, hope this helps.

[Chris Behm]

Interesting thoughts, Chuck. I have to say that I agree with you.

I have in my plane a "switch" (which I think is a "Y" valve, actually) for selecting the source for static, and this is so that if when dumping water, the ports on the side of the tail boom get plugged, I will still have an alternate good source of static (inside the cockpit, I believe it is).

Might be an idea to be entertained to do this for the TE going to either vario?

Thoughts? More complex plumbing and another bump in the pneumatic road?

Regards,

Chris

[Ron Sanders]

The last paragraph in this post is in my opinion very very sensible.

I have not used a pneumatic vario for the last 40 years and have never ever missed it.

Ron S

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[Jim Staniforth]

For years I've preferred the distance to the mechanical vario to be measured in kilometers or nautical miles.

The crosstalk problem leaves with the mechanical.

TE and static sources on the vertical fin (or if you're crazy enough and remove the stab cautiously, the horizontal stab) seem best for keeping water ballast out.

Jim

[John Ferguson]

Some theoretical and practical advice from Ilec on the subject of TE compensation and crosstalk

Knowledge – ILEC GmbH

Bsic advice for TE split is as far back to the probe as possible, otherwise behind the seat pan.

John

[John Ferguson]

Should have said ... if possible do not mix pressure and flow instruments, you are fighting a losing battle on that one and the advice aims to reduce not remove the influence of flow and pressure.

[Jeff Stetson]

My Ximango touring motorglider came from the factory with a valve that switches the S100 vario between the TEK (tail mounted) and Static (fuselage mounted ) lines. I presume, perhaps incorrectly, it's due to the possibility of damaging a mechanical vario from pressure pulses coming back from the prop. Regardless, I find it handy, especially when under power, acting like a VSI but with much better accuracy and faster response. 

[Robert Trumbly]

My DG 400 has a switch also? I thought all motogliders had this?

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[Mark Olinger]

Found this thread on S-100 settings as I searched for an issue with STF....aka, SC.   I have installed a number of these instruments in personal and club ships and have not seen "NET" instead of "SC" when cruising but I do now in several of them.   I can't find reference to this in the manual...or have missed it?   Did a word search for NET and did not see it.

What setting have I overlooked?  Thoughts?

Mark Olinger

[Jeff Stetson]

I'm confused - the only "NET" I find relates to navboxes and is simply short for "NETTO". One can set a vario needle to switch to NETTO while in SC mode, but haven't seen a NET anywhere else.

-J

[Mark Olinger]

Exactly…have had an S-100 for 8 years and Net can be seen in nav boxes if set up that way, etc.   This is NET at the bottom of the display where SC is seen when the vario is set to GPS detection for thermal assist and auto for STF/SC.   No mention of this in the manual…quite confusing as the various needle does seem to be displaying a net value when not circling…cruising.  Guess I’ll make sure the firmware is current, see if that sets things right.

Thank you for the reply….Mark

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[Jeff Stetson]

Do you have the latest manual, r72? I don't see the problem with displaying a NETTO, particularly a HAWK NETTO during cruise, assuming the loaded polar reference is accurate. Showing the vertical air motion is useful in any flight condition, though the LX recommends using RELATIVE in SC mode instead. This doesn't work well for me because LX and others insist on using only a 2nd order approximation of the real polar. As Reichmann pointed out decades ago, this tends to fail at higher speeds when the form drag is high and complicated (as with my motorglider); he recommended a 5th order poly. I'd much prefer entering a table of measured points then using a cubic spline interpolation. Not only more accurate, but extensible at low speed all the way to stall, which the polynomial equations can't do. 

-J