First off, notice the "might" in the title. It is not yet known what exactly happened. What I'll be talking about is something I heard from someone close to the people involved. It might turn out to be not true, or it might be true. To be sure we have to wait for the official report of the investigation.
Second, it might seem I am attacking the victims of the accident, this is not the case. But if they made mistakes, I will point them out.
So most of you have probably already heard of the accident with the M18 Hellcat. What I have heard from people close, is that the round went off when they opened the breech after a misfire, or slightly after they opened the breech. So, a misfire huh. Nasty stuff when it involves explosives.
So, what happened?
Well, misfires happen. There's nothing strange about that. I assume a lot of you have experienced misfires with small arms, and you know the procedure of dealing with them. But with misfires like these are handled (completely) differently. I asked around a bit, and apparently the gunner waited a few minutes after the misfire before he opened the breech. This is good, but not good enough. Not by a long shot. If I remember correctly, when your small arms firearm misfires you keep the barrel pointing down range for at least 30 seconds. After 30 seconds you can safely assume the round will not go off by itself. It's different when a proper amount of explosives is involved. You do not wait 30 seconds.
You wait at least 30 minutes. But between a misfire and waiting is another step. But I don't know if that step is possible on a Hellcat. More modern tank guns have two firing systems. The normal one, and an emergency one. If there was a misfire you were supposed to try the emergency firing system next, and if that didn't work: Time to wait.
After waiting 30 minutes there are two things you can do. The first is to open the breech and check everything. Carry the round to a safe place, and blow it up. This is usually what you can do with normal, proper rounds. But in this case, with more shady ammunition I would go for option two: Call Ordnance. There are multiple things that could be wrong with the round, and I'm go out on a limb here and claim that the gunner did not have Ordnance training. In the military, if something goes wrong, Ordnance immediately becomes the supervisor of everything that happens. There might be Generals running around, but that mere Sarge (or whatever rank they have in the US) is in charge.
This is what Ordnance would most likely do:
- Establish what round is actually in the gun. Is it an original WW2 round, or is it aftermarket? What primer did they use? What powder? Is it an AP shell, or HE? Does the shell have a fuse? If yes, what type of fuse?
- Try to establish what happened with the round before it went into the gun. How was it stored? Did you put it in your shed, or in a bunker with AC?
This is all to determine one thing: Is the round stable? In other words: Can I move the round?
If the round is determined to be stable, Ordnance can do two things.
1. Open the breech from a safe distance, and making sure the round will be caught before it hits something. Considering an historic piece of equipment is involved, this can result in the best possible ending. Which is a round being ejected without problems. But it is possible that the round will detonate inside the vehicle, destroying the tank and sending shrapnel all over the place. For Ordnance, the problem isn't the tank being nuked, it's the shrapnel.
2. Remove the gun from the turret and move it to a safe place. Ordnance will put at least three shaped charges on the outside of the chamber. One aimed at the primer, one aimed at the propellant and the last one aimed at the shell itself. The whole barrel will then be covered with several tons of dirt and the charges detonated. Voila, another safe ending to a dangerous situation. The gun is properly ruined, but nobody is hurt (except maybe some feelings).
I'm assuming that the gunner knew how to handle firearms and various weapons. He had fired the gun before, he knows how it works. He might not have much experience with misfires, but he does know that he should wait a bit before opening the breech. But at this point, it's not a round you have in the gun. It's not a misfired round. It's not a nuisance. It's a faulty round.
It's an explosive. It intends to kill. And it intends to kill you. And it intends to kill you immediately.
Treat it as such. Don't touch anything. Sod off to a safe place. Call Ordnance.
pic from TankNet.
I feel uncertain whether its cannon's caliber was 140mm or not, I found a figure at the document AD-A228 389 showed behind, which label the gun as LW 120.But in many ways I've found its data in websites all considered to be 140mm.
AFAIK,the first xm291(140)demonstrator was based on xm1 tank, and the successor was the''Thumper'' which was fitted with a new turret look like the CATTB but still m1a1 hull(Maybe it was CATTB's predecessor? )
I will really appreciate if anyone have valuable information to share
About tank guns and amunition, hope it will be interesting topic :-)
In penetration data I will base on russian sources -they are ussaly most credible (the best). I will ussaly give value for monolith steel plate slopped on 60@ - it's the best scenario for APFSDS penetrator. In sucht scenario (slopped on 60@ plate) penetration value can be bigger at even 17-20% then on 0.degree plate - this is caused by "asymmetry loads back surface" of the plate):
penetration at 2km, on plate slopped by 60@: 540-560mm RHA:
DOI - 1989 (in some sources - 1988)
penetration: at 2km, on plate slopped by 60@: circa 700mm RHA
this round was to weak to overcome T-80U and T-80UD and T-72B m.1989 whit Kontakt-5 ERA, what was "suprisly" discover on tests in circa 1994. The same story was whit DM43 prototypes..
DOI - 1992
penetration: at 2km, on plate slopped by 60@: circa 740mm RHA
Fist US round whit composite sabot.
(lack good photos)
insted of this:
KE-W so M829A1 but whit WHA penetrator, and KEW-E3 so M829A2 whit WHA long rod.
DOI - 2003
penetration: at 2km, on plate slopped by 60@: propably circa 800mm RHA, but is not sure value,
round devleoped to everpas heavy ERA but whit unkown result
DOI -2016 :-)
penetration - no idea
It's very interesting round
data link is for APFSDS round?!
I have a hypothesis...
Ok so it have data link to be programmed, it is said to be capable to defeat 3rd generation heavy ERA (Relikt, Knife, etc.) and active protection systems (hard kill). It seems that focus is primary on defeating heavy ERA. But then again, why do you need to program just a long rod fired by a big gun?
There are few options:
- Gudining the round,
- "Intelligent" control over propelant charge ignition (dependant on propelant temperature, environment temperature, gun service life, range to target etc.)
And truth to be told hypothesis that there is some sort of precursor in the rod is the only hypothesis that makes sense. Control over propelant charge ignition is not needed and probably not possible at all with current technology, besides the M829A4 (and all newer US ammo types for 120mm smoothbore) use insensitive propelant charges. And it is nowhere mentioned in any document avaiable for public. Guiding the rod to target? Perhaps possible from technical point of view, but why? Again it was nowhere said that FCS for M1A2SEPv3 have ability to guide any type of rounds. And manouvering of the rod during flight means loss of a lot of energy, even if this manouvering would be done to "cheat" the APS for example.
So perhaps the option is to somehow use a precursor that is "fired ahead" of the main rod.
So how the rod designs looks like here? The rod is made from two segments, the "precursor" and the main rod behind it. How they are connected? it might be some sort of polymer, glue that can be weakened by heat and the release precursor, and during flight rods heat up pretty nicely.
The precursor can also be relased based on a simple difference of speed between it and the main rod, and main rod can be slowed down by some sort of additional fins (aerodynamic breaks) released at specific point programmed by FCS. In such case precuros would initiate ERA and the main rod would have a clear way to main armor of the target.
How to cheat APS tough? Counting that precursor will be qualified by APS as threat and APS will be initiated, creating a time gap in APS reaction so it won't be able to counter the main rod? Possible yes, but then there is question, if APS will just not ignore the precursor, and this might happen, now of course there is a question how dangerous is precursor itself? For a MBT or vehicle with similiar levels of protection, for it's front it won't be dangerous in most cases, sides? If they do not have any addon armor, very possible. For lightweight platforms, yeah precursor also will be dangerous.
Of course these are only hypothesis, and we will see if other nations will also design APFSDS rounds with data link. Then we might get closer to the truth. Right now, treat it as food for thoughts.
of course this data link coud be placed only for security resons, as one person on TankNet had wrote:
ps. prefragmentet APFSDS during flying exist now, as smal-scale models and test object: