Can Grav Vehicles Operate in Space?

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EldritchFire
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Can Grav Vehicles Operate in Space?

Postby EldritchFire » Wed Jul 12, 2017 11:25 am

Just as the title asks: are grav vehicles restricted to atmospheric operation? If so, can you add a gravitic drive from High Guard to let them fly in space, too?
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Reynard
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Re: Can Grav Vehicles Operate in Space?

Postby Reynard » Wed Jul 12, 2017 12:18 pm

There have been several references in the various iterations of Traveller stating vehicular grav modules do not have the capacity to break free of a gravity well but can reach orbit. Adding a gravitic drive is creating a spacecraft.
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Re: Can Grav Vehicles Operate in Space?

Postby EldritchFire » Wed Jul 12, 2017 12:32 pm

Reynard wrote:
Wed Jul 12, 2017 12:18 pm
There have been several references in the various iterations of Traveller stating vehicular grav modules do not have the capacity to break free of a gravity well but can reach orbit. Adding a gravitic drive is creating a spacecraft.
I couldn't find anything from either the CRB or VH (2e) that said one way or the other. I remember hearing that prior editions had a stance, but couldn't remember if it was yes or no.

As for "Adding a gravitic drive is creating a spacecraft," I'm playing around with the VH rules to see if I can make Stargate-style X-302s which are atmospheric craft that happen to be space capable. And after re-reading the dogfight rules for spacecraft, I can now see how vehicular-scale fighter craft can be very potent. DM-6 for 100dT+ Craft to hit it combined with the DM-2 for spacecraft-scale shooting at vehicular/traveller-scale inflicts a DM-8 to all non-fightercraft trying to shoot it down. That's better then armour any day of the week, IMO!
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baithammer
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Re: Can Grav Vehicles Operate in Space?

Postby baithammer » Wed Jul 12, 2017 1:15 pm

The dm -6 only occurs when engaged at space ship scale close or adjacent, also doesn't apply to missiles. ( Small craft are limited to adjacent or close range.)

Further, pulse (+2 dm), beam (+4 dm) reduce the -6 DM significantly while also having far longer range than the fighters. ( Fragmentation missiles are a fighter killer which can attack up to 3 other targets adjacent to the primary.)

Vehicle scale craft have very little durability in this sort of environment and deal less damage against spacecraft scale targets. There is the option to mount spacecraft weapons on vehicle scale craft but no where the amount to be a serious threat.

The slowest spacecraft is considered hypersonic. ( Barring the station keeping thrust 0, which don't go into an atmosphere.)
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Re: Can Grav Vehicles Operate in Space?

Postby phavoc » Wed Jul 12, 2017 4:32 pm

EldritchFire wrote:
Wed Jul 12, 2017 11:25 am
Just as the title asks: are grav vehicles restricted to atmospheric operation? If so, can you add a gravitic drive from High Guard to let them fly in space, too?
The rules have never been clear on this. There was a Megatraveller supplement that had a Buick-like family grav car capable of interplanetary travel. However that's always been an anomaly. Most versions have kept grav vehicles capable of reaching low orbit and no further. Going beyond orbit requires some form of spacecraft propulsion.
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Re: Can Grav Vehicles Operate in Space?

Postby EldritchFire » Wed Jul 12, 2017 4:40 pm

baithammer wrote:
Wed Jul 12, 2017 1:15 pm
The dm -6 only occurs when engaged at space ship scale close or adjacent, also doesn't apply to missiles. ( Small craft are limited to adjacent or close range.)
If you've ever seen Stargate all engagements with fightercraft are close range or closer, so that's not that big of a deal.
baithammer wrote:
Wed Jul 12, 2017 1:15 pm
Further, pulse (+2 dm), beam (+4 dm) reduce the -6 DM significantly while also having far longer range than the fighters. ( Fragmentation missiles are a fighter killer which can attack up to 3 other targets adjacent to the primary.)
Right, but even with spacecraft-scale fighters, they are fragile until in close range. And I forgot that at such close range, the dogfighting rules say to make opposed Pilot checks, with the winner being harder to hit (so there's another DM-2).
baithammer wrote:
Wed Jul 12, 2017 1:15 pm
Vehicle scale craft have very little durability in this sort of environment and deal less damage against spacecraft scale targets. There is the option to mount spacecraft weapons on vehicle scale craft but no where the amount to be a serious threat.
The biggest drawback is that even with a DD weapon, the bonus to damage from the attack roll isn't multiplied by 10, but that can be easily houseruled. And yes, you can mount a spacecraft weapon on a vehicle, but the rules are…shall we say lacking? Sure, a spacecraft weapon takes up 4 spaces per ton, but we don't know how many tons each weapon weighs! Since weapons are 'free space' on spacecraft.
baithammer wrote:
Wed Jul 12, 2017 1:15 pm
The slowest spacecraft is considered hypersonic. ( Barring the station keeping thrust 0, which don't go into an atmosphere.)
I actually made the vehicular equivalent to the light fighter in HG this morning, complete with a 1DD laser cannon, Thrust:6 m-drive, and everything! It came in MCR0.7 or so less then the HG version. It even has armour 20, the equivalent of armour 2 spacecraft-scale.

It has 80 hull points, twice that of the space fighter…but with the scale difference it's not that much more protection against an attack.
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Re: Can Grav Vehicles Operate in Space?

Postby AnotherDilbert » Wed Jul 12, 2017 5:02 pm

EldritchFire wrote:
Wed Jul 12, 2017 11:25 am
Just as the title asks: are grav vehicles restricted to atmospheric operation? If so, can you add a gravitic drive from High Guard to let them fly in space, too?
Traditionally Grav vehicles can reach orbit, but cannot reach other planets or even moons. So we can go to space, but not very far.

In most editions (?, at least MT) manoeuvre drives are rather bulky with minimum sizes that bars them from use in vehicles. We can use other means of propulsion in vehicles, e.g. Reaction drives.
Reynard
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Re: Can Grav Vehicles Operate in Space?

Postby Reynard » Wed Jul 12, 2017 8:59 pm

"I couldn't find anything from either the CRB or VH (2e) that said one way or the other. I remember hearing that prior editions had a stance, but couldn't remember if it was yes or no."

Other editions separate in system thrust by the power they can produce. Lifters are what planet bound vehicles use because they are compact modules and efficient for their function. Their low power limits their ability to escape most gravity wells. Mongoose doesn't split interplanetary drives but some editions have the g-drive which is an early low power drive most effective near gravity wells and very inefficient but still usable between planets especially for small craft. The maneuver drive is the royalty of sublight travel not limited by gravity. Both G-drives and M-drives are too large and relatively fuel hungry for vehicles.
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Re: Can Grav Vehicles Operate in Space?

Postby heron61 » Thu Jul 13, 2017 12:22 am

I can't remember where (likely MegaTraveller), but I remember something about grav modules working out to 10 diameters, which gets you to a geosynchronous orbit or to a close in moon, but not further, and that sounds reasonable to me. It also means that unless someone enjoys misjumps a whole lot, grav modules aren't useful for starships, except as auxiliary drives for planetary landings. At minimum, this is a reasonable house rule.
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Re: Can Grav Vehicles Operate in Space?

Postby AndrewW » Thu Jul 13, 2017 1:06 am

Mongoose High Guard under Primitive and Advanced Spacecraft:
Limited Range: This manoeuvre drive only functions within the 100 diameter limit (see page 148 of the Traveller Core Rulebook).
Orbital Range: This manoeuvre drive only functions when the ship is within Short range (up to 1,250 km) of a planetary body. Orbital range requires two Disadvantages.
Reynard
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Re: Can Grav Vehicles Operate in Space?

Postby Reynard » Thu Jul 13, 2017 1:44 am

Ah, so the technologies found a home in Mongoose.

Can't remember at the moment whether it was MegaTraveller and/or T4 that describes starships having much larger contra-grav modules integral with the main drive system meant to give space ships and starships VTOL capability allowing flight up to the edge of the gravity well at which point you kick in your interplanetary drive. I shall do massive research as soon as I get a break.
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Re: Can Grav Vehicles Operate in Space?

Postby Sigtrygg » Thu Jul 13, 2017 4:27 am

It was TNE..
baithammer
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Re: Can Grav Vehicles Operate in Space?

Postby baithammer » Thu Jul 13, 2017 4:58 am

And yes, you can mount a spacecraft weapon on a vehicle, but the rules are…shall we say lacking? Sure, a spacecraft weapon takes up 4 spaces per ton, but we don't know how many tons each weapon weighs! Since weapons are 'free space' on spacecraft.
Anything smaller than a barbette is considered 1 space to mount and if turret based a further 4 space, the other restriction is below tl16 the vehicle must use a fusion power plant.

As to the free space idea, its covered in require a minimum 1 hard point which is 1 hard point per 100ts of ship.
80 hull points
Which is equivalent of 8 Hull points for space craft.

A further wrinkle with vehicle weapons is the range is far less than a space craft based one, often in kms where space weapons are greater than 1km at close range.
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Re: Can Grav Vehicles Operate in Space?

Postby Condottiere » Sat Sep 30, 2017 9:57 pm

Orbital range, which sort of qualifies if it's mostly vacuumed.

I tend to disagree on a set distance, which I believe should be based on the gravitational force exerted by ye well.

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