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United States Military Vehicle General: Guns, G*vins, and Gas Turbines


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Do you have images for the changes to the ammunition storage?  That is interesting; I thought the ammo rack had stayed more or less the same.

In the videos you posted there is no way to tell that the crew compartment remained protected as the ammunition burned, unless there are detailed after action reports for these incidents.  If the crew compartment remained intact but the ammunition blast doors were untouched than it isn't relevant to this conversation.  We know that the isolated ammunition storage works as long as the blast doors are closed and intact.  What I want to know is what happens if a shot penetrates both the ammunition bustle and the blast doors, eg. from a 6 oclock hit to the bustle, or from a frontal hit that comes in diagonally from the front.

If there isn't some other provision for dealing with this problem, I suspect that the crew would be disabled by the overpressure leaking through the hole in the blast door.  It doesn't take much overpressure at all, relative to the pressures generated by burning ammunition propellant, to disable a human.

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AAV-P7A1 CATFAE (Catapult launched Fuel Air Explosives).  Troop carrying capabilities were exchanged for 21 fuel-air ordnance launchers for the purpose of clearing minefields and other obstacles durin

Recoil system of the M256:  

About two and a half years ago i've stumbled across some russian book about western IFVs, which apparently was a mere compilation of articles from western magazines translated into russian. There was

Ammo racks for 120mm ammo was changed at least several times, 1st generation ammo racks hold only 17 rounds, so only 34 rounds in turret bustle in total, later it was changed to 18 rounds per rack so 36 in turret bustle.

There were also some changes to the ammo rack design and blow off panels.

abrams.JPG
These are original blow off panels for 105mm ammo racks.

m1a1_details_073_of_435.jpg

These are 1st generation blow off panels for 120mm ammo racks.

m1a1_25_of_71.jpg

These are 2nd generation blow off panels, and here the story starts to be interesting. As far as I know, this was attempt for quick reload mechanism for tanks. And it's the first time where ammo racks were connected with blow off panels. Idea was that for quick reload, using a crane, entire ammo racks can be replaced by pulling them out with a blow off panels. However for some reason it was unsuccessfull and the entire idea was droped but these blow off panels could be seen on some tanks.

m1a2_details_098_of_125.jpg

These are 3rd generation blow off panels, it seems they are remanufactured 2nd generation blow off panels, with these attachement points removed.

JB8GISW.jpg

And these are the newest 4th generation blow off panels and ammo racks. I have a theory that perhaps someone revisited the idea of ammo racks being connected with blow off panels, but instead for quick reload function, made this as additional safety meassure so blow off panel can pull off the ammo rack during ammo cook off event. Or perhaps both functions do not exclude eachother.

http://www.wegmannusa.com/mbt-ammo-racks/

Here you can see that blow off panels are flat but have two attachement points.

8325_169444000218_1417025_n_zpsb88d75f5.

For comparision these is one of the older ammo rack types but I have no idea which one.

297WS9w.jpg

And drawing shows difference between 17 round and 18 round ammo racks.

PS. here is also something about improved ammo racks for USMC tanks. http://www.dtic.mil/ndia/2012mcsc/Shrader.pdf

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53 minutes ago, Damian said:

PS. here is also something about improved ammo racks for USMC tanks. http://www.dtic.mil/ndia/2012mcsc/Shrader.pdf

The only safety improvements mentioned being better static charge handling and a lubricant to prevent stuck rounds

 

I doubt that a hole in the blast doors is a huge concern - while ammunition develops very high pressures in the chamber, the local pressure developed when burning with such an easy route to atmosphere will be much lower. Any hypothetical hole in the blast door will also be very small, so even with an appreciable pressure difference there won't be very much gas flowing into the crew compartment - I bet the penetrator that made the hole in the blast door will be a bigger issue for the crew.

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29 minutes ago, Xlucine said:

The only safety improvements mentioned being better static charge handling and a lubricant to prevent stuck rounds

 

I doubt that a hole in the blast doors is a huge concern - while ammunition develops very high pressures in the chamber, the local pressure developed when burning with such an easy route to atmosphere will be much lower. Any hypothetical hole in the blast door will also be very small, so even with an appreciable pressure difference there won't be very much gas flowing into the crew compartment - I bet the penetrator that made the hole in the blast door will be a bigger issue for the crew.

Perhaps yes. However it seems that there is some improvement and redesign of the entire ammo compartment in M1A2SEPv3, but no details, I guess we gonna need to wait a bit more, maybe entire year for another DOT&E report.

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5 hours ago, Damian said:

I don't know if you noticed that it was sarcasm, and irony, do not take it so personal.

 

I never said M1 is perfect, but so far it's the only mass produced tank that have such high crew survivability, and also vehicle survivability properties thanks to compertalization of main gun ammunition.

It's a fact. That's all, and I am certain that engineers working on the project taken all possibilities in to consideration.

As for videos, these are hard evidence, you have something better? Feel free to post it.

It's funny how the second the Iraqis or Saudis take something into battle its reputation suffers.

 

Part of the reason that so few M1s were lost until recently is that the ones seeing combat were all being operated by the US. US tankers, whatever their faults, don't seem to be in the habit of allowing their enemies to shoot them in the nuts with modern ATGMs.

It takes awful middle eastern conscript armies to truly show all of the weaknesses of a tank design.

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1 hour ago, Toxn said:

It's funny how the second the Iraqis or Saudis take something into battle its reputation suffers.

 

Part of the reason that so few M1s were lost until recently is that the ones seeing combat were all being operated by the US. US tankers, whatever their faults, don't seem to be in the habit of allowing their enemies to shoot them in the nuts with modern ATGMs.

It takes awful middle eastern conscript armies to truly show all of the weaknesses of a tank design.

I actually watched carefully what were going on over there and I must say that M1's actually proved it's high survivability and crew protection.

Sure watching terrorists propaganda can make your brain melt down, however I seen many M1's in these videos that were hit several times by various weapons used by the terrorists, and even after such beating tanks were still functional.

Actually majority of losses were when vehicles were abandoned due to no reason, and later burned or stuffed with explosives and blown up by the terrorists. Heck even ATGM's, altough the most dangerous besides large IED/SVBIED's, are not always super successfull.

In my opinion, as someone who serve in military reserve, M1 is the only MBT I would agree to go in to battle... besides T-14 but we can safely assume that all 4th generation MBT's will be designed in similiar way.

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On 2/12/2017 at 11:49 AM, Damian said:

I am certain tough that during development it was taken in to consideration such possibility and it was somehow solved.

One possibility is that the problem might had been solved with ammo racks and blow off panels design, where ammo rack is directly bolted to the blow off panel, and the concept is that in case of ammo cook off, when blow off panel is... well blow off, it takes outside also the entire ammo rack.

 

Gasses released during combustion of material like this have whacky compressability factors(Z sub i for a species) and don't prescribe to kinetic theory perfectly. 

What you are trying to say is, "It's probably fine, because someone smarter than me actually designed this tank."

 

 

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10 minutes ago, Mighty_Zuk said:

Shots resulting in penetration of both the ammo compartment and the separating door are quite likely in side or rear shots, but the crew manning the turret would be pretty much screwed regardless of detonating ammunition. 

Nothing like having your workspace suddenly full of high-velocity burning metal fragments to spice up your day.

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It's not exactly the case, there were plenty of cases where crew compartment was penetrated by shaped charge jet, and the crew either was not harmed or was only injured.

There were of course incidents where a single crew member was killed but he was in direct path of shaped charge jet.

More dangerous are kinetic energy penetrators that have a greater diameter than shaped charge jets, and in case of penetration of the crew compartment, tend to generate much more fragments and spall inside.

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36 minutes ago, Xoon said:

It's some honor thing or something like that. Not really that common, but some do.

This reminds me Nick Morans video about myths concerning US AFV's during WWII, and WIA and KIA ratios inside M4 medium tanks in US Army service and British Army service, it was discovered that British had more KIA because they didn't used helmets for tank crews, preffering berets. And head injuries were one of the most common reasons that crew members died.

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43 minutes ago, Damian said:

This reminds me Nick Morans video about myths concerning US AFV's during WWII, and WIA and KIA ratios inside M4 medium tanks in US Army service and British Army service, it was discovered that British had more KIA because they didn't used helmets for tank crews, preffering berets. And head injuries were one of the most common reasons that crew members died.

Of course during wartime or fighting abroad they use helmets.  

It's a bit weird in Norway. Soldiers dislike the ballistic helmet (for good reason, good god that thing is a pain in the ass), so it is rarely worn, usually by your average grunt, special forces, or if you need  a mount for your NVGs. Flak vest are also not really common, only for active personnel, conscripts don't get those.  Same story for plate vests.

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32 minutes ago, Bronezhilet said:

And why is that?

Because the biggest killer of tank crews and their vehicles is the ammunition stored inside when it cooks off. The M1 and T-14 are the only tanks that protects the crew and partially vehicle from results of ammo cook off through complete isolation of that ammo from the rest of vehicle in magazines with blow off panels.

 

Of course if you preffer to fight in a mobile crematory like T-90, Leopard 2, Merkava or any other tank, it's your right to do so.

 

Quote

Of course during wartime or fighting abroad they use helmets.  

It's a bit weird in Norway. Soldiers dislike the ballistic helmet (for good reason, good god that thing is a pain in the ass), so it is rarely worn, usually by your average grunt, special forces, or if you need  a mount for your NVGs. Flak vest are also not really common, only for active personnel, conscripts don't get those.  Same story for plate vests.

They dislike standard ballistic helmet... wait you guys do not have CVC's? And you do not have a widespread use of ballistic vests?

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10 minutes ago, Damian said:

Because the biggest killer of tank crews and their vehicles is the ammunition stored inside when it cooks off. The M1 and T-14 are the only tanks that protects the crew and partially vehicle from results of ammo cook off through complete isolation of that ammo from the rest of vehicle in magazines with blow off panels.

How big is the change that a frontal 30° arc pen doesn't kill you, but does set off the ammorack?

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4 minutes ago, Bronezhilet said:

How big is the change that a frontal 30° arc pen doesn't kill you, but does set off the ammorack?

We have plenty of example where M1's were hit from various angles, without or with ammo cook off, and in both cases crews had high survivability rates. And it's not about a single crew member survivability, it's about entire crew survivability. If only a single crew member dies, but rest survives, it's good for me.

PS. If US bothered with full ammo isolation, and Russians also went in that direction, it means something, we have here two nations that are probably one of the most experienced when it comes to use of tanks on the real battlefields.

Furthermore, we can safely assume that all new MBT designs, or so called 4th generation MBT's, will be very similiar to T-14 in general design, which means heavy armored crew capsule in the front isolated from the rest of vehicle, with unmanned turret that have isolated ammo storage with blow off panels.

 

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34 minutes ago, Damian said:

Because the biggest killer of tank crews and their vehicles is the ammunition stored inside when it cooks off. The M1 and T-14 are the only tanks that protects the crew and partially vehicle from results of ammo cook off through complete isolation of that ammo from the rest of vehicle in magazines with blow off panels.

 

Of course if you preffer to fight in a mobile crematory like T-90, Leopard 2, Merkava or any other tank, it's your right to do so.

 

They dislike standard ballistic helmet... wait you guys do not have CVC's? And you do not have a widespread use of ballistic vests?

We do have CVCs, we just call them helmets.

 

And no, ballistic vests are not widespread.
Conscripts usually don't get them, and only the army has widespread usage of balistic vests. The Homeguard, which is 99% of our manpower does not usually have ballistic vests. There is a reason we can equip 42 000 men with only 3% of the defense budget.

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23 minutes ago, Damian said:

We have plenty of example where M1's were hit from various angles, without or with ammo cook off, and in both cases crews had high survivability rates. And it's not about a single crew member survivability, it's about entire crew survivability. If only a single crew member dies, but rest survives, it's good for me.

As the forum motto goes: Referte aut morimini. Or "Link or die".

I can do without links if the one making the claim is someone I know I can trust, but if it's a new member who's circlejerking over the M1, I'd like to have my sources, thank you very much.

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31 minutes ago, Bronezhilet said:

As the forum motto goes: Referte aut morimini. Or "Link or die".

I can do without links if the one making the claim is someone I know I can trust, but if it's a new member who's circlejerking over the M1, I'd like to have my sources, thank you very much.

We can see tank commander getting out... which is a mistake, per procedures he should close the hatch and wait inside until ammo cook off event ends.

This is from 2003, USMC M1A1 was hit in turret roof injuring commander and loader. Loader got light injury in arm, and commander lost his eye due to shrapnel, still entire crew survived and tank had only cosmetic damage.

solved1.jpg

Here is M1A1 penetrated in to the side by shaped charge warhead (RPG most likely), altough commander and gunner were injured, they survived.

https://www.strategypage.com/military_photos/solved.aspx

https://en.wikipedia.org/wiki/History_of_the_M1_Abrams#Persian_Gulf_War

Here we have list from 1991 Gulf War, with notes of the sources, with vehicles bumper codes, what hit them, and with results.

Here we have a fragment of relation by Seargant First Class Anthony Steede, his M1A1 was hit in the side armor by a T-72 tank, penetration injured gunner and loader, but the crew survived.

In video it starts around 26:00.

Additional source is here.

https://books.google.pl/books?id=tekVy71S1qwC&pg=PT284&lpg=PT284&dq=Tony+Steede+tank+commander&source=bl&ots=4R-fkZr6YG&sig=ujEC6cz-GPNTCK4k2yJZNDJU2oY&hl=pl&sa=X&ved=0ahUKEwiVz9CunZLSAhWFjywKHSXKAa8Q6AEIJjAB#v=onepage&q=Tony Steede tank commander&f=false

There was also a list from OIF but can't find it now, I believe it was from Wikileaks or something.

http://www.fprado.com/armorsite/US-Field-Manuals/abrams-oif.pdf

Some additional source is also "Lessons Learned" about use of M1's in OIF.

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I'm perplexed by USAR/GDLS's decision not to coat the inside of the crew compartment with a spall liner (the only reference to spall protection, in Hunnicutt's Abrams book [p.209], refers to the three 105mm rounds stored on the basket floor, which were covered with "spall protection covers"). Were the engineers so confident about the protection the Abrams already boasted, they neglected such a feature (and just delegated the "last line of defense" to crew gear) or was this absence part of some sort of cost/weight-cutting effort?

...Or please don't tell me the SL is actually inside the armor pack boxes, on the innermost walls...that'd be a bit weird.

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