RD / Route Desirée, is it supposed to be functional?

[Kerdou]

I tried to use the RD feature as shown in this video but the indicator sends me all over the place. Is it supposed to be functional on the 2.7 OB or is it just a WIP feature for the moment?

[Steph21]

Tried it yesterday, works fine if you have a correct initial interception course, but that's true that it can send you all over the place sometimes if your initial interception course is way off. 

[Kerdou]

So it's not supposed to help you intercept a radial? In that case, it sounds like it's a useless feature. Which would be surprising.

[jojo]

From every account I have heard or read, it isn't the best feature of the plane, and it isn't really liked very much. It was probably refined for later Mirage 2000N and Mirage 2000D. But it is what it is.

Don't expect "RNP 1" routing

 

That being said, if you activate it from the previous waypoint, not too far off course, or should work fine to keep you on track...

 

It's rather a "tactical tool" than "IFR tool".

[Steph21]

1 hour ago, kerdougan said:

So it's not supposed to help you intercept a radial? In that case, it sounds like it's a useless feature. Which would be surprising.

 Yes it does, and it will help you doing so. But it seems that right now, as you described, it might struggle a bit to do so if your initial interception course is way off. It might need to be fine tuned.

 

Try it with a slight deviation from the radial, to see it working properly. Then increase the deviation. 

[myHelljumper]

This system has been coded with the help of SMEs that work on the aircraft evey day and the implementation is correct.

 

The RD is complex and not fool-proof but it can be a useful navigation help. It's purpose is to guide the aircraft on a line intercepting the DEST BUT with a TRUE heading that is equal to the PCN RD value for the BUT.

 

The way it works is a little complicated. but I have a little illustration to help explain it :

 

The RD will guide you on a 60°-70° interception course to the RD line in order to reach a tangent circle with a radius of 7500m. It will guide you on this circle until you are on the RD line but for this to work the contact point of the circle and the RD line needs to be at more than 2nm from the BUT.

If the contact point is not at more that 2nm, the RD will guide you directly to the point.

Edited April 16, 2021 by myHelljumper

[Kerdou]

Thanks for the explanations guys. Actually I tried to use it for guidance to the runway before an ILS landing, so I started at approximately 15nm from the runway but deliberately off the radial. The indicator indeed got me closer to the But at times, but it never led me straight to the proper radial.

 

I use the D/RLT as a plan B and fortunately it does the trick.

Edited April 16, 2021 by kerdougan

[jojo]

2 hours ago, kerdougan said:

Thanks for the explanations guys. Actually I tried to use it for guidance to the runway before an ILS landing, so I started at approximately 15nm from the runway but deliberately off the radial. The indicator indeed got me closer to the But at times, but it never led me straight to the proper radial.

 

I use the D/RLT as a plan B and fortunately it does the trick.

 

 

The problem is that RD will guide you on INS waypoint which is drifting, not the best thing for accurate lining up on runway, just to get you close...

[Kerdou]

29 minutes ago, jojo said:

 

The problem is that RD will guide you on INS waypoint which is drifting, not the best thing for accurate lining up on runway, just to get you close...

True, I spent too much time on the Hornet so I forgot about that issue. But that should be good enough to get me into the ILS cone if there is no Tacan around.

[Ramsay]

1 hour ago, jojo said:

The problem is that RD will guide you on INS waypoint which is drifting, not the best thing for accurate lining up on runway, just to get you close...

 

Yes, but now that INS overfly and offset updates work, there's a good reason to do a position update prior to an attack or landing.

 

It "feels" a good day to be a Mirage owner  

Edited April 16, 2021 by Ramsay

[Steph21]

2 minutes ago, Ramsay said:

 

It "feels" a good day to be a Mirage owner  

 

Yes indeed !

We feel the new 'French touch' added in the team   I like being chauvinist 

[Kercheiz]

Ground strikes must be carefully prepared with the Mirage. INS update being at the heart of the process.

That's a kneeboard page from my last large scale MP event where we had to strike at Batumi. The spot was perfect for update after crossing the whole map over the ocean.

This was fun

 

I hope they add BAP100 one day, it's the perfect duo with RD.

 

 

[jojo]

1 hour ago, Kercheiz said:

I hope they add BAP100 one day, it's the perfect duo with RD.

 

 

 

Just for "tactical culture".

IRL with BAP 100, they don't align in the axis on the runway, because if there is a gust of crosswind, all bombs can miss the runway.

So multiple planes will attack in diagonal to cut the runway in different places.

I think I read it in an article about Ouadi Doum attack by Jaguar Aagainst Libyans in Northern Tchad.
In the first attack they cut the runway with BAP 100 while the apron was attacked by other Jaguar.

On the second attack it was a Martel strike against SA-6 defending the airfield.

[Frederf]

I am confused. According to manual with RD/TD selector position:

• 00 shows ground track in range 0-359.9 and INS chronometer 0-399.9 minutes
• XX shows selected bearing to arrive from 0-359.9 and selected time 0-399.9 minutes

But when I set RD/TD and PREP 00 I see no info at all.

 

In temps desiree section of manual the times allowed are up to 359.99 not 399.99. It says to press the "TEL" PCA button which I cannot see.

 

With entering the bearing for RD it seems to be that the correct entry is course approaching not as the manual says bearing from. E.g. if you want to fly past waypoint east-to-west then you enter 270.0 in PCN and not 090.0 as manual says.

[Shiroka]

5 hours ago, Frederf said:

I am confused. According to manual with RD/TD selector position:

• 00 shows ground track in range 0-359.9 and INS chronometer 0-399.9 minutes
• XX shows selected bearing to arrive from 0-359.9 and selected time 0-399.9 minutes

But when I set RD/TD and PREP 00 I see no info at all.

 

In temps desiree section of manual the times allowed are up to 359.99 not 399.99. It says to press the "TEL" PCA button which I cannot see.

 

With entering the bearing for RD it seems to be that the correct entry is course approaching not as the manual says bearing from. E.g. if you want to fly past waypoint east-to-west then you enter 270.0 in PCN and not 090.0 as manual says.

Have the same problem with TD - I can't find the TEL button that the manual says. I tried pressing the TOP button but it's not doing anything.

[Frederf]

It must be a typo or something. I pressed TOP and it worked.

 

It only works if you're inside some limits of TTG, I think 50% to 150% of current. So you have to already have a TTG at current speed of say 20 minutes and then you're allowed to engage the system with TTG inside range 10-30 minutes. Before takeoff is no good because low/zero ground speed. Looks like the best way is to pre-populate your timed route (hold to split) with your times per leg and then show up to  a hold early enough that you know to leave hold at X time and Y speed.

[Shiroka]

I worked out my problem. I was trying to enter TD in the RD field on the PCN and vice versa. Working for me now.