On Thursday, 21 June 2018 22:23:46 UTC+10, wrote:
Hi-

I've searched the archives of this oft-discussed topic, but am not finding specific answers I'm seeking. If you have good experience or knowledge about the specific issues below, I would much appreciate your insights.
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Charlie Quebec mentioned that I was developing such a unit called Dynamis.
It is actually done and entering production.
Immune to horizontal gusts, both long and short period. Also provides very accurate vector wind display updated once a second (averaged over much more frequent calculations. Currently flying in a Quintus here in Queensland. Will be re-installed in an ASH25 (the test vehicle) and LS8 and Nimbus 3DM within the next few weeks.

All pressure based instruments will suffer from much the same problems. It does not matter whether the TE compensation is by TE probe or derived from the pitot - static. TE probes are easier as pitot - static compensation introduces potential mismatches between the time the pressure signals arrive at the sensors and as you are subtracting two large signals to look at a small one it is easy to get large transient indications.There are also noticeable second order effects from changing G loads and angle of attack.
We did a nice little experiment by placing a blown up balloon over the end of a TE probe and recording the time constant of the pressure signal. Flasks or other capacities are bad news.

Eliminating horizontal gust effects is NOT a filtering problem as both real vertical motion of the air and horizontal gusts cause effects on the variometer of comparable time scales and magnitude. Because of these gusts, existing variometers cannot be made all that fast in response. A time constant of 2 to 3 seconds is what you end up with. Faster than this you will be averaging the pointer bouncing around by eye and this results in slower perception of changes and is work load intensive.

By eliminating sensitivity to horizontal gusts the variometer can respond more quickly to real vertical component changes in the air. During testing we were seeing more structure in the thermals because of this and lower workload by being able to rely on the indication instead of constantly trying to decide whether the change is due to a gust or real lift.
Dynamis works on principles not used before in variometers and is the end result of over 40 years of thinking, testing and experimentation.

No I'm not going to tell you how it is done. I've even managed to write the manual without revealing that. Sufficient that it works and works well.

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Mike Borgelt