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

[Damian]

Propulsion systems and suspension

As mentioned before, M1 was designed with different types of engines and transmissions in mind. And indeed various types were tested, besides the standard AGT-1500 gas turbine engine, and tested as a competing design AVCR-1360 diesel engine, various different alternatives were tested.

One of the less known was AGT-1500 TMEPS (Transversly Mounted Engine Propulsion System), it was a standard AGT-1500 just mounted transversly to free up more space in the hull.

Another alternatives were LV-100-5 gas turbine engine and XAP-1000 diesel engine.

LV-100-5 was considered as new common engine for M1's and XM2001 Crusader self propelled howitzer. XAP-1000 was meanwhile tested in CATTB technology demonstrator.

http://www2.l-3com.com/cps/cps/1500_hp.htm

Another rare alternative would be to use 1500HP version of the well known and extremely reliable AVDS-1790 diesel engine, two configurations were proposed, one with standard mounted engine, and second with transversly mounted engine.
 

Finally we have a GDLS proposal to use the compact MTU MT883 diesel engine in 1650HP version.
 

As another alternative, a new BAE hybrid diesel-electric drive for heavy tracked vehicles, also can be potential candidate for AGT-1500 gas turbine replacement.

For the M1 at the moment only two types of transmissions are considered.

The currently used Allison X-1100-3B and Allison 5250MX.

http://www.allisontransmission.com/docs/default-source/defense/11568_atm_sales_sheets_x1100-3b.pdf?sfvrsn=2
http://www.allisontransmission.com/docs/default-source/specification-sheets/11119_atm_5250mx_sales_sheet.pdf?sfvrsn=2

When it comes to suspension systems, again, M1 was designed in mind, with capability to use different types of suspension.

This photo shows us very unique designs solution, of modular attachement points for suspension systems. This means that different types of suspension can be used besides standard torsion bars, it makes also upgrades for suspension easy and cheap as it does not demand expensive and time consuming cutting and welding work on suspension attachement points.

At the moment only alternative considered for torsion bars suspension system is hydropneumatic suspension system.

In the past Gadillac-Gage In-Arm system was tested, at the moment however avaiable is L-3 hyropneumatic suspension system model 3870.

http://www2.l-3com.com/cps/cps/3870_suspension.htm

In general these engine and suspension upgrades can be included in another ECP modernization phases.
 

 

 

[Collimatrix]

7 minutes ago, Damian said:

Propulsion systems and suspension

As mentioned before, M1 was designed with different types of engines and transmissions in mind. And indeed various types were tested, besides the standard AGT-1500 gas turbine engine, and tested as a competing design AVCR-1360 diesel engine, various different alternatives were tested.

One of the less known was AGT-1500 TMEPS (Transversly Mounted Engine Propulsion System), it was a standard AGT-1500 just mounted transversly to free up more space in the hull.

Another alternatives were LV-100-5 gas turbine engine and XAP-1000 diesel engine.

 

 

We've had this link in the resources section for a while on TMEPS.  The engine was not "a standard AGT-1500," as the document explains, it had a new high pressure turbine rotor, new high pressure turbine cylinder, new recuperator, new power turbines, a new electronic control unit and a new auxiliary power take off.

[sevich]

https://www.thefreelibrary.com/Army+pursuing+alternatives+to+heavy+vehicle+armor.-a0468700292

US Army pursuing alternatives to heavy vehicles.

 

Personally I think the vulnerability of electronics will simply make repairing tanks where there is heavy fighting will make supply costs higher, something like how it was unexpected that battery consumption would be higher in Desert Storm (or was it Iraqi Freedom).

 

It seems likely the next tank may have an electric transmission. And to have Christie tank capabilities.

[Walter_Sobchak]

Its funny, I never noticed that bit about the possibility of the transverse mounted AVDS-1790 in an Abrams before.  I know I had asked my dad once about transverse mounting the AVDS and he said Teledyne had asked Allison long ago about designing a transmission for such a mounting and Allison said there wouldn't be enough room for the linkages.  The reality was that Allison didn't want to do it.  For Allison, it was more important that they didn't piss off General Dynamics, who would not have appreciated Allison helping out their competitor, Teledyne Continental. 

[Damian]

19 hours ago, Collimatrix said:

 

We've had this link in the resources section for a while on TMEPS.  The engine was not "a standard AGT-1500," as the document explains, it had a new high pressure turbine rotor, new high pressure turbine cylinder, new recuperator, new power turbines, a new electronic control unit and a new auxiliary power take off.

Thanks for informations.

12 hours ago, Walter_Sobchak said:

Its funny, I never noticed that bit about the possibility of the transverse mounted AVDS-1790 in an Abrams before.  I know I had asked my dad once about transverse mounting the AVDS and he said Teledyne had asked Allison long ago about designing a transmission for such a mounting and Allison said there wouldn't be enough room for the linkages.  The reality was that Allison didn't want to do it.  For Allison, it was more important that they didn't piss off General Dynamics, who would not have appreciated Allison helping out their competitor, Teledyne Continental. 

I guess here the problem was the fact that US Armed Forces were happy at that time with AGT-1500, as it's reliable engine that meets requirements, and for a long time there was no requirements from DoD, thus there was no coordination, every attempt to find replacement was purely industry initiative. Only recently US Army started seriously look at AGT-1500 replacement, and we gonna see what will happen.

[Ramlaen]

 

[Collimatrix]

So, question about the isolated ammunition storage.

 

What happens if an Abrams gets nailed in the turret bustle from the 6 o'clock and not only does the ammunition get hit, but also the (relatively thin, ballistically speaking) firewall between the fighting compartment and the ammunition storage gets a hole poked in it?  Does the isolation of the ammunition do anything then, or does the crew just get cooked a little slower?

[That’s Suspicious]

Have they experimented with a self sealing foam or a flame retardant that deploys if something like that happened too the blast doors?

[Collimatrix]

I know there are several systems that can deploy fire extinguishers within milliseconds of a fire being detected.  But these are mainly useful for dealing with hydraulic system fires.  Ammunition propellant contains its own oxidizer, so trying to deny it oxygen doesn't do much to it.  It might be possible to extinguish an ammunition fire by removing heat from the fire by the evaporative cooling of whatever it is the extinguisher is spraying, but that would essentially amount to a far less effective version of a wet ammunition storage system.  I have read that the experience with Chieftains in the Iran/Iraq war was that the wet ammo stowage didn't help that much.

Self-sealing foam might work, but it would have to be some tough, fast-setting foam.  Burning ammunition won't generate the same pressure burning in an ammo rack as it would when fired in the barrel, but it still generates enough pressure to, say, throw the turret of a T-72 clean off.

[That’s Suspicious]

I meant as a safe measure in event of a penetration of the blast door or any break in seal of the blast doors. Like a KE penetration of a M1's blast doors that is sealed by a flame retardant foam.

 

[Damian]

The general rule is that flames, gases and other nasty stuff will seak easiest way outside, and this easiest way outside is through blow off panels, and not a tiny hole made by shaped charge jet or KE penetrator.

I think the best would be a small experiment, let's take a small box, made from metal, fill it with something that burns violently, like potassium nitrate, make a small hole in one bulkhead, and cut out two larger holes in roof, maybe cover them with something light, like cardboard to simulate lower weight of blow off panels, and see what happens.

 

One note tough, I never seen any material showing that when armored blast doors were closed, even with hit from behind, flames get inside crew compartment.

And there are at least two filmed incidents where M1 was hit in the turret rear, and at least on one video we can see that flames did not get inside crew compartment.

[That’s Suspicious]

On 2/4/2017 at 6:49 AM, LoooSeR said:

Screenshot by GRU from Otvaga. Commander hatch protection can be seen pretty well, giant RCWS that blocks almost all frontal view also visible,

 

 

Hasn't that been a problem in regards of the CITV? The M1 in regards too other vehicles seems to have a lot more in the way of the M1's Commander's sight compared too other tanks. IT seems like this could spell bad for a M1 crew in certain combat scenarios where that RCWS could get in the way.

[Damian]

In M1A2SEP, both CITV and CROWS can be used in auto scan mode. This means that CITV in auto scan observes one sector, CROWS in auto scan observes second sector, and third sector is observed by the gunner.

 

Commander on his displays can simultanouesly observe images from both CROWS and CITV, and CROWS have not worse optics than CITV and gunner primary sight.

 

I was inside M1A2SEPv2 with CROWS mounted, and honestly, visibility from commander cupola is extremely good, better than in case of Leopard 2A4 or Leopard 2A5 commander cupola.

 

Besides that, M1A2SEPv3/v4 will receive new low profile CROWS which is lower and smaller.

 

[Collimatrix]

I don't think expanding gas works that way at all.  If you have a container full of high-pressure gas that has two openings that lead to areas with lower pressure, and one of the openings is large and the other opening is small, the gas will escape through both openings.  My evidence for this is the fact that gas-operated firearms work.

[That’s Suspicious]

3 hours ago, Damian said:

In M1A2SEP, both CITV and CROWS can be used in auto scan mode. This means that CITV in auto scan observes one sector, CROWS in auto scan observes second sector, and third sector is observed by the gunner.

 

Commander on his displays can simultanouesly observe images from both CROWS and CITV, and CROWS have not worse optics than CITV and gunner primary sight.

 

I was inside M1A2SEPv2 with CROWS mounted, and honestly, visibility from commander cupola is extremely good, better than in case of Leopard 2A4 or Leopard 2A5 commander cupola.

 

Besides that, M1A2SEPv3/v4 will receive new low profile CROWS which is lower and smaller.

 

 

Hmm, I didn't know that, thanks for the info. IT just seemed too me that the CITV would be obscured by the hatches, GPSE, and RCWS more so than other tanks.

[Damian]

2 hours ago, AMX-56 Leclerc said:

 

Hmm, I didn't know that, thanks for the info. IT just seemed too me that the CITV would be obscured by the hatches, GPSE, and RCWS more so than other tanks.

Not really, RCWS have a 360 field of view, CITV as well. Sure all these additional shields can obscure a bit the view for CITV, but these shields can be taken off as they are just additional modules used for COIN operations.

[Damian]

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.

Proof of that might be this photo of Saudi Arabian M1A2/M1A2S.

We might assume that due to hit blow off panel was blown off taking out ammo rack, but the process was incomplete because ammo rack was empty and there was no ammo cook off that would create sufficent pressure to blow away entire ammo rack with blow off panel.

[Bronezhilet]

13 hours ago, Damian said:

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

How? By breaking physics or by the use of aluminium alloy 1776?

 

Arguments like this are pointless, I can reply with the exact same thing but in reverse:

Quote

I am certain that during development such possibility wasn't taken into consideration and that it wasn't somehow solved.

See how that doesn't work? It contains no real arguments or proof at all, not even rumours. It's just "I think [...]", which is useless if you don't back them up by facts. Like, I dunno, Colli did?

[Renegade334]

Oh, hey, there's new information and pics compared to the original AW version.

Nice meetin' ya here, Damian.

 

(Not sure whether you'll keep going to the AW forums now that the game is tanking hard - no pun intended - and haemorrhaging members)

[Xoon]

My guess is quite simple:

When the ammo rack ignites, the gases would go wherever to escape. Including any hole in the blast door. However, since the entire roof of the rack blows out and lifts the rack halfway out of the isolated compartment, the expanding gas gets more room to move freely, this causes the gas going through the hole in the blast door to act like a blowtorch. Anyone standing between the hole and the wall gets perforated or sliced in half by the flame. 

Worst case scenario the hole could rupture the entire door and kill the crew.

And welcome to SH, Renegade.

[Damian]

I kinda find it amusing, that there is this notion to find a weakness in M1's isolated ammo storage. It's fantastic concept that completely solved one of the greatest problems with vehicle and crew survivability... but it's American vehicle, and it must have weakness there.

 

Here we have two example of a turret bustle hit from the rear by ATGM's, with the ammo cook off event, and still, yet the crew compartment is not compromised.

[Bronezhilet]

1 hour ago, Damian said:

I kinda find it amusing, that there is this notion to find a weakness in M1's isolated ammo storage. It's fantastic concept that completely solved one of the greatest problems with vehicle and crew survivability... but it's American vehicle, and it must have weakness there.

I kinda find it amusing, that this is this notion that the M1 is pixel perfect. It's not a fantastic concept that solved all the great problems with tank and crew survivability... but it's an American vehicle, and that means it must have no weaknesses.

Stop pretending there is nothing wrong with the M1. It has a couple of problems and weaknesses, just like every other tank. This is SH, not "M1 Circlejerk United". If we think something has something worth discussing, we'll discuss it. If it turns out to be a weakness or a strength, we'll talk about how and/or why. But apparently you think we're not allowed that, because apparently it's faultless. We're discussing that it might have faults, but you think that's bullshit because of ...? Apparenlty we are to believe you because you say so and because of muh American superiority. Spoiler: We don't.

 

Oh, in both of those videos the HEAT jet would not intersect the crew compartment, because of the impact angle.

[Damian]

1 hour ago, Bronezhilet said:

I kinda find it amusing, that this is this notion that the M1 is pixel perfect. It's not a fantastic concept that solved all the great problems with tank and crew survivability... but it's an American vehicle, and that means it must have no weaknesses.

Stop pretending there is nothing wrong with the M1. It has a couple of problems and weaknesses, just like every other tank. This is SH, not "M1 Circlejerk United". If we think something has something worth discussing, we'll discuss it. If it turns out to be a weakness or a strength, we'll talk about how and/or why. But apparently you think we're not allowed that, because apparently it's faultless. We're discussing that it might have faults, but you think that's bullshit because of ...? Apparenlty we are to believe you because you say so and because of muh American superiority. Spoiler: We don't.

 

Oh, in both of those videos the HEAT jet would not intersect the crew compartment, because of the impact angle.

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.

[Collimatrix]

How can we tell that the crew compartment is unharmed from these videos?  Sure, there isn't any fire jetting out from the turret hatches like there would be if a T-72 got hit, but it takes a lot less than that to kill the crew.  A blast overpressure of 3.5 PSI (24 KPA) is sufficient to maim or kill.

The idea that the blow-off panel takes the ammunition rack with it is intriguing, but I don't think it actually works that way.  You can see the blow-off panel flying into the air in this image:

 

 

It might also be possible to stuff the blast doors inside the turret with a lot of loose, hinged pieces of metal sandwiched in between two layers like so:

 

That might work, but I see no evidence that the Abrams' blast doors are anything but solid steel.

[Damian]

31 minutes ago, Collimatrix said:

How can we tell that the crew compartment is unharmed from these videos?  Sure, there isn't any fire jetting out from the turret hatches like there would be if a T-72 got hit, but it takes a lot less than that to kill the crew.  A blast overpressure of 3.5 PSI (24 KPA) is sufficient to maim or kill.

The idea that the blow-off panel takes the ammunition rack with it is intriguing, but I don't think it actually works that way.  You can see the blow-off panel flying into the air in this image:

 

 

It might also be possible to stuff the blast doors inside the turret with a lot of loose, hinged pieces of metal sandwiched in between two layers like so:

 

That might work, but I see no evidence that the Abrams' blast doors are anything but solid steel.

There are at least several types of blow off panels and ammo racks used in M1 series, the current newest ones are so called 4th generation. It's possible that older generations didn't had this solution, and not all Saudi tanks were upgraded from basic old M1A2 to newer M1A2S that is besides armor and some other minor stuff, equivalent to M1A2SEPv2.

As for blast doors, it's hard to say for certain what is their construction based only on visual inspection.

Altough I do not understand your remark about presure, what this have to do with M1 if the crew is isolated from the ammo storage?