Heading Question

[Low N Slow]

First off I must say this is an outstanding aircraft and a complete joy to fly.

The one thing I have a question on though is the heading indicators.

I get different readings from the RMI and NACWS indicators  compared to the compass and gps unit. They can be out by 5 to 20 degrees.

I have never noticed this in any of my other aircraft.

Any input on the cause of this would be helpfull, thanks.

[Japo32]

Mmmm.. Extrange...

It should be the same reading because both are driven by same dataref.. but will take a look.

Be careful to switch RMI on, on right panel. If not will always point to north. but I suppose you already did that.

Will take a look.

[Japo32]

Ok.. Goran says me that maybe the problem is found on the animation. I have to take a look. For now trust the NACWS number.

[Low N Slow]

Thanks for the quick response, yes I do have the RMI on so that is ok.

Are you sure to trust the NACWS, the GPS and compass seem to line up with the map screen headings, the RMI and NACWS do not.

[Lukasz]

I've performed quick check and indeed there are errors in heading displays. Mentor has 4 heading displays: magnetic compass, RMI, NACWS and GPS and here is what I've found during short flight around Alaska with nose pointing directly to magnetic north pole:

- magnetic compass shows N - correct

- RMI (in real plane it's an electric directional gyro system, which is automatically corrected for gyro drift, with the help of magnetic sensor mounted on left wingtip) shows 15 - incorrect, should be N also

- NACWS in real plane takes heading from RMI and so is in our Mentor. It also shows 15 - incorrect (should be 360)

- GPS, to my best knowledge, could display whatever heading or track that user wishes, be it a combination of heading-track-magnetic-true. Our Mentor's GPS shows magnetic track combination (as indicated by another test with crosswinds). In both tests the GPS indications were correct, as it showed 360 (in second test I've corrected for winds while flying on VOR radial).

I've also taken X-Plane values and they were as following:

- magnetic & compass heading - 360 (which means I was flying straight ahead for magnetic north pole, as I meant to)

- true heading - 15 (in relation to geographical north pole - so called "true north")

- magnetic variation - -15 (minus 15, which is a difference between magnetic and true heading caused by offset between geographical and magnetic poles).

All of these values are consistent with Alaska region and real life principles of navigation.

So, the real error is only that RMI and NACWS point to geographical pole, instead of magnetic, as they should. Now, I'm not an expert in X-Plane's IT stuff, but I think this is the dataref, we're looking for RMI and NACWS:

sim/cockpit2/gauges/indicators/heading_electric_deg_mag_pilot float n degrees_magnetic Indicated magetic heading, in degrees.  Source: electric gyro.  Side: Pilot

Also there should be no gyro drift, as the system is constantly magnetically corrected.

By the way some good and excellent planes share this characteristics. I've almost lost a couple of long range flights, because I took corrections for magnetic variation, while it was already "corrected" by developers. Sadly, magnetic compass pointing to true north isn't something unthinkable in X-Plane world  

[Japo32]

you are right! It was my fault on selection of dataref!

I will change and as soon as I have the new version of the Mentor I will release it.

The difference between the true and the magnetic one on the airfield I was testing the Mentor was almost nothing so I didn't see that mistake.

Thanks Lis