Inverted Compass ??

[Lib]

Hi,

 

What happens with the 2 compass in our P51 ??

The Remote Indicator Compass shows a BAD HEADING since you’re on a runaway (approx. 8° to 10°)…

The Giro Compass shows the RIGHT HEADING, and I should adjust it on the RIC (witch is bad) every 15 min ??!!

Isn’t there a problem ?

 

When I read the user’s manual Page 68:

Remote Indicator Compass

The Remote Indicator Compass on the P-51D replaces the conventional magnetic compass of previous aircraft, although some models also include a conventional standby magnetic compass as a backup. The remote compass unit is installed in the left wing and transmits its readings electrically to the indicator on the instrument panel. This type of compass doesn’t float around and fluctuate when the aircraft is maneuvered. This provides all of the advantages of the directional gyro without the processions. However, the directional gyro is provided as a backup should the electrical system fail.

 

In our P51-D the RIC floats around and fluctuates when the aircraft is maneuvered !

In the opposite the Giro Compass don’t fluctuate where it should !

 

It just seems the datas sent by the software to those 2 instruments are inverted !

[Merlin-27]

I've pointed out the issue with the magnetic compass in a previous thread and I don't believe anyone provided any insight on it. I agree... it does not follow the description in the pilots manual for the remote indicator. It jumps around like a typical magnetic compass. The gyro compass by design does not jump around but like a non-GPS aided INS, its accuracy degrades over time. I believe that is why they point out that the gyro is the backup.

[Lib]

I've pointed out the issue with the magnetic compass in a previous thread and I don't believe anyone provided any insight on it. I agree... it does not follow the description in the pilots manual for the remote indicator. It jumps around like a typical magnetic compass. The gyro compass by design does not jump around but like a non-GPS aided INS, its accuracy degrades over time. I believe that is why they point out that the gyro is the backup.

 

So Remote compass has a (very) bad heading and Gyro compass accuracy degrades over time.... how do ED wants us to navigate without cheating ??

Does that mean no dev will have a look on it now ? they don't care any more about their realeased products ??

To ED, sorry if i'm a little irritated, but i've just bought a nice map TC-1 with all instruments to draw my road and calculate my flight....and i discover my plane has no flight instrument on witch i can trust !

[Merlin-27]

So Remote compass has a (very) bad heading and Gyro compass accuracy degrades over time.... how do ED wants us to navigate without cheating ??

Does that mean no dev will have a look on it now ? they don't care any more about their realeased products ??

To ED, sorry if i'm a little irritated, but i've just bought a nice map TC-1 with all instruments to draw my road and calculate my flight....and i discover my plane has no flight instrument on witch i can trust !

 

I don't think anyone said the compass has a bad heading... it just jumps around when not flying level. Also as far as we are concerned, I believe the gyro compass is plenty accurate. If you were returning home over the channel in fog after a 4 hour mission there might be a little guess-work. Welcome to WW2 era aircraft.

[seikdel]

I don't think anyone said the compass has a bad heading... it just jumps around when not flying level.

 

This type of compass doesn't float around and fluctuate when the aircraft is maneuvered. This provides all of the advantages of the directional gyro without the processions.

 

Merlin, you're correct in how it operates, but the flight manual says that's not how it should work.

 

Lib: Yes, I also find this very frustrating.

[Lib]

I don't think anyone said the compass has a bad heading...

 

Maykop has a runaway heading indicated at 218.

 

On the screen below i'm on "take of from runaway" at Maykop. Look at what indicates my Remote Indicator Compass : 203 !! a 15° difference ! not bad ??

 

 

[Silver_Dragon]

Magnetic variation

[Ich666]

Have you checked it while flying straight and level parallel to the runway?

[Lib]

Magnetic variation

 

Could you developpe it please ? Why sould we incriminate a mag var ? we don't want the compass to indicate the True North but the Magnetic North. And a Magnetic variation is the angle of difference between True North and Magnetic North.

 

If you read the manual, you can see :

The Remote Indicator Compass consists of a stationary compass rose, a current magnetic heading arrow, and a desired magnetic heading arrow.

Magnetic is magnetic, it should indicates the magnetic heading of the runaway... 218.

Even if we adjust it with a magnetic variation, a 15° difference - 6°, we still have a 9° difference.... enormous compass deviation...

Edited April 16, 2013 by Lib

[Anatoli-Kagari9]

At Maykop declination should be 6.842 East, so, still no justification, IMHO for the indications shown on the magnetic compass.

 

Lib, you certainly have a good point here!

[Der_Fred]

All this info doesn't sound right

Remote Indicator Compass

The Remote Indicator Compass on the P-51D replaces the conventional magnetic compass of previous aircraft, although some models also include a conventional standby magnetic compass as a backup. The remote compass unit is installed in the left wing and transmits its readings electrically to the indicator on the instrument panel. This type of compass doesn’t float around and fluctuate when the aircraft is maneuvered.

If it's an electrical compass, it would certainly lose direction with rolling the a/c and would take time to reset once in level flight - just like a/c today.

some compasses manually need resetting in flight

However, the directional gyro is provided as a backup should the electrical system fail.

An Oxymoron of note.... gyro's require electrical power to operate

 

So who's the cowboy/girl that wrote this up ?

[Der_Fred]

Been holding my breath for a while.. but need to breath sometime - hur hur :)

[Der_Fred]

Maybe they meant separate electrical systems.. then they should explicitly say so !!

[Luzifer]

An Oxymoron of note.... gyro's require electrical power to operate

 

Unless they're powered by pressurized air or vacuum, as the flight instruments in the P-51 are.

[Der_Fred]

Ahh yes.. sorry, forgot about that - I'm thinking too modern :)

[Echo38]

I don't know how the various navigation systems work I.R.L., so I don't know if this aspect of the simulation is in error or not. However, I must point out again that USAAF pilot manuals were notoriously unreliable and rife with errors of their own.

[EvilBivol-1]

The headings you see on the editor map/F10 are true (in-game), so in the cockpit you should be seeing the map heading minus magnetic declination, which should be about 6-8 degrees. To test you can try this in the A-10C and you will see the heading of the runway in the cockpit will be about 212, which is correct magnetic heading given the true runway heading of 218 in the game.

 

This means there could be a bug in the magnetic course indication in the P-51D, unless it's some feature I'm not aware of. Investigating.

 

P.S. The text in the flight manual was taken directly from the actual P-51D pilot's manual. That doesn't mean it can't be wrong, though.

[Lib]

The headings you see on the editor map/F10 are true (in-game), so in the cockpit you should be seeing the map heading minus magnetic declination, which should be about 6-8 degrees. To test you can try this in the A-10C and you will see the heading of the runway in the cockpit will be about 212, which is correct magnetic heading given the true runway heading of 218 in the game.

 

Hoo ! i'm afraid i misunderstood something... You mean runaway headings given on a jeppsen map and writen on the runaway (22) are TRUE headings ?

I thought it was Magnetic headings...

 

This means there could be a bug in the magnetic course indication in the P-51D, unless it's some feature I'm not aware of. Investigating.

Thank you very very much EvilBivol-1 !

[EvilBivol-1]

Hoo ! i'm afraid i misunderstood something... You mean runaway headings given on a jeppsen map and writen on the runaway (22) are TRUE headings ?

I thought it was Magnetic headings...

No, I mean on DCS maps, like in the Mission Editor and F10 view. So if the DCS map tells you the runway is 218, in the cockpit it should 218 minus magnetic declination (6-8 degr).

[Lib]

ho ! yes of course ! sorry :doh:

[EvilBivol-1]

From the devs:

 

"After further investigation we have found that it a normal indication when the aicraft is not level (which is the case for P-51 when it is staying on the runway). The reason of such behaviour is in the direction of the total magnetic vector relative to the aircraft - 5-7 degrees West and about 60 degrees down."

 

If you're not sure what that's about, as I wasn't initially:

http://magician.ucsd.edu/essentials/WebBookse11.html

 

Attaching screenshot showing correct magnetic indication when the aircraft is airborne and more level.

 

 

How's that for realism? :)

[Lib]

From the devs:

 

"After further investigation we have found that it a normal indication when the aicraft is not level (which is the case for P-51 when it is staying on the runway). The reason of such behaviour is in the direction of the total magnetic vector relative to the aircraft - 5-7 degrees West and about 60 degrees down."

 

If you're not sure what that's about, as I wasn't initially:

http://magician.ucsd.edu/essentials/WebBookse11.html

 

Attaching screenshot showing correct magnetic indication when the aircraft is airborne and more level.

 

 

How's that for realism? :)

 

:huh:... i wonder...Looking at attaching screenshot, i read 210° on the remote indicator compass, as the runaway has a magnetic heading of 218 , it should be nearest the 220 (like on the gyro compass if you look at it). For me there is still an 8-10° difference...

Thank you EvilBivol-1 for the time you spent for it.

But i think i will continu to navigate with the gyro compass witch is more precise in the sim ;)

Thank you again !

[EvilBivol-1]

as the runaway has a magnetic heading of 218

That's your mistake - the runway has a True heading of 218, making the magnetic heading about 210-212, which is what you see on the compass.

[Lib]

That's your mistake - the runway has a True heading of 218

 

Are you sure ? here is the jeppens chart legend :

http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/intro-USA.pdf

 

you can read in it : "Runway designators (numbers) are magnetic unless followed by a "T" for true."

 

And her, you can find a jeppsen of Maykop (page 9) indicating : 04 (for 039) - 22 (for 219) and there is no "T" for true...

http://www.checksix-forums.com/attachment.php?attachmentid=20674&d=1264876320

 

That's why i say : your magnetic compass has to indicate the magnetic heading painted on the runway.

[EvilBivol-1]

I understand what you mean, but DCS is not intended to include an exact model of each airbase. It's supposed to come close, but not necessarily match to each degree. The fact that Maykop is 218 Magnetic in reality doesn't mean that it is so in DCS.

 

In the DCS world, Maykop has a True heading of 218, which you can see on the Mission Editor or F10 map.

 

And so to navigate in DCS, you can use the Mission Editor/F10 map to get the True heading, then apply the magnetic variation to get the desired Magnetic heading in the cockpit.

Edited April 17, 2013 by EvilBivol-1