Using the INS for precission bombing

[kobeshow]

BAD is simply an offset value that belongs to a waypoint, any waypiont can have one offset.

 

If you have set up the BAD waypoint you have two options:

 

• You want your HSI needle pointing to the BAD instead of the IP, to get direct navigation, in that case just DEST "waypoint number" and then press BAD on the PCN.
  

 

• Use the BAD as your INS bombing target, in that case you need to DEST "waypoint number" (maybe PREP aswell not sure), this is not the offset, just your regular waypoint. Now prepare your bombs, as soon as you have them selected and master arm is on you should see your PCA mode row showing PI (point initial). This will tell the system that you want to use your currently selected waypoint as the reference point for a bombing run onto the corresponding BAD (offset), if you now fly over your waypoint it will automatically switch your navigation indications to the BAD point, and will assume that this is where you want to drop the bombs, so it will give you a bomb realease indicator when you approach it.
  

[CallsignFrosty]

Is anyone else having trouble with radar updating the INS? I am doing everything by the book but unfortunately the cross doesn't move to the 'real' IP after it should have changed - the INS display shows the offset to apply but I click VAL to 'confirm the update' and the cross has no movement

 

 

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[Frederf]

;2927820']Is anyone else having trouble with radar updating the INS? I am doing everything by the book but unfortunately the cross doesn't move to the 'real' IP after it should have changed - the INS display shows the offset to apply but I click VAL to 'confirm the update' and the cross has no movement

 

INS update eliminates the error between INS own position and truth but doesn't do the honest math that alters the INS own position by the amount reflected by the update process.

 

The result is you have some delta error between INS position and true position until you perform an INS update of any quality. Then the delta is zeroed. You have a perfect INS. It doesn't matter if you did a really poor INS update. So the second, third, nth INS update after the first will not produce any change because it's already perfect (unless you accumulate more drift over time).

[CallsignFrosty]

INS update eliminates the error between INS own position and truth but doesn't do the honest math that alters the INS own position by the amount reflected by the update process.

 

The result is you have some delta error between INS position and true position until you perform an INS update of any quality. Then the delta is zeroed. You have a perfect INS. It doesn't matter if you did a really poor INS update. So the second, third, nth INS update after the first will not produce any change because it's already perfect (unless you accumulate more drift over time).

 

 

 

Not to sound rude but that isn't really what I'm talking about. I can see the geographical position that is the 'true' position of the IP waypoint and it remains offset even after the delta has been zeroed. Obv the longer you leave it the more error is introduced but I am talking about the moment that the error is zeroed this is no change from the original waypoint position. To make this easier I used Inguri Dam as the IP.

 

 

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[zaelu]

;2927820']Is anyone else having trouble with radar updating the INS? I am doing everything by the book but unfortunately the cross doesn't move to the 'real' IP after it should have changed - the INS display shows the offset to apply but I click VAL to 'confirm the update' and the cross has no movement

 

Me... I finally got the PI to show up... went to waypoint tried to update nothing happened.

 

They say you shouldn't press VAL. Or you should at some point and I got it all wrong?

 

The instructions are not error proof. It's not even clear what you need to press. Instructions say: press "Radar Position Update" HOTAS KEY... there is no such key... we have INS Update and NAV Update (is there any difference between those two anyway?)

 

I am not sure that at this moment TAS is not bugged for 1.54...

 

Very... :joystick:

Edited October 16, 2016 by zaelu

[CallsignFrosty]

Yes I am starting to think the same - guess I'll wait till the next update before I play around with this further.

[Frederf]

;2928083']Not to sound rude but that isn't really what I'm talking about. I can see the geographical position that is the 'true' position of the IP waypoint and it remains offset even after the delta has been zeroed. Obv the longer you leave it the more error is introduced but I am talking about the moment that the error is zeroed this is no change from the original waypoint position. To make this easier I used Inguri Dam as the IP.

 

 

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This is where I suspect someone has made the mistake of inputting 1°23'45'' as 1°23.45' or it's a parallax due to elevation and not looking directly down on it from above.

 

What is the coordinate? How was it made? If you fly directly over it and pause the game does the input coordinate, 00 coordinate, and F2 coordinate all agree or not?

[CallsignFrosty]

This is where I suspect someone has made the mistake of inputting 1°23'45'' as 1°23.45' or it's a parallax due to elevation and not looking directly down on it from above.

 

What is the coordinate? How was it made? If you fly directly over it and pause the game does the input coordinate, 00 coordinate, and F2 coordinate all agree or not?

 

 

 

I will test this again tonight when I am home from work. Something fishy is going on.

 

I have tried with both HOTAS commands - nav update and INS position update.

 

 

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[kobeshow]

So again, for people to have an overview, this is the latest changelog for 2.0

M-2000C

• added separate mode for M-2000c ground ranging
  
• TAS (radar ranging) upgrade.
  
• AG gunsight upgrade.
  
• HSI VAD enabled.
  
• WP display on VTB bug fix.
  
• OBL not displaying bug fix.
  
• TAS for OBL/IP bug fix.
  
• RWR Threat library updated
  
• RWR Sounds updated
  
• RWR Launch detection mode enabled
  
• Radar NCTR library included
  
• Radar NCTR enabled
  
• Decoy release program enabled.
  
• Built-in Jammer upgraded.
  
• New keyboard bindings.
  
• INS N.DEG light bug fixed
  
• Bullseye coordinates fixed
  
• INS "Always Aligned" not working bug fixed
  
• Radar CCM bug fixed
  
• DRM button added to Module Manager
  

if you are on 1.5: radar/TAS/sights/IP position updates, are all faulty. I can not say anything about the effect of the 2.0 patch, I don't have it installed.

[zaelu]

Good to know. I'll setup a mission in 2.0 and see.

[CallsignFrosty]

Using the INS for precission bombing

 

Cool! Thanks for the change log.

Is this from today or from the last update?

 

 

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[kobeshow]

It was the latest 2.0 update on Oct. 7th.

 

https://forums.eagle.ru/showpost.php?p=2920337&postcount=18

[CallsignFrosty]

It was the latest 2.0 update on Oct. 7th.

 

https://forums.eagle.ru/showpost.php?p=2920337&postcount=18

 

 

 

Thanks

 

 

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[zaelu]

I tried in 2.0 but when I do the update I see instead of --O-- some sort of Ø with long straight line.

 

Btw what exactly is the button to press when you do the update? INS Update or NAV Update? Because I pressed both.

 

The cross from the IP is not on the actual ground object where my waypoint/PI was set and it's off to one side. After I press the update buttons I see the PCN changing but the cross stays in the old spot (wrong one) then as I overpass the waypoint (the actual object) the Ø appears on the HUD, I steer towards the target and nothing else appears on the HUD. I press and hold weapon release hoping it will show something in the last seconds but no. The first one is released instantly (it hit near but not sure if intended) but I had 4 bombs set to release armed at 20m interval. Then nothing can be dropped anymore.

 

I can see the cross for the BUD on the ground... way off from where the actual BUD was suppose to be.

 

 

EDIT

 

actually... it might work but I need to attack always from IP to BUD on exact vector (why would be this required?!?). Maybe that's why it launched on bomb only and nothing after as I was trying to bomb from opposite side.

 

here are some pictures extracted from the recorded movie (to big to process for what is needed here)

 

the set up

 

approaching IP

 

making the update (TACAN antena is the IP)

 

Update done and now overflying the IP

 

Closing on target

 

Release as I said... badly... few seconds after and the result:

 

One bomb released. One impact. No other release ques received as I came from the other side

Edited October 17, 2016 by zaelu

[CallsignFrosty]

I tried in 2.0 but when I do the update I see instead of --O-- some sort of Ø with long straight line.

 

Btw what exactly is the button to press when you do the update? INS Update or NAV Update? Because I pressed both.

 

The cross from the IP is not on the actual ground object where my waypoint/PI was set and it's off to one side. After I press the update buttons I see the PCN changing but the cross stays in the old spot (wrong one) then as I overpass the waypoint (the actual object) the Ø appears on the HUD, I steer towards the target and nothing else appears on the HUD. I press and hold weapon release hoping it will show something in the last seconds but no. The first one is released instantly (it hit near but not sure if intended) but I had 4 bombs set to release armed at 20m interval. Then nothing can be dropped anymore.

 

I can see the cross for the BUD on the ground... way off from where the actual BUD was suppose to be.

 

 

 

Sounds like the same problem as on 1.5 to me

 

 

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[Zeus67]

I tried in 2.0 but when I do the update I see instead of --O-- some sort of Ø with long straight line.

 

Btw what exactly is the button to press when you do the update? INS Update or NAV Update? Because I pressed both.

 

The cross from the IP is not on the actual ground object where my waypoint/PI was set and it's off to one side. After I press the update buttons I see the PCN changing but the cross stays in the old spot (wrong one) then as I overpass the waypoint (the actual object) the Ø appears on the HUD, I steer towards the target and nothing else appears on the HUD. I press and hold weapon release hoping it will show something in the last seconds but no. The first one is released instantly (it hit near but not sure if intended) but I had 4 bombs set to release armed at 20m interval. Then nothing can be dropped anymore.

 

I can see the cross for the BUD on the ground... way off from where the actual BUD was suppose to be.

 

 

EDIT

 

actually... it might work but I need to attack always from IP to BUD on exact vector (why would be this required?!?). Maybe that's why it launched on bomb only and nothing after as I was trying to bomb from opposite side.

 

here are some pictures extracted from the recorded movie (to big to process for what is needed here)

 

the set up

 

approaching IP

 

making the update (TACAN antena is the IP)

 

Update done and now overflying the IP

 

Closing on target

 

Release as I said... badly... few seconds after and the result:

 

One bomb released. One impact. No other release ques received as I came from the other side

 

Do you still have the mission file? Can you submit it?

[Chrinik]

Closing on target

 

 

 

What is the target elevation? Because from that angle, it looks like the target elevation is 0...effectively the Waterline of the river right under the target.

[zaelu]

Target elevation was not zero. The cross looket to be on the hill not under the bridge. At least I did entered it correctly the "delta alt" and it showed some hundreds of feet in PCN after I subtracted the difference (the IP is high on that hill). But it was on that bridge... maybe that was the little problem?

 

Maybe in the end I got decent result after all the unknowns?

 

 

 

Let me try one more time.

 

 

I attached the mission Zeus. I played it in single player so no record and also I deleted the movie after I took the screenshots because it was big.

INS.miz

Edited October 17, 2016 by zaelu

[kobeshow]

Nah it still is the same as 1.5 apparently.

You get everything the way you should, except that you probably still can't enter decimals for the distance of the BAD. IP does not update correctly and you don't fly level and on the right course, so your steering cue --0-- is pretty much pointing where I would expect it too, and you can release bombs, so that part is working.

What we still have a problem with is the precision, it should never be laser precisioin, but right now it is impossible to get bombs even remotely close.

Well I hoped those fixes meant something, are you sure you are on the latest update 2.0.3.57442 Update 3?

Edited October 17, 2016 by kobeshow

[zaelu]

Yup.

 

I tried again same results but now I understood what that steering cue wants from me. I see the release cue and I press and hold trigger before it reaches the FPM and still the bomb falls way after the target.

 

Notes:

 

-I really don't know what is the correct name of the button for TAS position update. I know is trivial but seriously... this shouldn't be let like this. There are 2 buttons for NAV and INS updating and one for radar locking yet the instructions say that RADAR Update should be pressed.

-GBU 16 bombs are not released all even if I programm them to do so. Is this because they are laser bombs?

-the BAD setting is not clear (again too much uncertainty) if you need to press VAL after you set its values on the ground. Instructions say that you should not press VAL after the IP position update. I am not sure if as a result of this all waypoints share same BAD. Meaning I set BAD for WP2 and it I switch Dest to WP3 still has the same values for BAD. Or are they the same untill I set new ones? Because I set values just for WP2.

- cross of the IP does not move after update. That's known I think now

- cross of the target is off by some good distance too. Bombs are not falling there anyway.

 

I will try tomorrow with Snake Eyes.

[jojo]

- to perform AG ranging use "Magic Slave/ AG designate/ INS update" in "HOTAS" category.

It's true for CCRP, CCRP + PI, OBL navigation update.

 

The same button is used to slave Magic to radar in AA, or designate waypoint to perform "OBL" NAV update.

 

To perform "overfly" NAV update you can hit "REC" on PCN, or just press "NAV Update/ MAGIC unlock" (again in "HOTAS" category) when you're on top of waypoint.

 

After NAV update you must validate with "VAL" key on PCN.

 

However it's not needed when you're doing your CCRP + PI attack run at 300ft/ 500kt.

Designate your IP, then on overfly the guidance switch from IP to BAD target. So follow the roll command around you're FPM.

 

Currently the release cue appears too late. At 5Nm from target engage after burner, climb 30 degrees and wait for release cue. You will do loft attack like you should...(it isn't perfect yet)

 

Each WP can have it's own BAD. And you must set it for each WP.

 

I hope this will help...

[Frederf]

I feel there are a lot of opportunities for small mistakes on this sortie. What coordinates did you use? What values were held by the INS? What elevation were the points? What was your INS error before and after the IP update? There is very little real analysis and reporting of details going on here.

 

I attempt to recreate this sortie with details listed as they become apparent to me:

 

1. By map inspection I find the locations for the BLD VORTAC and Bridge (mid span):

BLD

35°59'44''N (.733)

114°51'48''W (.800)

3,553'

 

Bridge

36°00'45'' (.750)

114°44'29'' (.483)

1,558'

 

Confidence in the above is that E-W resolution of 1'' longitude is 80' and N-S latitude is 105'. VORTAC elevation was read directly off the ME map with cursor on the gray of the building. Bridge elevation was taken to be equal to the map terrain elevation at either end.

 

2. The aircraft start was chosen to be a "hot runway" type start at Nellis. The following are the initial INS and true (F2) positions:

 

INS

36 13 65

115 02 75

-1847

 

F2

36 13 633

115 02 750

+1846

 

3. It was attempted to refine the coordinates using 0.001' resolution but it was quickly seen that the values jumped in 0.016666' increments or jumps of 1'' and provided no precision over 1'' resolution as found before. However it was noted that MGRS coordinates were more sensitive and 11S QV 03526 87709 was converted externally to find N36 00 45.49 W114 44 29.85 which agrees with the F10 map when truncated to the nearest 1''.

 

4. Waypoint 02 was then compared to the position of the BLD VORTAC. The displayed value was:

 

02

N35 59.75

W114 51.82

+3553

 

5. The above values were corrected to best match the pre-planned.

 

6. As no suitably accurate method is practical to determine rho-theta using in-game tools an external website was used to calculate the true bearing and distance. The F10 map ruler bounds this value between 79-80 degrees (79.3 if I had to estimate) which doesn't compare well to the 80.22 as calculated externally.

 

7. This turns out not to matter too much as only integer values as possible to enter in the PCN. 6.01nm and 80.2° are truncated unceremoniously to 6 and 80 respectively. This isn't looking good.

 

8. At least we can do the delta altitude properly. BLD is 3553', target is 1558 target is -2005' delta.

 

9. In a fit of paranoia I check my ownship coordinates against reality before takeoff (sitting on the runway 20m). Paranoia pays off as my lat. is 36 13 65 again after I explicitly set it 36 13 63. I fix it back to reality.

 

10. #9 makes me suspicious so I go and change the BAD delta a few times and back to -2005 to see if my 00 lat. is being changed behind my back. OK, it's still 0.63'... weird.

 

11. In order to make better use of time I set waypoint 03 to have coordinates equal to my bridge target.

 

12. I take off and head to 02. On the way I pause and check 00 PREP against F2 coordinates. I've already drifted

 

00

36 07.84

115 02.19

 

F2

36 07.233

115 02.950

 

13. I use active pause to make the latitude and longitude match reality, elevation is already correct. This is problematic because while I enter in a number it won't read that number immediately after entry when added in active pause. I'm flying due N at 273kt and when I enter 35 59.37 it is immediately adjusted to 36 00.03. When I input 144 51.92 it gets changed to 114 51.07. Entering 00 coordinates in flight in active pause definitely confuses the system.

 

14. No matter I'll just do an overfly update on the VORTAC. After the update the cursor seems to still be displaced to the east.

 

15. I fly directly the VORTAC at a few meters and compare 00 readout to F2

 

F2

35 59.733

114 51.816

3589' (I'm about 45' over)

 

00

35 59.75

114 51.81

Not bad, it's showing a little more N and a little less W than F2. But this small change is significant over the size of the bridge roadwidth.

 

16. It seems the INS drift was significant over short time spans. So I decided to try to find which PCN coordinates put the symbol over the TACAN station immediately after an INS update. I relied upon the fact the INS update produces the same result no matter how you do it and time acceleration. I was able to do several updates and 02 waypoint changes all within a few seconds thanks to 1/64th time.

 

One result was that immediately after an INS update the INS read:

35 59 86, 114 51 24

and F2 read

35 59 850, 114 51 233

 

The best I could do to get the symbol on top of the VORTAC facility was

35 59 74 (or 75), 114 51 82 given the best INS update ~1s ago. The N coordinate was either side of the building +-50' approximately. I also adjusted the elevation 10' above terrain assuming the building's height.

 

The F10 map places the VORTAC more closely to .733 than .750 (1'' step). Perhaps the INS thinking it is more north than it is caused a more northerly entry to read on-target visually. That would be consistent.

 

 

Summary: The symbol shift shown in previous posts only represents a few seconds error and/or elevation error of a possible magnitude. The INS drifts significantly over even a short time (IP to target flight). The INS update method may or may not correct the INS position to a suitably high precision. The INS update will not allow a correction to an arbitrary misalignment of truth and assumed position.

 

I did find that my once the INS drift was minimized that my preplanned bridge coordinates existed satisfactorily close to the desired DMPI (~20').

[zaelu]

- to perform AG ranging use "Magic Slave/ AG designate/ INS update" in "HOTAS" category.

It's true for CCRP, CCRP + PI, OBL navigation update.

 

The same button is used to slave Magic to radar in AA, or designate waypoint to perform "OBL" NAV update.

 

To perform "overfly" NAV update you can hit "REC" on PCN, or just press "NAV Update/ MAGIC unlock" (again in "HOTAS" category) when you're on top of waypoint.

 

After NAV update you must validate with "VAL" key on PCN.

 

However it's not needed when you're doing your CCRP + PI attack run at 300ft/ 500kt.

Designate your IP, then on overfly the guidance switch from IP to BAD target. So follow the roll command around you're FPM.

 

Currently the release cue appears too late. At 5Nm from target engage after burner, climb 30 degrees and wait for release cue. You will do loft attack like you should...(it isn't perfect yet)

 

Each WP can have it's own BAD. And you must set it for each WP.

 

I hope this will help...

 

Thank you jojo. It helps.

 

Some more questions though :).

 

 

When you set up the BAD (on the ground... at least I do it on the ground) you need to press VAL after you entered the offset distance/heading and altitude?

 

 

Also just to clarify.

 

INS update is for OBL and IP update?

NAV update is for overflight update?

 

OBL works now? (at least in 2.0?)

 

 

-

 

@Frederf

 

Nice findings but a lot of work and the game should do it properly I think...

[Frederf]

If you type it 1-4-3-2-5-INS then no VAL key needed. If you capture it instead of type it, VAL key.

 

OBLique and overfly are two methods to update the INS and either can be used at any time the other can (correct me if I'm wrong). You choose which one you want by selecting OBL or not on the PCA.

 

When in IP-BAD attack mode the INS update is somewhat more automated and it can use your INS update in temporary memory without permanently committing its changes. In normal navigation updates the INS update doesn't take effect until you validate it.

 

In contrast while in the special offset attack capturing an update (but not validating it) applies that shift immediately without ever pressing VAL. At the end of the attack you can choose to keep it or discard it as it was temporary.

 

Oblique works in Open Alpha to the same result as overfly. What's suspicious about it is that when I press the HOTAS update key I see on the PCN that despite hitting OBL on the PCA the PCN numbers reflect the distance from my airplane to the designated point and not the distance from the radar LOS point to the designated point. I've mentioned a few times (not to rag on the devs just so people aren't tearing their hair out not understanding what's going on) that right now all INS updates are perfect. As such there's nothing functionally different about oblique and overfly. You can miss either by a mile and the result is the same.

[zaelu]

I tried several times for now. It's not working.

 

- IP position is not updating on HUD - the cross remain off and most importantly: it's off always in other place. More than that. Coordinates in Mission Editor differ from F10 map in multiplayer by a bit, especially the North coordinates. Basically when I do the INS alignment on the ground I always have to enter different coordinates (a tiny bit different) although I always spawn in the same place.

- The BAD position is also always in some other place but never on the target.

- Bombs impacts are also way off. Funny thing. I moved the targets from the bridge to the road that goes from the dam towards Boulder City (not far, same 6 miles off from IP but 2 degrees North) and when I released my bombs once they fell on the bridge where the targets used to be. LOL.

 

I modified the mission a bit so now there are 2 sets of targets. One on the bridge and one in the new position. I placed also a soldier to be FAC in case someone wants to test the lasing.

 

There are 2 MIrages to pick. One with Mk82s the other with one single GBU16 bomb.

 

The offset from WP02/IP are like this:

 

First group 6nm, 77°, -2164feet altitude difference (actual altitude of targets: 1391feet)

Second group 6nm, 79°, -2000feet difference (actual altitude of targets is : 1557feet on bridge, 709feet the ground bellow)

INS.miz

Edited October 18, 2016 by zaelu