BK90 turn about 90 degrees away from target

[T-Pickle]

Hello everyone,

I've just gotten the Viggen a couple of days ago and been doing the training missions.

During the BK90 training mission I noticed how both BK90s would turn away form the target point M1 that was directly ahead, the one on the left wing turning about 90° left and the one on the right wing turning about 90° right. I was within the release envelope between 50-500 meters at 0.5-0.9 mach with the altitude warning light out and released between min and max range.

I was able to reproduce this multiple times and even in multiplayer, so I assume it's a bug.

Hope to see this looked into soon, thanks!

Edited February 3, 2023 by T-Pickle

[MYSE1234]

32 minutes ago, T-Pickle said:

Hello everyone,

I've just gotten the Viggen a couple of days ago and been doing the training missions.

During the BK90 training mission ...

Any chance you can get a track file for us to look at? I'm unable to reproduce them turning away from the target waypoint in that same mission.

Edited February 3, 2023 by MYSE1234

[T-Pickle]

vor 16 Stunden schrieb MYSE1234:

Any chance you can get a track file for us to look at? I'm unable to reproduce them turning away from the target waypoint in that same mission.

 

Sure, here's my track file and a screenshot of another try to explain the behaviour I'm getting.

 

Edited February 4, 2023 by T-Pickle

[MYSE1234]

Your Viggen looks a lot like an F-5 in that track for me. 
It sure does look weird in that screenshot though, don't think I've ever seen them doing that myself.

Edited February 3, 2023 by MYSE1234

[T-Pickle]

vor 50 Minuten schrieb MYSE1234:

Your Viggen looks a lot like an F-5 in that track for me. 
It sure does look weird in that screenshot though, don't think I've ever seen them doing that myself.

 

I wonder what's going on  Sorry but I didn't edit the file or the mission, I will try this again tomorrow but so far I have no idea why it would become a F-5 in the track?

[T-Pickle]

Allright, here is the track again which hopefully should work this time. I had the exact same problem with the BK90s again.

P.S.: If this helps anyone, the track file problem was caused by me forgetting about "disable_write_track = true" in my "autoexec.cfg". This causes DCS to create a placeholder F-5 track file if you force it to save one.

10 - AJS37 Training BK90.miz_04022023_00-07.trk

[The_Tau]

Is it just me or BK90 is almost uselessly inaccurate? It always flies left or right of target waypoint. I thought its wrong at calculating wind as it seem BK90 drops into wind, overcompensating for it but there is something else at play here as well. I tried to mark target waypoint coords taking wind into consideration but there is something else at work here as well.

 Tacview-20230205-013432-DCS-Flashpoint_Levant_v1.9.4.4X_morning.zip.acmi

Taking this tacview. Wind was like DCS 081 for 3m/s at 0ft (meteo wind from 261 )First 2 BK90s launched by me were supposed to drop at offset target waypoint taking only wind (green arrow) into consideration (Yellow X as M3). As you can see first 2 BK90 dropped north of target

Only after I did BDA and moved M3 coords to Red X Bk90s landed directly on target. 

But what is the reason for this drift? I was forced to cheat to get those BDA so in RL settings it would be very hard and dangerous.

TERNAV was on, was working (indication 5), drift was 0.

[Machalot]

On 2/5/2023 at 5:48 AM, The_Tau said:

Is it just me or BK90 is almost uselessly inaccurate?

It's likely something specific about your situation. I can usually place BK90s on target. So l they are useless. Did you check the accuracy of your target waypoint relative to the target radar returns? 

[The_Tau]

4 hours ago, Machalot said:

It's likely something specific about your situation. I can usually place BK90s on target. So l they are useless. Did you check the accuracy of your target waypoint relative to the target radar returns? 

Yes it was, but BK90 is pure preplanned weapon, it was not designed as TOO as viggen radar is too weak for accurate radar coord update. So it has to be accurate on given coords otherwise its kinda useless

I repeated the situation in Instant Action on Persian Gulf with BK90s, after updating M2 position (by default coords are a bit too South of target) and same thing. BK90 overcompensates for wind and misses the target. I did a test in that mission and set wind manually to 0 and BK90 was waaay more accurate. BTW I could not change wind back from manual to auto calculated, code 00000 -> LS didnt work...

Edited February 9, 2023 by The_Tau

[T-Pickle]

During the BK90 Training mission, did you manage to get the bombs on target @Machalot & @The_Tau?

I'm pretty sure I followed the instructions but perhaps I missed something? I also wonder if it has to do with wind now...

[The_Tau]

12 hours ago, T-Pickle said:

During the BK90 Training mission, did you manage to get the bombs on target @Machalot & @The_Tau?

I'm pretty sure I followed the instructions but perhaps I missed something? I also wonder if it has to do with wind now...

work for me, wind in training is 0 anyway

[T-Pickle]

Very strange, I can't figure out what I'm doing wrong...

[The_Tau]

1 hour ago, T-Pickle said:

Very strange, I can't figure out what I'm doing wrong...

What are exactly the steps you do? 

Weapons to Attack, Mode to ANF, M waypoint selected, QFE entered, dive to 500 - 50m alt range, unsafe, when in range fire. 

Whats ur version of game? Maybe u need update?

[T-Pickle]

I followed the explanations of the training, the waypoint was already M1 if I remember correctly. Game version was latest open beta. I'm also pretty sure I did all those steps, I tried it multiple times. Even the single drop switch does not change it, just that only one BK90 does that weird turn away from target then.

Since it's such a weird pattern where they fly basically 90° to each side, I couldn't believe it would happen with a wrong QFE or altitude, surely it would rather look like they "miss" the waypoint due to wrong data (like in your situation), but not fly away from it.

I had a couple of aircraft mods installed (to play on Grayflag for example) and was thinking maybe they mess with some data, so tried uninstalling them but still got the same effect.

Edited February 10, 2023 by T-Pickle

[The_Tau]

17 minutes ago, T-Pickle said:

I followed the explanations of the training, the waypoint was already M1 if I remember correctly. Game version was latest open beta. I'm also pretty sure I did all those steps, I tried it multiple times. Even the single drop switch does not change it, just that only one BK90 does that weird turn away from target then.

Since it's such a weird pattern where they fly basically 90° to each side, I couldn't believe it would happen with a wrong QFE or altitude, surely it would rather look like they "miss" the waypoint due to wrong data (like in your situation), but not fly away from it.

I had a couple of aircraft mods installed (to play on Grayflag for example) and was thinking maybe they mess with some data, so tried uninstalling them but still got the same effect.

 

Hmm I watched ur track and I must say I find it weird your placement of M1 moves immediately after you drop your weapons. You are not pressing T1-TV when launching BK90 arent you? That would update M1 position and as you are not moving it, it will update it to ur current plane location 

[T-Pickle]

Here is how my setup looks (the point M1 marked on the radar map looks correct to me):

vor 3 Minuten schrieb The_Tau:

Hmm I watched ur track and I must say I find it weird your placement of M1 moves immediately after you drop your weapons. You are not pressing T1-TV when launching BK90 arent you? That would update M1 position and as you are not moving it, it will update it to ur current plane location 

In fact my binding is a bit specific, I have TV on my first trigger stage and Release Weapon on the second stage. So when I release the BK90 I would indeed press TV first, but not T1 (that's a completly different button in my bindings). As far as I know, the waypoint update should not happen as long as I don't press T1 before, correct?

Edited February 10, 2023 by T-Pickle

[The_Tau]

well there is ur problem. 

T1 TV is on separate stick for reason. Look closely at exact moment u drop BK90s, you are 5km to target in front of you but then marker moves behind you and distance is 0. BK90 try to bomb new designation you overflew it forcing them to turn around

Edited February 10, 2023 by The_Tau

[T-Pickle]

vor 2 Minuten schrieb The_Tau:

well there is ur problem. 

T1 TV is on separate stick for reason. Look closely at exact moment u drop BK90s, you are 5km to target in front of you but then marker moves behind you and distance is 0. BK90 try to bomb new designation you overflew it forcing them to turn around

 

Thank you! I tested it now and it was indeed the problem, did not think about this at all. But again, I do not press T1 so I am not sure why the waypoint changes, but I see what you described now, when I only press TV M1 already resets. I thought for a waypoint/target fix I always need to press T1 first... Now I need to think of a better binding, I only have so many buttons

[The_Tau]

12 minutes ago, T-Pickle said:

Thank you! I tested it now and it was indeed the problem, did not think about this at all. But again, I do not press T1 so I am not sure why the waypoint changes, but I see what you described now, when I only press TV M1 already resets. I thought for a waypoint/target fix I always need to press T1 first... Now I need to think of a better binding, I only have so many buttons

I always use one throttle button as modifier which essentially doubles all my throttle and stick buttons. And if necessary adding 2nd modifier tripples buttons  Of course learning it can be a bit of pain but with enough practice its all worth it

Edited February 10, 2023 by The_Tau

[Machalot]

3 hours ago, T-Pickle said:

But again, I do not press T1 so I am not sure why the waypoint changes,

In the real jet, T1 is the first trigger detent and TV is the second. So there is an implied momentary T1 any time you press TV.  

[T-Pickle]

vor 3 Minuten schrieb Machalot:

In the real jet, T1 is the first trigger detent and TV is the second. So there is an implied momentary T1 any time you press TV.  

Makes sense, thanks. I managed to bind it nearly exactly like I had it before now by switching my T1 and TV buttons. So I can still relatively quickly aim and fire RB75s but without interfering with the BK90 target waypoint anymore (or any other waypoint, I assume the problem would have been for any other weapon I just didn't notice it).

Regarding the fixes: As far as I understand from testing now, in attack T1 does not start the "wait for waypoint fix" routine, so it's usually fine to press. TV though will update the target waypoint to your current location, so it shouldn't be pressed in attack mode except when using RB75s and you want to lock on with them.

[Machalot]

I wold not recommend binding T1 like that. It can put the radar and flight computer in unintended modes. For example in NAV mode (which is the mode for HD bombs, btw), initiating a radar or visual nav fix, unlocking the RB75 crosshairs, or toggling the RUTA polygon in SPA mode.

In Attack mode, T1 starts a radar fix for the BK90 or RB15, and uncages the RB75 seeker.

I think you should only press T1 with intent. 

Edited February 10, 2023 by Machalot

[T-Pickle]

vor 34 Minuten schrieb Machalot:

I would not recommend binding T1 like that. It can put the radar and flight computer in unintended modes. For example in NAV mode (which is three mode for HD bombs, btw), initiating a radar or visual nav fix, unlocking the RB75 crosshairs, or toggling the RUTA polygon in SPA mode.

In Attack mode, T1 starts a radar fix for the BK90 or RB15, and uncages the RB75 seeker.

I think you should only press T1 with intent. 

 

I'll think about another configuration for my controls, I guess you are right and it's probably better to not have anything happen unintendedly.

[Machalot]

If you already have a two-position trigger, take the suggestion above and use a modifier button on your throttle.  When you hold the modifier, the trigger is T1-TV, and when you don't hold the modifier, the trigger is (no-op)-Weapon Release.  Something like that.

[LazyBoot]

On a 2-stage trigger, I personally find that using the first stage for unsafe is best. So depending on your setup, that could be somewhere you could "recover" a free button for TV or T1

Edited February 11, 2023 by LazyBoot