Ship Design Philosophy

[Condottiere]

It's implied that inertia is compensated for by being removed or neutralized.

If the manoeuvre drive creates a field that neutralizes inertia, whether totally or partially, this won't likely work:

 

[AnotherDilbert]

It's implied that inertia is compensated for by being removed or neutralized.

Where?

CT to TNE explicitly says otherwise.

Tech level requirements for maneuver drives are imposed to cover the grav-plates integral to most ship decks which allow high-G maneuvers while the interior G-fields remain normal.

Artificial gravity G compensators create an artificial gravity field in direct opposition to the axis of acceleration, thus negating the acceleration

 

[Sigtrygg]

Just about every CT supplement and adventure that details ships has some version of this:

Acceleration compensators are also installed to negate the effects of high acceleration and lateral G forces while
maneuvering.

So the acceleration compensators don't just compensate for the maneuver drive thrust, but also the g-forces inherent in turning.

 

[Condottiere]

Understanding how inertial compensation works, gives a direction as to how to design spaceships in Traveller.

If we know that the jump drives don't require an exterior vent, nor aligned in the direction of the jump, we can basically stick them anywhere.

 

[Condottiere]

Spaceships: Weapon Systems, Incoming Ordnance and Dogfighting Range

If you ascribe missiles and torpedoes as spacecraft, once they enter dogfighting range, anti missile (and torpedo) weapon systems should then be able to ramp up to six second rates of fire.

Missiles and torpedoes aren't really potentially faster than warships.

 

[baithammer]

Depends on how complicated you want to make the math.

 

[Ishmael]

Spaceships: Weapon Systems, Incoming Ordnance and Dogfighting Range
Missiles and torpedoes aren't really potentially faster than warships.

Only because Traveller has always ignored the square-cube law. Its the reason a Boeing 747 can't manoeuvre like a Zlin Acrobat.
( I really mean 'accelerate' as fast... not top speed )

 

[AnotherDilbert]

Only because Traveller has always ignored the square-cube law. Its the reason a Boeing 747 can't manoeuvre like a Zlin Acrobat.
( I really mean 'accelerate' as fast... not top speed )

There is no reason for a small craft to have higher acceleration than a large craft.
There is reason to believe that a small craft might rotate quicker (smaller dimensions, so lower moment of inertia for the same mass), hence change direction of acceleration.

 

[baithammer]

It is mainly the fall off of thrust performance at higher mass and distance required to cover equivalent rotation.

 

[Condottiere]

You can always turn tail and accelerate in the other direction.

 

[Ishmael]

Only because Traveller has always ignored the square-cube law. Its the reason a Boeing 747 can't manoeuvre like a Zlin Acrobat.
( I really mean 'accelerate' as fast... not top speed )

There is no reason for a small craft to have higher acceleration than a large craft.
There is reason to believe that a small craft might rotate quicker (smaller dimensions, so lower moment of inertia for the same mass), hence change direction of acceleration.

Structural considerations, actually.
Consider doubling the size of a ship in each dimension... twice as long, tall, and thick,
mass increases eight-fold ( assuming ship density remains constant )
load bearing area of the structure increases only four-fold. The larger ship can only handle half the force, half the acceleration, of the smaller ship unless the larger ship increases the volume of its load bearing structure by nearly 3 times ( * 2.828 ) to make up the difference.
You'd also be providing 8 times the thrust through 4 times the area ( you'd have to increase the man. drive by nearly 3 times to keep the same level of thrust per unit area )

The square-cube law should also determine the number of hardpoints available to a ship as ship volume increases (assuming hardpoints scale with surface area).

https://en.wikipedia.org/wiki/Square%E2%80%93cube_law

Naturally, larger ships will have greater moments of inertia and thus should have lower agility. There will also be less force available to change heading due to structural issues noted above.

 

[AnotherDilbert]

Consider doubling the size of a ship in each dimension... twice as long, tall, and thick,
mass increases eight-fold ( assuming ship density remains constant )
load bearing area of the structure increases only four-fold.

Agreed, obviously.

But the skin of the hull (the armour) would only increase by four, offsetting the increased internal structure. By TNE, that modelled this (accurately or not), the big ship need less mass fraction for armour and structure.

Note that even "unarmoured" Traveller ships require significant hull thickness.

You'd also be providing 8 times the thrust through 4 times the area ( you'd have to increase the man. drive by nearly 3 times to keep the same level of thrust per unit area )

Again by TNE, this is not a significant problem, at least until the megaton range, since M-drives need very little surface area per thrust.

The square-cube law should also determine the number of hardpoints available to a ship as ship volume increases (assuming hardpoints scale with surface area).

Agreed, and TNE did this by tracking surface area, not "hardpoints". But I have the impression that the level of detail in FFS wasn't universally appreciated.

One hardpoint per 100 Dt is a simple approximation, just as an M-drive of 1% of the ships volume produce 1 G acceleration, regardless of ship's current mass. Both are probably somewhat inaccurate, but simple to use.

 

[Condottiere]

You could install paper thin fins to increase surface area.

I'm kinda comfortable with the hundred tonne hardpoint formula, since it should be supported by some form of superstructure.

 

[Ishmael]

Agreed, obviously.

But the skin of the hull (the armour) would only increase by four, offsetting the increased internal structure. By TNE, that modelled this (accurately or not), the big ship need less mass fraction for armour and structure.

Note that even "unarmoured" Traveller ships require significant hull thickness.

The extra armor thickness is used as decks and bulkheads, given the scaled up distances between decks and bulkheads in the larger version. I can no longer check how FF&S1 did things, but if it was as you say, then it is wrong, and it would imply that as ship mass approaches infinity, then the mass ratio for load bearing structure approaches zero.
FF&S2 seems to be proper as far as it goes; I have no idea how it works with real-world structural strength of materials though.
Of, course, that is irrelevant to MongTrav rules, eh?

Again by TNE, this is not a significant problem, at least until the megaton range, since M-drives need very little surface area per thrust.

I don't know about FF&S1 anymore, but FF&S2 requires .005m^2 per tonne of thrust, so you're probably right, as it means a type 'S' scout only needs 10m^2 for its thrusters by FFS2. But even then, doubling the scale of the type 'S' would mean 8 times the thruster area for the same performance even when the available area increase only 4-fold. This would eventually rob area needed for turrets, bays, sensors, etc.
[/quote]

Agreed, and TNE did this by tracking surface area, not "hardpoints". But I have the impression that the level of detail in FFS wasn't universally appreciated.

One hardpoint per 100 Dt is a simple approximation, just as an M-drive of 1% of the ships volume produce 1 G acceleration, regardless of ship's current mass. Both are probably somewhat inaccurate, but simple to use.

I fully agree that keeping track of square meters of hull is cumbersome, and that tracking hardpoints is easier.
But area scales with volume^(2/3) and thus the number of hardpoints a ship may have should too, otherwise huge ships become vastly overgunned when compared to smaller ships, at rates that would allow a type 'S' to have a dozen turrets, if applied equally.
Personally, I use a 100dt cube as a baseline where it has ~600m^2 area. I say each 'hardpoint' uses 100m^2 for convenience. This gives a type 'S' 6 hardpoints. However, I also use hardpoints to mount thrusters, sensors and radiators ( 2 for thrusters, 2 for radiators, one for sensor and one for a turret, et al. ... I have not bothered to work out details ). This gives hardpoints = vol^(2/3) * .285
I know I am deviating from canon and rules, but I prefer my TU to be a little less space-opera-y.

 

[baithammer]

If your mounting thruster, ect to hardpoints you will end up having to deal with area taken by fuel and the like and then comes the shape of the hull which just makes a mess of things.

 

[AnotherDilbert]

The extra armor thickness is used as decks and bulkheads, given the scaled up distances between decks and bulkheads in the larger version. I can no longer check how FF&S1 did things, but if it was as you say, then it is wrong, and it would imply that as ship mass approaches infinity, then the mass ratio for load bearing structure approaches zero.

What I tried to say was that Armour is proportional to surface area and structure is proportional to volume (≈mass), so the mass ratio of armour approaches zero as ship size approaches infinity.

Checking, I see that I misremembered: Structure is proportional to surface area in TNE, not volume (≈mass) as I remembered. I would agree that is a strange choice.

FF&S2 seems to be proper as far as it goes; ...

I have never looked at T4, from what little I have heard FFS2 is fairly similar to FFS.

Of, course, that is irrelevant to MongTrav rules, eh?

Not entirely, it says something about canon, about how the universe is supposed to work before all the simplifications.

 

[Sigtrygg]

GT:ISW has a simplified system for hardpoints that takes surface area and hull configuration into account to calculate hardpoints.

Over a decade ago on CotI there was this thread:
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=3797

 

[Ishmael]

Over a decease ago on CotI there was this thread:
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=3797

That post seems to go with the following;
hardpoints ~= vol_dtons^(2/3) * .093 * 'area mod'

I use a slightly different method to find surface area*, but this is good too.

* posted years ago on this board.
https://sites.google.com/site/moukotiger/sf-rpg/rules/vehicles/hulls

Like many people, I use a spreadsheet.
My sheet, so far, has a couple of added bits relating volume, area and streamlining.
Its not MgT compatible, so I won't post it here.

 

[Condottiere]

Spaceships: Carriers, Tenders and Sortie Generation Rate

At some point, a warship just has so many smaller combat vessels stationed on it, that it just automatically becomes a carrier.

But before that, the difference between a spacecraft carrier and a tender, is that a tender's subsidiary craft can operate on their own, whereas carriers cater to spacecraft far more reliant on their maintenance services, not just simple resupply and the occasional once over, as well as more subjected to it's command and control.

Cockpitted spacecraft with default twenty four hour life support would tend to fall into this category.

Spacecraft with primarily ordnance orientated weapon systems, and non gravitated manoeuvre drives would rely on a carrier's sortie generation rate.

 

[Condottiere]

Spaceships: Fighters and Sortie Generation Rate

It can be a fine line separating attack spacecraft from fighters, though it could come down to either having a cockpit or a bridge.

The advantage a bridge can give a small combat spacecraft is an increased endurance, at least in regards to it's very human crew. that would allow them to maintain a standing patrol, rather than require the time needed to launch from the mothership, assuming a fast launch if the aerospace wing was desirable.