"What Keeps Hover Tanks From Zooming Backwards ...?" Topic

… When they fire their giant cannon while floating?

What's the science behind why it would or wouldn't skim off in the opposite direction?

Aren't they floating frictionless on those grav thingies?

Thanks,

Dan
PS. I meant to say grav tanks. Sorry.

I've often wondered this myself. I suppose the answer is that, at least with beam weapons, there isn't enough recoil to matter. Even with cannon, a grav vehicle has the power to move a lot of mass very quickly, so a shot won't make it do more than rock in place or slide back a few feet at most.

Really a hovertank is more like a VTOL with a less vulnerable propulsion system in most settings than it is a tank. And yet the tactics and doctrine used are pretty much entirely reproducing ordinary tank use.

It's kind of sad because it's an opportunity to explore how doctrine is created from technological and strategic realities, but I suppose most people aren't into that and so that's WHY they don't bother.

rule of cool?

inertial compensators?

makes the argument to use energy weapons instead of kinetic ones

Chances are, when we achieve the tech level to mass produce grav tanks à la 'Hammers Slammers,' we will have made complementary strides in the technology of the weapons we put on them. So instead of ballistic weapons with recoil, grav tanks will have either lasers or railguns which render Newton's Third Law moot.

an essay on the same concept but for robots

link

The hand break?

Unobtanium.

If they can apply thrust to move forward they can just use a computer controlled recoil compensator that counters the recoil by adjusting thrust.

We already have computer systems that keep the gun on target by adjusting for the movement of the vehicle.

@Wellspring

The Traveller RPG has grav tanks acting as attack aircraft against opponents with weak AA systems. But against a comparable opponent they would be used Nap-Of-Earth as a precaution against AA.

At the very least a tank-like grav tank should be considerably faster than a tracked tank, and should be able to do nifty things like move at full speed sideways.

Some threads on hover armor (some more heated in discussion than others):

TMP link
TMP link
TMP link

As stated computers, to adjust and compensate for recoil, energy weapons that do not produce recoil or minimal amounts of kinetic force that does not require compensation. Of course more advanced ballistics for main tank guns that do fire a projectile would be fitted to grav tanks with all this in mind.

As also mentioned the other thing that would make a grav tank superior to its traditional tracked/wheeled/GEV cousin is that it would be capable of higher speeds, more maneuverable, and less affected by terrain. Then there is that whole pop up attack thing that would be just nasty in my mind. You have an FO team at the ridge and as the enemy force come in view the grav tanks hovering behind the ridge pop up, blast away and drop back out of LOS before the other side has a chance to respond.

AIR BRAKES :D

If you can lift a 80 to 100 ton or greater tank by being able to control gravity you can use the same power to fire a weapon that will use hypervelocities to push a metal rod through the opposing vehicle. Or I suppose you could use the power it would require to also power a laser.

That is one reason I only game near future. Too much handwavium makes it just another fantasy game.

Yep. If the technology exists to neutralize the force of gravity, then neutralizing the much weaker reaction force of propelling a shell should be trivial. And who says that even physical shells in such a setting would bother with explosive propellant? Propellant is mass, and eliminating that mass, or exchanging it for shell mass, would be desirable. So the gun itself is likely based on a gravity repulsing technology, which could obviously be used against any object with mass, and would eliminate a counter thrust reaction.

Applied Phlebotinum, of course.

link

Energy weapons won't have recoil, but what about railguns? What about: Reasons why not to use balistic weapons on a gravtank? What about just pressing the gas real hard when you fire a balistic weapon?

Surely the keyword here is "fiction". Make up whatever reason you want?

well for no other reason the recoil has to overcome the inertia of tons of AFV to get it to move.

An object at rest will remain at rest unless acted on by an unbalanced force. Cannon fire not as much of a unbalanced force as you would think to get say 45tons to move and add forward motion to it and it does not stand much of a chance at all.

In the real world, hovering helicopters dont seem to have any problem to fire 25mm automatic cannons.

A 120 mm gun will send a 8 kg round at a 1500 m/s speed. So the reaction force should be able to send the same round, at the same speed, in the reverse way (sorry about my english). what effect will have this force in a 40 tonnes vehicle (thats a body 5.000 times bigger)? Well, a effect 5000 times smaller. It would give the tank a speed of 0.3 meters per second, thats 30 cm per second.

I'll just say:

Slammer's Powerguns and lasers – no (or not much) recoil
Missiles, ditto.
Recoiless rifles: the clue's in the name!
Thrust (on Slammers blowers, at least) computer controlled to counteract effects of hits and recoil.

Oh, and as pegasusfridge said: it's Science Fiction

John T

Quaker, thanks! I'm glad some setting takes the idea of grav tanks being more like helicopters than tracked vehicles seriously.

As Terrement said… technology of a sufficiently advanced sort = 'FM'

Hammer's Slammers tanks are explicitly hover vehicles, not AGrav. They also mass 170 tons, so that's an awful lot of inertial mass to deal with.

The "hogs" (self-propelled artillery) fire from a grounded, fans stopped position.

The DP9 Earth forces use "hovertanks" that are more precisely "directed thrust vehicles", and their HRT68 light artillery units fire 90mm shells during a computer-controlled "jump" for single-tube Time-on-Target volleys (in addition to having a ~240 rounds per minute cyclic rate!). However, the HRT72 heavy artillery needs to stop to fire.

Yeah, John and others covered it pretty well … as noted if you have GEV/ACV or Grav Tech … you are "smart" enough to fix any recoil, etc. problems … if there are any …