Questions about shields

[JointStrikeFighter]

Um purple; you sure can mount a gattling of types on a tank; here is one on a humvee

[Purple]

Um purple; you sure can mount a gattling of types on a tank; here is one on a humvee

[img]

I stand corrected.
Still try fitting that on a small fast rotating point defense turret to hit incoming shells. It would be the equivalent of using your commanders MG to do that. Somehow I wonder if you could even aim it that quickly.

[JointStrikeFighter]

CROWS isn't exactly fast rotating, and it's aimed via a TV screen, but small tank CIWS turrets are within the realm of possibility, if not practicality.

[Number Theoretic]

There is no way one can mount a gattling turret on a tank thou. At least not unless I redesign the whole tank to be a mount for it scraping all the rest. I mean these things are just massive, power intensive and generally more suited for a battleship. I was thinking of something more along the line of real world APS systems like the Arena or Drozd. Most likely a combination of all three.

http://fofanov.free.fr/Tanks/EQP/shtora.html
http://fofanov.free.fr/Tanks/EQP/arena.html
http://fofanov.free.fr/Tanks/EQP/drozd.html

Nice links. I didn't know about these APS systems but they look convincing. If robot gatling APS turrets aren't your cup of tea, go for them.

This said, I had the idea for a weapon back in the day that might be useful as a point defense system. After all it takes way less energy to fry a shell than a tank. But I have no idea if it would work. Ill lay it out here and you (and others) tell me what you think.

Say I fire a laser beam at an incoming shell. The laser it self is not the damage mechanism. Instead it only serves to ionize the air along the path to the shell sufficiently. Hooked up to the laser thou is a really strong capacitor. As soon as the laser does its job (practically instantly due to the speed of light and all) the capacitor discharges releasing what is in essence a bolt of lightning through that path. Now, this has a 50% chance of being awesome or just plain idiotic and make you facepalm. But physics is not my strong side so you tell me.

This is entirely possible and has in fact even been demonstrated. Although it obviouly is still somewhat futuristic but i'd say that if you can do battle lasers you can also do this.

Yup, that is messed up indeed. Like they say, war is hell. And yes, that "if your tank flips over you have worse problems than getting out of a flipped tank" rationale is the one they use. Or, if you screw it up in peace time, you can be turned back by a salvaging tank or a crane.

Although that would be quite an embarrassment.

Absolutley! I briefly remember some Failblog images though featuring something like this ...

Somehow I wonder if you could even aim it that quickly.

That's where the robot turret comes in, constantly scanning the surroundings of the tank and zapping everything which is incoming fast. But a normal infantry-style MG or Browning .50 cal MG wouldn't do. Firing rate is simply too low and their precision isn't that great either. Gatling-style weapons can compensate quite well for a lack of precision simply by sheer number of bullets. Maybe they are more precise than a standard MG but i don't know that. Depends, and would demand some research.

@JointStrikeFighter: Thanks for the images. They show nicely that smaller gatling guns are possible.

[Purple]

Nice links. I didn't know about these APS systems but they look convincing. If robot gatling APS turrets aren't your cup of tea, go for them.

I figure this could give me better very short range protection. The idea being that they only fire if a projectile has passed through my shields and I have already gotten to the oh shit point.

This is entirely possible and has in fact even been demonstrated. Although it obviouly is still somewhat futuristic but i'd say that if you can do battle lasers you can also do this.

Reading that link I am very tempted to forget it being a defense system and just slave it to the commanders sights and his laser range finder as a sort of Tesla Coil (command and conquer style) commanders machine gun. Edit: Screw it I am doing both.

Absolutley! I briefly remember some Failblog images though featuring something like this ...

The double irony being that the one fool that made it happen actually is the only one that can escape before the reporters arrive.

That's where the robot turret comes in, constantly scanning the surroundings of the tank and zapping everything which is incoming fast. But a normal infantry-style MG or Browning .50 cal MG wouldn't do. Firing rate is simply too low and their precision isn't that great either. Gatling-style weapons can compensate quite well for a lack of precision simply by sheer number of bullets. Maybe they are more precise than a standard MG but i don't know that. Depends, and would demand some research.

I have a personal thing against gattling style weapons. Most notably I think they strike way too many fanboy cords. This said, my research turned up that the Russians of all people actually had a plan for a gattling commanders machine gun on their T-10. Sadly the heavy tank newer came to be.

[Number Theoretic]

Absolutley! I briefly remember some Failblog images though featuring something like this ...

The double irony being that the one fool that made it happen actually is the only one that can escape before the reporters arrive.

Indeed. "Screw you guys!"

Reading that link I am very tempted to forget it being a defense system and just slave it to the commanders sights and his laser range finder as a sort of Tesla Coil (command and conquer style) commanders machine gun. Edit: Screw it I am doing both.

I have a personal thing against gattling style weapons. Most notably I think they strike way too many fanboy cords.

Fair enough. There are too many gatling users out there anyway. Laser-guided lightning guns on the other hand aren't that common, so people will remember your tank.
And i must say, your tank will be well protected: 2 APS systems, that energy shield which can absorb shells and convert their kinetic energy into electricity and then we haven't even reached the hull armor.
Btw, what kind will be your main cannon? Coilgun, Laser or Railgun? Or something entirely different instead?

[Purple]

Fair enough. There are too many gatling users out there anyway. Laser-guided lightning guns on the other hand aren't that common, so people will remember your tank.

Also, I imagine that it would have the advantage against power armored infantry. Where a bullet would just penetrate or not this thing will, even if it does not kill them short circuit the whole electronics thing they have going. Good luck walking in your 500kg suit of armor when the servos are fried.

And i must say, your tank will be well protected: 2 APS systems, that energy shield which can absorb shells and convert their kinetic energy into electricity and then we haven't even reached the hull armor.

Well the idea is that the lightning gun is used along with a laser dazzler for further than shield defense. Than you have the actual shield, than the APS (limited ammo is countered by the fact that it won't be used often since the shield won't be breached often) and than finally the armor.

This said, I was just thinking of using a normal modern day layout with a composite ceramic and steel mix but with buzz words like futuristic starship hull plating steel replacing normal one.

Btw, what kind will be your main cannon? Coilgun, Laser or Railgun? Or something entirely different instead?

I was thinking of using a 90mm coilgun with a variable power level. The idea would be that since its a coil gun I can load any projectile in it that I want. Also, I can very the power level to achieve a desired speed for the projectiles.

That way I can fire things like the fallowing (condensed list made on short notice):
- Full sized 90mm HE/HESH/HEAT, the size of a modern shell propellant included but with the space freed up by not needing propellant filled up with explosive goodness. I wager I could get as much as 100% increase in the volume this way, and futuristic propellants will bust that to make it an equivalent of an 155mm easy. I know I will lose effectiveness on HEAT rounds due to the cone diameter and I will have far less fragmentation but with that much HE it might not be a bad trade off.
- Kinetic Penetrator for anti armor work. Think modern sabot round but made of futuristic metals and fired out of the gun at speeds that make modern tanks cry.
- 25-30mm autocanon rounds. Again, the size of a modern shell propellant included but with the space freed up by not needing propellant filled up with explosive goodness.

The rounds would be stored all inside the turret (ergo it would still be quite large but with no crew inside it balances out to modern tank sized). And they would be stabilized inside the gun via a magnetic field. (If I can have room temperature superconductors I can have this too.) And here is the clever bit. The heat wasted by the gun as we know coilguns waste a lot of heat would be picked up by the cloak and returned into the batteries making for a very energy efficient weapon especially over many shots.

Opinions?

[Number Theoretic]

Sounds reasonable. And if you stick with the capacitor bank we assumed earlier, you'll have enough energy to pack quite a punch into your shells. Because if they can release up to 216 MW in one second, you'll get 2160 MW in one tenth of a second, assuming you deplete the entire capacitor energy during that time. If your Coilgun has for example 50% conversion efficiency, this can still pack around 1 gigawatt of kinetic energy into your projectile. And since the projectile would exit the barrel typically much faster than in one tenth of a second, you really can achieve projectile energies that make modern tanks cry.
To get an idea what an energy number means in terms of velocity and projectile mass, set it equal to 1/2 * m*v^2. Insert for example your shell's mass and you'll get a velocity corresponding to that energy figure.
And in efficiency terms, i reckon it is possible to get reasonable percentage numbers if you use superconducting coils and multiple coil stages.

Concerning ammunition types, i'd suggest a "shotgun shell", which basically opens after leaving the barrel and sprays many small bullets along a narrow cone-shaped path. Infantry will hate this Or did you have something like this in mind when loading the gun with autocannon ammo?
Your thoughts on HEAT and anti-armor shells also sound reasonable, i support that.

[Purple]

Concerning ammunition types, i'd suggest a "shotgun shell", which basically opens after leaving the barrel and sprays many small bullets along a narrow cone-shaped path. Infantry will hate this Or did you have something like this in mind when loading the gun with autocannon ammo?

Something like that. I got the idea from the french of all people. Their AMX-30 featured a main gun, a 20mm autocanon and a machine gun. I figured that since I can fire anything I want from a railgun what with there being no need for a tight fit for sealing off gases I could relegate the first two to the main gun and have the MG be separate in the form of a commanders lightning rod of death.

This said, this gives me an idea. Why just make the thing a shotgun shell and not go further. I am thinking HEFRAG shotgun shells but with an airburts mode. I can prime it to go off like a shotgun strait from the barrel or fly any distance and repeat the same thing once there.

Your thoughts on HEAT and anti-armor shells also sound reasonable, i support that.

So, at this point I have:
- Kinetic penetrators for anti armor work, hopefully I can blunt force my way through any shields the enemy has
- HEAT rounds for light vehicle/IFV work
- Autocanon rounds for anti infantry and light vehicle (unarmored) work
- Zap gun of doom for anti infantry work
- Shotgun shells, or maybe shotgun airburts for 3 and 4

[Number Theoretic]

Something like that. I got the idea from the french of all people. Their AMX-30 featured a main gun, a 20mm autocanon and a machine gun. I figured that since I can fire anything I want from a railgun what with there being no need for a tight fit for sealing off gases.

You actually have even more flexibility, because if your coilgun can stabilize the alignment of undercalibre ammunition reasonably well (for example with highly precise and stable magnetic fields or an adjustable action), it can fire any ammunition type below 90mm. For railguns, you'd need adjustable rails and equally adjustable sabot casings if your ammunition isn't superconducting and can't sustain extremely high currents.

This said, this gives me an idea. Why just make the thing a shotgun shell and not go further. I am thinking HEFRAG shotgun shells but with an airburts mode. I can prime it to go off like a shotgun strait from the barrel or fly any distance and repeat the same thing once there.

Reminds me of the XM-25. With the difference that we now have it in a tank's main weapon. I imagine the gunner lasering the distance to the enemy and then adjusting an offset plus or minus a few meters to set the detonation point of the grenade. Or just flips a switch to set it to out-of-the-barrel shotgun mode.

So, at this point I have:
- Kinetic penetrators for anti armor work, hopefully I can blunt force my way through any shields the enemy has
- HEAT rounds for light vehicle/IFV work
- Autocanon rounds for anti infantry and light vehicle (unarmored) work
- Zap gun of doom for anti infantry work
- Shotgun shells, or maybe shotgun airburts for 3 and 4

An impressive display of ammunition types to choose from. Your tank is a very flexible war machine. A random thought: How about target-seeking or EMP ammunition?

[Purple]

You actually have even more flexibility, because if your coilgun can stabilize the alignment of undercalibre ammunition reasonably well (for example with highly precise and stable magnetic fields or an adjustable action), it can fire any ammunition type below 90mm. For railguns, you'd need adjustable rails and equally adjustable sabot casings if your ammunition isn't superconducting and can't sustain extremely high currents.

Just for the record. I have this brain bug where I tend to use the terms "railgun" and "coilgun" interchangeably, or rather call a coilgun a railgun. I usually catch it before posting or during an edit but if it does sneak by like it did now know that it's a bug on my end.

Reminds me of the XM-25. With the difference that we now have it in a tank's main weapon. I imagine the gunner lasering the distance to the enemy and then adjusting an offset plus or minus a few meters to set the detonation point of the grenade. Or just flips a switch to set it to out-of-the-barrel shotgun mode.

Scary ain't it...

An impressive display of ammunition types to choose from. Your tank is a very flexible war machine. A random thought: How about target-seeking or EMP ammunition?

Some sort of gun launched ATGM is definitively not a bad idea. As for EMP, I have to admit that I am clueless on just how non nuclear versions of it work. I know they exist but that's the limit of my understanding.

[Number Theoretic]

I know that nuclear EMP works because of the interaction of the blast's gamma rays with the molecules of the atmosphere, but non-nuclear EMP is also one of my weak spots. You could still introduce EMP shells later or shift that task entirely into the realm of electronic warfare and microwave emitters.

[Purple]

The more I think about EMP the more I see a pressing issue with it. Namely fratricide. Assuming the enemy will have access to roughly similar equipment as I do his electronics are going to be relatively hardened. Plus he will have armor and shields roughly compatible to mine in strength. Ergo, if any EMP weapon can penetrate his protection it will penetrate mine as well. And given the average engagement ranges of just a few kilometers that tanks are limited to I can't see how I can EMP him without messing up my tank as well. Ill probably reserve EMP for artillery.

[Number Theoretic]

This could even be justified by arguing that non-nuclear EMP warheads are simply too large to be loaded into a tank gun. And of course by the EMP blast radius, like you said.

[Void]

The more I think about EMP the more I see a pressing issue with it. Namely fratricide. Assuming the enemy will have access to roughly similar equipment as I do his electronics are going to be relatively hardened. Plus he will have armor and shields roughly compatible to mine in strength. Ergo, if any EMP weapon can penetrate his protection it will penetrate mine as well. And given the average engagement ranges of just a few kilometers that tanks are limited to I can't see how I can EMP him without messing up my tank as well. Ill probably reserve EMP for artillery.

noep.

Inverse square law bro. A non nuclear EMP will have an effective range of tens of meters, more than a blast frag warhead but waayyyy less than the range to the target. That and an antenna is an integral part of them, antennas can of course be directional (gain and directivity is limited by the small size of munitions though).

These:
http://www.otvaga2004.narod.ru/publ_w4/064_emo.htm
Are real examples of non-nuclear EMP... RPGs.

Globalsecurity also has this little tidbit:
http://www.globalsecurity.org/military/ ... ns/hpm.htm

The US Navy reportedly used a new class of highly secret, non-nuclear electromagnetic pulse warheads during the opening hours of the Persian Gulf War to disrupt and destroy Iraqi electronics systems. The warheads converted the energy of a conventional explosion into a pulse of radio energy. The effect of the microwave attacks on Iraqi air defense and headquarters was difficult to determine because the effects of the HPM blasts were obscured by continuous jamming, the use of stealthy F-117 aircraft, and the destruction of Iraq's electrical grid. The warheads used during the Gulf War were experimental warheads, not standard weapons deployed with fielded forces.

Raytheon much more recently publicly revealed it had successfully tested an HEMP warhead.

Gatling gun APS... don't use them. They were tested in the 90's and then abandoned (I'd provide the link, but it's in a journal article accessed through my University Library I am not allowed to share...). Slewing, stabilizing, spinning up and firing enough rounds to create a useful Pk all take way to long on the timescale of a normal APS engagement (usually a few hundred milliseconds from detection to kill including a fair block of time for the sensors to lock on). Actually hitting a bullet with a bullet is hard to and the amount of ammunition you would expend would be prohibitive. Some kind of proximity fuzed blast fragmentation warhead is preferred (which is why they are used on nearly all real APS systems). A multiple explosively formed perpetrator warhead (MEFP) that produces a smaller number of larger, higher speed fragments is also possible. Trophy uses these. A non-nuclear EMP warhead was even proposed for an American system that will protect aircraft.

Laser APS would be challenging. You need a lot of power on target, which means a big mirror. Which is bad because that mirror will need to be slewed FAST to put it on target in time, but because lasers need absolute precision in pointing you also need to wait for it to settle. The bigger the mirror the longer it will take to settle after moving and time in an APS engagement is always in short supply. You could try some kind of alternative beam steering arrangement like Risley Prisms or optical phased arrays but of all of these distort the beam to steer it and significantly reduce spot intensity at high angles.

[Purple]

First of all, thank you for your input. The links to the articles are enlightening and I am currently asking on another forum to have the Russian one translated and commented on so I will link to it here once(if) its done if anyone is interested.

Now, to the mater at hand.

noep.

Inverse square law bro. A non nuclear EMP will have an effective range of tens of meters, more than a blast frag warhead but waayyyy less than the range to the target. That and an antenna is an integral part of them, antennas can of course be directional (gain and directivity is limited by the small size of munitions though).

The issue I am having with it is that the enemy will likely use some sort of energy shields that will extend several meters away from the vehicle and more importmantly be able to absorb ungodly amount of energy. That's the reason why I was thinking of using a scaled down version of this: link as my main AP weapon. In this case thou, I would be firing a 2 meter long 40mm diameter non stabilised metal rod at something like 5-7km/s just to be sure. But back to the point. Given the amount of energy I can expect the enemy to be able to absorb the corespondigly designed the EMP warhead will have to be extremely powerfull. It will have to be many orders of magnitude stronger than anything those articles indicate. And at that point range starts growing... The question is just by how much. But than again, I have you to fill that part up hopefully.

Gatling gun APS... don't use them. They were tested in the 90's and then abandoned (I'd provide the link, but it's in a journal article accessed through my University Library I am not allowed to share...). Slewing, stabilizing, spinning up and firing enough rounds to create a useful Pk all take way to long on the timescale of a normal APS engagement (usually a few hundred milliseconds from detection to kill including a fair block of time for the sensors to lock on). Actually hitting a bullet with a bullet is hard to and the amount of ammunition you would expend would be prohibitive. Some kind of proximity fuzed blast fragmentation warhead is preferred (which is why they are used on nearly all real APS systems). A multiple explosively formed perpetrator warhead (MEFP) that produces a smaller number of larger, higher speed fragments is also possible. Trophy uses these. A non-nuclear EMP warhead was even proposed for an American system that will protect aircraft.

That's pretty much what I figured as well. Especially since an APS would only be used in the limited range when the projectile has already gone through my shield at which point all I have time to do is fire a shotgun burst in its general direction and pray.

Laser APS would be challenging. You need a lot of power on target, which means a big mirror. Which is bad because that mirror will need to be slewed FAST to put it on target in time, but because lasers need absolute precision in pointing you also need to wait for it to settle. The bigger the mirror the longer it will take to settle after moving and time in an APS engagement is always in short supply. You could try some kind of alternative beam steering arrangement like Risley Prisms or optical phased arrays but of all of these distort the beam to steer it and significantly reduce spot intensity at high angles.

That's why I would not use the laser as a damage mechanism but only as a dazzler and carrier for the lightning gun. You don't need that much focus or precision to generally flare up an area and burn out/confuse seeker heads at a distance and once the target does get in close I will just zap it with a thunder bolt.

[Purple]

PS. Got linked to a similar article on that other forum I mentioned.
http://z4.invisionfree.com/NSDraftroom/ ... opic=10143

[Void]

PS. Got linked to a similar article on that other forum I mentioned.
http://z4.invisionfree.com/NSDraftroom/ ... opic=10143

This is Kyiv actually.

[Purple]

Back again with more questions.
I am currently designing the shape and size of the vehicle and was wondering if anyone (especially NT) could give me a rough idea of how high modern tanks are around the place where the driver is seated. That way I can scale the size of the body accordingly.

[Number Theoretic]

The ground clearance of the Leopard 2 chassis body is about 50 centimeters and it is, if i recall correctly, about as high as a relatively tall man (1,8 meters on average). The driver is located somewhat in the center of the body, but in front of the turret socket. So, geometrially speaking, i'd estimate that the driver's ass is 70 to 80 centimeters away from the ground.

This image gives a rough impression of the dimensions, compared to humans.


I reckon that the Abrams and Merkava tanks have roughly similar dimensions. However, googling would dig out more precise numbers.

edit: If an average sized man stood near the front, it would be roughly the height of his neck.

[Purple]

Hm... Taking that into account I estimate the fallowing (correct me if I am wrong at any point):
The Leo 2 is 3m tall (by Wikipedia), or by that image you provided 118pixels. The body on the image is 57mm tall, translating to:
3000:X = 118:57
3000x57=118xX
X=(3000x57) /118
X=1.45 meters.

Now, taking the obligatory 70-50=20cm of clearance betwen the floor and the driver that gives us about 1.25 meters of inside space for the driver. Do you think that's about right?

Also, on a side note. How to hell did the Russians get away with tanks half a meter shorter than the western ones? I mean, I can get the part where the turret crew was cramped but the driver must have been prone or something?

[Number Theoretic]

Don't know any exact numbers anymore, but these 1.25 meters of driver interior height sound about right. I would have guesstimated a similar number, based on memories of my subjective impressions. The driver is indeed half-prone, but on his back, not on his belly. Like a "very laid back" chair.

I think the Russians optimized their tanks for having as small a silouhette as possible, at the extent of interior space for the crew. And ther T-72 and T-90 tanks replaced the human loader with a mechanical one, which also contributed to saving space. Third reason may be the engine. Both T-72 and T-90 have V12 diesel engines with about 700-950 kW of power, maybe with some variants that exceed 1 MW, but they are indeed somewhat underpowered. And the Leopard 2 (and perhaps the Abrams too, but i'm not sure) have their engines designed in a way which makes it easy to replace them, so perhaps they are bigger than they need to be. I don't know if the Russian tank engines are also designed that way, but if not, this design feature could explain the bigger length of Western tanks fairly well.

[Purple]

I was thinking in terms of height actually. Think about it, a Leo 2 is 3m tall whilst a T-72 is 2.23m. If the driver in the Leo 2 is already half prone what to hell are the Russians doing? You can't account for that with just putting a height cap on crews.

Edit: Found it. Apparently they lowered the hull where the drivers section is.
From another forum.

That can't be good for mine safety.

[Number Theoretic]

Indeed, the mine safety of that design can't be that good. And if i recall correctly, the T-72 tanks haven't got that much armor. I once heared the story that during Desert Storm, an Abrams tank scored a "double kill" with its L44 main cannon: The sabot round entered the front of the Iraqi T-72, exited it on the rear and then still had enough energy to kill a second T-72 right behind the first one. One of many hints that the M1 Abrams is indeed superior to the old versions of the T-72.

[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.