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Posted

Just a question: how can the Mirage know what ILS heading is the runway?

In every other aircraft I have to tune the frequency AND select the right runway heading on the HSI, but the mirage does it automatically. How?

 

 

Thanks

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Posted
Just a question: how can the Mirage know what ILS heading is the runway?

In every other aircraft I have to tune the frequency AND select the right runway heading on the HSI, but the mirage does it automatically. How?

 

 

Thanks

 

In real, the ILS system don't really care about the heading. The pilots need it, so he approach with the right course and just do minimal adjusments...

 

When you are inside the ILS LOC beacon, it tells you if you are on the left or the right of the axis. So you just follow left/ right orders and you're good.

2000px-ILS_localizer_illustration.svg.png

 

On other (mainly US) aircraft, you set the course to be able to use the course deviation bar on HSI. But M-2000 HSI doesn't have that course deviation bar.

2000px-Horizontal_situation_indicator-en.svg.png

 

Instead you enter runway heading in PCN and it displays a tick on HUD's horizon.

But the HUD ILS display isn't not fully operational within DCS for now. There remains some limitation with runway axis display.

  • Thanks 1

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Posted

Thanks for the info.

One thing though, in us aircraft (and others as well) the track setting on the HSI is not only for the course deviation bar, but it directly affects the ILS needle in the ADI as well. The two instruments are connected.

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Posted
Just a question: how can the Mirage know what ILS heading is the runway?

In every other aircraft I have to tune the frequency AND select the right runway heading on the HSI, but the mirage does it automatically. How?

 

 

Thanks

 

Well, you still have to tune the correct ILS frequency for the selected runway. The M-2000C INS, which is the device that controls all navigation including ILS, just calculates heading to beacon.

 

There are deviation and glideslope bars in the main ADI (The Ball) although you will mainly follow the directions in the HUD. where all you have to do is keep the FPM centered in the ILS square and the AOA brackets to have a perfect landing. >] |-O-| [<

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

"The three most dangerous things in the world are a programmer with a soldering iron, a hardware type with a program patch and a user with an idea."

Posted

The Director bars still need to refrence a published fron course or Localiser course. In pretty much every aeroplane I know this Localiser comes from manual pilot entry or Data Base from a selected procedure.

Posted (edited)
The Director bars still need to refrence a published fron course or Localiser course. In pretty much every aeroplane I know this Localiser comes from manual pilot entry or Data Base from a selected procedure.

Maybe there's a confusion here, deviation bars are pure ILS and don't need any heading data, the dashed line as well as the box in HUD corresponds to the deviations.

 

Director (ie flight director) will need heading data in order to compute the right intercept course, as you say the director will need a heading that comes either from pilot input or a database.

In the Mirage's case, it's a database I think, the same that allows to draw the synthetic runway.

I'm not sure what flight director looks like in the Mirage

Edited by PiedDroit
Posted
Maybe there's a confusion here, deviation bars are pure ILS and don't need any heading data, the dashed line as well as the box in HUD corresponds to the deviations.

 

Director (ie flight director) will need heading data in order to compute the right intercept course, as you say the director will need a heading that comes either from pilot input or a database.

In the Mirage's case, it's a database I think, the same that allows to draw the synthetic runway.

I'm not sure what flight director looks like in the Mirage

 

Well, in theory it's true, the ILS deviation needle should be independent, but for e.g. in the A-10C, it's slaved to the HSI. If you don't have the correct heading, you will miss the runway.

 

I'm starting to wonder if this is actually a bug with the A-10??:huh:

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Posted
Maybe there's a confusion here, deviation bars are pure ILS and don't need any heading data, the dashed line as well as the box in HUD corresponds to the deviations.

 

Director (ie flight director) will need heading data in order to compute the right intercept course, as you say the director will need a heading that comes either from pilot input or a database.

In the Mirage's case, it's a database I think, the same that allows to draw the synthetic runway.

I'm not sure what flight director looks like in the Mirage

 

In real you have to input the parameters into the PCN. You can already partially do that in DCS.

Larry is still working on it.

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Posted (edited)

I will post a bug in the A-10C section. It makes no sense that the ILS deviation needle is slaved to the HSI heading.

 

 

EDIT: I was looking at the flight director in the A-10. No bug there.

Edited by bkthunder

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Posted (edited)
Well, in theory it's true, the ILS deviation needle should be independent, but for e.g. in the A-10C, it's slaved to the HSI. If you don't have the correct heading, you will miss the runway.

 

I'm starting to wonder if this is actually a bug with the A-10??:huh:

Not only in theory, in real life too!

 

The ILS deviations are really only deviations, the ILS antenna don't know anything about the runway heading.

 

There is really two different things (deviation and director) and it's important to distinguish the two.

- Deviation will only show you the deviation relatively to the course thanks to the ILS antennas.

- Director will compute the flight path so you can intersect the runway heading, it needs the runway heading in addition to the deviations.

 

The bars on the ADI can be of different types, depending on the aircraft. I'm not sure about A-10C but the way you describe it make me think they are director bars (edit: OK I saw your edit).

On the MiG-21 those bars are flight director too, they will tell you how to fly the aircraft in order to intercept your radial or your runway, according to the course you set.

 

But in the Mirage-2000C, the little square in the HUD - and the bars on ADI - is not a flight director, it only shows deviations, so you need to interpret it differently.

In the end you must have the FPM on top of the square - and the bars in the middle of the ADI - but the way you will do it is different.

Same for the dashed line, it doesn't show the heading, it only shows the deviations versus the localizer transmitter. If the dashed line is on the right, it means your position is too much on the left.

You could be flying 90° relatively to the runway or on the same heading, that wouldn't change anything because it is only a deviation.

Edited by PiedDroit
Posted

" it only shows the deviations versus the localizer transmitter. If the dashed line is on the right, it means your position is too much on the left.

You could be flying 90° relatively to the runway or on the same heading, that wouldn't change anything because it is only a deviation"

 

Thats interesting so the HUD Localiser line angle doesnt reflect realtive angle to the localiser ?

 

JoJo stated 2 posts up that ILS localser front course can be entered into the PCN. That makes sense to me and I think would probably be part of the procedure.

Posted

The runway heading is entered into the PCN.

When the runway WP is selected and you go into APP mode

- a mark is displayed on horizon to represent that heading

- when the LOC is captured the dashed lined extend from the mark on horizon, and open box appears

- when the glide is captured, the boxed is closed

- put the FPM into box to follow both ILS & glide.

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Posted (edited)
Thats interesting so the HUD Localiser line angle doesnt reflect realtive angle to the localiser ?

 

JoJo stated 2 posts up that ILS localser front course can be entered into the PCN. That makes sense to me and I think would probably be part of the procedure.

It does reflect it, although probably not 1 to 1.

 

A real ILS doesn't know the angle, it only read DDM (difference in the depth of modulation) values, max DDM = max scale and that's it, it might be shown as a dashed line of 45° but the actual angle may not be 45° (probably less).

 

- put the FPM into box to follow both ILS & glide.

This needs some more details, bindly chasing the box invariably leads to wild oscillations.

The box only represents deviation, so you need to adjust your heading and altitude correction based on how close you are from the runway (just like you would fly ILS, because that's exactly what it is)...

Edited by PiedDroit
Posted

This needs some more details, bindly chasing the box invariably leads to wild oscillations.

The box only represents deviation, so you need to adjust your heading and altitude correction based on how close you are from the runway...

 

Yep, but the same is true if you follow ADI needles roughly, nothing new here :smilewink:

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Posted
Yep, but the same is true if you follow ADI needles roughly, nothing new here :smilewink:

I know nothing new I'm just adding this for anyone who's completely new to the Mirage and might read this and think the box is a magical device :D

Posted
" it only shows the deviations versus the localizer transmitter. If the dashed line is on the right, it means your position is too much on the left.

You could be flying 90° relatively to the runway or on the same heading, that wouldn't change anything because it is only a deviation"

 

Thats interesting so the HUD Localiser line angle doesnt reflect realtive angle to the localiser ?

 

JoJo stated 2 posts up that ILS localser front course can be entered into the PCN. That makes sense to me and I think would probably be part of the procedure.

 

The only thing you enter is the runway heading. No data parameter for ILS course in the PCN.

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

"The three most dangerous things in the world are a programmer with a soldering iron, a hardware type with a program patch and a user with an idea."

Posted
No, the magical device is the AP Loc & Glide capture, but it has yet to come...look Mum, without the hands :lol:

It already sorta half works.

 

I did a few runs with it today (after concluding months ago it was still very much a work-in-progress). And if I activate it while flying established and level inside the glideslope. (3 or so miles out). It works just fine.

 

It got me down to ~200ft before having to take over (as expected) every single time. With just having to work the throttle. :thumbup::thumbup:

Posted

"The only thing you enter is the runway heading. No data parameter for ILS course in the PCN"

 

Yep understand and in most ILS installations the ILS localiser is aligned exactly with the runway heading.(In some locations however it is offset)

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