*** BK-90 now available!***

Hello pilots ! :)

 

 

 

Is the BK90 fixed for multiplayer ?

The Bk90s was update a while back and doesn’t explode when player dies anymore + has cluster munitions in MP.

Any way to launch BK-90 from higher altitudes and longer range? For example, 10 km Altitude, 30 km range. To use is as poor replacement of JDAM

Nope, only the RB-15 can kind of do that (it can be launched up to 2km in altitude), and only against ships.

Try it out. It will light up the red launch warning light, but it still works if you allow the BK90s a nice glide path to the target.

Launching BK90s from 25km away, at 4000m works great.

Launching BK90s from 25km away, at 4000m works great.

yeah, but wont the wind blow the cluster munitions off target? or is there a way to make the BK90 dive onto the target and release them.

yeah, but wont the wind blow the cluster munitions off target? or is there a way to make the BK90 dive onto the target and release them.

At that range and altitude they will dispence just as normal though my testing. The BK90s will come to their usual height just before overflying the target or thereabouts. Works great.

And as long as there's no wind, they can dispence from any altitude, the submunitions will of couse spread out more than usual however, and it will take quite some time for them to land. :lol:

Launching BK90s from 25km away, at 4000m works great.

Is that realistic or a bug?

The best is to launch BK90 within parameters in the picture......

Can anyone help - what am I doing wrong? Load up the BK90's, set a target on the F10 map and import wp's into data cartridge, release cue about 7-8km out, at 450m alt, doing mach 0.85, but each time the bombs detonate a few hundred metres right of the target location? I tried realigning compass with runway, I set QFE according to target alt and the equation, I even checked magnetic variation was corrent for the map. Am I missing something?

Hi @Sprool. Was there any wind in your mission?

You must ensure the navigation system does not drift. Was the TERNAV at its best? (5th digit must be "5" in mode AKT POS) If not, don't forget you have to correct drift by doing a position fix on a standard waypoint (Bx) before going for the target.

only about 3 kts wind. Not familiar yet with ternav or fixing on a std waypoint, i was using a grim reapers video to get a quik and simple way of using the clusters standoff via f10 map marker. If you have any pointers to the processes you mention above, I'd be most grateful.

With great pleasure. For starters, let's talk about the Bk-90 a bit. It's driven by an inertial navigation system: on release, the Bk-90 "knows" where to go because the aircraft tells it. To simplify things, let's pretend the aircraft says "hit that target on your 250 for 7 kilometers" : the gliding-missile will fly towards azimuth 250 for 7 km, then it will release its ammunitions over the right place.

Unfortunately, it happens quite a lot that the Viggen navigation system is drifting, which means the aircraft doesn't know where it is exactly. When that happens, the Bk-90 still does as told, and delivers the ammunitions at the wrong place. You get the picture: the Bk-90 is never wrong, the aircraft is.

This video covers the navigation fixes and tells about TERNAV status. TERNAV is a system comparing what the ground radar "sees" with a digital map stored in the aircraft. When you fly over a hill, for instance, TERNAV might recognize it because of its shape, and it will inform the aircraft of its exact position.

When TERNAV indicates "5" (set your datapanel to AKT POS and look at the 5th digit), it means the aircraft is certain of its position.

"1" means TERNAV is OK but not able to determine its position (happens when the aircraft is on the ground)

"2" means TERNAV is lost but has started searching (that's the situation you want to avoid when using the Bk-90).

"3" means TERNAV is working his best to determine the aircraft's position (follows "2").

"4" means TERNAV works fine but the aircraft doesn't need it right now (happens in SPA mode).

Page 169 of Heatblur's Viggen manual covers the TERNAV system.

TERNAV is a great tool, especially for the time the Viggen was made, but sometimes it won't be of any help. Imagine you're coming from the sea to hit a target located on a beach: you'll be flying over the sea -a very flat surface- for a long time before being in range, and your TERNAV will get lost ("2"). You can try it: fly over a not-so-flat land ("5") then fly a bit over the sea, you'll get a "2" pretty quickly.

When you want your Bk-90 to reach its target, the most reliable way to tell your Viggen its precise location is to do a navigation fix. A nav fix can and should only be done with a standard waypoint (B1, B2, B3...). To do a nav fix, you have to be briefed about the waypoint's real position. It can be the tip of an island, a bridge, a hilltop... Let's assume you're to strike a target at M4, you know B3 is over a hilltop, and you want to do a visual nav fix. As you're getting close to B3:

1. Hit "A0": your CI radar view is disabled.*
2. Hit "T1": your destination indicator will change from B3 to E3, which means you're about to do a fix.
3. Wait until you fly right over the B3 hilltop, then hit "TV": you've just done your visual nav fix.
4. You're now ready to do your approach on your M4 target waypoint and release your Bk-90.

*If your radar view is on, the aircraft will do a radar fix, not a visual fix. That's another story.

EDIT: I forgot to tell you about wind. Actually, I don't know much about it, but I've read in the manual that you can either trust TERNAV to calculate the wind drift on its own, or inform the aircraft about the wind speed and direction yourself using the datapanel VIND mode.

Thanks for your comprehensive answer. However, this is strange as other threads have posted about TerNav issues on the Caucasus map, and a potential bug from a caucasus update (which seems like years ago now...). So I did some more testing on the Gulf map using exact same procedure. I leave wind off as I dont need to introduce another variable at this stage.

It seems I get no problem setting up the BK90's to hit a ground target via F10 map marker in the Gulf, when I do same process in Caucases they miss by a few hundred yards and the CK37 last 2 digits only ever get to 10 or 20. In the gulf it goes to 50 straight away?

1 hour ago, Sprool said:

the CK37 last 2 digits only ever get to 10 or 20. In the gulf it goes to 50 straight away?

Are you flying over hilly terrain? I rarely have trouble getting status 5 in the Caucasus by flying over a few hills. 

Just to quickly clarify - TERNAV does not use the radar picture as input to be compared with its database, it uses the radar altimeter. This means it stops taking accurate fixes if you are flying higher than a few hundred meters. As long as you approach your target below that altitude and over the ground rather than water, its fixes should be accurate enough that you don't need to do it manually.

You can test this quite easily by flying e.g. one of the missions in the Red Flag campaign. While you hold at 5000 meters your TERNAV accuracy will go down to 2, but after you pass Irish and descend to low level it goes back up to 5 and takes you quite accurately straight on your target.

9 hours ago, Flappie said:

With great pleasure. For starters, let's talk about the Bk-90 a bit. It's driven by an inertial navigation system: on release, the Bk-90 "knows" where to go because the aircraft tells it. To simplify things, let's pretend the aircraft says "hit that target on your 250 for 7 kilometers" : the gliding-missile will fly towards azimuth 250 for 7 km, then it will release its ammunitions over the right place.

 

Unfortunately, it happens quite a lot that the Viggen navigation system is drifting, which means the aircraft doesn't know where it is exactly. When that happens, the Bk-90 still does as told, and delivers the ammunitions at the wrong place. You get the picture: the Bk-90 is never wrong, the aircraft is.

In other words:

Sorry, couldn't ressist

#NotHelpful

6 minutes ago, QuiGon said:

 

In other words:

 

 

Sorry, couldn't ressist

#NotHelpful

 

That's the best explanation of infernal navigation I've ever heard! 

I didn't know that one. It's Monday here, 9am, I was still trying to catch up with the daylight saving time transition, then my brain just exploded!

7 hours ago, Machalot said:

Are you flying over hilly terrain? I rarely have trouble getting status 5 in the Caucasus by flying over a few hills. 

Im taking off from Batumi heading west over the sea then turning northeast, staying at about 450m alt. Ternav never gets abouove 10 or 20. When I fly north out of khasab with all those mountains around the airport it goes to 50 straight after takeoff.

Does anyone ever need to set or check magnetic declination? Is that an influence at all?

How about cold start vs hot on parking vs hot on runway? Would that have any influence?

Magnetic declination is always set correctly in the Viggen when you jump in, whether it's cold or hot (and it's better that way because it's impossible to read it in the cockpit - the pointer is missing).

So I ran a few more tests - mini SP missions from differnt airbases in Caucases map, same issues, takeoff hot from runway, BK90 explodes 3-500yds left or right of target mark. Doesnt happen in the gulf. ternav got up to 3 when taking off from Krasnador but out of Batumi it stays at 1 or 2. Very strange.

45 minutes ago, Sprool said:

So I ran a few more tests - mini SP missions from differnt airbases in Caucases map, same issues, takeoff hot from runway, BK90 explodes 3-500yds left or right of target mark. Doesnt happen in the gulf. ternav got up to 3 when taking off from Krasnador but out of Batumi it stays at 1 or 2. Very strange.

 

 Out of Batumi you usually fly over the Black Sea, meaning the TERNAV has no terrain that it can correlate.

Flying out of Krasnador way inland, about 30km - target also drifted almost half a mile to the left of the F10 marker.

Flying straight out of Khasab on the Gulf map, straight over the sea towards Qeshm Island the BK90 hit exactly on target, no drift. Is the black sea strangely magnetic?

If ternav doesnt work over black sea water it certainly doesnt stop it in the gulf map!

6 hours ago, Sprool said:

Flying out of Krasnador way inland, about 30km - target also drifted almost half a mile to the left of the F10 marker.

Flying straight out of Khasab on the Gulf map, straight over the sea towards Qeshm Island the BK90 hit exactly on target, no drift. Is the black sea strangely magnetic?

If ternav doesnt work over black sea water it certainly doesnt stop it in the gulf map!

It's also highly dependent on how straight you roll down the runway or how accurately you fix the reference azimuth after lining up.