IFR using the D-1000

Edwardoc

I love flying!
Joined
Dec 6, 2011
Messages
159
Location
Colorado
I recently flew some real IFR in my RV-8 behind a D-1000.  I have about 300 hours using it so far mostly VFR.  I wanted to ask if there are others who think the sensitivity of the Pitch, airspeed,  ball and VVI are just a bit to rapid in their response to turbulence etc.  Maybe it is just my installation so that is what I want to get a feel for. 
In relatively smooth air the airspeed constantly hunts 1-3 kts and in turbulence slightly larger oscillations occur.  The changes are very rapid.  The same for Pitch indications.    Although the RV pitch and yaw changes in turbulence can be significant, the actual change in aircraft position is little.  However the Pitch response rate of the EFIS is instant as is the Ball which instantly slides from stop to stop with the slightest yaw.  VVI has the same instant response.  Although the altitude may remain within 20 feet during turbulence, the VVI can show 500FPM climb and decent almost instantly.
I have a Piper heated pitot tube in the standard Van's wing location and utilize the Static Port in the Pitot tube.  The ADAHRS is mounted on a shelf behind in rear baggage wall.
My main reason for posting is to see if there is anyone else who would like to see the response of the Pitch, A/S, VVI etc dampened  slightly to slow their response and make it easier to fly on the gauges. It was an awful lot of work bouncing around in the clouds and trying to stay on altitude. 
I had a D1 as a backup and found it easier to fly using it as it did not respond quite as rapidly as the 1000.  Maybe I'm just getting old and slowing down? :cool:
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
Edward,
What you describe sounds like something isn't right. With clean airspeed inputs, I've seen SkyView stay at 143 knots (for example) with zero fluctuation for minutes on end. If it really is fluctuating all the time, in clean air, that's an issue with your pitot / static, not SkyView's AHRS.

I see you have the Piper underwing pitot/static. In an RV, these are kind of known to be sub-optimal. We ran into this when we were doing autopilot development. Since the static is under the wing, the wing pressure affects the static. So when you pitch up, and your AoA goes up, the pressure under the wing increases, and the pitot shows you going down! Reverse happens when you pitch down. In turbulence, this means the VSI will be all over the place, and so will your airspeed since it's related to static.

We had to do a lot to make our AP work with this so it didn't chase the negative VSI as the nose was going up and over-react.

A mechanical gryo is by definition "instant." If it lags at all, it loses accuracy. So damping the Attitude would be kind of moving backwards from what people are used to.

We have had reports the VSI could be a bit more dampened. It's on our list. Not so many comments about the ball, but we're happy to listen.

One interesting test would be to unhook your static on your AHRS and see if that helps. This will screw up your altitude for sure, as a function of airspeed, but it will let you see if the static is the issue or not for your airspeed fluctuations. Don't do this with your transponder on if you are using SkyView as your altitude encoder.
 

Edwardoc

I love flying!
Joined
Dec 6, 2011
Messages
159
Location
Colorado
Thanks for the input. I'll do some evaluation flights and try unhooking the static to see what the results are. Will let you know.
As for the pitch damping, lag in the response is more what I am used to in light aircraft. In that way deviations that are momentary are not as noticeable when on the gauges and tends to smooth out any unnecessary pitch corrections.
I noted the D1 seems to be less sensitive then the 1000. Maybe it is because of the smaller display makes it seem that way. :)
 
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