DCS: AJS-37 Viggen Discussion

[renhanxue]

So what exactly does this imply for its usage? Do you mean it's not sensorfused?

Both MJ1 and MJ2 have a pulse-doppler radar altimeter that acts as a proximity fuze and detonates the submunition at a certain altitude. As a backup there is also a contact fuze that detonates on hitting the ground, an a timer-based autodestruction one to avoid UXO.

 

The description implies (but does not state outright) that the MJ2 forms more than one EFP, which isn't all that weird to think considering that it weighs 17 kg. Looking at the cutaway picture of it, I wonder if the weird jaggy edges of the cut are supposed to represent the parts of the steel shell that forms the EFP's. Just speculating, though.

 

 

Both MJ1 and MJ2 are equipped with parachutes, by the way.

[Agremont]

The Viggen is definitely "fulsnygg". :)

[Lupson]

So what exactly does this imply for its usage? Do you mean it's not sensorfused?

 

(Edit: Saw that renhanxue just answered this while I wrote my post.)

 

Good question that I'm also curious about.

 

According to the Bk 90 document posted a few pages back the MJ2 submunition seems to use EFP (https://en.wikipedia.org/wiki/Explosively_formed_penetrator) warhead(s). Given the ~18 kg warhead weight, is it likely that each MJ2 submunition releases several EFPs distributed over the space below or is there only one EFP per submunition?

 

24 unguided MJ2s evenly distributed over a 250x400 meter area from a single Bk 90 dispenser would yield approx. 1 MJ2 per every 4166 m2. Given that a typical APC has an approximate top-facing surface area of let's say 20 m2, the chance to actually hit a single APC within that 250x400 area with one of 24 unguided MJ2 is ... 1/208 or roughly 0.5%.

 

Of course, the chance to hit something increases with the number of targets present in the targeted area.

 

Anyway - could the crude calculation above indicate that each MJ2 might yield multiple EFPs? If (for example) each MJ2 would yield 16 EFPs in an downward cone the hit probability would increase accordingly.

 

Or are we somehow are missing some crucial part regarding submunition guidance that could have been deliberately left out from that Bk 90 document?

 

Just wondering - and really looking forward to the AJS-37!

[TomCatMucDe]

As a Swede and a Viggen lover i here by nominate you a honorary Swede.

 

Anybody who sees the beauty of the Viggen (The Sexiest bird ever to float in the sky in my opinion ^^) is worthy to be a honorary Swede ^^.

 

tastes are always debatable, but you have to be very Swede to find it the "sexiest bird ever" :D

[renhanxue]

(Edit: Saw that renhanxue just answered this while I wrote my post.)

Your reply was better though :)

 

In other news, an email came in:

 

2016-10-21

 

Hej!

 

TAA 1982 är under granskning, men har inte hunnits med ännu, så du får vänta lite till på den. Flera andra äldre taktiska anvisningar är emellertid avhemligade och kommer in i bibliotekskatalogen inom kort.

 

Jag meddelar dig som vanligt när publikationen är färdig att läsas.

 

Med vänlig hälsning

<name redacted>

 

Krigsarkivet

Box 12541

102 29 Stockholm

Besöksadress: Banérgatan 64

Tel: 010-476 70 00 Fax: 010-476 75 20

Webb: riksarkivet.se/krigsarkivet

[mattebubben]

tastes are always debatable, but you have to be very Swede to find it the "sexiest bird ever" :D

 

The Viggen is my baby and its beautiful.

 

All other Babies are ugly.

 

But mine is Beautiful ^^.

 

Yes the Lines of the Viggen are not the most beautiful.

 

But if you have ever seen it in action you have to agree that in its entirety its sexy,

the lines it has together with the pure brutal power it exudes makes it sexy.

 

But when it comes to aircraft looks everybody has their own tastes.

 

For example i cant understand those that find the Blackburn Buccaneer or Panavia tornado good looking / sexy just like others cant understand my feelings on the Viggen.

 

Hell i dont even find the F-16 good looking (and i know im in a minority on that ^^).

 

But for me the Viggen is a beauty (Especially with the Right Paintscheme and from the right angles).

Im just saddened that the only viggen flying was left in the Metal/Silver finish instead of painting it in the Green Camo that it belongs in ^^.

Edited October 21, 2016 by mattebubben

[TomCatMucDe]

The Viggen is my baby and its beautiful.

 

All other Babies are ugly.

 

But mine is Beautiful ^^.

 

Yes the Lines of the Viggen are not the most beautiful.

 

But if you have ever seen it in action you have to agree that in its entirety its sexy,

the lines it has together with the pure brutal power it exudes makes it sexy.

 

But when it comes to aircraft looks everybody has their own tastes.

 

For example i cant understand those that find the Blackburn Buccaneer or Panavia tornado good looking / sexy just like others cant understand my feelings on the Viggen.

 

Hell i dont even find the F-16 good looking (and i know im in a minority on that ^^).

 

But for me the Viggen is a beauty (Especially with the Right Paintscheme and from the right angles).

Im just saddened that the only viggen flying was left in the Metal/Silver finish instead of painting it in the Green Camo that it belongs in ^^.

 

agreed :D

[iLOVEwindmills]

(Edit: Saw that renhanxue just answered this while I wrote my post.)

 

Good question that I'm also curious about.

 

According to the Bk 90 document posted a few pages back the MJ2 submunition seems to use EFP (https://en.wikipedia.org/wiki/Explosively_formed_penetrator) warhead(s). Given the ~18 kg warhead weight, is it likely that each MJ2 submunition releases several EFPs distributed over the space below or is there only one EFP per submunition?

 

24 unguided MJ2s evenly distributed over a 250x400 meter area from a single Bk 90 dispenser would yield approx. 1 MJ2 per every 4166 m2. Given that a typical APC has an approximate top-facing surface area of let's say 20 m2, the chance to actually hit a single APC within that 250x400 area with one of 24 unguided MJ2 is ... 1/208 or roughly 0.5%.

 

Of course, the chance to hit something increases with the number of targets present in the targeted area.

 

Anyway - could the crude calculation above indicate that each MJ2 might yield multiple EFPs? If (for example) each MJ2 would yield 16 EFPs in an downward cone the hit probability would increase accordingly.

 

Or are we somehow are missing some crucial part regarding submunition guidance that could have been deliberately left out from that Bk 90 document?

 

Just wondering - and really looking forward to the AJS-37!

 

Yeah this is what I was thinking as well, it would seem the amount of submunitions is really low for the amount of area each container is supposed to cover. The chance of a direct hit against something as small as a vehicle would be remote.

 

If each submunition works with multiple EFPs shooting out horizontally in all directions though, that would certainly cover more ground. The proxy fuse would detonate at something like a meter of altitude, and then should have a decent chance of striking a vehicle nearby depending on the amount/range of the EFPs.

 

Certainly not as effective as a top hit, but probably useful against any think skinned vehicle.

[Kelevra9987]

Hell i dont even find the F-16 good looking (and i know im in a minority on that ^^).

 

 

The Viper itself ist not the prettiest, thats true. But what I like is the Israeli Viper with the CFTs attached. They just give the little thing more "muscles" IMO.

[Sporg]

Both MJ1 and MJ2 have a pulse-doppler radar altimeter that acts as a proximity fuze and detonates the submunition at a certain altitude. As a backup there is also a contact fuze that detonates on hitting the ground, an a timer-based autodestruction one to avoid UXO.

 

The description implies (but does not state outright) that the MJ2 forms more than one EFP, which isn't all that weird to think considering that it weighs 17 kg. Looking at the cutaway picture of it, I wonder if the weird jaggy edges of the cut are supposed to represent the parts of the steel shell that forms the EFP's. Just speculating, though.

 

 

Both MJ1 and MJ2 are equipped with parachutes, by the way.

 

I think you are right, I think it is the walls of the MJ2 that forms multiple EFPs when it is detonated.

 

When you study the picture, the walls have a sort of honeycomb pattern that forms multiple conical shapes.

 

The question is then, how many EFPs does it yield, what kind of dispersal pattern does it have and at which altitude is it detonated.

[Sporg]

I found some more description on the MJ 1 and 2 on this page (Swedish):

http://robotmuseum.se/Mappar/Robothistorik/13_Bombk/ARM_bk.htm

 

It has the following description:

Stridsdelar

Substridsdelarna var av två typer: MUSJAS 1 och MUSJAS 2.

 

MUSJAS 1 bestod av fallskärm, tändrör och 1,4 kg sprängämne omgärdat av en mantel med ca 2 000 tungmetallkulor. Vikten var 3,7 kg. Sexton utskjutningsrör var laddade med vardera tre MUSJAS 1. Denna stridsdel var optimerad för verkan över stora ytor mot icke splitterskyddade mål.

 

MUSJAS 2 bestod av fallskärm, tändrör identisk med MUSJAS 1 och med en stålmantel som preparerats att bilda splitter genom den s.k. EFP-principen (Explosively Formed Projectile). Sprängämnesvikt ca 6,0 kg. Stridsdelen är tre gånger så lång som MUSJAS 1 och fyllde vardera ett utskjutningsrör. 8 av utskjutningsrören var laddade med MUSJAS 2 vilket möjliggjorde bekämpning av splitterskyddade mål med samma kapsel som icke splitterskyddade mål.

In short, the MJ 1 had 1.4 kg explosives, surrounded with 2000 heavy metal balls. Total weight 3.7 kg.

Optimized for covering large areas against soft targets.

 

The MJ 2 had a steel casing shaped to produce multiple EFPs.

6 kg of explosives.

Made to cover same areas as the MJ 1, but against semi-hardened targets.

Edited October 21, 2016 by Sporg

[Lupson]

I think you are right, I think it is the walls of the MJ2 that forms multiple EFPs when it is detonated.

 

When you study the picture, the walls have a sort of honeycomb pattern that forms multiple conical shapes.

 

The question is then, how many EFPs does it yield, what kind of dispersal pattern does it have and at which altitude is it detonated.

 

You are correct.

 

See images on page 24 of this document: http://www.unog.ch/80256EDD006B8954/(httpAssets)/73BAC38BBEA45AEFC1257B3B0039008D/$file/Sweden+Initial+Report+2013.pdf

 

Definitely honeycomb. Should be relatively easy to approximate the number of EFPs per submunition.

[Sporg]

You are correct.

 

See images on page 24 of this document: http://www.unog.ch/80256EDD006B8954/(httpAssets)/73BAC38BBEA45AEFC1257B3B0039008D/$file/Sweden+Initial+Report+2013.pdf

 

Definitely honeycomb. Should be relatively easy to approximate the number of EFPs per submunition.

Perfect, very clear pictures.

 

 

 

The question is then just about dispersal pattern.

[microvax]

We know its calibre, its 132mm, if we had the length we could calculate the number of EFPs reasonably accurate, since the indentations in the mantel are pretty surely the forming parts.

 

The perimeter length should be something like 40cm.

 

The submunition length both by wild guestimates of the explosives density and mantel density and rough guessing relative to the calibre should be something like 40cm.

 

So I guess its 6 rows of 6 EFPs, which also matches up with the cutthroguh pretty well.

For the effective range I am going to throw guestimates at you all again.

The MUSA/MUSPA submunition has an effective range of 100m in terms of anti personel fragments. Since EFPs are nothing else then just shaped fragments which gives them better aerodynamics then your average anti personel shrapnel. So I dunno, I would say 100m as well. obviously beeing a kinetic weapon it looses penetration over distance.

 

EDIT: got sniped with the pics, will readjusts the calcs. standbye :D

Edit2: My length estimation was spot on, be proud of me ! :D

 

Will throw togeter a graphic quickly to estimate what hit probability looks like.

Edited October 21, 2016 by microvax

[Goblin]

Yes the Lines of the Viggen are not the most beautiful.

 

No, it comes in second after the Gripen... ;)

[renhanxue]

Great research job on the MJ2 EFP's guys!

[microvax]

Okay new clacs based on the [very good find, very helpfull] pictures.

 

We can see that the indentations are higher then wide and the rows are stacked into each other.

We can see 8 rows from the side so that would be something like 16-18 rows.

 

Estimating the preformed munition length at 35cm and stacked, so 17,5cm preformed length, which leads to one indentation beeing roughly 2,9cm in height, so in width its probably something like 2 - 2,5cm from guestimates.

 

Perimeter beeing 40cm in length yields 8-10 rows, plus 8-10 stacked rows with 5 indentations each. Since we can see 8, I would go with 8 or 9 rows totalling at 16 or 18 rows as expected. From the visuals I would expect 16.

 

So 88 EFPs.

 

Weight of each EFP should be around 90gram. [Entire submunition weighs 17kg -1 for parachute electronics etc -6 for explosives, leaves 10kg, lets expect 80% efficiently used for penetrator building divided by 88.]

[Sporg]

Yes the Lines of the Viggen are not the most beautiful.

No, it comes in second after the Gripen... ;)

 

Which comes in second after the Draken..

 

:D:D

[Sporg]

Estimating the preformed munition length at 35cm and stacked, so 17,5cm preformed length, which leads to one indentation beeing roughly 2,9cm in height, so in width its probably something like 2 - 2,5cm from guestimates.

And iron EFPs should be able to penetrate armour around 0.5 x its diameter, so will work against up to around 10-12 mm armour?

[microvax]

And iron EFPs should be able to penetrate armour around 0.5 x its diameter, so will work against up to around 10-12 mm armour?

 

I dunno, its pretty non standard form of EFP. Didnt see something like that so far. Speed plus projectile weight is probably a better basis for penetration estimation. But anything like BTRs BMPs artilery, SAMs shilkas etc. should be penetrated.

 

 

Small graphic I made, 4 BTRs and 3 SA8s randomly oriented. Each line represents 5 or 6 EFPs.

 

Question is, is 250-400m the effective coverage of the submunitions dropped, I guess so. ATM my model would space them equally and eject them about 40m to each side.

 

Each vehicle was at least hit once.

Edited October 21, 2016 by microvax

[Pocket Sized]

Despite the often heard "Its ugly" I have to say that in my eyes this is one sexy looking bird.

 

 

She thick ;)

 

I'm looking forward to it because it's a different design philosophy.

 

Also I just noticed there's inner and outer elevons, what's the difference between them?

[microvax]

Now for penetration, I took a look at the 2a42 APBC-T ammunition.

 

Projectile weight for that one is 0,4kg @ 970m/s muzzle velocity.

So 1/2*0,4*970^2 = roughly 180 thousand joule of muzzle energy.

 

Our EFP will probably be around 90 gramms, speed is speculation but all the EFPs I found data on pretty much move at 2000m/s, probably defined by the explosion speed of the explosive used.

 

1/2*0,08*2000^2 = 180 thousand joule of initial energy.

 

Since its not hardend in the same way a projectile is, is less aerodynamic, it will loose its energy faster and will not be able to transform it into penetration performance as efficient, but I guess we are pretty safe to say that within 100m you should be well capable to punch some light armor, aka anything which isnt a MBT.

 

The 2a42 APBC-T shell punches 20mm thick plate at 60 degree impact, 700 m range.

So even if we do some naiv approximations and give our EFP 30% of the performance of the propper APBC projectile, it should punch that at 200m still.

 

So I would guess 40-50mm pen straight within 100m.

Edited November 6, 2016 by microvax

[microvax]

So yeah one BK90 spawns 2112 penetrators flying around.

 

Now it makes sense why they didnt go for some 250 bomblets. :D

 

Inb4 4 bk90s at the same target, 8448 projectiles to track for DCS. This is fine. ;D

[Sporg]

So yeah one BK90 spawns 2112 penetrators flying around.

 

Now it makes sense why they didnt go for some 250 bomblets. :D

 

Inb4 4 bk90s at the same target, 8448 projectiles to track for DCS. This is fine. ;D

Oops..

 

Maybe it's not only the target that gets hit.

Our FPS too..

 

But nice calculations, thanks. :thumbup:

Edited October 21, 2016 by Sporg

[JaNk0]

Leatherneck, you could easily outsource the R from the R&D department of the Viggen project to members of this forum. Good work!