Question about Vertical Speed indicator for D6

glasair

New Member
Joined
Oct 8, 2009
Messages
33
I was having a discussion about replacing the VSI steam gauge with the D6, since the D6 has a VSI display.  Could you share with us what the minimum altitude resolution of the D6 is, and what is the sampling period that the altitude trend is sampled over? 
I was saying that if, for instance, the D6 has a 10 foot resolution and it samples over 6 seconds, the minimum resolution in feet per minute would be 100 fpm, since 10 feet altitude change in 6 seconds is 100 feet in one minute.  If you sampled for a shorter period like 3 seconds, the resolution would be degraded since a 10 foot change in 3 seconds would display as 200 fpm.
I was just interested to know if the D6 resolution matches that of a steam gauge, which I can read to about 100 feet per minute.  That is about the pointer width of the steam gauge.
Does the VSI on the D6 use anything other than altitude from the static line and time from its internal clock?  Does it try to integrate pitch information from its sensors into the equation?  
Thanks for your willingness to share this information with us. We would have little luck getting this good stuff out of Garmin, Bendix, Chelton, L3, etc. with their "certified" units.
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
All of the Dynon products "display" 20 ft increments in altitude on the numbers, but it rolls smoothly between 20 ft increments, like an old odometer does on the 0.1 mile digit. Internally we have much higher resolution, and we use this higher resolution data for the VSI.

The VSI is continuously integrated, but uses only the static pressure and the clock, just like a mechanical VSI. We can display a smooth bar with 1K, 2K, or 4K per minute scales. The D10A can display a digital vsi down to 25 ft/min, but the D6 doesn't have this feature.

Given that a VSI is supposed to be based on your path through the air mass, you can't use pitch info to accelerate it since an updraft will cause a VSI change with no pitch change.
 
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