High drag bombs - incorrect fusing behavior

[Diesel_Thunder]

Found a bug with both the AIR and Snake Eye variants of high drag bombs across multiple aircraft. In all cases, setting the weapons to tail only fuzing will have the bomb detonate when hitting the ground, which is the incorrect behavior (it should not detonate).

The tail "fuze" is replaced with the high drag tail kit and has no provision for an actual fuze to detonate the bomb. Releasing the bomb in tail only fuzing should only have the weapon drop in high drag configuration, but without detonation since the nose fuze was not armed.

Here are two track files that shows the incorrect behavior. One is with the Mk-82 AIR, the other with Mk-82 Snake Eyes.

mk82 AIR bug.trk mk82 snake eye bug.trk

[Tholozor]

As far as I know, the Mk-82 AIR with the BSU-85 or BSU-49 ballute kit does permit the installation of a fuze in the tail well, you can see the M905 fuze spinwheel installed on the bombs in the first track, so setting the fuze to TAIL should result in detonation.

I'm not entirely sure regarding the installation of tail fuzes on the Snakeye, someone with more immediate information can probably fill in the gaps.

[graveyard4DCS]

You're right, there can be a M-905 mechanical fuze with high drag bombs. 

However, note that technically speaking the nose/tail option let you select a wire on the bomb, and it can be different from the actual fuze arming.

For example, in general on high drag bomb the tail wire will open the chute and the nose wire will arm the fuzes, whether they are nose and/or tail.

Obviously making the nose wire arm the nose fuze and the tail wire arm the tail fuze is the most logical, but the case of the Snakeye shows you that it's not always the case. The same question arises for LGBs, because for example the Paveway guiding kit must be ignited and the tail wing deployed, and that also the role of arming wires as selected by the tail/fuze option. 

Ideally, these details should be modelled so that we know more precisely what consequences the nose/tail options will have in game. Currently, we can only make guesses... 

Edited March 13 by graveyard4DCS

[Tholozor]

Looking through a Chilean -34 manual, the Snakeye can have an FMU-139 fuze installed in the tail or nose well. The initiation for either setup controlled via a wire routed through the bomb casing from the FZU armed on the MAU-12's center solenoid or TER's nose solenoid.

[Scrape]

Tail fuses aren't used with high drag 82s and 84s.  Certainly not in the US and I'm not sure if other countries have some different fuses going on but generally this is true.  No tail fuze in the AIR or SNAKEYE bombs because it's needlessly redundant.  The ATU-35 drive would not be installed when the AIR package is present, and an initiator that goes through the center well is redundant and I'll explain.  

In the case of the MAU-12 there are 3 solenoids but only two options.  NOSE (on/off) and TAIL (on/off).  The BOTH selection in the aircraft is telling the weapons computer NOSE on and TAIL on.  There is no BOTH signal electrically, only a signal for NOSE and a signal for TAIL.  The center solenoid is wired to NOSE and is not independent.  Since dropping in high drag is an option for the pilot, the only way to provide that option is to use one of the solenoids.  The tail package is mechanical and not electrical and the only way to affect any option mechanically is through the solenoids.  The TAIL option is used because it's closest to the AIR package and name wise makes sense.  The nose fuze is reserved for the fuze that will initiate detonation.  The remaining solenoid is the center solenoid.  Plugging a tail fuze into the same solenoid as the nose fuze is the redundant part I mentioned earlier.  There's no point to this and it serves no purpose.  There's already a fuze in the nose, don't need two fuzes in the nose solenoid.  One is all you need.  

In addition, there is no way to perform maintenance on a tail fuze while the high drag package is installed.  If the fuze needed to be safed, disarmed, it could not be reached by hand without first removing the tail package.  Meaning if for any reason an unsafe condition would occur with the tail fuze, the tail package would have to be removed before the munition could be rendered safe to be around.  The access window in the AIR package is to verify there is no fuze installed, not to perform maintenance on the fuze like the door that exist on normal low drag tail packages.  Since slow moving bombs have severely reduced penetrating properties there is little if any reason to prefer a tail fuse over a nose fuse.

In the case of a TER rack there are only 2 solenoids.  One less than the MAU-12, but the same number of options exist.  Nose and TAIL, and of course the option of BOTH.  Again the high drag or low drag release of the SNAKEYE and AIR packages is an option, and like the MAU-12 the tail solenoid is used to exercise this option.  The NOSE solenoid on the TER would be reserved for the nose fuze.

Is it possible to install a nose plug into the bomb and use a tail fuze with a Mk-82AIR?  Sure it can be configured this way, but it is not standard practice, nor a safe one unless other concerns are addressed.  Could it be done?  Yea I suppose. 

Is the bug that's highlighted indeed a bug?  Yes it is.  Selecting TAIL only on a high drag Mk-82 or Mk-84 should result in a dud when it hits the ground.  

NOSE only = Bomb explodes but high drag device does not deploy
TAIL only   = No explosion, high drag device deploys

BOTH         = Bomb explodes, high drag device deploys
JETTISON (any) = No explosion, high drag device does not deploy

Edited March 17 by Scrape

[Kirk66]

Tail fuzes were absolutely an option for Mk 82 Snakeyes. FMU-54s. Whether they were used probably depended on fuze reliability requirements. Extract below is from -34-1-2. Tons of details in that TO about Snakeye fuze options and how and when to use them.

 

null

Edited March 17 by Kirk66

[Scrape]

I'm tracking when you reference the 54.  Not withstanding the different delivery methods experimented with and used across the decades of combat aviation - sorry for not specifying the specific dates of the absolutism of my statements.  The point is, regardless of where the fuse sits on the bomb, in the nose or tail well of the munition, it would not be connected to the TAIL arm option, which is the point of the conversation.

[SpecterDC13]

On 3/13/2025 at 8:38 AM, graveyard4DCS said:

The same question arises for LGBs, because for example the Paveway guiding kit must be ignited and the tail wing deployed, and that also the role of arming wires as selected by the tail/fuze option. 

The wings on the tail package of the GBU12/10/24 do not "ignite". The wire that attaches to the wing release latch gets safety wired directly to the sway brace of the MAU-12 or sway brace on the TER (there is no arming loop that goes into a solenoid). In the case of the MAU-12 with a GBU12 on it, you have two arming loops that go into the solenoids: one for the initiator that goes into the center solenoid, and one for the BFD on the CCG that goes into the nose solenoid which is slid onto the wire for the BFD. If you have a GBU12 on the TER, both BFD and wing release latch wires get safety wired to the sway braces of the station that the bomb is on, while the initiator goes into the nose solenoid on that station. So, in the case of the GBU12/10/24 on a MAU-12 the choice of NOSE is for the BFD arming loop and the initiator arming loop. This is considering the fuze you are using is either the FMU-139 or FMU-152. You can equip a M905 but it is not a typical configuration in real life.

If you have GBU12s on a TER the choice of NOSE is for the initiator only.

MAU-12 Selecting (GBU-12 with FMU-139/152):

NOSE = Bomb will arm and guide (will DUD if using M905)

NOSE/TAIL = Bomb will arm and guide

TAIL = Bomb will DUD and not guide (will go unguided but will still explode if using M905)

Just gotta remember what fuzes you put in the bomb. But you are always safe going with the N/T option.