Ultramarine Dreadnought vs M1A2 Abrams

[Balrog]

Figured this might be a bit more fair than the previous mess.

A Space Marine Dreadnought of the Ultramarines Chapter faces off against a US M1A2 Abrams. The Abrams is fitted with TUSK, the Dreadnought has twin-linked lascannons for its left arm, it's right arm ends in a power fist with attached storm bolter. Both start within range of each other's main weapons. Assuming a variety of different battlegrounds (forest/desert/plains/urban/etc.) who fares better?

[Honorius]

Lascannon one hit kills the Abrams before the loader gets a round in the chamber.

At least let them start outside weapons range so both have an equal chance of seeing and shooting first.

[Tribble]

Lascannon one hit kills the Abrams before the loader gets a round in the chamber.

At least let them start outside weapons range so both have an equal chance of seeing and shooting first.

Well that's just it. Assuming that both have weapons that are capable of killing the other, a lot will depend on range and LOS. If the Dreadnought has LOS on the Abrhams it will almost certainly win since the laser canons would be much faster than the Abrhams weapon. At distances beyond LOS the Abrhams would likely have the advantage, assuming that it could hit the Dreadnought before the ladder gains LOS. IMO you'd have to have obstacles that the Dreadnought can't shoot through in order for the Abrams to stand a chance when its within the Dreadnought's weapon range.

[Sea Skimmer]

So if they start 'in range' then why would the battleground matter? You recall the whole point of armored vehicles is that they move right? Why not a dreadnought against Festung Hanstholm or Ouvrage Hackenberg at that point?

Weapons choice also a tad illogical. The principles of the bolter are contrary to to all anti tank developments since about 1942, so I see no reason to think it would be effective against a vehicle with spaced-laminate armor four feet thick designed to erode a meter of solid uranium into burning dust in about 1/1500th of a second or so. Think about it. How long is the fuse delay on a Bolter round? If it can go through 4 feet of anything, then it would always heavily overpenetrate smaller and softer targets unless equipped with certain features I know it is never mentioned as having. Nor would said features entirely solve the problem.

40K armor is generally given as and depicted as being homogeneous and thin meanwhile, which is not inspiring. Rather clearly Bolters are a weapon optimal soft-semi hardened targets, and a good idea for that purpose, which has for whatever reason then fawned over by people whom apparently think the height of technology must have been 1911, or something. I dunno, but far too many times I've encountered people who literally think the idea is novel.

Nor does it sound likely that anything remotely resembling a laser would be effective, since 40K troops can still be seriously held up (for years no less) by dirt trenches and the like, which indicates that their small-medium weapons cannot be overwhelmingly penetrating. A 120mm sabot will go through at least 30-40 feet of compact earth.

Plus thermal attack is a terrible way to defeat armor in basic principle, never mind the practical reality of trying to melt armor. Thermal energy follows the path of best conductor, which will be lateral rather then axial on contact. That is not what you want! At that point the numerous spaced layers in M1 tank armor gain a tremendous advantage; the result may be extensive lateral damage to the armor package, relevant in a larger battle but not here, but it would not at all favor outright penetration.

The Dreadnought would probably be far better served by a missile launcher and a plasma cannon, the later primarily because its wider damage path might blind the tank. If that happened the tank is in trouble and could be picked off.

As is, the Dreadnought is well over 1 meter taller,yet has its weapons mounted fairly low, and certainly doesn't look like it's meant to withstand tank fire of any sort. I predict it gets spotted first the overwhelming majority of the time, and promptly dies. Indeed it could be reasonably spotted in many situations where it could not return fire for lack of LOS to its guns vs its head, tanks mount the gun as high as possible for a reason. The only reason its not at the literal roof line is to allow some depression. The Dreadnought does win on weapons depression, which is useful for an anti infantry platform as it seems to be, but not worth its disadvantages in the anti armor role at all.

Also I see the official stats give the dreadnought an off road speed of 5kph, the walking speed of a casual human, so putting it up against a Nazi fortress might seriously be a much better idea then a modern turbine driven tank known for high performance. It certainly won't make itself hard to hit.

[Kojiro]

I'm actually curious, if anyone has the expertise to work it out, what the chances of simply knocking a dreadnought over would be with a hit from a Abrams? Assuming that a full frontal hit to the dreadnoughts sarcophagus doesn't penetrate, how much force is being applied? Dreadnoughts are notoriously top heavy and once they fall over... well I can't see any way they could possibly stand on their own. Their legs are far from anything resembling agile, though I would expect they have some internal gyroscope that attempts to keep them upright.

Apparently 12 tonnes is around the standard weight.

[Abacus]

My question: why does it matter what Chapter the Dreadnought is from?

[NecronLord]

So if they start 'in range' then why would the battleground matter? You recall the whole point of armored vehicles is that they move right? Why not a dreadnought against Festung Hanstholm or Ouvrage Hackenberg at that point?

Weapons choice also a tad illogical. The principles of the bolter are contrary to to all anti tank developments since about 1942, so I see no reason to think it would be effective against a vehicle with spaced-laminate armor four feet thick designed to erode a meter of solid uranium into burning dust in about 1/1500th of a second or so. Think about it. How long is the fuse delay on a Bolter round? If it can go through 4 feet of anything, then it would always heavily overpenetrate smaller and softer targets unless equipped with certain features I know it is never mentioned as having. Nor would said features entirely solve the problem.

Bolters are not considered an anti-tank weapon in the 40K setting either. The anti-tank gun this machine is equipped with is the laser.

40K armor is generally given as and depicted as being homogeneous and thin

Thin, certainly, but not homogenous. Space marine gear is particularly said to be multi-layer composites, ranging from their suits to their vehicles.

[madd0ct0r]

My question: why does it matter what Chapter the Dreadnought is from?

rules out some weapons and weapon combination, and implies a certain degree of 'standard marine behaviour and tactics' instead of 'batshit space monk ripping a hole through hell to beat you into the ground with a club'

[Starglider]

Lascannon one hit kills the Abrams before the loader gets a round in the chamber.

I don't know why you'd expect this, when lascannons usually fail to one-hit-kill a Leman Russ tank, which has only 150mm of 'plasteel' hull armour with minimal slope. While it's true that plasteel could be stronger than contemporary composite armour, the Leman Russ is supposed to be a fairly cheap and low-end tank in the setting. For rapid laser ablation in particular I'd expect overall mass interposing the beam and specific heat of vaporisation to be more important than tensile strength anyway, and the armour on the M1 is likely to be superior there.

[Sea Skimmer]

Tensile strength doesn't really matter for anything, not taken alone anyway, unless it is stupendously high. If you wanted to keep things simple then probably hardness + modulus can tell you a lot in comparisons. A pure tensile strength comparison would suggest carbon fiber should be some of the best armor around right now, but in fact it pretty well sucks. Against hypersonic impacts it will fail long before it can develop its full tensile strength. A lot of things work on small scales that don't apply against tank fire or in the application of structural vehicle armor. I assume at least, one would wish the supposedly long living Dreadnoughts not to physically fall to pieces.

Likewise other properties can hit surprising limits, say boron carbide, by far the best ceramic for body armor, is far inferior to several other actually cheaper ceramic materials as tank armor.

No doubt a lot of better armors should be possible then what we have now in service, I have a pile of stuff on it at this point, all kinds of metal matrix composites notionally for one if anyone can solve the thermal expansion issues, but stopping present monobloc sabot, segmented sabot (this negates all kinds of trickery, and now service reality in 2016) and the HEAT rounds on this kind of scale, with thin light plating would still be a pretty incredible advance. Also any such super material would directly lead to better projectiles, as a thin jacket for example. Much is not done with long rod ammo these days as is, because we don't need it just yet. Kind of tied into nobody built 140mm gun 85 ton ultra tanks yet.

As far as thermal resistance goes, you've got layer of DU wires to get past and then a layer of ceramic blocks. Both seem like a very serious problem, the DU for shear mass and reactiveness, it's going to blow burning spall back into the laser beam, the ceramic because it's only going to melt at 5,000F, and melt does not remove the material from the hole. Vaporization of ceramic, sounds fun. We could be talking about a couple gigajoules to make this work well against an MBT. I really don't see firepower like that present in 40K. Burning though the flank armor on almost all present tanks would be immensely more viable.

[Honorius]

Lascannon one hit kills the Abrams before the loader gets a round in the chamber.

I don't know why you'd expect this, when lascannons usually fail to one-hit-kill a Leman Russ tank, which has only 150mm of 'plasteel' hull armour with minimal slope. While it's true that plasteel could be stronger than contemporary composite armour, the Leman Russ is supposed to be a fairly cheap and low-end tank in the setting. For rapid laser ablation in particular I'd expect overall mass interposing the beam and specific heat of vaporisation to be more important than tensile strength anyway, and the armour on the M1 is likely to be superior there.

Relative to the setting of 40K not our world where the Leman Russ would easily ass rape an Abrams just from the feats it demonstrates in the fluff. The M1 Abrams' Armor isn't expected to absorb the recoil of a 16" gun, a Leman Russ's main gun is that powerful in recoil alone and its armor has to be able to survive that kind of force. That is materials science far in advance of what we have today. And last I checked, the standard issue "cardboard vest" issued to Guardsmen is rated to deflect LMG rounds which no modern body armor is capable of. ear in mind these forces also literally fight the Demons of Hell and not always lose...

So if a Lascannon is considered a choice weapon for the AT role, I dare say no Tank we have today would want to get tagged with it.

[Sea Skimmer]

Wow good one. You've just made an argument for 40K tank to be made out of a bunch of cast low strength low alloy steel about 2 inches thick, because that's what 16in gun mounts were actually made from back in WW1-WW2. Anti tank anything from today would shoot through them. Recoil is far easier to deal with then hypersonic impact energy because its a much slower impulse. Have you ever seen a real gun mount up close? Or even know what a recoil system is?

Course if you understood physics you might also grasp that a 40K tank would be limited at that point by the recoil throwing the vehicle backwards and off target, not the strength of the recoil mechanism proper. That's why the larger 175mm/8in self propelled artillery pieces of the world have hydraulic spades to dig themselves in before firing. Since 40K tanks are not thrown around by their own guns they can't have muzzle energy like high caliber battleship guns.

Oh and please do provide your numbers for this random body armor claim that's been thrown in, because you know, we do in fact have body armor that stops armor piercing machine gun fire today. So what are your specifics?

[Balrog]

So if they start 'in range' then why would the battleground matter? You recall the whole point of armored vehicles is that they move right? Why not a dreadnought against Festung Hanstholm or Ouvrage Hackenberg at that point?

Within range, not necessarily within line-of-sight. Trees in a forest, buildings in a city, etc. Idea was to avoid a situation where if one horrendously outranged the other it couldn't just win right at the start by dint of plinking away with impunity.

[Sea Skimmer]

Its not really much of a tactical demonstration at that point, if both sides were crewed by pros they'd go hide somewhere and wait for friendly forces while observing the main avenue of approach, and an engagement only happens by chance. Blundering around blindly...make whatever assumptions you want but like I already pointed out, the Dreadnought is taller, and being high powered internally, its going to be hot on FLIR too. It's also slow and needs fairly level, firm ground. None of this is great for maneuver warfare. It's slower then the infamously slow British Matilda II tank.

But really a 1 v 1 comparison makes no sense if you want to take terrain into account. In bigger battles life is different, the Dreadnought and lots of other things have their logical niche. But in real battles your goals are different too. Destroying enemy tanks is great and all, but the tank doesn't really want to kill other tanks, it wants to overrun the enemy battalion headquarters, then the brigade. 40K has lots of advantages in that kind of combat over an earth force. But it does not handle its weapons for surface to surface combat well. WW1.5 with swords or something. If it wasn't so slow I'd call the Dreadnought a future version of armored horse cavalry.

Dreadnoughts are actually something I like, but comparisons like this doesn't bring out the strengths. Lasercannon for example, illogical weapon against tanks, but the fact that the Dreadnought has a near unlimited ability to fire it, and power for propulsion is a big deal. This means where as real life tank needs fuel and ammo multiple times perday in combat, wasting 1-2 hours each time, the Dreadnought can always be in the line until damaged. Against an enemy like unlimited Nids this is invaluable kind of advantage. The emphasis on armor for the pod for the operator too, is something that would be useful in a long battle with the Dreadnought used for a lot of close quarters fighting. But here...if the more lightly armored bits can be penetrated at all, or even just a leg shot off the thing is screwed. Its pretty literally an foot mobile infantry fighting vehicle, not an MBT like platform.

[Sea Skimmer]

https://www.youtube.com/watch?v=3kWkoc3Dad0

To illustrate the problem of excessive vehicle recoil in a more definitive way, here's a nice video of the 24cm K3 firing. This weapon weighs about 60 tons in firing position, the same as the Russ tank. The video quotes 83 tons, which is the transport weight.

So notice the double recoil system, and how most of the entire mass of the mount moves back considerably after an extremely violent primary recoil stroke, and that's firing at a pretty high angle compared to a tank gun. This only gets worse the lower the angle of fire. This also only about a 71 MJ cannon! 16in is around 450 MJ if your talking a WW2 era version. Only about six times greater, meaning six times the recoil, and thus that example cannon going back six times as much. Even allowing for a proportionally smaller powder charge you still have a tremendous problem. And that's an artillery piece dropped flat on solid ground.

On a MLC 70 scale of vehicle you could probably get something like a 10in/45 cal gun or 25cal long 305mm howitzer and drive around shooting it, but you'd still need recoil spades or similar anchoring measures for anything like a low angle. Weight of the ordnance, which would be under half the values of WW2 tech, or material strength in general would not be the limitation even today.

[Elheru Aran]

I think we established in the last thread (whatever that was, Leman Russ versus Abrams or something?) that the measurements they give in the various paper stats simply don't jive with the illustrations we have. A Leman Russ *model* cannon could quite possibly fit the head of a Imperial Guard miniature within, so something like 10 inches' diameter when scaled up... but where in that tank would they store such ammunition? The barrel of a 'realistic' Leman Russ model would look like a pencil (would actually be about that width) in comparison. The rounds are supposed to be ~120mm, IIRC... same caliber as an Abrams.

So on the face of it, claiming that a Leman Russ fires 16" ammunition is simply ludicrous, as is claiming that it has recoil of same. Honorius needs to step up and support that claim.

[Sky Captain]

As far as thermal resistance goes, you've got layer of DU wires to get past and then a layer of ceramic blocks. Both seem like a very serious problem, the DU for shear mass and reactiveness, it's going to blow burning spall back into the laser beam, the ceramic because it's only going to melt at 5,000F, and melt does not remove the material from the hole. Vaporization of ceramic, sounds fun. We could be talking about a couple gigajoules to make this work well against an MBT. I really don't see firepower like that present in 40K. Burning though the flank armor on almost all present tanks would be immensely more viable.

Wouldn't it be fairly easy to achieve mission kill with powerful laser even if main armor aren't penetrated? Damage targeting optics, sensors, maybe cause some overheating problems too and combat effectiveness of a modern tank will be greatly reduced even if it still can drive and shoot.
What if laser is pulsed each pulse flash vaporizing a bit of armor making effect similar to a small bomb. One pulse may not do much, but if there are hundreds of pulses their effect would add up.

[Elheru Aran]

40K lascannons are more like Star Wars blasters than proper lasers. I don't think you can judge them the same way. Regrettably however I'm not sure we have a lot of data to calculate from. Maybe in one of Connor's old threads?

[Sea Skimmer]

Wouldn't it be fairly easy to achieve mission kill with powerful laser even if main armor aren't penetrated?

Assuming no countermeasures were taken to this, sure, the tanks should be carrying at least a few replacement optics they can switch out though. In many cases you can do that without getting out of the tank. But then real life already got pretty crazy at that by the early 1990s, and that is why the laser blinding treaty was signed when it was. FLIR is much more resistant,and easily made more resistant then visual stuff of course, but tank optics already do have some laser protection on them.

We got way further then you might think too,the Bradley Stingray was able to blind a whole enemy positions hundreds of meters wide. So pretty artificial weakness. Also when you use a laser like you highlight your own position on FLIR and NVGs with a literal laser beam, and anyone you don't blind will return fire with an aiming beacon to shoot at. The speed of light beats a 1,500m/s shell, but even out to 5km this is only a few seconds of time before the laser's life becomes interesting. I pointed out the Dreadnought should have an missile itself, I'd hope it would be fire and forget.

One of the points of a tank gun is you aim and fire, you can move to hide at once. Also smoke and dust have no functional effect on your shellfire, only your ability to aim. Smoke shells and grenades make lots of smoke. Laser weapons would highly encourage firing more artillery smoke. Nothing stops a weapon like BM-21 from firing WP smoke before an attack to instantly blanket all the enemy laser beams. The tank is very well suited to forcing the fight down closer ranges.

Damage targeting optics, sensors, maybe cause some overheating problems too and combat effectiveness of a modern tank will be greatly reduced even if it still can drive and shoot.
What if laser is pulsed each pulse flash vaporizing a bit of armor making effect similar to a small bomb. One pulse may not do much, but if there are hundreds of pulses their effect would add up.

If you could take your time you can burn through nearly anything with a 100 watt cutting laser at point blank range. The pulse idea is nothing new, in practice it would be very sensitive to the air conditions. Might work sometimes, doomed others. The higher the power of the pulse the more the air itself violently reacts to the passage of the beam, compared to a continuous wave laser of the same average power. You start to hit lots of conditions in which a real laser beam simply can't transit more power through the air. Also your vaporizing effect will blow mass back into the beam. That's where the frontal armor being deep matters, deep inside of that the vapor has got nowhere else to go and will be reflected back. Simpler side armor would be much more vulnerable, barring easy but notional thermal protection enhancements.

Core problem is the temperature to vaporize iron is twice that to melt it, with resulting enormous increase in required heat. So by attempting to explosively breach it you've greatly upped your required energy transmission for end effect. Very tiny explosions are not only to be violent enough to deform thick steel plates in any direct manner. Pulsed lasers would be the way to go if you could build them, but I think I said before expect gigajoule range kind of weapons at the least.

In the vacuum of space a laser would work rather better, nothing limits you but the laser you can build and keep cool.

[Sea Skimmer]

40K lascannons are more like Star Wars blasters than proper lasers. I don't think you can judge them the same way. Regrettably however I'm not sure we have a lot of data to calculate from. Maybe in one of Connor's old threads?

If someone else wants to search I'm sure some is present... but I do agree. They are...lascannons. But I've seen enough in the past to know 40K isn't some massive laser blinding battle and artillery duel. I imagine them being more like...bolt of light gun for whatever sense they are bound to make.

But can't help but point to the Ponce video of a 100kw laser barely setting a small boat on fire though. 40K claims superarmor materials, but they are vulnerable to lasercannons which are also magic like. This does not prove much vs modern tanks since 40K has gonzo lost technology monastery problems that need suppression and may have led to a reversion to 1915 standards of weapons quality. Damage inflicted against buildings and ground position will indicates more about its gross power then killing vehicles with unknown armor.

[Elheru Aran]

40K las weapons do definitely get described in-universe as being far more "pew-pew-[target goes]BOOM" than "[silent dot of red on target goes]BOOM". They share some characteristics of SW guns as well such as having 'power packs'/'magazines'. So... yeah, I'm pretty sure they aren't *laser* weapons specifically, and can't really be assumed to be such.

[Simon_Jester]

The idea of laser weapons having exchangeable power packs is reasonable, and not particularly unrealistic in my opinion, but that doesn't detract from your overall point. Capacitors and batteries are used in real life for applications where you need a lot of electrical power for a short amount of time but don't need a constant power supply, and where weight and bulk are a factor that make the use of large generators impractical. Both those factors are in play for laser weapons, at least for man-portable ones.

However, again, that doesn't detract from the real point that 40k las weapons don't behave very much like real lasers in the fluff, and behave more like generic "blasters."

[Elheru Aran]

The idea of laser weapons having exchangeable power packs is reasonable, and not particularly unrealistic in my opinion, but that doesn't detract from your overall point. Capacitors and batteries are used in real life for applications where you need a lot of electrical power for a short amount of time but don't need a constant power supply, and where weight and bulk are a factor that make the use of large generators impractical. Both those factors are in play for laser weapons, at least for man-portable ones.

However, again, that doesn't detract from the real point that 40k las weapons don't behave very much like real lasers in the fluff, and behave more like generic "blasters."

SW blasters however don't use electric 'power packs', they're filled with Tibanna gas (or whatever). Presumably 40K las-weapons use a similar operating mechanism as they behave similarly in the fluff, although what exactly is in those power packs I have no idea given that you can recharge them (albeit poorly) by putting them in an open fire...

Anyway. Without data to conjecture from, we can't particularly say how well a Dreadnought lascannon would perform against Abrams armour. Going off game stats, Dreadnoughts have a reasonable chance of penetrating armour with the lascannon as it's one of the best anti-armour weapons in the game, melta weapons being better inside their short range. I would feel reasonably confident saying the Dreadnought could probably penetrate Abrams armour with at least a burst, if not a single shot, from its lascannon. Of course, within that time, the Abrams can traverse its turret and open fire on the taller vehicle with a gun more or less equivalent to a Leman Russ cannon, so...

[Sea Skimmer]

You'd almost have to do coolant or ammo/coolant packs, unless you've gotten the thing to actual 100% efficiency. Say we want a 1 GJ thermal beam weapon that fires in .1 seconds. That's only 1 TW of power, about the rating of the entire US electrical grid, through an apparently man portable barrel for the smallest 40K lasguns. What material are these guns made out of, and why can't they just use that as armor becomes relevant, as even a very small thickness would have to be able to withstand the bore heat. Otherwise you get massive bore or lens or whatever the hell erosion on each firing. This is not a minor issue, because it's what holds back gun bores and thus muzzle energies too.

Just being able to withstand the heat though, means the material can soak up more energy, but it's still got to radiate that into the air which isn't happening quickly with that kind of sudden thermal load. A 99% efficiency we just had 1 GW specific heating rate, that dumped 100 MJ of heat into the bore. Maybe you can make that work for one shot with insulation and a very bulky weapon, but repeated shots with the gun already hot? This is a problem. That's enough heat to boil10 gallons of water in to steam.

Disposable ammo packs would mean you could integrate expendable coolant with the ammo, which would help reduce problem a lot, all the more so if you have sci tech magic coolant to use with an extremely high specific heat of vaporization. Or devise some mechanism to allow the gun to consume vaporized tungsten as a coolant, and get that space the Space EPA.

Also think about that in comparison to water cooled WW1 MG teams. In that situation you have runners for coolant and ammo. That gives more options for a realistic thermal weapon.

But if you need ammo and a crew, your also now competing against xyz form of guns and missile/grenade launchers on a more direct level. The tech to make the thermal weapon will improve those sort of weapons as well, they'll get hotter powders and hotter fuels and hotter more intensive explosives.

Nanotech and magic can make us much better capacitors and batteries, but by nature you can induce explosions into that kind of energy density in the design phase. So super nanoenergetic technology actually runs together on many levels concerning energy storage and possible high explosive yields. Actually we fully expect 2-3 times greater metal driving forces and 10-20 times more thermal energy out of mid term future explosives, but it remains unclear if anyone will ever produce a way to manufacture many of them even on a pilot scale. Some can't even be made in a lab, just notional. May prove to have no useful stability. Certainly not physically impossible at all though.

Building High explosive generator cartridges outright are themselves not an implausible way to fire electrical driven weapons, you would just need a machine gun like piece attached to cycle them, but it would have to be for a very specific purpose, such as 3km/s railgun rifle where no gunpowder or likely ETC tech would ever work (barrel just too long), to make any real sense at all.

[Sea Skimmer]

SW blasters however don't use electric 'power packs', they're filled with Tibanna gas (or whatever). Presumably 40K las-weapons use a similar operating mechanism as they behave similarly in the fluff, although what exactly is in those power packs I have no idea given that you can recharge them (albeit poorly) by putting them in an open fire...

Problem is fluff at different times has said its a coolant or actual ammo, they have recoil so mass must come from something. But that alone doesn't tell us if the tibanna is an energetic material or not. It may be the functional version of lube oil being burned off in a 2 stroke engine.

As far as end lasgun effectiveness goes, even if it is multi gigawatt no armor in 40K I've ever noticed employed a deep spaced armor configuration, nor probably an armor package that has ~750lb square foot density. That's about all I care further on. I'm sure a lasgun could wreck a tank with repeated hits, honestly about anything can, and everything will try.

Thinking more from the other thread which got locked again, I think a lot of the repeated historical bouts of the 'tank is doomed' are because people become so focused on how well anti tank weapons appear to work on paper they forget why anyone cared about killing the tank first in the first place. The cannon on the tank is going to end you and once it fires killing the tank is no salvation.