GBU12 Fuze

[microvax]

The fuze type selection [nose/tail+retarded] doesnt influence the gbu12 fuze,

the gbu12 allways explodes on impact.

 

Since you can change the gbu12 fuze type on the a10c, I expect this to be a bug, since fuze selection on the mk82 series is possible and the gbu12 is literally a mark82 with wings. :))

 

 

kind regards

[Rlaxoxo]

Odd, for me if I don't put them Into RET they won't explode

 

Was this changed?

Edited September 14, 2016 by Rlaxoxo

[jojo]

The fuze type selection [nose/tail+retarded] doesnt influence the gbu12 fuze,

the gbu12 allways explodes on impact.

 

Since you can change the gbu12 fuze type on the a10c, I expect this to be a bug, since fuze selection on the mk82 series is possible and the gbu12 is literally a mark82 with wings. :))

 

 

kind regards

 

According to these documents, there is no nose fuze on Paveway 2 serie.

http://navyaviation.tpub.com/14313/css/Gbu-12-Gbu-16-And-Gbu-10-Paveway-Ii-40.htm

http://www.tpub.com/aviord321/142.htm

Edited September 14, 2016 by jojo

[microvax]

Interesting, then its even more weird that it doesnt explode retarded like the mk82/s do. :D

 

Nice find ! :)

[jojo]

There are many types of fuzes.

 

I'm not weapons specialist but I think that you can put instant fuze in the tail, triggered by deceleration, or classical delayed fuze depending on intended effect.

 

Mk-82 would have instant fuze in the nose and delayed fuze in the tail.

 

The A-10C may have a "smart" store management system, which can talk to "programmable" fuze in the tail.

 

But these are my speculations, anyone with better knowledge is welcomed to correct.

[Frederf]

There is no nose detonation fuze on the GBU-12 because the CCG goes on the nose. The detonation fuze goes in the rear of the main bomb body before the tail is attached.

 

I do not know the function of the inst/ret/inert switch in the Mirage 2000C. It may be a simple selector for physical wire release bomb rack solenoids (nose, tail, combinations thereof) or it may be a fuze electronic programming circuit or it may be a hybrid of those two concepts.

 

The GBU-12 CCG is a pull wire activation only as are most contemporary US fuzes as would be used with Mark 82s type warheads at introduction. In order to have detonation action selection there would either have to be two fuzes installed and only the retarde pulled for retarde behavior or one fuze that is programmable electronically or physically that I'm unfamiliar with.

 

The GBU-12 guiding and exploding with the switch in the "inert" position is extremely unlikely to be tolerated in reality. I haven't checked if it explodes and/or guides in selective jettison.

[jojo]

Mirage 2000C being a late 80' I bet on wire system :thumbup:

[microvax]

Hmm interesting. It doesnt guide and or explode on inert, at least it didnt in the past.

 

Against moving targets nobody wants a delayed fuze, for low level bombing nobody wants a instant fuze, but if there is only one option due to the gbu12 only having one stupid fuse, well so it is.

 

Would be nice though if Zeus could comment if we are correct or not. :D

[jojo]

I like google...

 

Meet FMU-139 tail fuze:

[url]http://www.dtic.mil/ndia/2006fuze/liberatore.pdf[/url]

 

Can be programmed for instant, delayed or even airburst detonation (coupled with DSU-33 device).

 

It is said to allow limited in flight programming for US Navy use.

But obviously for M-2000C instant or delayed would be done on ground.

 

But GBU-12 is a DCS World weapon. I don't know if it's possible.

Then would it make a difference on targets in DCS World ?

Area effect is too small for surface tatgets IMHO, so I don't know if instant/ delayed would matters ?

Edited September 15, 2016 by jojo

[Frederf]

Delayed action usually means something like 50 milliseconds or whatever is needed for a bomb to travel a few meters through a hard material. The severe delay of the Mirage DCS bombs of a second or more is quite surprising. I don't know of any fuzes of that era that did that. The most common delay of a few milliseconds doesn't really change if you hit or not a moving target but how dangerous you are to bunkers vs troops in the open.

 

In DCS I would just make the various delay/instant fuzed bombs just do more penetration and less blast. The bomb body itself has a "hit" value like a giant bullet. I'm pretty sure DCS has those three parameters for exploding weapons, perhaps a 4th for radius of blast.

 

FMU-139 is only electronically programmable for arming delay, not action. An electrically-selectable action is not something I'm familiar with in US inventory of that vintage. I do know that in 1940 the Luftwaffe had electrically selectable, circuit-based fuzes with quite a bit of in-flight control (well, two voltages and two plungers for 4 selections) which included action so it's perfectly believable that there was some French-made fuze that electrically interfaced with the jet. It's also perfectly believable it's a relabeled nose-tail solenoid selector and the selection was a wire-selected one.

[jojo]

Smart bombs were not in original Mirage 2000C requirements.

From a ballistic point of view, both Mk-82 and GBU-12 are released with ballistic from French SAMP 250kg bombs.

 

So in late 80' for an air defense fighter, with AG as secondary mission (like 20% of training), smart bombs were nowhere in sight. Dumb bombs, rockets, guns...

 

So no the plane don't "talk" to AG weapons, no in flight programming.

 

I don't understand your point about FMU-139, but there are several variants.

The one depicted in PDF above shows that you can select different settings of arming delay and detonation delay (from instant to 60ms delay). This seems to be done on ground before tail assembly.

 

That would fit with Mirage 2000C simple store management system.

[microvax]

noice finds. The mk82s on the mirage seem jsut to arm late enough that you can bomb down to 60ft. If you drop them from higher up they pretty much blow up instantly.

 

Thats the only usage a delayed gbu12 fuse would have pretty much I guess.

[mvsgas]

Here are some examples of GBU-12 wiring and fuzing. You can see that it can have fuzes in the nose and the tail and many different configurations.

[ATTACH]148306[/ATTACH]

[jojo]

Here are some examples of GBU-12 wiring and fuzing. You can see that it can have fuzes in the nose and the tail and many different configurations.

[ATTACH]148306[/ATTACH]

 

Nice document. Maybe they found a way later to put a nose fuze despite the Paveway II nose kit ?

[mvsgas]

AFAIK, nose fuzing on GBU-12 has always been there, the problem is pilots can't change the settings on the ground while doing the walk around inspection. So whatever parameters where entered in the nose fuze by AMMO while building the bomb is what you get. The tail fuze can be reach so if pilots need to they can make adjustments before flight. Keep in mind in RL, on most ordnance (not all) you can not change the fuzing in flight.

[jojo]

I don't know.

The first link here

https://forums.eagle.ru/showpost.php?p=2900890&postcount=3

 

Clearly state

The CCG mounts on the nose of the bomb body (this preclude the use of nose fuzing)

And the drawing shows a bomb assembly without nose fuse.

 

But your documents shows Paveway II with both nose and tail fuse.

I don't have the date of these documents, but it makes me think of design change between the 2...

[mvsgas]

Here is a good weapons info PDF

https://docs.google.com/viewer?url=http%3A%2F%2Fcsef.ru%2Fmedia%2Farticles%2F4361%2F4361.pdf

 

When you read this, you quickly realize how many options are for each weapon and how it can get very complicated very quickly.

GBU-12 starts in page 5-8. Some part here only say tail fuzes, but then the chart in page 5-11 to 5-12 list nose fuzes.

Edited September 16, 2016 by mvsgas

[Frederf]

It looks like GBU-12/B couldn't have a fuze in the nose but 12A/B B/B C/B D/B can.

[mvsgas]

It looks like GBU-12/B couldn't have a fuze in the nose but 12A/B B/B C/B D/B can.

My earlier posted table, taken from a F-16 -34, shows GBU-12B able to carry the FMU-81/B and the FMU-139 in the nose.

It is very possible that French GBU-12 where different, since there are so many combinations. Like I also mention, pilots can't verify nor modify the nose fuzes, so they do not like them AFAIK.