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The imperium, at some point, had the technology to build Anti-grav bikes, as well as reconnoissance vehicles with anti grav technology (or at least something analogous). Are/were there any Imperial anti-grav tanks?

Would there be any fluff excuse explanation as to why there is an imperial anti-grav tank?

DrunkPhilisoph wrote:
The imperium, at some point, had the technology to build Anti-grav bikes, as well as reconnoissance vehicles with anti grav technology (or at least something analogous). Are/were there any Imperial anti-grav tanks?

Would there be any fluff excuse explanation as to why there is an imperial anti-grav tank?

AFAIK, Custodes had anti-grav Rhinos that they sent into the human Webway Pre-Heresy at least.

There were. Jetbikes and Land Speeders are the most common examples. I suspect the reason is the same as always. Technology lost.

Anti grav vehicles were allot more common back in the day, though the imperium does still possess STCs to make them. However only a few forgeworlds will possess the knowledge to make them and even these would take a long time to build, unlike the easily mass produced leman russ. Even more rare would be the replacement parts for a grav tank if it were to get damaged.

Anti-grav technology is incredibly difficult to replicate. Likely because its either really complicated and/or requires expensive/hard to find materials.

So while they could make more anti-grav vehicles, they instead go with the more easily made/repaired conventional vehicles because they need stuff in quantity. And the benefits of hover vehicles would not outweigh the increased cost of production and whatever drawbacks they may have.

A tank crew can easily replace a thrown tread, but they may not be able to replace a damaged grav plate. So a damaged hover tank would require more logistical support than a Lemun Russ.

Easy to make and easily replaced versus cash drainer and really hard to replace.

They won't be around post-Heresy, Rhinos and Russes are just too cheap and convenient. If you wanted an excuse to make one (or more) though, you could pull the old "Acquired from Forge-World X through sequence of events Y" card.

Perhaps tanks were too big and heavy for antigrav technology.

 Mr Nobody wrote:
Perhaps tanks were too big and heavy for antigrav technology.

Well no one told me that....
If a Rhino chassis could have hover tech, why not larger things?
just because they are "rare" doesn't mean they don't exist.

Perhaps tanks were too big and heavy for antigrav technology.

I think this is the main reason.

Eldar have wraithbone, which is lightweight, and superior tech to produce antigravity engines, and haven't lost any technology to the spoils of time or bureaucracy.

The Imperium could make antigravity tanks, but they would probably be too heavy, slow, and unreliable to be effective in combat.

Ah that hit the spot.

Probably also the fact that anti-grav technology works best with energy weapons (as we see on the Eldar hover-tanks) and other low-recoil weapons (like shuriken cannons), rather than the honking-huge battle-cannons that the Imperium equips its tanks with. Blame Newton, but the force pushing that massive shell out of the barrel is going to push the floating tank backwards as well, which (as we've seen with landspeeders and the jetbikes) is not exactly the most stable platform. Anti-grav tanks were possibly discontinued as simply being non-viable for their battlefield role.

That depends. If the tank is heavy enough it won't go back super far, it still has its mass and inertia after all.


Speeders actually don't use anti-grav tech, they use Magnetic Levitation to counter the force of gravity as opposed to actually ignoring it.

 TheNewBlood wrote:

Perhaps tanks were too big and heavy for antigrav technology.

I think this is the main reason.

Eldar have wraithbone, which is lightweight, and superior tech to produce antigravity engines, and haven't lost any technology to the spoils of time or bureaucracy.

The Imperium could make antigravity tanks, but they would probably be too heavy, slow, and unreliable to be effective in combat.

From what i just read on the 40k wiki, the Custodes and sister of silence used them (anti-grav rhinos) during the Great Crusade as transport into the Webway. They looked something like this:

Interesting. And the recoil could explain it.

 Psienesis wrote:
Probably also the fact that anti-grav technology works best with energy weapons (as we see on the Eldar hover-tanks) and other low-recoil weapons (like shuriken cannons), rather than the honking-huge battle-cannons that the Imperium equips its tanks with. Blame Newton, but the force pushing that massive shell out of the barrel is going to push the floating tank backwards as well, which (as we've seen with landspeeders and the jetbikes) is not exactly the most stable platform. Anti-grav tanks were possibly discontinued as simply being non-viable for their battlefield role.

Considering Tau hammerheads can be armed with railguns...

 Dingdoodah wrote:

 Psienesis wrote:
Probably also the fact that anti-grav technology works best with energy weapons (as we see on the Eldar hover-tanks) and other low-recoil weapons (like shuriken cannons), rather than the honking-huge battle-cannons that the Imperium equips its tanks with. Blame Newton, but the force pushing that massive shell out of the barrel is going to push the floating tank backwards as well, which (as we've seen with landspeeders and the jetbikes) is not exactly the most stable platform. Anti-grav tanks were possibly discontinued as simply being non-viable for their battlefield role.

Considering Tau hammerheads can be armed with railguns...

Railguns don't fire conventional rounds. They use magnets along the barrel to accelerate the projectile to high speeds. A hammerhead's main weapon would have comparatively little recoil to it's size.

As for the main topic, I would assume either the technology is either lost or impractical. Why would a Leman Russ need anti grav tech? It would help with all those piles of rubble that keep causing it to throw a track but for the cost you could make another russ.

 TheCustomLime wrote:

 Dingdoodah wrote:

 Psienesis wrote:
Probably also the fact that anti-grav technology works best with energy weapons (as we see on the Eldar hover-tanks) and other low-recoil weapons (like shuriken cannons), rather than the honking-huge battle-cannons that the Imperium equips its tanks with. Blame Newton, but the force pushing that massive shell out of the barrel is going to push the floating tank backwards as well, which (as we've seen with landspeeders and the jetbikes) is not exactly the most stable platform. Anti-grav tanks were possibly discontinued as simply being non-viable for their battlefield role.

Considering Tau hammerheads can be armed with railguns...

Railguns don't fire conventional rounds. They use magnets along the barrel to accelerate the projectile to high speeds. A hammerhead's main weapon would have comparatively little recoil to it's size.

As for the main topic, I would assume either the technology is either lost or impractical. Why would a Leman Russ need anti grav tech? It would help with all those piles of rubble that keep causing it to throw a track but for the cost you could make another russ.

That's wrong. As Newton states, "Actio equals reactio."
Railguns accelerate the projectile to even higher speeds than normal guns to compensate for the lack of explosive payload, and have higher recoil than their chemical based cousins (unless you have hyper long barrels which can accelerate slower but for a longer time (think aircraft carrier long)).


And to come back to my question, so far we got a lot of reason against using anti-grav. What about some scenarios where you could see the Imperium employing anti-grav technology?

Huh, didn't know that. It does make sense in retrospect.

The Imperium uses Land Speeders which use anti grav technology which allow them to perform fast recon missions (Or to melta some tank before dying horribly).

I would assume that reconnaissance missions would be a role anti grav vehicles are suited for. They don't need technology much stronger than multimelta and their anti-grav nature would allow them to pass over obstacles with ease. Land Speeders are a prime example of such a use for the technology.

I could also see them using it on Titans so that they can walk along without causing any cave ins or destroying bridges. It wouldn't cause them to hover but it would lighten them up.

Ya, I could see them using anti-grav on Titans. However, wouldn't the Titans want as much boom as possible?

When we talk about technology and why it isn't used I think we need to come at it from a different direction.

The Empire isn't necessarily as technologically bankrupt as it may seem. There is lost technology to be sure, but vast amounts of technology is stored at Mars. Doled out periodically for use with the Marines or higher orders as is necessary.
The Mechanicum holds a very tight reign on these things to suit their own purposes. Releasing complex advanced devices, to the Imperium, would unlock a Pandoras Box of independant thought and inevitable loss to chaos.

Besides, why supply high technology when there are untold trillions of human beings that can be thrown at the "enemy" drowning them in bodies. The Imperium doesn't need a technological edge when it has an organic one... this suits the Mechanicum just fine... the flesh is weak after all.

In the end, the Imperium while certainly decadent and existing primarily through inertia does things the way it does because they can. The technology to build massive spaceships that look like Gothic Cathedrals isn't necessary, but it's possible so it's done that way.

Technology at this level is simply taken for granted.

Oh yeah, in the great crusade, the Imperium came upon several more advanced civilizations and it was a matter of pride that the Marines, in particular, could conquer these peoples despite that deficit and much was made of it.

The strength of the human condition against other species adds a perverted twist to the lack of advanced devices as well.

Back in the days before GW had vehicle models in plastic, you could use grav tanks in imperial forces for 40k.

It was called the "grav attack" tank.

Then again, ALL anti-grav tanks were "Grav attack" tanks - no matter if you played orks or marines, or army or eldar. Eldar ones tended to be "captured" imperial ones (at least the ones in the first Astronomican book list were).

This was first exemplified in a model with the deodorant flask tank.

Since then, they have used the excuse of "lost" tech (they haven't been made in soooo long, no-one remembers how to build them and the admech, if it has the specs, are too paranoid to share.)

DrunkPhilisoph wrote:

 TheCustomLime wrote:

 Dingdoodah wrote:

 Psienesis wrote:
Probably also the fact that anti-grav technology works best with energy weapons (as we see on the Eldar hover-tanks) and other low-recoil weapons (like shuriken cannons), rather than the honking-huge battle-cannons that the Imperium equips its tanks with. Blame Newton, but the force pushing that massive shell out of the barrel is going to push the floating tank backwards as well, which (as we've seen with landspeeders and the jetbikes) is not exactly the most stable platform. Anti-grav tanks were possibly discontinued as simply being non-viable for their battlefield role.

Considering Tau hammerheads can be armed with railguns...

Railguns don't fire conventional rounds. They use magnets along the barrel to accelerate the projectile to high speeds. A hammerhead's main weapon would have comparatively little recoil to it's size.

As for the main topic, I would assume either the technology is either lost or impractical. Why would a Leman Russ need anti grav tech? It would help with all those piles of rubble that keep causing it to throw a track but for the cost you could make another russ.

That's wrong. As Newton states, "Actio equals reactio."
Railguns accelerate the projectile to even higher speeds than normal guns to compensate for the lack of explosive payload, and have higher recoil than their chemical based cousins (unless you have hyper long barrels which can accelerate slower but for a longer time (think aircraft carrier long)).


And to come back to my question, so far we got a lot of reason against using anti-grav. What about some scenarios where you could see the Imperium employing anti-grav technology?

The grav-chutes and lift-packs of the various "airborne" units, but those are for infantry, not heavy support vehicles.

Though, on the Tau railgun weapons... they're an advanced alien society, we can't really apply our understanding of railguns and railgun technology to theirs, as they may have developed methods and materials that get around such limitations (such as a recoil-suppression barrel that pushes back on itself, not the vehicle mounting it).

It must also be borne in mind that anti-grav technolgy is deeply mistrusted within the Imperium. Since many alien races freely make use of anti-grav it is seen as an alien technology, so much so, that even human built anti-grav is seen as somehow polluted by association.


On the subject of recoil would not a quick burst of the engines providing equal forwards thrust be a simple measure to keep an anti-grav tank in place whilst firing? Afterall, coming up with a mechanism to time a little bit of forward momentum to compensate for recoil doesn't seem OTT on an already technologically complex vehicle.

Right with you.

DrunkPhilisoph wrote:That's wrong. As Newton states, "Actio equals reactio."
Railguns accelerate the projectile to even higher speeds than normal guns to compensate for the lack of explosive payload, and have higher recoil than their chemical based cousins (unless you have hyper long barrels which can accelerate slower but for a longer time (think aircraft carrier long)).


And to come back to my question, so far we got a lot of reason against using anti-grav. What about some scenarios where you could see the Imperium employing anti-grav technology?

Actually that's not entirely correct on either point. As railgun doesn't use kinetic force to launch the projectile, it doesn't technically have recoil. Technically there is no moving part apart from the projectile that is being accelerated. The "reaction" in the case of a railgun is the heat that is generated in the mechanism itself and the plasma wake of the projectile.

And you don't need a massively long track to get projectile speeds that would be fast enough to punch through most tank armour - there was a projected called EDO-1 in the 1980s, that achieved speeds of 3,000 m/s (9,800 ft/s) firing a 700g (15lb) projectile from a track length of 0.7 m (2.3 ft). That is small enough to be carried by a something like a Bradley.

The main drawback with a railgun is they need massive amounts of energy to power the magnetic system, even the smallest we currently have takes as much power to fire as a small village uses. But then in the 40k universe they have had 40 millennia to improve the design and create smaller, more efficient and more powerful generating sources.

There are some incredibly complicated maths you can use to work out the speed to which a given length of track could accelerate a certain size of projectile but its a bit beyond me. And yes, I studied railgun design as part of my university electronics degree.

Rail guns have recoil. Or at least current prototype ones do. if only a small amount



the gun kicks back a little in its cradle. its not as much as the 120mm off an abrams (which has the breach recoil 3 feet into the compartment) but its still recoil.

Anyways, in terms of grav tanks in the imperium. I think its the same matter of "lost tech" and the superstition surrounding them. A regular person would not think a 70 ton leman russ could hover... then they see it happen how do you think they would react? with fear. which is the big thing.

Some of them possibly exist in far flung forgeworlds gathering dust since no one knows how to make them work.
In regards to personal armies, it can be a stretch but its possible to have them (I think, I built a Grav Russ, and Chimera basing the design off the Custodes Grav Rhino propulsion system.)

 Engine of War wrote:
>youtube video of awesomeness<

I love that the "bullet" is just a big hunk of metal. No casing, no propellant, just a big hunk of metal. Glorious.

 Ross74H wrote:
Actually that's not entirely correct on either point. As railgun doesn't use kinetic force to launch the projectile, it doesn't technically have recoil.

Absolutely wrong. There is no getting around conservation of momentum. If you fling a shell forwards with X momentum something must go backwards with X momentum, and heat has nothing to do with it. The magnetic field exerts a force on the shell, with an equal force pushing the magnet back. The only slight difference might be that the railgun only moves the shell, while the conventional gun has recoil from the shell and the propellant.

Of course given the size of the shell relative to the tank the recoil isn't going to be much. I can't bother calculating it again, but the tank slowly drifts back a bit and can easily be corrected by its engines.

And yes, I studied railgun design as part of my university electronics degree.

Apparently not very well.


Automatically Appended Next Post:

 Engine of War wrote:
its not as much as the 120mm off an abrams (which has the breach recoil 3 feet into the compartment) but its still recoil.

That's because it's a nice heavy fixed mount. A tank gun recoils that much because the longer the recoil distance the softer the shock on the mount. You could make a tank gun fire with little/no recoil distance, but it probably wouldn't be very kind to the aiming mechanism.

Absolutely wrong. There is no getting around conservation of momentum. If you fling a shell forwards with X momentum something must go backwards with X momentum, and heat has nothing to do with it. The magnetic field exerts a force on the shell, with an equal force pushing the magnet back. The only slight difference might be that the railgun only moves the shell, while the conventional gun has recoil from the shell and the propellant.

Unless you use a multi-stage stepped magnetic field to pull the round down the barrel before pushing it from behind. The magnets could also be shaped in such a manner (and powered) to put spin on the round as it leaves (the magnets would activate in a spiral, basically, causing the round to spin as it is pulled, and then pushed, up the barrel).