True and Magnetic

[Joni]

Hi guys,

 

Now that I jumped into the Mirage, I need to know exactly how is the information presented in DCS in regards of headings. Im a pilot and these things are very important for my sim experience.

 

1. The ruler in the mission editor is in true or magnetic heading?
   
2. the ruler in the F10 map is in true or magnetic heading?
   
3. all the VAD charts say that there is a 6° magnetic variation in the caucasus zone, is it actually that way in game?
   
4. Batumi for example has rwy 13 at a heading of 126 according to the mission editor, so that means that the true heading is 126 but the magnetic heading necessary to fly 126° is actually 120°. Thats how it is in real life, is it that way in game?
   Does anyone know exactly if all the inputs in the INS PCN of the Mirage are in true or magnetic heading? Im asking about inputs, not readings.
   

 

 

I guess these are questions for ED more than anything, since user answers would be nothing more than a guess or a confirmed guess at the most. But im happy so see what the community thinks.

 

 

Thanks a lot.

[Art-J]

Re. 1 & 2 - it's neither. The map (same for ME and F10) has always been using Grid North. Fellow Towsim explained it better a couple of years ago:

https://forums.eagle.ru/showpost.php?p=2117082&postcount=10

 

Re. 3 - it kind of is, but one has to remember that: a) Caucasus terrain is projected on a flat surface, with reference point for all coordinates located in the middle of Crimea Pennisula, so the further from it we are, the less accurate our calculations are anyway; b) some airbases on the map are alligned incorrectly.

 

RL pilots have been trying to use their correct nav methods in DCS for years, but these never work all that great. Civilian flight sims have an edge over the DCS in this regard.

 

NTTR and Normandy terrains are projected properly over a sphere, though, so I guess you should divide the question into two: navigation over old map vs over new maps.

 

I don't own Mirage, however, so someone who does and who knows it will have to answer the rest.

[Joni]

Wonderful information, thank you Art!

 

I knew about inconsistencies in DCS maps but what I did not know was that not all modules show the same information in their compass, that is SO wrong and sad; because not only we dont count with a proper map system but also each module deals with it differently, wow.

 

I guess that as long DCS disregards the meridians lines we're fine. The problem is when dealing with GPS or INS systems. I understand now why the Mirage doesnt have the correct spots even after starting from the air with "perfect" alignment.

 

Other sulution will be as simple as make both rulers (f10 and me) show bearing angle from meridians lines and bearing angle from grid north.

[Weta43]

I knew about inconsistencies in DCS maps but what I did not know was that not all modules show the same information in their compass, that is SO wrong and sad; because not only we dont count with a proper map system but also each module deals with it differently, wow.

 

"SO" wrong ? :-)

 

The old map dates back to Lock On Modern Combat, and has issues because to the technology that was used then.

 

All new maps use and will use the same technology from now on.

 

Short of simply removing the old free map, all other options to resolve the issue entailed a lot of (free) work.

 

Do you think E.D. should have removed the old map to avoid the confusion that finding true / magnetic North on the two different systems brings ?

[Joni]

I wasnt bringing blames up. Dont know what to say to all of that.

 

The thing is a fact, but I didnt want to put it on anyone's back.

 

Thanks.

Edited July 31, 2017 by JohnnyQ
added something

[JG14_Smil]

Great answer, Art-J! Very well put.

[feefifofum]

Also, remember ED is currently in the process of updating the Caucasus map to the same standard as NTTR and Normandy:

https://forums.eagle.ru/showthread.php?p=2851944

Soon-ish all of this will become pretty much a moot point. :) In the meantime, if you're flying in the Caucasus in a Mirage, selecting true heading (cVnav) on the HSI will line you up correctly with BRAA calls from the AWACS.

 

There was a time when the magnetic declination was borked specifically in the month of January, as well, but I'm not sure if this is still going on.

[Joni]

Also, remember ED is currently in the process of updating the Caucasus map to the same standard as NTTR and Normandy:

https://forums.eagle.ru/showthread.php?p=2851944

Soon-ish all of this will become pretty much a moot point. :) In the meantime, if you're flying in the Caucasus in a Mirage, selecting true heading (cVnav) on the HSI will line you up correctly with BRAA calls from the AWACS.

 

There was a time when the magnetic declination was borked specifically in the month of January, as well, but I'm not sure if this is still going on.

 

I dont think that cVnav is necessary. Why do you think that exactly?

 

Like I said before, as long as the meridians are disregarded (they are now in 1.5) we are fine. Since all calls, rulers, comms, etc. will be based on the grid, and the magnetic will also be based on the grid + - declination.

 

So the only real problem here is that in this scenario we will never be able to use real charts, but in game it works fine.

[feefifofum]

I dont think that cVnav is necessary. Why do you think that exactly?

 

You'll find a pretty significant disparity between what the AWACS is telling you and what your instruments are telling you.

[Joni]

You'll find a pretty significant disparity between what the AWACS is telling you and what your instruments are telling you.

 

I wonder why, since the mirage in magnetic mode should use grid + local declination=awacs call.

 

So I guess the problem is the awacs that is giving calls in grid north?

[feefifofum]

That seems to be the case; the FC3 birds also appear to be configured to show true heading, at least the F-15C shows 126 for Batumi RWY 12.

[Joni]

Aaaaah, ok. Then that should be why the awacs is configured that way. I guess an fc3 bird is a naturally "easy" plane for users that probably wont be looking to calculate magnetic and would like to see the mission editor numbers match the ones in the cockpit.

 

Ill check tonight what course does the mirage show in batumi while in magnetic mode.

 

thanks!

[Art-J]

While we're at it, I wonder how deep the rework of the Caucasus map is going to be. We know about textures, 3D mesh and static object, but do they plan to tidy up all the grids, variations'n stuff somewhat? I know that would be lots of work for a free map and at certain point they have to say "enough is enough", but I'm just curious about it.

[Joni]

I also wonder about this. Mainly because the NTTR map has already shown issues with the geographic projection, objetcs location, and of course grid north/true north. This was brought up by the Mirage when certain inconsistencies started to appear in Nevada.

 

So I wonder how accurately done this is going to be and if it is a matter of how the map is done or how well the work is done.

[Joni]

So yes, I checked the mirage in batumi and it shows 120 magnetic and 126 "true" (its actually grid but in game works as true)

[Joni]

Can someone who owns the NTTR map confirm if a straight line with the ruler in the mission editor shows 0°? If thats the case, then the new maps will suffer from the same error as the Black Sea one.

 

If the NTTR is correctly modeled, then the ruler will only show 0° when aligned with the meridians.

[Frederf]

I did the math and yes the C map reflects accurately the expected grid convergence for UTM. This raises the question of whether the Mirage in Cv mode flying 360/180 flies constant longitude or not.

 

If modeled accurately it should by of constant longitude and simply the grid heading reported by the UI will not match the cockpit instruments (as they are showing different heading types: grid vs true).

[Art-J]

Can someone who owns the NTTR map confirm if a straight line with the ruler in the mission editor shows 0°?

 

Yup, looks like it does.

[Joni]

I did the math and yes the C map reflects accurately the expected grid convergence for UTM. This raises the question of whether the Mirage in Cv mode flying 360/180 flies constant longitude or not.

 

If modeled accurately it should by of constant longitude and simply the grid heading reported by the UI will not match the cockpit instruments (as they are showing different heading types: grid vs true).

 

No, the Mirage uses grid north when set to true. But this also raises the question of whether it does because the caucasus is wrong or because the Mirage was modeled with this issue.

 

Pls check if it shows true North in NTTR and then we can find out.

[Joni]

Yup, looks like it does.

 

Wait! So the ruler in a straight line upwards shows 0°??? So the NTTR was modeled in the same wrong way as the Caucasus???

 

That's some bad news folks.

[Joni]

Could someone check this? I dont have NTTR nor the money to get it.

 

Its just placing the Mirage on any runway with ILS and see if the true heading matches the one that the mission editor has in the ILS white arrow.

[Esac_mirmidon]

One Mirage 2000 on Creech runway.

 

F10 Mission editor data for one of the ILS runways:

 

ILS Heading INSIDE F10 = 092º

 

Inside Cockpit HSI-HUD in Nav mode = 079º ( correct magnetic deviation -13º )

 

Inside Cockpit HSI-HUD in CvNav mode = 092º ( The same as F10 map readings )

 

So F10 Map is showing data in True Heading and inside cockpit the HUD and the HSI is showing data taking in count the correct magnetic deviation in Nevada ( -13º ), and also in CvNav mode both HSI and HUD is showing the same True Heading than inside F10 map.

[Joni]

One Mirage 2000 on Creech runway.

 

F10 Mission editor data for one of the ILS runways:

 

ILS Heading INSIDE F10 = 092º

 

Inside Cockpit HSI-HUD in Nav mode = 079º ( correct magnetic deviation -13º )

 

Inside Cockpit HSI-HUD in CvNav mode = 092º ( The same as F10 map readings )

 

So F10 Map is showing data in True Heading and inside cockpit the HUD and the HSI is showing data taking in count the correct magnetic deviation in Nevada ( -13º ), and also in CvNav mode both HSI and HUD is showing the same True Heading than inside F10 map.

 

Hi Esac, thanks for taking the time for this.

 

However we were discussing grid vs true rather than magnetic dev.

 

We need to know if the ruler extended through the ils in the map shows the same heading in order to determine if it follows meridians or cartesian grid lines (just vertical lines).

 

First it would be tracing a vertical line and see what the ruler says.

 

Then tracing a line through the ILS white arrow and see the reading.

 

Then trace a line along a meridian near the airport you are testing and see the reading. Make sure its not the center UTM meridian every map has.

 

Next, with the data you found out in your first time, we find how the map was projected and if it suffers the same error as the caucasus.

 

 

Thanks so much

[Esac_mirmidon]

The map is not the same in F10 than inside cockpit.

 

Inside cockpit i think the world follows the rules of true meridian lines because the world is curve, taking in count magnetic declination. But i´m not 100% sure about that.

 

Inside F10 is plain following only true headings.

 

 

So use the real incockpit world and take the F10 map info only as a helper for navigation.

[Joni]

Mmmm no, true north is meridians north, we are trying to find out if dcs still sees true north as grid north which is wrong.

 

Thats why my large post before.

 

What is an inside cockpit map for you?

Edited August 7, 2017 by JohnnyQ