M1 Abrams MBT Replacement

So at 54 tones, this AbramsX design is lighter that it’s Russian counterpart T-14 Armata at 55 tones. it’s even lighter than the KF-51 Panther.

That is quite the achievement for General Dynamics.
 
lantinian said:
So at 54 tones, this AbramsX design is lighter that it’s Russian counterpart T-14 Armata at 55 tones. it’s even lighter than the KF-51 Panther.

That is quite the achievement for General Dynamics.
Click to expand...
If that includes Trophy and all, that's quite the feat indeed. Talk about the Abrams hitting the gym and getting back in shape...
 
But then how does its survivability compare to the latest Abrams? When it comes to tanks I'm not a big fan of active defense as a substitute for passive defense. Belt AND suspenders, not belt OR suspenders.
 
MihoshiK said:
If that includes Trophy and all, that's quite the feat indeed. Talk about the Abrams hitting the gym and getting back in shape...
Click to expand...

If true it would call into question whether it even needs 1500hp from the ICE in a hybrid architecture, as TomS wondered in the engine thread.
 
Colonial-Marine said:
The RWS with the 30mm looks like it it is higher than it has to be. I'm also perplexed as to why the coax MG is higher above the main gun than on today's Abrams.
Click to expand...

Partially because it's an off-the-shelf RWS -- possibly you could do one bespoke that was a bit lower. But also because the gun needs to elevate quite a bit and the breech has to drop down somewhere to facilitate that. The high bore axis probably also makes it easier to depress to fire close to the vehicle, meaning reduced dead zones.
 
sferrin said:
But then how does its survivability compare to the latest Abrams? When it comes to tanks I'm not a big fan of active defense as a substitute for passive defense. Belt AND suspenders, not belt OR suspenders.
Click to expand...

Well, they lose the hull front fuel tanks in favor of crew stations, but have less fuel consumption as well. Otherwise, it looks very comparable to the current Abrahms.
 
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
 
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
Click to expand...

There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

Trident said:
MihoshiK said:
If that includes Trophy and all, that's quite the feat indeed. Talk about the Abrams hitting the gym and getting back in shape...
Click to expand...

If true it would call into question whether it even needs 1500hp from the ICE in a hybrid architecture, as TomS wondered in the engine thread.
Click to expand...

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
 
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Kat Tsun said:
The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.
Click to expand...

My thought was about the use of hybrid electric drive. Civilian vehicles with hybrid power trains can use smaller ICE engines than their all-ICE counterparts and compensate by using both battery and ICE power together for initial "launch" acceleration. I don't know enough about the duty cycle of tank engines to know whether you could do the same here.
 
aonestudio said:
https://twitter.com/x/status/1579824751538622465
View: https://twitter.com/2805662/status/1579824751538622465
Click to expand...

This one is meant as a retrofit, right?

Compact autoloader - Parker Meggitt Defense Systems Division

The compact autoloader is an all-electric, fully automatic ammunition handling system designed for easy integration into the M1 weapon station. The magazine subsystem stores 34 ready rounds of 120mm ammunition in the envelope of the M1 bustle. The transfer unit resides completely behind the...
meggittdefense.com meggittdefense.com

The compact autoloader is an all-electric, fully automatic ammunition handling system designed for easy integration into the M1 weapon station. The magazine subsystem stores 34 ready rounds of 120mm ammunition in the envelope of the M1 bustle. The transfer unit resides completely behind the recoil path of the cannon. Its operational swept volume does not encroach into any useable space within the turret, thus allowing the retention of the full four man crew.
Click to expand...

An autoloader designed for the new unmanned AbramsX turret might not need that swinging loading arm.
 
TomS said:
aonestudio said:
https://twitter.com/x/status/1579824751538622465
View: https://twitter.com/2805662/status/1579824751538622465
Click to expand...

This one is meant as a retrofit, right?

Compact autoloader - Parker Meggitt Defense Systems Division

The compact autoloader is an all-electric, fully automatic ammunition handling system designed for easy integration into the M1 weapon station. The magazine subsystem stores 34 ready rounds of 120mm ammunition in the envelope of the M1 bustle. The transfer unit resides completely behind the...
meggittdefense.com meggittdefense.com

The compact autoloader is an all-electric, fully automatic ammunition handling system designed for easy integration into the M1 weapon station. The magazine subsystem stores 34 ready rounds of 120mm ammunition in the envelope of the M1 bustle. The transfer unit resides completely behind the recoil path of the cannon. Its operational swept volume does not encroach into any useable space within the turret, thus allowing the retention of the full four man crew.
Click to expand...

An autoloader designed for the new unmanned AbramsX turret might not need that swinging loading arm.
Click to expand...
True, but this one is basically off-the-shelf. One would assume that Megitt already has most of the problems ironed out with this one.
 
Kat Tsun said:
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
Click to expand...

There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

Trident said:
MihoshiK said:
If that includes Trophy and all, that's quite the feat indeed. Talk about the Abrams hitting the gym and getting back in shape...
Click to expand...

If true it would call into question whether it even needs 1500hp from the ICE in a hybrid architecture, as TomS wondered in the engine thread.
Click to expand...

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
Click to expand...

It is very strange that in the mid-1970s a power of 1,500hp was considered adequate for a 55 metric ton MBT (Leo 2; Abrams in the early variants) and almost 50 years later the same power is apparently accepted for 75 ton tanks by the armies. This is all the more astonishing when one considers the power explosion that has taken place in the meantime in modern diesel engines for cars, which is not far from 100 hp/liter displacement for everyday vehicles. These specific outputs, or even higher ones, are also easily achievable for tank engines and have been available on the market for almost 20 years, e.g. in the form of the MTU 890 series. An excerpt from the MTU press release from october 2003:
"With 0.60 kg/hp and a 1848 hp/m3 it is the most powerful diesel engine series in the world in terms of power-to-weight and power-to-volume ratio."

In this respect, a MTU 883 or comparable diesel engines with modern electronic common rail injection would today have to be at least at 2,500 hp (with or without hybrid electric assistance), which should be self-evident for such heavy combat vehicles and for the sprint capability required on today's battlefields. I have not yet found an explanation why corresponding engine power has been relegated so much to the background in modern main battle tanks. Even the KF51 apparently remains at an engine rating of 1,500 hp.
 
Basil said:
Kat Tsun said:
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
Click to expand...

There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

Trident said:
MihoshiK said:
If that includes Trophy and all, that's quite the feat indeed. Talk about the Abrams hitting the gym and getting back in shape...
Click to expand...

If true it would call into question whether it even needs 1500hp from the ICE in a hybrid architecture, as TomS wondered in the engine thread.
Click to expand...

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
Click to expand...

It is very strange that in the mid-1970s a power of 1,500hp was considered adequate for a 55 metric ton MBT (Leo 2; Abrams in the early variants) and almost 50 years later the same power is apparently accepted for 75 ton tanks by the armies. This is all the more astonishing when one considers the power explosion that has taken place in the meantime in modern diesel engines for cars, which is not far from 100 hp/liter displacement for everyday vehicles. These specific outputs, or even higher ones, are also easily achievable for tank engines and have been available on the market for almost 20 years, e.g. in the form of the MTU 890 series. An excerpt from the MTU press release from october 2003:
"With 0.60 kg/hp and a 1848 hp/m3 it is the most powerful diesel engine series in the world in terms of power-to-weight and power-to-volume ratio."

In this respect, a MTU 883 or comparable diesel engines with modern electronic common rail injection would today have to be at least at 2,500 hp (with or without hybrid electric assistance), which should be self-evident for such heavy combat vehicles and for the sprint capability required on today's battlefields. I have not yet found an explanation why corresponding engine power has been relegated so much to the background in modern main battle tanks. Even the KF51 apparently remains at an engine rating of 1,500 hp.
Click to expand...
It's not that it is accepted on purpose, it's that engine upgrades or replacements are not funded anymore since 2003. Actual tank upgrades are already operating on a shoestring compared to even early 90's programs, and engines do not sell well to politicians. And the guys responsible for tech demonstrators today have lost the institutional knowledge of 80's tank designers, so they barely ever try to make anything even half as ambitious as 90's upgrades.

I am still freaking finding offers for 1800hp engines as early as 1979, in the Garrett GT1801 gas turbine that was also meant to provide fuel consumption and size reductions compared to AGT-1500 (long before the AIPS program even started). The German company Klockner-Humboldt-Deutz and the German government were willing to fund it to provide a follow-on engine for M1 and Leopard 2, but it fell appart as the US Army didn't want to fund a new engine yet and by the time AIPS started Garrett and the Germans had moved on.
 
Basil said:
Kat Tsun said:
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
Click to expand...

There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

Trident said:
MihoshiK said:
If that includes Trophy and all, that's quite the feat indeed. Talk about the Abrams hitting the gym and getting back in shape...
Click to expand...

If true it would call into question whether it even needs 1500hp from the ICE in a hybrid architecture, as TomS wondered in the engine thread.
Click to expand...

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
Click to expand...

It is very strange that in the mid-1970s a power of 1,500hp was considered adequate for a 55 metric ton MBT (Leo 2; Abrams in the early variants) and almost 50 years later the same power is apparently accepted for 75 ton tanks by the armies.
Click to expand...

Why is it strange?

The AbramsX has almost twice as much sprocket horsepower as the M1A1 anyway as I literally just said. The M1 is 18 and the AbramsX approaches 30, which is the ideal from the HIMAG studies of the 1970's, because the biggest horsepower thing they tested was the M113 HOTROD with ~26 shp/t.

It's substantially more mobile than any main battle tank in the world.

1,500 hp at 50-55 tons is approximately 30 hp/t...

The limitation has been transmissions, not engines, clearly. You might as well say it's strange that people used a engine from 1938 in a howitzer in 1998. Except it isn't, because engines don't matter much beyond providing sufficient power.

If you want to see if a more powerful engine or higher sprocket horsepower is better for certain terrains, you're gonna have to pony up production of automotive testbeds and trials. This is hard for the relatively decrepit and decaying industrial economies of Europe and America after the past 40 years of Reaganomics and financialization. Perhaps the Chinese will do it though but I don't think it will enter Western military thought anytime soon. It's hard enough just making basic incremental upgrades to tanks and controlling the ever spiraling weight increases that have resulted in 1980's AFVs with mobility barely better than their WW2 ancestors.

KF51 is also just a warmed over Leopard 2 so of course it has the same engine as the Leopard 2A6? It's a bunch of off the shelf parts Rheinmetall made for the Challenger 3 upgrade program and is trying to fob off the cost of through export sales (which isn't working).
 
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https://apps.dtic.mil/sti/pdfs/ADA105411.pdf
"Propulsion system technology for military land vehicles"
Here is a DTIC doc from 1980 on engines and transmissions in development to achieve 30hp/t and generally improve on existing gear. Mentions the GT1801 and a 1000hp turbocompound version of Bradley's Cummins VTA-903.

On the AVCR-1360-2 as a backup if AGT-1500 fails, 1979 hearings.
1665820825911.png

On what GT 1801 was about.
1665820836632.png
1665820947231.png
 

Attachments

  • Turbines for tank power reqs.pdf
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Kat Tsun said:
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
Click to expand...

There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
Click to expand...

I don't quite understand why 30 hp/t should be considered the ideal power-to-weight ratio for furure MBTs - especially on today's battlefield. Modern agricultural tractors often have higher power ratings per ton.
In the early 1970s, 35-50 hp/t was considered as a future necessity. At that time until the early 1980s, experimental vehicles like the casemate tank VT 1-2 with 2,200 hp and over 50 hp/t and even with a power-to-weight ratio of over 80 hp/t (the german RVT 2) were successfully tested.

Unfortunately I could not find much information about the new ACT transmission of the AbramsX, but I would like to understand how such a transmission efficiency increase is possible that now 30% more power is available at the sprocket.
 
Kat Tsun said:
Why is it strange?

The AbramsX has almost twice as much sprocket horsepower as the M1A1 anyway as I literally just said. The M1 is 18 and the AbramsX approaches 30, which is the ideal from the HIMAG studies of the 1970's, because the biggest horsepower thing they tested was the M113 HOTROD with ~26 shp/t.

It's substantially more mobile than any main battle tank in the world.

1,500 hp at 50-55 tons is approximately 30 hp/t...

The limitation has been transmissions, not engines, clearly. You might as well say it's strange that people used a engine from 1938 in a howitzer in 1998. Except it isn't, because engines don't matter much beyond providing sufficient power.

If you want to see if a more powerful engine or higher sprocket horsepower is better for certain terrains, you're gonna have to pony up production of automotive testbeds and trials. This is hard for the relatively decrepit and decaying industrial economies of Europe and America after the past 40 years of Reaganomics and financialization. Perhaps the Chinese will do it though but I don't think it will enter Western military thought anytime soon. It's hard enough just making basic incremental upgrades to tanks and controlling the ever spiraling weight increases that have resulted in 1980's AFVs with mobility barely better than their WW2 ancestors.

KF51 is also just a warmed over Leopard 2 so of course it has the same engine as the Leopard 2A6? It's a bunch of off the shelf parts Rheinmetall made for the Challenger 3 upgrade program and is trying to fob off the cost of through export sales (which isn't working).
Click to expand...

Efficient and powerful transmissions for vehicles are always a technically interesting task, but it is by no means a hurdle for Western industry to produce a compact tank transmission for, say, 2,500 hp.
 
Basil said:
Kat Tsun said:
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
Click to expand...

There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
Click to expand...

I don't quite understand why 30 hp/t should be considered the ideal power-to-weight ratio for furure MBTs
Click to expand...

...

Because the HIMAG studies showed that 30 sprocket horsepower/ton was great in offroad performance given adequate flotation.

We're literally just now approaching this. The fact that it took 40 years to go from the mid-teen's of sprocket horsepower is in line with the past. It took 40 years to get out of the single digits of sprocket horsepower you saw in WW2.

I expect in another 40 years we might be asking ourselves if tanks really need bigger engines to take advantage of 95-98% efficient transmissions and breach the 30 hp/ton sprocket horsepower barrier that HIMAG established. But that will only be after new mobility trials and more powerful automotive testbeds with higher sprocket horsepowers are tested. Tanks of the future may also very well be heavier than 55-tons standard, but that would require improvements in road infrastructure. We're still using 20th century infrastructure in much of the developed world.

You can literally google 'Advanced Combat Transmission' and find a report on it: http://gvsets.ndia-mich.org/documents/MOB/2020/Mobility_1110_Advanced Powertrain Demonstrator Integration_Paper.pdf

Put simply, more power is a crutch for when transmissions are bad. Transmissions are no longer as bad as they were in the 1970's, so you can have 1,500 HP engines providing far more sprocket horsepower than they used to. Less powerful engines are also more fuel efficient, although this is fairly minor tbh and stuff like EFI or engine control computers can do this just as well.

The ACT can give 1980's mobility (~16-18 shp/ton) to a 55-ton main battle tank with a ~900 HP engine. Alternatively, you can achieve the HIMAG mobility requirements with a ~1,500 HP engine (26 shp/t) on the same tank. WW2 level of mobility could be achieved with a 500 hp engine. This assumes an approximate 90% capture of the net horsepower. With a previous generation transmission, you'd need 1,500 HP, 2,200 HP,. and 750 HP respectively, net horsepower, because older transmissions capture approximately 70% of net horsepower, as stated in Ogorkiewicz's Technology of Tanks.

Besides bigger engines demanding bigger tanks, power densities have shrunk engine sizes obviously: How is it the AbramsX is able to field a survivable crew capsule in the front of the hull that eats the front fuel cells and still have adequate fuel for comparable range to the M1A1? Because that tiny engine in the back is surrounded by more fuel cells, obviously!

Why is this confusing? I literally do not understand.

There are monumental, tremendous differences in mobility beyond "horsepower".

As for how ACT is possible, I dunno? Something about having oodles of gears and fancy lubricant to keep temperatures down, and the torque converter is gone (poof). Torque converters result in around 10-15% efficiency loss to heat, with another 10-15% from gear ratios. Eliminating the converter is probably the biggest reason ACT is so efficient and then you get a couple single digits percentage improvement in heat loss from having zillions of gears (it has 64 gears, although you can add more I suppose).

However, I'm not a mechanical engineer, nor do I work for GDLS Canada, so I only know the barest rudiments of the subject like "engine spins metal cylinder with exploding piston". I just know that ACT is what would be necessary to achieve HIMAG performance and it took about 40 years to get there. Which is coincidentally 40 years it took to go from WW2 sprocket horsepower (8-10) to 1980's High Mobility shp (16-18). Perhaps in another 40 years we can breach the 30 shp/t barrier? Who knows.

Basil said:
Efficient and powerful transmissions for vehicles are always a technically interesting task, but it is by no means a hurdle for Western industry to produce a compact tank transmission for, say, 2,500 hp.
Click to expand...

Good thing they made a transmission for 1,500 HP then so they don't need to make a 2,500 HP engine?

Mobility isn't about gross output of the engine my guy. It's about sprocket power, flotation, and traction and armor protection.
 
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GTX said:
Kat Tsun said:
Colonial-Marine said:
For such a major redesign I thinking it might be better to move up to a 130mm or 140mm gun.
Click to expand...

None of those actually exist though.
Click to expand...
errr…

Rheinmetall

Rheinmetall is one of the world's leading suppliers of large-calibre weapons and ammunition, e.g. the smoothbore L44 and L55 tank guns.
www.rheinmetall-defence.com www.rheinmetall-defence.com
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Yup, Panther, a tech demo of KF-51, with a working 130mm gun was intro'd in June Eurosatory.
 
Kat Tsun said:
Basil said:
Kat Tsun said:
Moose said:
It looks like some of the weight savings is coming from the turret armor needing to cover less vertical space thanks to the unmanned turret being lower. I'm also curious as to whether they recovered some of the fuel volume lost in the front end by adding elsewhere in the hull.
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There's nowhere else to add fuel, unless the engine is tranversely mounted or something. Advanced Powertrain is supposed to be smaller than legacy engines but who knows if that's true for the M1 powerpack. In which case you can recover a single front fuel cell, maybe two? Honestly, they're probably making up the range losses by a combination of using a diesel and simply not caring too much about it.

M1's range is the least of its concerns.

...what.

1,500 HP at 55 tons is 27 hp/t, which is pretty close to the ideal tank pwr of ~30 hp/t. It's absolutely necessary and if anything it should be higher, at 1,600 HP or something. Right now, the M1 has as much power-to-weight at the moment as a M4 Sherman. The AbramsX is literally just restoring M1's mobility to what it was in 1985, i.e. actually modern mobility, rather than WW2 mobility.

The ACT just means a normally wimpy diesel can propel like a turbine and you're getting actually good mobility out of the 1,500 HP instead of mere adequate mobility. AbramsX probably has a sprocket hp/t of around 23-25 whereas M1 (the old M1) is 18. Of course that 1,500 HP will be good for, if the US Army buys it, when AbramsX inevitably grows to 75 tons again, because the Army made every road wheel independently electrically powered or something.

The real question is whether or not AbramsX's track and flotation are up to snuff to keep up with that fat sprocket power. HOTROD was also around 25 hp/t on the sprocket, even if it used older technology, and it was really good until it wasn't. So AbramsX might need wider tracks, or track extensions, or grousers or something, to take advantage of its power fully in soft soil.

Of course AFAIK the M113 HOTROD was never actually bad in any soil conditions by any metric, just in a couple it was worse than M1.
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I don't quite understand why 30 hp/t should be considered the ideal power-to-weight ratio for furure MBTs
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...

Because the HIMAG studies showed that 30 sprocket horsepower/ton was great in offroad performance given adequate flotation.

We're literally just now approaching this. The fact that it took 40 years to go from the mid-teen's of sprocket horsepower is in line with the past. It took 40 years to get out of the single digits of sprocket horsepower you saw in WW2.

I expect in another 40 years we might be asking ourselves if tanks really need bigger engines to take advantage of 95-98% efficient transmissions and breach the 30 hp/ton sprocket horsepower barrier that HIMAG established. But that will only be after new mobility trials and more powerful automotive testbeds with higher sprocket horsepowers are tested. Tanks of the future may also very well be heavier than 55-tons standard, but that would require improvements in road infrastructure. We're still using 20th century infrastructure in much of the developed world.

You can literally google 'Advanced Combat Transmission' and find a report on it: http://gvsets.ndia-mich.org/documents/MOB/2020/Mobility_1110_Advanced Powertrain Demonstrator Integration_Paper.pdf

Put simply, more power is a crutch for when transmissions are bad. Transmissions are no longer as bad as they were in the 1970's, so you can have 1,500 HP engines providing far more sprocket horsepower than they used to. Less powerful engines are also more fuel efficient, although this is fairly minor tbh and stuff like EFI or engine control computers can do this just as well.

The ACT can give 1980's mobility (~16-18 shp/ton) to a 55-ton main battle tank with a ~900 HP engine. Alternatively, you can achieve the HIMAG mobility requirements with a ~1,500 HP engine (26 shp/t) on the same tank. WW2 level of mobility could be achieved with a 500 hp engine. This assumes an approximate 90% capture of the net horsepower. With a previous generation transmission, you'd need 1,500 HP, 2,200 HP,. and 750 HP respectively, net horsepower, because older transmissions capture approximately 70% of net horsepower, as stated in Ogorkiewicz's Technology of Tanks.

Besides bigger engines demanding bigger tanks, power densities have shrunk engine sizes obviously: How is it the AbramsX is able to field a survivable crew capsule in the front of the hull that eats the front fuel cells and still have adequate fuel for comparable range to the M1A1? Because that tiny engine in the back is surrounded by more fuel cells, obviously!

Why is this confusing? I literally do not understand.

There are monumental, tremendous differences in mobility beyond "horsepower".

As for how ACT is possible, I dunno? Something about having oodles of gears and fancy lubricant to keep temperatures down, and the torque converter is gone (poof). Torque converters result in around 10-15% efficiency loss to heat, with another 10-15% from gear ratios. Eliminating the converter is probably the biggest reason ACT is so efficient and then you get a couple single digits percentage improvement in heat loss from having zillions of gears (it has 64 gears, although you can add more I suppose).

However, I'm not a mechanical engineer, nor do I work for GDLS Canada, so I only know the barest rudiments of the subject like "engine spins metal cylinder with exploding piston". I just know that ACT is what would be necessary to achieve HIMAG performance and it took about 40 years to get there. Which is coincidentally 40 years it took to go from WW2 sprocket horsepower (8-10) to 1980's High Mobility shp (16-18). Perhaps in another 40 years we can breach the 30 shp/t barrier? Who knows.

Basil said:
Efficient and powerful transmissions for vehicles are always a technically interesting task, but it is by no means a hurdle for Western industry to produce a compact tank transmission for, say, 2,500 hp.
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Good thing they made a transmission for 1,500 HP then so they don't need to make a 2,500 HP engine?

Mobility isn't about gross output of the engine my guy. It's about sprocket power, flotation, and traction and armor protection.
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Add in a hybrid system, you can cut the engine size by 25-33% and still get 1500HP when you need it. Nissan just launched a petrol car with electric only drive, in UK. No me neither, but electric drive could give more options for layout, as the engine doesnt have to be close to the drive/gearbox.
 
There is no electric motor strong enough to drive a tank, which is why the ACT exists in the first place?

The battery generator is probably entirely to eliminate the need for a diesel APU and allow for silent watch.
 
GTX said:
The next U.S. battle tank could use AI to identify targets
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I understand such things as artistic license but sometimes I just cannot accept the level of disinterest in fact here. "The Abrams tank has gone through various changes in the past century, but it has been plagued with several issues: It’s costly and gas-guzzling, and it isn’t as nimble on the battlefield as lightweight armored vehicles, such as the Bradley Fighting Vehicle, military experts said".
 
Kat Tsun said:
There is no electric motor strong enough to drive a tank, which is why the ACT exists in the first place?

The battery generator is probably entirely to eliminate the need for a diesel APU and allow for silent watch.
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GDLS says "limited silent mobility." Which probably does mean that the battery electric portion certainly can't got very far, and possibly not at full speed. But there are a lot of ways to arrange a hybrid drivetrain to get power from some combination of mechanical gearbox and electric motors. (For example, ACT has an integrated generator, which perhaps could be run in reverse as a motor.)
 
TomS said:
Kat Tsun said:
There is no electric motor strong enough to drive a tank, which is why the ACT exists in the first place?

The battery generator is probably entirely to eliminate the need for a diesel APU and allow for silent watch.
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GDLS says "limited silent mobility." Which probably does mean that the battery electric portion certainly can't got very far, and possibly not at full speed. But there are a lot of ways to arrange a hybrid drivetrain to get power from some combination of mechanical gearbox and electric motors. (For example, ACT has an integrated generator, which perhaps could be run in reverse as a motor.)
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TBF I was imagining a in-hub sprocket motor.

The ACT's generator is only 160 kW, though that the Bradley's and possibly the AbramsX has a bigger one. Might even explain where the turret basket went and why it's using a double stacked bustle loader instead of a carousel.
 
jsport said:
Getting back to the actual title of the thread "abrams replacement", here is a notional TARDEC NGCV OMT concept blurred and a concept. View attachment 658115
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The Ukraine war has shown the need for counter-battery, and countering UAV launch sites as well as engaging targets at over 8km on a dispersed battlefield. If the US Army is serious about Penetration to point of creating new Penetration division then the 120mm gun on the AbramsX is insufficient.
 
jsport said:
jsport said:
Getting back to the actual title of the thread "abrams replacement", here is a notional TARDEC NGCV OMT concept blurred and a concept. View attachment 658115
Click to expand...
The Ukraine war has shown the need for counter-battery, and countering UAV launch sites as well as engaging targets at over 8km on a dispersed battlefield. If the US Army is serious about Penetration to point of creating new Penetration division then the 120mm gun on the AbramsX is insufficient.
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As long as the 120mm can penetrate a T72 and whatever China is producing, why change?

Clearly a tank unit, is going to need embedded long range ATGM, and drone/air/heli defense, in every troop. Above that Air defence systems, then fighter cover, then ballistic defence.
On the current drone thing in Ukraine, I'd think the local shotgun clubs could add a fair bit of assistance, quickly. With 80% of them shot down, each 'successful' hit is costing Russian $200K or so.
 
If fast, dispersed and thin on extras, are goals for deep battle, one wants the most options, and longest range effects and self defense from a main battle platform. You want the least amount of escorting, more vulnerable, thin skinned vehicles. Pigeon holeing tanks into traditional constrained roles is an idea trap.

Conventional wisdom is you never want tank on tank grinding, you want their tanks destroyed by other means ie CAS, BAI, Infantry w/ javelins inserted via helio etc so your tanks are freed up to exploit and infiltrate.
 
Kat Tsun said:
TBF I was imagining a in-hub sprocket motor.
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Thing is, though, with electrics, you can have motors at each corner, ala 'Ferdinand / Elefant', or even, with the right track design, a motor in every road wheel . . .

cheers,
Robin.
 

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