Questions about shields

[Purple]

Hm... what angle do you think the front tracks should have compared to the ground? Do you think 45 degrees is enough or maybe too much? This said, the initial drawing will be done tonight. Ill post it here once done.

[Number Theoretic]

I would say, 45 degrees is a good starting point, but i have seen angles closer to 60 degrees (or 30, depending on your reference plane), especially with the Abrams tanks:


Leopard tracks were closer to 40 or 45 degrees, so i'd suggest: just try some angles and choose the one that you like.

[Purple]

Hm... how exactly does the angle effect mobility anyway?
And where do you get those awesome images?

[Number Theoretic]

Intuitively, i'd guess that the angle helps a tank when cruising through rough terrain and when climbing a trench, a hill or any other terrain feature where the ground angle changes. After all, the tank drives on its tracks, so while driving, it needs to lay the track over that part of the ground which it wishes to drive over. And if the terrain is crooked, buckled, covered with stones or any other rough nature features, it is easier to lay the track over those features and get a grip on them if you have an angle at the front of your tracks.

Images are from Google and Wikipedia, i admit it

[Purple]

I am retaining the 45 degrees than since I want a more leo and less M1 look with this thing.

Also, as promissed even thou with a delay. Spoiler

PS. I know the bustle is way too long. But that is on purpose.

[Number Theoretic]

Nice! Looks like it could work. Is the gunner seated in the turret's socket? I cannot read that out of your drawing.

However the gun seems rather small to me. If i recall correctly, coilguns require strong bracings, otherwise the magnet stages repel each other and the coilgun flies apart. Might require some checking.

One small detail i just remembered about modern day tank operation: Usually, the commander has his hatch open as much as possible to have a better overview. Only if infantry is near, he closes it and uses his optics. But we already established that your tank has much more advanced vision systems and so can afford the entire crew to be buried inside the tank, so this detail is purely anecdotical and can be ignored

[VarrusTheEthical]

I suspect you could also dispense with a lot of the crew if your tank is automated enough. Say a crew arrangement similar to an attack helicopter, where the commander drives the tank, but most of the weapons are operated by a dedicated gunner. You could probably reduce the size of the turret in order to take advantage of the space savings on no longer having to have either a driver or a loader. Or fill the extra space with more armor or ammo.

[Purple]

Nice! Looks like it could work. Is the gunner seated in the turret's socket? I cannot read that out of your drawing.

Yea, the two seets are side by side so it can't be seen since I was too lazy to include a front crossesction.

However the gun seems rather small to me. If i recall correctly, coilguns require strong bracings, otherwise the magnet stages repel each other and the coilgun flies apart. Might require some checking.

Hm, Ill have to make it wider than. Right now its a rectangle of 300mm x 120mm around a 90mm barrel. I thought that would be sufficient.

One small detail i just remembered about modern day tank operation: Usually, the commander has his hatch open as much as possible to have a better overview. Only if infantry is near, he closes it and uses his optics. But we already established that your tank has much more advanced vision systems and so can afford the entire crew to be buried inside the tank, so this detail is purely anecdotical and can be ignored

My worry is that my commander and gunner won't be able to get out of the tank (or in) since I have no idea where to put the hatches for them. This is especially problematic as the turret is sort of full of equipment and stuff. So, any suggestions? Maybe if I put them on the side under a set of armored doors?

I suspect you could also dispense with a lot of the crew if your tank is automated enough. Say a crew arrangement similar to an attack helicopter, where the commander drives the tank, but most of the weapons are operated by a dedicated gunner. You could probably reduce the size of the turret in order to take advantage of the space savings on no longer having to have either a driver or a loader. Or fill the extra space with more armor or ammo.

I see several issues there. Firstly, the commander of a tank is over worked as it is. He has to keep track of other vehicles and friendlies in his formation, operate the cloaking and sensor equipment, designate targets and generally be the eyes and ears of the whole tank. His job is to constantly scan everything around him and maintain a high degree of situational awareness. So keeping him also focused on driving the tank would probably be too much. Secondly, the driver has to have a stable seat (one that does not rotate with the turret) so that he can actually keep track of how the vehicle is moving and not get disoriented. A commander meanwhile has to rotate with the turret to keep his face pointing where the action is. Finally, field maintenance and refueling is going to be much harder to do with just one man doing it whilst the other keeps watch. Modern 3 man tanks already have problems with that since they went down from as much as 5 men during WW2.

[VarrusTheEthical]

I see several issues there. Firstly, the commander of a tank is over worked as it is. He has to keep track of other vehicles and friendlies in his formation, operate the cloaking and sensor equipment, designate targets and generally be the eyes and ears of the whole tank. His job is to constantly scan everything around him and maintain a high degree of situational awareness. So keeping him also focused on driving the tank would probably be too much. Secondly, the driver has to have a stable seat (one that does not rotate with the turret) so that he can actually keep track of how the vehicle is moving and not get disoriented. A commander meanwhile has to rotate with the turret to keep his face pointing where the action is. Finally, field maintenance and refueling is going to be much harder to do with just one man doing it whilst the other keeps watch. Modern 3 man tanks already have problems with that since they went down from as much as 5 men during WW2.

A good point, and I'm not really sure what plausible automation would allow for in terms of reducing the tank's crew requirement. If you're comfortable with having an AI take over the driving, then I could see a two man crew being viable. Of course, that would likely exacerbate the maintenance issues that you've mentioned.

My worry is that my commander and gunner won't be able to get out of the tank (or in) since I have no idea where to put the hatches for them. This is especially problematic as the turret is sort of full of equipment and stuff. So, any suggestions? Maybe if I put them on the side under a set of armored doors?

Well, Merkava's have a hatch at the rear of the tank, since the engine is mounted in the front. Granted, I'm not sure if your tank's internal arrangement allows for that. Here's an good example of how the hatch works. Mind the adds though.

http://www.youtube.com/watch?v=Kk-tUdJP ... ge#t=2m31s


Of course, you could just put a couple of hatches on the top of the turret just above the commander and gunner positions, just like on most modern tanks.

[Purple]

A good point, and I'm not really sure what plausible automation would allow for in terms of reducing the tank's crew requirement. If you're comfortable with having an AI take over the driving, then I could see a two man crew being viable. Of course, that would likely exacerbate the maintenance issues that you've mentioned.

Pretty much. And I want to stay away from AI automation of vital tasks.

Well, Merkava's have a hatch at the rear of the tank, since the engine is mounted in the front. Granted, I'm not sure if your tank's internal arrangement allows for that. Here's an good example of how the hatch works. Mind the adds though.

BTW, don't trust anything that video tells you. As far as protection goes front engine is perhaps the worst inside arrangement of any tank currently used. With the engine in the front the tank crew has less protection than in a modern tank (since it replaces a block of composite armor with the engine) all the while being an easy mobility kill for any enemy with weapons more powerful than a RPG-7. Except that modern RPG-7 have tandem charge HEAT so they can kill it too. And the rear escape hatch is going to come real handy for the crew once the tank that just shot them starts strafing the area behind their vehicle with its machine gun.

Of course, you could just put a couple of hatches on the top of the turret just above the commander and gunner positions, just like on most modern tanks.

That is probably what I will end up doing. Have a double hatch, one on the roof and the other on the turret floor that is above the crews heads.

[Number Theoretic]

Other tasks that AI could handle can either be the gunner's job (with the commander's possibility to override, of course) or a tactical AI on company level, able to supply each tank commander with exact the information he needs. But if this kind of automation is not feasible, i agree: Three men are the absolute minimum crew that is necessary. I could even supply another reason to Purple's points: mission profile. Tanks usually operate much longer on the battlefield than helicopters. I remember training exercises that lasted up 16 hours before sleeping was considered an option. I'm not entirely sure, but i doubt that (modern day) attack helicopters stay that long in the field.

Yup, the front engine of the Merkava doesn't make much tactical sense to me too. But if the tank takes a hit, the engine could possibly absorb the shell and so increase the crew's survival odds. But that's just speculation, straight out of my head.

[Purple]

This whole talk about automation does give me an idea thou. I am going to have the commander and gunner have the exact same interface and equipment before them and be cross trained for both roles. That way if one is injured, incapacitated or just wants a break they can trade positions without trading seats. As in, the gunner can just flip a switch and enable the commanders functions to be transfered to his console and vice versa. So the tank would be designed to operate with a minimum of 2 men for limited durations if the need exists (like say if the tank looses a crew member in the middle of a battle). But the normal operating crew would still be 3 for the sake of optimum efficiency.

[Number Theoretic]

A good idea, because it takes the current situation a bit further: The Leopard 2 has a commander's sight that can be rotated independent of the turret and enables the commander and the gunner to operate in a "hunter-killer" fashion: If the commander sees a target, he can press a button and the turret spins around immediatly and is pointed at the target. The gunner can then fire at the target, while the commander continues searching for new targets. Other kinds of task sharing, at least in the professional German tank troops: The gunner takes the commander's role if the commander is dead. Vice versa, the commander can operate the turret from his seat, but it's not optimal. It works much better from the gunner's seat. Also, everyone knows how to drive the tank and how to load the gun, so everyone can do every job, if required.
However, your idea works better, because commander and gunner have the same interface and the gun is operated automatically.

[VarrusTheEthical]

BTW, don't trust anything that video tells you. As far as protection goes front engine is perhaps the worst inside arrangement of any tank currently used. With the engine in the front the tank crew has less protection than in a modern tank (since it replaces a block of composite armor with the engine) all the while being an easy mobility kill for any enemy with weapons more powerful than a RPG-7. Except that modern RPG-7 have tandem charge HEAT so they can kill it too. And the rear escape hatch is going to come real handy for the crew once the tank that just shot them starts strafing the area behind their vehicle with its machine gun.
.

Oh I wasn't saying that you should make your tank like a Merkava, I just thought the rear hatch idea has potential. The problem with top hatches is that they can't really be armored, since doing so would make them too heavy for the crew to open. This is why a lot of modern anti-tank weapons will "pop-up" in order to strike the top of the tank. This is also why tanks are so vulnerable to attacks from above, either from an airplane or a dude on the roof of a building with an RPG. The main problem I would see with a rear hatch, other than internal arrangements, would that it would make the rear of the tank more vulnerable to attack. Of course, if your tank is being attacked from the rear, you're in pretty deep trouble anyway.

[Purple]

A good idea, because it takes the current situation a bit further: The Leopard 2 has a commander's sight that can be rotated independent of the turret and enables the commander and the gunner to operate in a "hunter-killer" fashion: If the commander sees a target, he can press a button and the turret spins around immediatly and is pointed at the target. The gunner can then fire at the target, while the commander continues searching for new targets. Other kinds of task sharing, at least in the professional German tank troops: The gunner takes the commander's role if the commander is dead. Vice versa, the commander can operate the turret from his seat, but it's not optimal. It works much better from the gunner's seat. Also, everyone knows how to drive the tank and how to load the gun, so everyone can do every job, if required.
However, your idea works better, because commander and gunner have the same interface and the gun is operated automatically.

Have you considered writing an essay on the topic of the Leo2? Or just summing up everything you know about the thing? Or maybe registering on Wikipedia and filling that article up so much that it overloads their hard drives? Or, better yet just dumping all the juicy details such as that one right here in a mega post? As far as I can tell you my man are an expert beyond any I have yet met. When ever I bump into some idea you have a ready made comment on how German engineering made it better. And it would be fun to know all of that in advance.

Oh I wasn't saying that you should make your tank like a Merkava, I just thought the rear hatch idea has potential. The problem with top hatches is that they can't really be armored, since doing so would make them too heavy for the crew to open. This is why a lot of modern anti-tank weapons will "pop-up" in order to strike the top of the tank. This is also why tanks are so vulnerable to attacks from above, either from an airplane or a dude on the roof of a building with an RPG. The main problem I would see with a rear hatch, other than internal arrangements, would that it would make the rear of the tank more vulnerable to attack. Of course, if your tank is being attacked from the rear, you're in pretty deep trouble anyway.

Thing is, you can't really have a rear hatch if the engine is in the way. So for it to happen you have to put the engine in front of the crew. And that's where the unmanned turret concept comes in. It basically makes the entire turret and all internal equipment act as a huge armored box on top of the crew compartment. Hence the top attack vulnerability is removed.

[VarrusTheEthical]

Thing is, you can't really have a rear hatch if the engine is in the way. So for it to happen you have to put the engine in front of the crew.

Well, that's true with a traditional power plant such as a turbine or reciprocating engine. What I was thinking was rather than one large central power plant housed inside the tank's hull, you had a number of smaller engines housed inside the wheel hubs of the tracks. This should give you enough space for a rear hatch without a frontal engine mount. I admit that I'm not sure how feasible this setup would be since I don't know the exact kind power-plant you're planning on using. But if you don't mind adding a little handwavium to your tank, I think this could be a believable , if not plausible design.

That being said, there's nothing wrong with sticking to a conventional tank design with a few advanced improvements.

[Purple]

Well, that's true with a traditional power plant such as a turbine or reciprocating engine. What I was thinking was rather than one large central power plant housed inside the tank's hull, you had a number of smaller engines housed inside the wheel hubs of the tracks. This should give you enough space for a rear hatch without a frontal engine mount. I admit that I'm not sure how feasible this setup would be since I don't know the exact kind power-plant you're planning on using. But if you don't mind adding a little handwavium to you tank, I think this could be a believable , if not plausible design.

It would also cause all sorts of problems with maintenance, what happens when one of the micro engines fails or is hit and you have to take apart the whole suspension rather than just pulling the whole unit out with a crane and stuff like that. Plus, keeping all the engines in line would be a software nightmare on the levels of jet fighter fly by wire systems. Plus, I am not sure that all wheel drive would even work with tracks.

I went with a conventional design becouse it is tried and proven to work. Or as we say in the engineering business, simple is better. (Engineering high school behind me.)

That being said, there's nothing wrong with sticking to a convectional tank design with a few advanced improvements.

That was my idea. Basically take an electric engine powered by batteries, a fuel cell to charge those batteries as needed, hydro-pneumatic suspension for adjustable ground clearance, fully sealed air filtering and exhaust systems to let it drive under water etc. But at the same time keep the good old tracks and single engine setup for ease of maintenance.

PS. Don't think your input is not appreciated. I appreciate all input even if I disagree with it becouse it helps me think outside the box for solutions.

[VarrusTheEthical]

PS. Don't think your input is not appreciated. I appreciate all input even if I disagree with it becouse it helps me think outside the box for solutions.

Oh it it's fine, it's your setting and your tank, so you get the final word. I freely admit that I am no expert on tank design and you seem to know what you're talking about, especially considering that you're a purple space-cube. When I post my ideas on vehicles for my settings on the forum, you're welcome to suggest and critique all you want.

[Number Theoretic]

Well, that's true with a traditional power plant such as a turbine or reciprocating engine. What I was thinking was rather than one large central power plant housed inside the tank's hull, you had a number of smaller engines housed inside the wheel hubs of the tracks. This should give you enough space for a rear hatch without a frontal engine mount. I admit that I'm not sure how feasible this setup would be since I don't know the exact kind power-plant you're planning on using. But if you don't mind adding a little handwavium to your tank, I think this could be a believable , if not plausible design.

For electric motors alone, this certainly could work. From an aesthetic point of view, keep in mind that this would require the supporting wheels (the one, that are good visible above the track) to be equipped with spokes. Advantage of such a design could be better distribution of power, getting rid of a transmission and increasing efficiency. Control overhead is moderate and could be handled even by today's military grade computer systems.

A problem, however could be the power source: Chemical fuels usually have much higher energy densities than batteries and iirc, Purple already chose the energy source to be a high-power chemical fuel. Combined with gas turbines, this is, at least by today's technology the state of the art in maximizing power vs minimizing space requirements. It doesn't stretch my imagination that this would also be true in Purple's setting.

Have you considered writing an essay on the topic of the Leo2? Or just summing up everything you know about the thing? Or maybe registering on Wikipedia and filling that article up so much that it overloads their hard drives? Or, better yet just dumping all the juicy details such as that one right here in a mega post? As far as I can tell you my man are an expert beyond any I have yet met. When ever I bump into some idea you have a ready made comment on how German engineering made it better.

If i'd known, that this knowledge would later be in high demand, certainly However, at least the German article on the Leo 2 is already filled with details even i've forgotten. Don't know about the English article, though, but i would guess it also contains much detail. Anyway, thanks for the appreciation
And speaking of a "mega post": i caught myself thinking earlier this week, that perhaps, this thread now has the wrong title. "Tank Design 101" or "How to design a battle tank" may be more fitting, i guess.

And it would be fun to know all of that in advance.

Alas, the retrieval problem. Been some time since i've been there and therefore memory is somewhat buried and only emerges when triggered by something like one of your ideas.

[Dass.Kapital]

Been following the thread for a while and thought I'd add some small things.

As an example of electric power drives/transmissions, Porsche tried a "Diesel motor driving electric motors" in his bid for the first Tiger project (Which failed and the hulls completed turning into boxy 'Tank destroyers') .

"Link" Nice picture of one from the side where the eight wheels can be seen.

As for 'Number Theoretic' comments about a hit on the motive wheels being a problem, I'd like to throw in something again from the late war German tanks.

The Germans liked the over lapping road wheel design for its benefits (Again, first used in the Tiger to help in regards to the vehicle's weight). Its draw backs were its complications and real p.i.t.a. of maintenance and just fixing things after battle damage blew wheels off.

Porsche also seemed not to like the over lapping torsion bar system, his hulls using a different system. Later in the war (And I think it was used on some late production hulls? Tiger II?) was to 'restructure' his original design (Which was built into the 'Elephant) into a 'modular' idea where the two sets of over-lapping wheels were effectively on the same 'bogey'/'strut'.

So, having the wheel/suspension system kind of 'modular' would allow field engineers to simply 'unbolt' the damaged components from the hull and bolt on new ones.

Which is mentioned in the later article about the 'JagdTiger', with the mention that the weight of that monster over-stressed the suspension and one 'snapped off' on the testing fields.

Also, I think the Russians developed some method of putting springs into the tanks wheel hubs to aid in the suspension? Something I think the Germans even copied? Not sure about this last bit.

Hope the ideas help.

Much cheers to you and yours.

[Number Theoretic]

Interesting input, indeed. I didn't know that they tried a diesel-electric hybrid drive train for tanks back then. Sorry for the late answer, i had much to do these days. But i did read your link.

What i don't understand is how they implemented power transmission from engine to tracks. I always believed they chose the simple approach that is also visible in today's tanks: a sprocket wheel at the rear while using the rest of the wheels to carry the tank's weight and to add suspension to the tracks. Did they do that on the Jagdtiger design as well or did they experiment with power transmission in the weight-carrying track wheels on the ground?

[Dass.Kapital]

Interesting input, indeed. I didn't know that they tried a diesel-electric hybrid drive train for tanks back then. Sorry for the late answer, i had much to do these days. But i did read your link.

You're most welcome and hello. Real Life does tend to get in the way of general fun.

What i don't understand is how they implemented power transmission from engine to tracks. I always believed they chose the simple approach that is also visible in today's tanks: a sprocket wheel at the rear while using the rest of the wheels to carry the tank's weight and to add suspension to the tracks. Did they do that on the Jagdtiger design as well or did they experiment with power transmission in the weight-carrying track wheels on the ground?

Okay, as far as I know the WWII German tanks had their drive sprockets on the front, with the main gears for the clutching a big box between the driver, hull gunner/radio operator, then the transmission running back under the fighting compartment (Over the multi-bar torsion suspension) and into the engine compartment in the rear. So, you can kind of see a reason for Tiger/Panther/etc generation tanks being the height they were.

Of course there were also machines in German general service that weren't originally built by them. The Czech light tanks (Pz38) and the nasty little tank hunter/destroyer based on the same chassis, the Hetzer. These followed the every one elses design of drive sprocket at rear, short transmission, no torsion bars under the floor etc.

Now, as for the Porsche diesel/electric idea. (Which was also later used to power the Mause) I do believe the drive sprocket was located at the rear of the machine. Professor Porsche possibly realizing that all that stuff at the bottom of the tank was effectively adding to height and hence weight of the design.

Now, as to the why of designing the machines with the gearbox/drive sprocket at the front as opposed to the rear. For that I have no idea. Not wanting to derail the current thread about shields with tank suspension/transmission. I assume there was some mechanical advantage/thinking about why they did it their way. Perhaps a wise and knowledgable other forum-ite can enlightne us?

Much cheers to you and yours.

[Number Theoretic]

It's OK i guess. We have been discussing all sorts of issues related to battle tank design, like guns, energy requirements or APS systems.

I have no idea either why anyone would place the drive sprockets in the front of the tank. From a tactical point of view i'd guess that it would make much more sense to place them at the back, where enemy fire is less likely to reach them, at least in standard situations. Perhaps they placed them in the front to exploit the better armor there to protect the drive wheels. But when it comes to hits by a tank shell, i see more disadvantages than advantages in this design.

[Terralthra]

I'd probably go with the same kind of radiator your use in space along with the spiked things like you see on computer heat sinks.

The problem with heat-sink radiators (as on a CPU cooler) in space is that in air, they work via conduction, and maximizing surface area to volume ratio increases the amount of heat conducted away by air; increasing air flow via a fan does the same thing. In space, heat energy only transfers via radiation, and having the sort of corrugated many-lobed surface used by a heat-sink radiator only increases the amount of radiant heat re-absorbed by other lobes of the radiator, decreasing overall efficiency significantly over a smooth surface. Better would be an array of long, thin vanes connected with heat pipes, projecting far enough away from the ship to provide adequate radiant surface area, while thin enough that most of the radiated heat energy is not reabsorbed by the other vanes (or the ship).