BK90 accuracy/effectiveness

I've been doing some BK90 trials on a MP server lately. And even if I have my nav system nicely lined up using the visual waypoint correction the bombs still don't seem to land on target.

I approach the target at Mach .70 at 10AGL, around 20km from the target I pop up to 200-500m max and accelerate to around Mach .80 to .90, drop my ordenance and pull out 5G, dropping for the deck again. No matter how many times I try it, it never seems to land where I want it to land, even though I'm doing everything I can to have my NAV system as accurate as possible.

Given this is the only somewhat standoff air to ground weapon for the Viggen I really want to know how to use it properly. On all the YT videos I've seen people seem to be landing the damn thing right on target.

For data and waypoint entry I', usually using the F10 map catridge with manual entry of the target coordinates as Mx wapoints.

On a sidenote, is there a bug on MP where the ARAK rockets show the "shoot" cue at crazy ranges, way before the weapon is in range? That is after rearming them after having used BK90's on the second sortie.

Any feedback would be greatly appreciated. :thumbup:

I'm the last one who should be to be trying to give advice, but...

Have you tried using your radar to zero onto the target? The accuracy has to be very good, and the Viggen navigation is a bit old and the tolerance for errors is very small.

Also, I always release two BK90 at a time, to improve the chances of a good hit :)

... I approach the target at Mach .70 at 10AGL, around 20km from the target I pop up to 200-500m max and accelerate to around Mach .80 to .90, drop my ordenance and pull out 5G, dropping for the deck again. No matter how many times I try it, it never seems to land where I want it to land, even though I'm doing everything I can to have my NAV system as accurate as possible.

20 Km is out of range for the BK90, the maximum is around 10 Km .. I havent used them on Multiplayer, but on single player they are precise enough to be used on soft targets like infantry or inactive aircrafts .. here is one of the test flights I did when learning to use them:

xxwl1GUIOjE

What about wind?

What about wind?

On my video there was no wind, but here is a video of another person, where he show the use of the CK37 wind correction options:

trg-yVycMNg

Yeah wind is present at times, but if the target is SAM and MANPAD infested I dont really wanna do a manual correction of any sort. Pop up point is 20km away, launch usually happens at 10km or less. I did some more prectice on different servers and had partial effect on target - of course never the optimal spread.

Also, if it possible to correct the Mx point in ANF mode (so it can be seen through the HUD on the ground) using the T1 - TV fix method? Because that could actually make it work.

I noticed that the BK90 in default mode delivers a decidedly 'area' effect which overlaps your target area to a lesser or greater extent - it is a guided glide-bomb that uses a GPS-like instrument to navigate and disperse its' load at the programmed coordinates after it is released - you need only aim it in the general direction and release it when within gliding distance. This target location is affected by the local air-pressure, so you can improve accuracy, depending on conditions, by ensuring that you have set your compass pressure for the local air-pressure at the target site. This can be found on a page of your knee-board waypoint chart.

More interestingly, if you consult your manual you will discover that you can program your on-board computer (using the TACT setting) to set your BK90 delivery program to a choice of 3 different dispersal patterns: long, wide, and compact bomblet dispersion. The default pattern is compact. Instructions in the manual are clear. You can experiment with different settings using the built-in BK90 training mission, observing the effects. It is helpful to understand as much as possible about your target before choosing a dispersal pattern.

It is also possible to set the above-ground gliding height of the BK90, which will be required to hit targets in cities with tall buildings. The default glide height is 60 metres (about 190 feet).

Finally, select your BK90 type (M1, M2, M1/2) based on expected target types. The M1 disperses a lot of anti-personnel air-burst bomblets. The M2 disperses a lesser number of armour-piercing shaped-charge bomblets for attacking vehicles. The M1/2 carries both types of bomblet.

it is a guided glide-bomb that uses a GPS-like instrument to navigate and disperse its' load at the programmed coordinates after it is released

It's not using any kind of satelite navigation (like GPS). Instead it's using an inertial navigation system (INS).

This target location is affected by the local air-pressure, so you can improve accuracy, depending on conditions, by ensuring that you have set your compass pressure for the local air-pressure at the target site. This can be found on a page of your knee-board waypoint chart

The BK90 doesn't use barometric altitude, instead it is using its build in radar altimeter to keep a pre-defined height above ground.

It is also possible to set the above-ground gliding height of the BK90, which will be required to hit targets in cities with tall buildings. The default glide height is 60 metres (about 190 feet).

That's not possible anymore. This feature has been removed with the BK90 rework back in September: https://forums.eagle.ru/showthread.php?p=3777466#post3777466

QuiGon 1...fencible 0.

:lol::lol:

Thanks for the clarifications, QuiGon. I am pretty new to the Viggen, so missed some of these details. Inertial guidance, of course - not GPS - makes sense. I had read another post that encouraged the setting of the target local air pressure as being recommended but. I see that was just wrong.

Do you know if the release pattern setting feature still works? It seems to in my tests.

Thanks for the clarifications, QuiGon. I am pretty new to the Viggen, so missed some of these details. Inertial guidance, of course - not GPS - makes sense. I had read another post that encouraged the setting of the target local air pressure as being recommended but. I see that was just wrong.

 

Do you know if the release pattern setting feature still works? It seems to in my tests.

The release pattern still works. Setting QFE is still a good idea, if you dont the target indicator ring can seem a bit off as it is placed at the wrong altitude.

Thanks for the clarifications, QuiGon. I am pretty new to the Viggen, so missed some of these details. Inertial guidance, of course - not GPS - makes sense. I had read another post that encouraged the setting of the target local air pressure as being recommended but. I see that was just wrong.

 

Do you know if the release pattern setting feature still works? It seems to in my tests.

As corvinus already said, it can still make sense to sert the QFE (it's something you should always do in the Viggen prior to attack), as it impacts the accuracy of your HUD cues.

The pattern settings still work as far as i know.

I've been endeavoring to use the BK90 in multiplayer for some time now, there are a number of challenges to this however. You don't know where the enemy is going to be, so the auto-generated waypoints are your friend. A number of the AA clusters are created to challenge the A-10, Su-25, F/A-18 and AV8B. So these are quite hectic to approach in a Viggen. Some are just Igla's/Shilka's, which are less troublesome. Lastly you basically have to fire the things and egress at high speed, so it can be a bit annoying to use F6 to see if they're going to disperse correctly, overfly or crash into the ground whilst also trying to fly out of the area without any TFR.

Generally I've taken an ECM, Chaff/Flare pod and 2x BK90 for the harder AA clusters and 4x BK90 for the lighter AA clusters.

I haven't made a decision yet on MJ1/MJ2 or both. So generally I tend to take the combined option as the bomblet count in the MJ2-only version is so low. Not sure if anyone else has an opinion on this.

I did try using the wide-spread dispersal, I've never seen a tacview recording where the BK90's manage to not hit such an immense cluster of ground redfor in spite of deploying correctly. I might upload it if I can get fraps working.

I might look into the wind-correction options, I keep having the BK90 slightly overfly the target in spite of having TERNAV 5 and no stated nav drift.

If anyone else has any thoughts on using these in MP or against heavy AA clusters, feel free to post them up.