Mirage INS Guide

[EntropySG]

another question, if I may, since I didnt get a chance to test the updated mirage much yet.

How bad is INS drift really?

assume the following scenario:

 

2 Mirages are on XCAS standby in formation with the tanker since 30 min, now AWACS calls because a JTAC needs a quick GBU-12 drop BoC. Enroute, mirage pilots get coordinates, they are to drop on that area, and the JTAC will guide the bomb in by lasing. All that from high altitude without the mirages ever visually aquiring the target.

 

Would that work, or is the INS drift too much for such a scenario?

[ZHeN]

another question, if I may, since I didnt get a chance to test the updated mirage much yet.

How bad is INS drift really?

assume the following scenario:

 

2 Mirages are on XCAS standby in formation with the tanker since 30 min, now AWACS calls because a JTAC needs a quick GBU-12 drop BoC. Enroute, mirage pilots get coordinates, they are to drop on that area, and the JTAC will guide the bomb in by lasing. All that from high altitude without the mirages ever visually aquiring the target.

 

Would that work, or is the INS drift too much for such a scenario?

that works already, mate. since second update of INS in 1.5.3 Beta, I think

I've already applied this many times online

You just need a higher altitdue (20-40k feet) - the bomb will catch the laser spot

 

would work even better if they'd implement ZBI mode & automatic bomb release

[baltic_dragon]

OK so a question from me - is the offset implemented already? And if it is, how is it used? IIRC when trying to use it, you only get 5 spaces to input data, so it doesn't work on LAT / LONG...

And another one - are the markpoints functional?

[QuiGon]

OK so a question from me - is the offset implemented already? And if it is, how is it used? IIRC when trying to use it, you only get 5 spaces to input data, so it doesn't work on LAT / LONG...

And another one - are the markpoints functional?

 

Haven't tried it, but 5 digits for an offset sounds like heading/range (e.g. 27550 for a heading of 275° and a distance of 50nm), usally from the selected waypoint.

[Frederf]

another question, if I may, since I didnt get a chance to test the updated mirage much yet.

How bad is INS drift really?

assume the following scenario:

 

2 Mirages are on XCAS standby in formation with the tanker since 30 min, now AWACS calls because a JTAC needs a quick GBU-12 drop BoC. Enroute, mirage pilots get coordinates, they are to drop on that area, and the JTAC will guide the bomb in by lasing. All that from high altitude without the mirages ever visually aquiring the target.

 

Would that work, or is the INS drift too much for such a scenario?

 

A semi-old F-16 using only INS reports 0.8nm drift per hour. For a GBU-12 that's not really good enough. It's possible that you'd still hit but never would you trust a coordinate-only bombing without verifying its accuracy first. It's like putting on a blind fold, counting the steps as you walk into a pistol firing range, and shooting.

[EntropySG]

Yeah from your replies I realize I did not phrase the question clear enough. What I wanted to ask is if the drift over time accumulates over the course of let's say half an hour that entering coordinates will get so inaccurate that you won't be able to drop a GBU-12 on BoC,even with ground lase.

[jojo]

I said multiple times, and people don't want to get it, that Mirage 2000C isn't meant to perform "blind bombing" on coordinates from high altitude.

 

So any trick allowing to do it now is relying on bug and maybe won't work in the future.

 

So half an hour of flight may result to nearly half a nautical mile error.

If you aim at INS target in the HUD, you could be aiming half a nautical mile away from the real target.

So you should update your NAV before attack or visually locate your target before release.

[ZHeN]

I said multiple times, and people don't want to get it, that Mirage 2000C isn't meant to perform "blind bombing" on coordinates from high altitude.

 

So any trick allowing to do it now is relying on bug and maybe won't work in the future.

 

So half an hour of flight may result to nearly half a nautical mile error.

If you aim at INS target in the HUD, you could be aiming half a nautical mile away from the real target.

So you should update your NAV before attack or visually locate your target before release.

half a mile for a GBU, dropped from 40k feet is not a big deal, I'm telling you. It will still catch the spot.

[FSKRipper]

half a mile for a GBU, dropped from 40k feet is not a big deal, I'm telling you. It will still catch the spot.

 

Under cloud free circumstances maybe, but also most of the folks here are more used to drop at 12K instead of 40K which will get you problems for sure. :smilewink:

 

Anyway as Jojo said I know from times where GPS was black magic that an INS update point short of the IP was mandatory.

Edited July 11, 2016 by FSKRipper

[jojo]

half a mile for a GBU, dropped from 40k feet is not a big deal, I'm telling you. It will still catch the spot.

 

IRL, the bomb may encounter winds from different directions through its fall.

It would loose all energy and fall short of the target.

 

Most of the time GBU-12 is lased only the last seconds before impact, because its guidance system is all or nothing. So making corrections it would fall short of target if lased too soon.

 

40000ft release with GBU-12 is not a good choice. If it works in DCS, you're relying on a bug.

[Frederf]

I said multiple times, and people don't want to get it, that Mirage 2000C isn't meant to perform "blind bombing" on coordinates from high altitude.

 

So any trick allowing to do it now is relying on bug and maybe won't work in the future.

 

So half an hour of flight may result to nearly half a nautical mile error.

If you aim at INS target in the HUD, you could be aiming half a nautical mile away from the real target.

So you should update your NAV before attack or visually locate your target before release.

 

50/50 coin flip I'd say. 0.4nm is edge of basket for most releases. The video that said that the Earth's rotation causes drift is wrong. INSs are programmed to anticipate the coordinate change over time based on latitude, even the old gyro systems have a dial for that for the same reason.

[Rlaxoxo]

50/50 coin flip I'd say. 0.4nm is edge of basket for most releases. The video that said that the Earth's rotation causes drift is wrong. INSs are programmed to anticipate the coordinate change over time based on latitude, even the old gyro systems have a dial for that for the same reason.

 

Well I assumed information in the manual were correct and I still think they are

[jojo]

Fact: INS drift over time, no matter why or how.

 

IRL, there's no way a GBU-12 released from 40000ft on half a mile wrong coordinates would reach target.

 

That said, play as you want.

[EntropySG]

I said multiple times, and people don't want to get it, that Mirage 2000C isn't meant to perform "blind bombing" on coordinates from high altitude.

 

So any trick allowing to do it now is relying on bug and maybe won't work in the future.

 

So half an hour of flight may result to nearly half a nautical mile error.

If you aim at INS target in the HUD, you could be aiming half a nautical mile away from the real target.

So you should update your NAV before attack or visually locate your target before release.

 

Thank you, that was exactly what I wanted to know :)

[QuiGon]

Isn't the amount of drift also depending on the way you fly? Meaning, that it won't drift much if you fly in a straight line, but will increase if you maneuver much? Is that simulated in RAZBAMs M2000 or is it just a fixed amount of drift regardless of the way you fly?

[ZHeN]

most of the folks here are more used to drop at 12K instead of 40K

well, Mirage is not an A-10C, at 12k it feels pretty vulnerable against SAMs. for safety reasons folks here should learn how to drop from higher altitudes :)

Anyway as Jojo said I know from times where GPS was black magic that an INS update point short of the IP was mandatory.

well, I can understand that. that's fair.

IRL, the bomb may encounter winds from different directions through its fall.

right

It would loose all energy and fall short of the target.

not necessarily so

it depends on the speed of the carrier

 

Most of the time GBU-12 is lased only the last seconds before impact

may be it is so IRL

but in DCS you may tell JTAC whenever you want him to lase

if you tell him to lase before drop from 40k feet, the bomb will catch the spot at ~38k and winds and other deviating forces won't really matter here at all since the bomb becomes guided from this point

because its guidance system is all or nothing. So making corrections it would fall short of target if lased too soon.

I can't comprehend this :)

40000ft release with GBU-12 is not a good choice. If it works in DCS, you're relying on a bug.

yeah, most probably

I'm pretty sure IRL GBU-12 won't be able to catch the spot @ 38k no matter how perfect conditions are

Edited July 12, 2016 by ZHeN

[Andrei]

I can't comprehend this :)

 

I guess he meant to say that upon laser spot acquisition, Paveway starts making corrections which are aerodynamically... aggressive. That you can clearly see from the F6 view. ED did mention on several occasions that this jerky pitch up/pitch down movements are indeed as it is in real life. And while doing that, weapon bleeds horizontal speed component that was provided by launching platform pretty fast. And since those LGBs are terrible gliders, it falls short on distance.

[ZHeN]

ah, ok

makes sense

[Rlaxoxo]

Then again I doubt that GBU-12's can do this in real life as well ...

 

 

It's not a perfect simulation guys take it easy

[jojo]

I guess he meant to say that upon laser spot acquisition, Paveway starts making corrections which are aerodynamically... aggressive. That you can clearly see from the F6 view. ED did mention on several occasions that this jerky pitch up/pitch down movements are indeed as it is in real life. And while doing that, weapon bleeds horizontal speed component that was provided by launching platform pretty fast. And since those LGBs are terrible gliders, it falls short on distance.

 

That's it, thanks.

 

Then again I doubt that GBU-12's can do this in real life as well ...

 

 

It's not a perfect simulation guys take it easy

 

Yes, GBU-12 Paveway II flight model is bugged. It's not capable of gliding IRL, and has more or less the same ballistic as Mk 82.

 

Paveway III system can glide, but it has more "wing surface"

Edited July 12, 2016 by jojo

[ZHeN]

okay, if ED will ever modify GBU-12 flight model, I'll still be dropping from high alt, but just a bit closer to the target

seeker's search cone is not really wide, that's why I think increasing altitude can compensate huge INS drift error

[=Pedro=]

Is there any way to quick mark the current position of the aircraft and store it into new wpt ?

[myHelljumper]

Is there any way to quick mark the current position of the aircraft and store it into new wpt ?

 

You will have to use the MRQ button on the PCN and then VAL. You will then have a new waypoint 91 that you can use as a DEST waypoint.

[=Pedro=]

You will have to use the MRQ button on the PCN and then VAL. You will then have a new waypoint 91 that you can use as a DEST waypoint.

 

I'll give it a try. Thank you :)

[ZHeN]

the only thing I don't like about MRQ is that I can't PREP it and put a mark of it on VTB screen