Dynon Heading Display Performance

All,

I'd like to hear from those flying a D-10A EFIS with an EDC-10 remote compass.

How well does the heading tape reflect reality? Is it always, that's always, spot on just like a non-precessing DG, no matter what the heading or turn rate.

OR...

Does the heading tape lead, lag, and have errors as great as 15 degrees off actual (once it settles down), the amount of error varying with the heading - just like using a wet compass?

John Siebold
Boise, ID

I'd like to hear from those flying a D-10A EFIS with an EDC-10 remote compass.

How well does the heading tape reflect reality?

Click to expand...

Very nicely.

Is it always, that's always, spot on just like a non-precessing DG, no matter what the heading or turn rate.

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Yes.

When I first got my D10A I used it without the remote sensor and it pretty much was almost OK. Usually less than 5 degrees error but sometimes more. Then I got a Garmin 396 that I mounted in the same area of the panel. Despite doing the complex calibration procedure multiple times, it was just not acceptable.

I then installed the remote sensor in the tail. Simple calibration and no problems. I haven't done an exhaustive test, but I have never noticed a significant error of any kind. It just works really well.

Dead on

Once calibrated, my D-10A is very accurate. I compare it the 396 on the ground and it tracks very nicely. Does well in turns, too.

Mine works well in straight and level flight and in moderate turns. Steep turns greater that 45 deg bank and 180 turns, the tape takes a moment to catch up with actual heading. Remote sensor is in the tail.

Heading read out wanders

From the posts above, it seems that most people are pleased with the compass heading. I have a D10A and I was hopeful that the compass could be used in the same manner as a directional gyro. I tested this theory by flying on a due North heading and rolling the plane 20 degrees and holding heading with the rudder. I was in a good side slip, but still on a heading of 360 I would expect a true DG to show that the heading does not change. Looking at the heading read out on the Dynon showed the heading tape changing by up to 20 degrees.

My hope was to use the Dynon as a DG for planned IFR training. I am not so sure this is feasable.

I have a remote compass, mounted in the rear fuselage. I have done the calibration and set up per instructions.

I am interested in hearing how other Dynon's perform in similar situations.

Steve Ciha

Is your remote compass aligned in pitch, roll and yaw with the efis?

Brantel said:

Is your remote compass aligned in pitch, roll and yaw with the efis?

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Yes, all three axis.
steve

steveciha said:

From the posts above, it seems that most people are pleased with the compass heading. I have a D10A and I was hopeful that the compass could be used in the same manner as a directional gyro. I tested this theory by flying on a due North heading and rolling the plane 20 degrees and holding heading with the rudder. I was in a good side slip, but still on a heading of 360 I would expect a true DG to show that the heading does not change. Looking at the heading read out on the Dynon showed the heading tape changing by up to 20 degrees.

My hope was to use the Dynon as a DG for planned IFR training. I am not so sure this is feasable.

I have a remote compass, mounted in the rear fuselage. I have done the calibration and set up per instructions.

I am interested in hearing how other Dynon's perform in similar situations.

Steve Ciha

Click to expand...

Do you intend to fly your plane in a "good side slip" in the clouds?

In my opinion, the magnetometer derived heading indicators are superior to a DG that precesses.

steveciha said:

...I tested this theory by flying on a due North heading and rolling the plane 20 degrees and holding heading with the rudder. I was in a good side slip, but still on a heading of 360 I would expect a true DG to show that the heading does not change. Looking at the heading read out on the Dynon showed the heading tape changing by up to 20 degrees...

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As Sam points out, it is really pretty academic, but I happened to think of this thread while flying today. It was pretty bumpy which clouds the results somewhat, but as best I could tell when going from wings level to a 20 degree bank and back to wings level while holding the nose on a point on the horizon, I could not see the Dynon display change at all.

My magnetometer is mounted on the deck between the horizontal stabilizers.

Sam Buchanan said:

Do you intend to fly your plane in a "good side slip" in the clouds?

In my opinion, the magnetometer derived heading indicators are superior to a DG that precesses.

Click to expand...

No, don't intend to fly a side slip in the clouds, not on purpose anyway. What made me try this was to see if it does indeed compare to a vacuum or electric DG. Even in coordinated turns, my experience is that my D10A does not react as a true DG does. There seems to be lead and lag. If i was flying the C152 with a slow roll rate, no big deal. But an RV will roll and turn a very nice coordinated turn with no rudder input.

steveciha said:

No, don't intend to fly a side slip in the clouds, not on purpose anyway. What made me try this was to see if it does indeed compare to a vacuum or electric DG. Even in coordinated turns, my experience is that my D10A does not react as a true DG does. There seems to be lead and lag. If i was flying the C152 with a slow roll rate, no big deal. But an RV will roll and turn a very nice coordinated turn with no rudder input.

Click to expand...

There is a problem with your Dynon installation, there should be no lead or lag in the heading indicator.

Make sure the mag is mounted on exactly the same panel inclination as the control head. It must also be aligned exactly with the longitudinal axis of the plane. Then calibrate it very carefully. If this doesn't clear up the heading errors, give Dynon a call.

The reasons why a whisky compass leads and lags does not exist in a magnometer... Something is wrong with the install, the calibration or the magnometer.....

Just to help people understand how the compass works and is calibrated, which may help diagnose issues:

As Brantel correctly says, there is no physical needle or inertia that can cause lead/lag in an electronic compass.

What causes the appearance of lead/lag is that we use a 3D compass, and we blend this with other data.

In a turn, we use the 3D aspect of the compass to electronically tilt the compass so that it is always sensing in the plane of the horizon. We do this by using the artificial horizon to know where level is (which is why the EFIS and the EDC need to be at the same angle).

At the factory, we do a full 3D calibration on the compass. But when you do a calibration in the plane, we can only do a 2D calibration.

If you have the compass in a place with a lot of magnetic interference, we may be able to calibrate the compass when level. But once you start a turn, you are using more of the 3D sensors in the compass, and you may not have a great calibration. This causes what looks like lead/lag, but is really just error. When you roll level you go back to the 2D compass and it is OK again.

So it really is worth looking at your install and what might be messing with it. Recently we have encountered some people using stainless screws to install the compass, and these are not always completely non-magnetic. Brass is always the best choice. That's just one possibility for error.

Also, your pitch adjust does need to be correct when you do your calibration, so that the horizon is accurately shown on the screen. If you do it in a taildragger and zero out the pitch on the screen while the tail is down, this will make for a bad cal. The horizon needs to show level when the plane is in level cruise flight for your compass cal to work well.