Advanced grav tanks - why do they have turrets?

[tbeard1999]

IMHO the designers of grav tanks made the error of thinking of them as flying tanks rather than heavily armored helicopters - which is the closes analogy to the grav tank.

Imagine an Apache with the armor of an Abrams.

An Apache with the armor of an Abrams would no longer be an Apache. Nor would it be required to *act* like an Apache, since a significant percentage of attack helicopter tactics exist to minimize helicopter vulnerabilities that would not exist with grav tanks.

IMHO the defining combat characteristics of attack helicopters are:

1. Airmobility.

2. Very light armor (even the Apache, one of the best protected helicopters in the world, is at least as vulnerable as the lightest armored vehicles). I'd add that most helicopter armor is designed to ensure crew survivability, rather than mission survivability. So the Apache can be rendered mission-incapable almost as easily as an unarmored helicopter. The difference is that the Apache will get back to base most of the time.

3. Very limited endurance.

4. Heavy armament but limited ammo (compared with Main Battle Tanks)

The defining combat characteristics of main battle tanks are:

1. Limited mobility (compared with attack helicopters).

2. Extremely heavy armor.

3. High endurance (compared with attack helicopters).

4. Heavy armament capable of defeating any armor likely to be encountered. Lots of ammunition (45-60 rounds vs 8-16 for attack helicopters).

The defining combat characteristics of Traveller grav tanks are:

1. Airmobility.

2. Extremely heavy armor.

3. High endurance (fusion power plants).

4. Heavy armament capable of defeating any armor likely to be encountered. Lots of ammunition.

At the end of the day, they are much more like highly mobile tanks, than well protected helicopters.

 

[tbeard1999]

Form always follows function. Grav tanks look like tanks because grav tanks fight like tanks.

Well said. I totally agree (this is of more than passing interest to me, since there will be a sci-fi version of A Fistful of TOWs 3 and I'm already doing some development work on it).

Per Striker, TL15 avionics limit NOE speed to about 190 kph.

My rules will assume a more aggressive limit, but there won't be supersonic NOE capabilities. And I see no reason that the general trend in warfare that you allude to -- if you're seen, you're dead -- won't continue in the future. Grav tanks will fly at high altitude only in safe areas. Once at the FEBA, they will drop to NOE and stay there, except in unusual circumstances.

 

[Ishmael]

it seems to me that grav tanks are thought to be very fast AND very massive.
In order to be maneuverable, a very large amount of thrust must be available.
THAT is probably a good reason why the NOE speeds are so low. Also, having a turret swinging a gun back and around will change the aerodynamic profile which would cause problems at higher speeds.

( of course, I hate the OTU grav tech as it gives you lots and lots of free potential energy without any significant cost or disadvantage. )

It might be interesting to compare an AH-64 to a OTU grav tank in terms of thrust/mass ratios to see how they stack up in terms of maneuverability. ( I'd use my own calcs for heli's thrust based on a momentum model of props I made for model airplanes <as opposed to blade element theory>; FFS1's chart numbers are crap and inflexible )

 

[tbeard1999]

( of course, I hate the OTU grav tech as it gives you lots and lots of free potential energy without any significant cost or disadvantage. )

Yeah, me too. My own campaign lacks contragrav tech -- my Commonwealth Marines ride fusion powered TL12-13 tiltrotor gunships that are lineal descendants of the V-22 Osprey or fusion powered 8 wheel APCs that look much like the Stryker.

Cheap and easy gravitics are also a drama-sink. Much like Star Trek's transporter, they make it way too easy for PCs to avoid trouble and escape from trouble. As a referee, I resent being forced by the system to spend energy finding ways to deny them grav belts and the like.

If I were gonna allow gravitics, I'd make them essentially a drop-in replacement for aircraft engines. Grav vehicles would then look more like helicopters than flying tanks.

 

[far-trader]

...If I were gonna allow gravitics, I'd make them essentially a drop-in replacement for aircraft engines. Grav vehicles would then look more like helicopters than flying tanks.

That's pretty much the way I've always run and imagined it. I never saw a disconnect with the OTU. To stop on a dime flying a grav vehicle in MTU you need to pull a pretty fancy spin and tip to get the grav module pointing where you want it to stop your velocity and then just as quickly level it back out so you don't drop like a rock.

 

[ThunderChilde]

Just my .02 CrImp,

A grav tank should be a balls to the wall MBT, massively armoured and armed with a variety of ways to deal death. Your description of a helicopter gunship on steroids comes across as more of a scout vehicle to me. Perhaps smaller, and less well armed than a grav tank, and if it isn't, then why go with something that doesn't use a proven armour scheme, I.E. the MBT?

Whipsnade already offered the best cogent point, form follows function. Want a well protected, heavy armed vehicle capable of dominating the battlefield of the 1100's? Form follows function, a tank is a tank, its a traveller meme that the future isn't that much different than the present.

A bronze sword of antiquity is not that much different from the swords of the late Rennaisance. It's obviously a sword, many late period swords were derived from much, much earlier patterns, can't mess to much with perfection in form and function.

Just my take on it, YMMV.

 

[Greylond]

Exactly. A "Tank" isn't going to have the same Thrust to Mass ratio as something that can turn on a dime and jink back and forth. Whatever the thrust output of any given size engine, there's always going to be a place for a vehicle with the Max Armor/Weapon loadout that you can reasonably power with said engine, simply because the more massive it is the more damage it can take and the more powerful weapons it can mount. Sure those fast maneuverable vehicles are going to be nimble but when it comes to smashing defenses and taking some dirt(planets) then nothing is going to beat a Massive MBT style vehicle backed up by the PBI(poor bloody infantry), or vice versa...

 

[Trent]

Maybe so they can move in one direction and fire in any direction.

 

[Icosahedron]

I was involved in a lengthy discussion a few months ago on another board regarding the agility of grav vehicles. I argued there that Traveller, and Striker in particular, allows grav vehicles too much agility. Considering that in general they use only a couple of Gs or so, they would not be able to 'turn on a dime'. Grav vehicles would react more like LBB2 vector movement, where it takes a long time to stop and turn if you're travelling fast.
Unless, of course, your grav vehicles also have wings. IMTU I have both types of vehicle. Grav is simply one variety of thrust agency.

 

[Greylond]

Grav is simply one variety of thrust agency.

Yes, that's why I said it depends on the Thrust/Mass ratio. High Thrust/Low Mass will be able to "Turn on a dime" but a true "Grav Tank" isn't. That is how I view it. I haven't had a chance to GM Traveller in quite a few years but that's how I'm going to run it...

 

[aramis]

The Trepida (as listed in MT) is 400 Tons thrust, and 110 tons mass unloaded, 125.9 tons loaded. That' 3-4 G's.

 

[Ishmael]

The Trepida (as listed in MT) is 400 Tons thrust, and 110 tons mass unloaded, 125.9 tons loaded. That' 3-4 G's.

wow
Must have one hell of a signature then with all that power it has to use ( equals easy target ). Unless all the parts are 100% efficient ( magic tech )
oh yeah
magic thermal tech to go along with magic grav tech... never mind

 

[Andrew Boulton]

The TNE version can only manage 0.3g...but it uses HEPlaR...:toast:

 

[lucasdigital]

People keep comparing it to an Apache. FYI, the Apache as a Gun Turret mounted underneath the nose. It has a +/- 100 Degree traverse(that's off centerline, so that means it can traverse 200 Degrees).

Source;
http://www.aviationphotoalbum.com/H...ecifications/AH_64_Apache_Specifications.html

A grav tank is a tank that flies. If you gave the Apache tank armour, it would also look like a grav tank (and not a helicopter). The Apache is moderately bullet resistant - but has nowhere near a tank's survivability. The turret is the result of barrel length - if you don't need a long barrel, you'd use a gimbaled mount, probably like that of the Apache's chaingun.

 

[aramis]

I was going to point out that the astrin looks vaguely like a helo on its side, and the treipda is literally an astrin hull plus a turret. (Astrins and trepidas get carried in the same Trepida berths.)

 

[Starviking]

it seems to me that grav tanks are thought to be very fast AND very massive.
In order to be maneuverable, a very large amount of thrust must be available.
THAT is probably a good reason why the NOE speeds are so low. Also, having a turret swinging a gun back and around will change the aerodynamic profile which would cause problems at higher speeds.

I'd assume at TL-15 they'd understand the aerodynamics of the tank well enough to be able to use supa-smart deployable spoilers to counter aforesaid profile problems at any speed in the flight envelope.

 

[Zparkz]

I was involved in a lengthy discussion a few months ago on another board regarding the agility of grav vehicles. I argued there that Traveller, and Striker in particular, allows grav vehicles too much agility. Considering that in general they use only a couple of Gs or so, they would not be able to 'turn on a dime'. Grav vehicles would react more like LBB2 vector movement, where it takes a long time to stop and turn if you're travelling fast.
Unless, of course, your grav vehicles also have wings. IMTU I have both types of vehicle. Grav is simply one variety of thrust agency.

I agree that in Traveller grav vehicles in general (not only tanks) got poor movement rules. How fast does a grav tank stop at any speed? How much space does a grav tank need to turn?

FASA had a tank game for Renegade Legion that had very good rules for tank movement. That game treated the tank like it was on ice. only the air friction stopped it from moving, if thrust was dropped.. Maybe it could be possible to adapt those rules to Traveller?

 

[Ishmael]

I'd assume at TL-15 they'd understand the aerodynamics of the tank well enough to be able to use supa-smart deployable spoilers to counter aforesaid profile problems at any speed in the flight envelope.

Which results in increased drag and thus, lowers its speed.

 

[Starviking]

Which results in increased drag and thus, lowers its speed.

Undoubtedly, but these aren't your 21st Century spoilers - they're 57th Century ones designed to have as small an impact on the tank's performance when in operation.

 

[Icosahedron]

I agree that in Traveller grav vehicles in general (not only tanks) got poor movement rules. How fast does a grav tank stop at any speed? How much space does a grav tank need to turn?

FASA had a tank game for Renegade Legion that had very good rules for tank movement. That game treated the tank like it was on ice. only the air friction stopped it from moving, if thrust was dropped.. Maybe it could be possible to adapt those rules to Traveller?

Sounds good. Know what it was called? That's an adaptation I wouldn't mind trying - except, of course, old rulesets are too difficult to get hold of.

<wrestles with own hand to stop it writing another tirade against copyright rules that benefit nobody>