Tank Layout

[Toxn]

Just now, Xoon said:

How does filling wheels with water act as a shock dampener? 

If you run over a mine, the wheel is the first thing that gets blown up by it. Filling the tire with water means that part of the explosion's energy is spent in moving all that water mass out of the way before it gets to the hull. So, uh, sacrificial dampening I guess.

[Xoon]

2 minutes ago, Toxn said:

If you run over a mine, the wheel is the first thing that gets blown up by it. Filling the tire with water means that part of the explosion's energy is spent in moving all that water mass out of the way before it gets to the hull. So, uh, sacrificial dampening I guess.

More mass to absorb the energy from the blast basically. 
 

To be honest, it sounds about as effective as track/concrete armor during WWII, or improvised slat armor in the Syrian Civil War.

[Toxn]

Just now, Xoon said:

More mass to absorb the energy from the blast basically. 
 

To be honest, it sounds about as effective as track/concrete armor during WWII, or improvised slat armor in the Syrian Civil War.

It should be a bit better than improvised solid armour, because it won't transmit the shock wave very well and uses up a significant amount of energy in dispersion.

 

If you mean instead that its mainly a psychological comfort rather than something practical, I think you should remember that explosive injuries are less all-or-nothing than kinetic ones. Anything you do to disperse or redirect the blast and associated shockwave results in less injuries. Sling seats, for instance, have been shown to have a measurable effect in reducing blast injuries despite doing very little to directly protect the occupants of the vehicle. Instead they function by providing a few more centimetres of standoff and lowering transmission of the shockwave through the body.

[Xoon]

2 hours ago, Toxn said:

It should be a bit better than improvised solid armour, because it won't transmit the shock wave very well and uses up a significant amount of energy in dispersion.

 

If you mean instead that its mainly a psychological comfort rather than something practical, I think you should remember that explosive injuries are less all-or-nothing than kinetic ones. Anything you do to disperse or redirect the blast and associated shockwave results in less injuries. Sling seats, for instance, have been shown to have a measurable effect in reducing blast injuries despite doing very little to directly protect the occupants of the vehicle. Instead they function by providing a few more centimetres of standoff and lowering transmission of the shockwave through the body.

I was thinking about the fact that filling the wheels with water would reduce the effectiveness of the wheels, and the sandbags would weigh down the vehicle. 
Also about the psychological part, if the troops feel safe, then it is good enough makeshift measure.

 

Reminds me of how the Norwegian Armed Forces used to sometimes fill the empty cavity in the doors of their cars with sand for extra bullet protection in the middle east.

[TokyoMorose]

I got to thinking on the merits of the actual double-V (and not the compound V that I was thinking was double-V whoops) - and since the idea seems to be to minimize the amount of area that has to be reinforced (only the trough, and even it is supposed to be slightly concave and open at the ends to vent blast forwards/back) would something like a triple-V not be better? Put third V where the trough is to make two smaller troughs, these will be more concentrated and have to be more heavily reinforced but would not heavily reinforcing those two very small troughs be similar in weight to reinforcing the single large trough while taking up less interior space?

[Alzoc]

To come back on electrical propulsion and whether it would be better to have one electrical engine per track or one central engine and a transmission.

I was at a conference-debate about electrical mobility this evening and one of the contributor was a regular participant of the Monte-Calro eRallye (for 100% electric or hydrogen cars).

 

According to him, last year one of the electrical car which entered the competition had motor-wheels which gave it quite fantastic performances, compared to more common vehicles with a single central engine.

However the RPM of an electrical engine being vastly greater than the one of a wheel (or a track) a reductor was still needed and it was under heavy stress which led to a high wear rate.

He also claimed that it increased the noise generation quite a lot.

 

Increased noise would be irrelevant for a tank since I guess that the tracks would make way more noise on themselves anyway.

A high wear rate could be more problematic.

 

Since I'm not really well versed in mechanics I don't know if his claims are valid or not.

 

Edit: I think he was talking about this particular system (maybe others layout bypass the problem)

 

 

[Xlucine]

I would love for electric motors to result in a return to convertible tanks, like the christie tanks

 

The situation for wheeled vehicles isn't quite comparable, as you're force limited by the tyres. 4 wheel drive helps with this for cars, but with the inefficiency of the transfer cases and such sapping power. For a tank the drive sprocket is essentially geared to the track, so driving the road wheels wouldn't get you any better transfer of force to the ground (as the tracks will slip long before the drive sprocket shears teeth or skips a tooth for properly tensioned track, and all of the weight of the vehicle is already giving you friction to apply motive force).

 

One potential benefit is retaining mobility if you lose a drive sprocket, but I'd imagine it would be rare for something big enough to a) hit the drive sprocket and b) not wreck the engine bay. Mines normally damage the front road wheels, and those can be bypassed with short tracking.

[That_Baka]

2 hours ago, Xlucine said:

Snip

BT-IS with ridicuously complicated transmission comes to mind.

[Xoon]

15 hours ago, Alzoc said:

To come back on electrical propulsion and whether it would be better to have one electrical engine per track or one central engine and a transmission.

I was at a conference-debate about electrical mobility this evening and one of the contributor was a regular participant of the Monte-Calro eRallye (for 100% electric or hydrogen cars).

 

According to him, last year one of the electrical car which entered the competition had motor-wheels which gave it quite fantastic performances, compared to more common vehicles with a single central engine.

However the RPM of an electrical engine being vastly greater than the one of a wheel (or a track) a reductor was still needed and it was under heavy stress which led to a high wear rate.

He also claimed that it increased the noise generation quite a lot.

 

Increased noise would be irrelevant for a tank since I guess that the tracks would make way more noise on themselves anyway.

A high wear rate could be more problematic.

 

Since I'm not really well versed in mechanics I don't know if his claims are valid or not.

 

Edit: I think he was talking about this particular system (maybe others layout bypass the problem)

 

 

There is really no point in having a transmission for a series hybrid electric tank. The PWM motor controller works as the gearbox, the gearbox would only cause a drop in efficiency and take up considerable space. 
All motors should be geared, as it is more efficient than adding poles to reduce the RPM and increase the torque. This is accomplished by the final drive.

 

For wheeled death traps, it can be a pretty huge thing. Being able to remove the drive shafts under the crew compartment would mean a much lower vehicle. Being able  to move the motors outside the chassis and inside the wheels would greatly increase space. Also, the vehicle can effectively torque steer. 

 

However, it comes at a cost. You can only fit a so and so big motor and reduction gear inside the wheel, limiting power. The motor and reduction gear is also more exposed to damage and the outside environment, leading to more wear and tear. Cooling can also be a issue. 

 

I would not expect more than 600hp combined. So no super heavy wheeled death traps.

[ro1994]

Hello, I'm new here. Just saw this and it looks interesting so I decided to dig it up.

 

I wonder why I didn't see anyone bring up the Object.640-style layout? I think it'd also be compatible with crew capsule. For example, taking autoloader out from under Armata's turret, add the bustle-type autoloader, and put Commander and Gunner inside the free space inside a turret basket, with crew capsule around it, and make all of them sit below the hull line. It would also decrease the chance of the one-penetration crew massacre.

 

 

As far as I can remember, one of the major disadvantage of it is lacks of "Mk1 eyeball-style" surveillance capability, the commander cannot see much peeking through the periscope as the FOV is very limited, and then-use-only-panoramic-sight solution isn't the best option for maximum situational awareness...but that might be solved by redesigning it so that other parts of the tank doesn't block its FOV as much as it was (although it may increase profile of the tank), or one can supplement it with the fiberscopes that would not require as much area as adding more rigid and bigger-than-normal (since crew sits inside the hull, or nearly, in case of the real Obj.640) periscopes

 

It could also be supplemented by surveillance system similar to Israeli IronVision

Something like this, I imagine.

There'd be a lot of space to put the Hard-kill APS (presumably launcher-based, blast-type one that has long range to counter heavy, especially top-attack ATGMs) and associated electronics (such as the APS' surveillance/tracking radars, LWR, and aircraft-like MAWS) and still having lower turret profile than the full turret tanks (although may have bigger hull), and also room on driver's side to put the air conditioning unit (that would also act as cooling system for the more and more sophisticated electronics), electronic systems and batteries (which would be required more and more due to the same reason) AND another Hard-kill APS (presumably box-based, flyer-type one for the anti-KE job, this one would function like Ukrainian Nozh ERA but instead of shaped charges being launched to cut the penetrator apart, it use electromagnetically-propelled metal flyers, I think I've read it somewhere that it's effective against KE in tests but weren't given development priority due to the major asymmetric warfare threats tend to be shaped charges, especially from shoulder-fired weapon at relatively short range)

 

Also, I think the basket/capsule could be designed to be "disconnected" from the turret (with another pair of hatches), hence it may have higher chance for the crew to survive the top-attack ATGMs (as they need to go through a lot of things inside the turret, including the empty space - thus creating more distance, which is important to be optimum for the shaped charges to be effective, and the crew has another layer of "basket's roof" protection)

[Lord_James]

Welcome to SH! 

 

Personally I love the Obj. 640, it's quite the innovative design (at least, if it works as advertised, which is always and adventure when talking about prototypes and test beds). But some of the things you mentioned I don't think would help. 

 

9 hours ago, ro1994 said:

put Commander and Gunner inside the free space inside a turret basket, with crew capsule around it, and make all of them sit below the hull line. It would also decrease the chance of the one-penetration crew massacre.

 

Yes, sure, this is indeed a solution to a problem. But how much of a problem is it? Often times, when a vehicle is penetrated, comparatively few crew become casualties, as described here. (just click the text and it will take you to another site, where I got my info). 

 

Quote

 

The biggest threat to a "complete crew kill" would be a catastrophic ammo explosion, but since the ammo is separated, there's not a lot of threat from that. In general, placing crew below the turret line would be a better solution that separating out the crew, rather than with some within a crew capsule and some outside (this might cause resentment and animosity from the crew placed outside the capsule, as the capsule obviously has better protection). 

 

 

 

9 hours ago, ro1994 said:

As far as I can remember, one of the major disadvantage of it is lacks of "Mk1 eyeball-style" surveillance capability, the commander cannot see much peeking through the periscope as the FOV is very limited, and then-use-only-panoramic-sight solution isn't the best option for maximum situational awareness...but that might be solved by redesigning it so that other parts of the tank doesn't block its FOV as much as it was (although it may increase profile of the tank), or one can supplement it with the fiberscopes that would not require as much area as adding more rigid and bigger-than-normal (since crew sits inside the hull, or nearly, in case of the real Obj.640) periscopes 

 

It could also be supplemented by surveillance system similar to Israeli IronVision

 

 

this is exactly the problem products like "Iron Vision" are trying to solve. No matter how many periscopes you place around the tank, you will never have as much situational awareness as if you just stick your head out a hatch, without possibly compromising the armor of said tank. With Iron Vision, and similar products, you don't even need your crew in the vehicle (so long as you can keep a secure connection), but it's probably better to keep them in (some of) the tanks. And as you said, this would negate the problems with having all your crew in the hull (though, purportedly, the Armata doesn't have bad situational awareness). 

 

 

 

9 hours ago, ro1994 said:

Also, I think the basket/capsule could be designed to be "disconnected" from the turret (with another pair of hatches), hence it may have higher chance for the crew to survive the top-attack ATGMs (as they need to go through a lot of things inside the turret, including the empty space - thus creating more distance, which is important to be optimum for the shaped charges to be effective, and the crew has another layer of "basket's roof" protection)

 

Hmmm, so they have to open a hatch to get into the turret space, then another hatch to get outside? That sounds like a little to much work. 

 

 

 

If I were to make a design, I would make the tank similar to the Merkava (front engine, rear crew space). With the introduction of the Mark 4, the front hull armor is quite good yet doesn't impede maintenance of the engine, while the rear compartment places the crew as far away from enemy gunfire as possible (whilst still remaining within the tank). The turret would be unmanned, with a bustle loader, launcher based APS (Iron Fist, more specifically), autocannon resistant (lets say resists 25mm M791 from the M242 at 250m), and placed upon the hull roof, separated from the crew. All 4 crew (commander, gunner, driver, robotic wingman operator*) would be in the hull, just below the turret (with the turret mass generally covering the crew from above), and equip them with an under armor surveillance system (i.e. Iron Vision). 

 

* The "robotic wingman operator" would be a crew member who manages (and possibly controls, if armed) the various unmanned ground, aerial, and (if applicable) floating/submerged vehicles that assist the tank in battle. 

[LoooSeR]

   Object 490 had turret bustle mounted autoloader, with additional rounds mounted between engine and crew compartment. Both ammoracks were protected/separated from the crew and had blow out panels. Object 640 is not a new designs, it is just attempt to mix T-80 with some of ideas that were used on Object 490.

 

 

   This layout have problems. Having big ass turret bustle is not going to increase overall survivability of tank under fire. It increases side projection and frontal projection in 60 degr arc of a tank in worst place - area higher above the ground, where statistically more hits are happening. Placing ammo in the hull is preferable. 

   Also increasig size of turret isn't good idea for vehicles fighting in urban conditions. They already have long gun barrels to worry about, but gunner can at least see what is happening near muzzle end of guns (usually), unlike turret bustle. 

[Andrei_bt]

5 hours ago, LoooSeR said:

   Object 490 had turret bustle mounted autoloader, with additional rounds mounted between engine and crew compartment. Both ammoracks were protected/separated from the crew and had blow out panels. Object 640 is not a new designs, it is just attempt to mix T-80 with some of ideas that were used on Object 490.

 

 

   This layout have problems. Having big ass turret bustle is not going to increase overall survivability of tank under fire. It increases side projection and frontal projection in 60 degr arc of a tank in worst place - area higher above the ground, where statistically more hits are happening. Placing ammo in the hull is preferable. 

   Also increasig size of turret isn't good idea for vehicles fighting in urban conditions. They already have long gun barrels to worry about, but gunner can at least see what is happening near muzzle end of guns (usually), unlike turret bustle. 

 

 

The first version had "big ass turret bustle " for 1400 mm long round and charge, but then they -

On subsequent version with a double-flow automatic loader with separate loading rounds was proposed.  The projectile and charge were placed in turret bustle and hull sequentially (… round-charge-round …). http://btvt.info/7english/490_eng.htm

This made loading a bit longer, but the turret bustle length was 2 times shorter.

[LoooSeR]

1 hour ago, Andrei_bt said:

 

 

The first version had "big ass turret bustle " for 1400 mm long round and charge, but then they -

On subsequent version with a double-flow automatic loader with separate loading rounds was proposed.  The projectile and charge were placed in turret bustle and hull sequentially (… round-charge-round …). http://btvt.info/7english/490_eng.htm

This made loading a bit longer, but the turret bustle length was 2 times shorter.

I was talking about Object 640/Black Eagle turret. It does have a big turret bustle.

[heretic88]

Objekt-490A layout was the best I think. Crew below turret and separated from ammo, massive frontal hull armor, low turret, also with heavy armor. Sad that this tank didnt see serial production.

[Andrei_bt]

2 hours ago, heretic88 said:

Objekt-490A layout was the best I think. Crew below turret and separated from ammo, massive frontal hull armor, low turret, also with heavy armor. Sad that this tank didnt see serial production.

 

You are talking about obj 490, not 490A.

Both 490, but completely different.

[Andrei_bt]

490A has crew separated from ammo, but has no blow off panels.

 late variant of 490A had also autoloader  separated from crew only by a steel case.

[heretic88]

10 hours ago, Andrei_bt said:

You are talking about obj 490, not 490A.

Both 490, but completely different.

 

Yes, I meant the 490A. I read on your site that 2 prototypes were made. Do you know what happened to them? Is there any chance that at least one of them survived?

[Andrei_bt]

Partially survived - only the hull which was used to test molot engine.

The turret was used for fire trials, so it has obj 476 turret and add onn plate to imitate weight.

[Eliz]

On 12/8/2017 at 10:38 PM, Serge said:

It depends on what you want to achieve but the rule is the following : when heavy load must be carried, use track drive train. 

It more compact by a 1/3.

 

Considering just the weight, if you want to put Leclerc MBT on wheels, you will have 6 more tons. Abrams or Leopard will be higher by 2t. I don’t want to think about Challenger 2 or Merkava Mk4.

And I don’t think about cross country capability. 

 

Why? 

 

 

Independent axle with subframe, suspension and everything but the wheels and tires and load capacity with 15 tons weighs 1 ton.

Tires and wheels capable of 7.5 ton weighs 200-300 kg.

Transmission for trucks with max 3000 nm input weighs about 500kg compared to renk transmission for trucked vechiles which for 60 ton machine weighs more then 2 tons.

And wheeled vechiles multiply torque by axles and wheelhubs.

 

So for 4 axles and 8 tires with weight of 6 ton gives you capacity to carry 55-60 tons.

 

Ok there are driveshafts that are not used in track vechile, but those weigh not too much (i dont know how much but each maybe max 100kg). for 4axle you need 3 of them. 

 

Also because of torque multiplication and low resistance from wheels you gonna need less powerful engine then on tracked ?! (Maybe) 

 

 

https://www.tatratrucks.com/trucks/customer-segment-catalog/defence/more-trucks/8x8-high-mobility-heavy-duty-chassis/ this chassis with everything weighs 13 tons, but on it you got frame (tatra frame with it tube is robust but weighs too much) which is unnecessary on heavy vechiles.

 

 

 

Any approximate weight of  suspension of tracked vechiles of 60 tons?

 

[XDrake]

Is it true that some tank designs incorporate fuel tanks as armor? How do fuel tanks work as armor and is there any literature on that?

[Renegade334]

Yes, Challenger and Abrams (just to cite two) use some of their multiple fuel tanks (side sponsons and the entire hull area around the driver, respectively) as makeshift protection against HEAT-based weaponry. The fluid simply slows down the HEAT copper jet. I don't have the number in my head right now, but IIRC 8cm of fuel in a HEAT jet's path is the rough equivalent of 1cm of steel (and you have two advantages here: that [filled] fuel tank is obviously going to be lighter than a solid slab of steel and you don't waste internal volume, instead using it to transport more fuel and therefore extend your operational range).

 

You need to ask Bronezhilet for dead-tree and online literature, though.

 

Spoiler

https://www.scribd.com/document/33225104/Tank-Combat-120mm-Challenger-Part-1-Automotive-System

 

^--- Pages 105 & 106 (in viewer) describe the location and shapes of the Challenger fuel tanks, but doesn't address the anti-HEAT properties of these modules.

 

[Collimatrix]

5 hours ago, XDrake said:

Is it true that some tank designs incorporate fuel tanks as armor? How do fuel tanks work as armor and is there any literature on that?

 

According to Richard M. Ogorkiewicz's absolutely indispensible Everything You Ever Wanted to Know About Tanks* but Were Afraid to Ask, diesel fuel has a mass efficiency of about 3 against shaped charges.  That is to say, it is 3 times as effective as steel RHA, pound for pound.  But, given the disparity in densities, this means that you need about 3 inches of diesel to match the protection of 1 inch of conventional steel armor.  He does say that cellular fuel storage systems can "in practice it can be more than that."  I think @SH_MM had some information on these sorts of fuel cell armor arrays.

 

So, a good old-fashioned Malyutka will penetrate about 450mm of RHA.  To stop the shaped charge jet just with diesel fuel, you would need a fuel tank that's nearly a meter and a half deep.  That's clearly impractical.  But supposing instead you had a hull design with 220mm RHA LOS (e.g. a 93mm glacis plate set back at 65 degrees, just like the M60 has) followed by 700mm deep fuel tanks, wrapped around the driver.  That could work.  If it's the 1970s, and you've just noticed that MBTs are dying in droves to guided missiles, and that fancy composite armor the boffins keep talking about isn't quite ready for mass-production yet, this would be a practical approach to making main battle tanks don't die quite so easily.

[Renegade334]

Factor of 3. I stand corrected, it's been a while since that topic's been broached.

[XDrake]

@Renegade334 @Collimatrix Thanks for your responses I thought I read something about fuel tanks being used as armor. Interesting stuff. I think its not only internal fueltanks that serve as chemical penetrator protection in some cases. The Stridsvagn 103 also has some jerry cans placed alongside the hull sides. Id imagine that placement has the same goal in mind. 

 

Spoiler