Low tech ships - Need help

[baithammer]

Vehicle scale is slower than Spacecraft scale, as thrust 1 at spacecraft scale is hyper sonic on the vehicle speed chart. ( Also shorter range.)

 

[Sigtrygg]

Yup, you have to adjust the scale - 10km range bands and velocities measured in km/s. You still use the 6 second round of personal combat.

A combat in or around orbit is going to involve ships moving at orbital velocities initially (7km/s), even deep space encounters between ships on hohmann transfer orbits are going to be pretty sedate compared to regular Traveller gravitic drives.

 

[Condottiere]

Well, if you remain within orbit, you can continue to accelerate to a dangerous degree to other traffic.

 

[DivineWrath]

I've been thinking about making up a scenario for these ships. Since there is no jump at TL 7, I'm thinking that maybe there should be a solar system with 2 worlds. These two TL 7 worlds could be at war or otherwise not friendly with each other. That scenario could see some TL 7 ship battles.

Anyways, I've revised the weapons I want to give these ships.
Autocannon, 1D, short, mag 250, auto 4
Heavy Cannon, 2D, short, mag 30

I'm also kinda thinking of also adding rockets at 3D, but I think that is awfully similar to missiles. Maybe its best to drop it.

I'm really not sure what kind of volume to assign to the ammo of these weapons.

 

[baithammer]

Vehicle rules give notes on ammunition spaces used.

Can also use spacecraft missiles for a heavier punch, just remember to change the die from xd6 to xdd6. ( 12 missiles = 1t = 4 spaces.)

 

[AnotherDilbert]

Can also use spacecraft missiles for a heavier punch, just remember to change the die from xd6 to xdd6. ( 12 missiles = 1t = 4 spaces.)

Not quite, 4 spaces = 1000 kg = 1 tonne ≠ 1 displacement ton = 14 m³, apples and oranges...

 

[baithammer]

Contradicted by Mgt 2ed Main book.

The size of a ship, its components and cargo is
measured in displacement tons, or simply tons.

and Vehicles.

So, for example, a light autocannon has a Mass of 0.25 tons, which is equal to
1 Space.

Not to mention.

To place a spacecraft weapon into a vehicle, simply
multiply the tonnage of the weapon by four.

In mechanics, no difference.

 

[AnotherDilbert]

The size of a ship, its components and cargo is
measured in displacement tons, or simply tons.

Yes, ships are measured in displacement tons ≈ 14 m³.

So, for example, a light autocannon has a Mass of 0.25 tons, which is equal to
1 Space.

Yes, vehicles are measured in Spaces ≈ 250 kg = ¼ tonne.

Not to mention.

To place a spacecraft weapon into a vehicle, simply
multiply the tonnage of the weapon by four.

In mechanics, no difference.

Yes, that is a curious conversion factor that is extremely advantageous for vehicles, but it is not the only conversion factor, e.g. each vehicle hull type has a shipping size in Dt per space. Shipping sizes vary between 0.1 - 2 Dt per Space, and further vary with the size of the vehicle.

Note that that conversion factor is specifically for weapons, e.g. missile racks, not ammunition such as missile magazines. This leads to the ridiculous consequence that a missile rack mounted in a fixed mount takes 1 Space and includes some missiles, perhaps 4 missiles.



A current anti-ship missile (≈ torpedo) with a volume of about 1 m³ masses about 500 - 800 kg, say RBS-15 (https://en.wikipedia.org/wiki/RBS-15). They can be packed about 4 / Dt launch-ready:

So, in 1 Dt we can pack 4 "torpedoes" à ~750 kg (≈ 3000 kg ≈ 12 Spaces), at 3 Spaces / "torpedo" or 12 Spaces / Dt.



Machinery, say an MB 873 Ka-501 tank engine (http://www.mtu-online.com) has a size of about 4 m³ and a mass of 2.2 tonnes for a density of about 0.5 tonnes / m³ or 7 tonnes / Dt, so 28 Spaces / Dt.



Steel has a density of about 8 tonnes / m³, so masses ~112 tonnes / Dt or 448 Spaces / Dt.
Water has a density of 1 tonne / m³, so masses ~14 tonnes / Dt or 56 Spaces / Dt.
Corrugated cardboard had a density of about 0.05 tonnes / m³, so masses ~0.7 tonnes / Dt or ~3 Spaces / Dt.

I would assume that missiles have a slightly higher density than cardboard...

 

[baithammer]

I believe the intent is the same as rounding up for 1g = 10 m/s^2, basically simplify calculations and as long as there is some consistency it tends to work.

 

[DivineWrath]

Should a ship have engineers for solar panels? I've been finding solar panels are a must have for TL 7 ships. Chemical power plants require too much space for fuel. To keep fuel within reason, I've been reducing the fuel until it will last a day or so. Chemical fuel (as set forth in High Guard) will definitely not last to travel to another planet.

Anyone know a reasonable number for reaction drive engine fuel? I'm trying to figure out a reasonable number for interplanetary ships, ships that are expected to do battle once they finish a long journey.

 

[Condottiere]

Beyond basic maintenance, solar panelling looks relatively hands free.

The ship's computer could monitor if power suddenly drops from one, and someone could go and have a look or send an artoo unit to fix it.

 

[AnotherDilbert]

Should a ship have engineers for solar panels?

I would. Given their size and output they have to be thin films, rather than rigid panels. At a guess they have to be continually repaired for micrometeorites to prevent ripping and shredding when folding or unfolding.

To keep fuel within reason, I've been reducing the fuel until it will last a day or so. Chemical fuel (as set forth in High Guard) will definitely not last to travel to another planet.

You can probably reduce fuel consumption by reducing power output to only power essential systems (basic systems). Or use fission plants, they are smaller, the same price, and use much less fuel.

Anyone know a reasonable number for reaction drive engine fuel?

I have no rule of thumb, you have to consider the basic use case. If we are going to Mars, is it cheaper to use more fuel and get there faster (hence more trips per year), or use less fuel and make fewer trips?

"Station-keeping" M-0 is available at TL7. Even at, say 0.1 G or 0.01 G, it will be much more efficient for interplanetary travel than reaction drives.

E.g. Terra to Mars is in the region of 100 000 000 km. At constant 0.01 G it would take 2 × √(10¹¹/0.1) = 2 Ms ≈ 23 days. Boosting at 3G for an hour (and again to brake into orbit) it would take ~1 Ms ≈ 12 days. A M-0 drive is much smaller than the reaction fuel, but it would require power the entire trip.

For combat you have to consider how long you expect combat to take, and how likely it is that you want to avoid combat by outrunning the enemy. Warships probably want a lot of reaction fuel, but they also want a lot of weapons and defences...

 

[Reynard]

Coming in a bit late here. I think Maneuver/0 is for controlling to far more sophisticated Maneuver drives so not necessary if you use reaction drives. The capabilities of the Library program should be beyond what is available for essentially the 1970s. Don't worry about needed either.

I'm at work at the moment so can't reach 3 feet to access my copy of MegaTraveller but I seem to remember a fission rod supplied power for a year. T5 uses the formula Drive Potential x Hull tonnage divided by 100 for the number of rods needed for 10 years. However, these rods are only commercially available at TL 8 starports. TL 7 access with be through a limited government or corporation source.

 

[MongooseMatt]

We did a TL7 ship for the Great Rift (which, as a referee, you just have to get your players on!). For sensors, I will be recommending they look out of the windows...

Made a boo-boo here - we actually did a TL5 (!) ship for the Great Rift...

 

[AnotherDilbert]

Traveller Steampunk?

 

[AnotherDilbert]

However, these rods are only commercially available at TL 8 starports. TL 7 access with be through a limited government or corporation source.

MgT2 makes fission power available at TL6.

 

[MongooseMatt]

Traveller Steampunk?[/img]

We actually once looked at doing a Traveller version of Space 1889, but nothing came of it...

 

[Condottiere]

Manoeuvre drive zero is ill defined; going by canon, not possible since the technology isn't invented until two technological levels later.

As compared to detachable bridges, where thrust zero is supposedly enough to make a soft planetary landing, presumably Terra.

 

[Reynard]

TL 5 ships? Getting into Flash Gordon territory there. Does it look like an old flatiron?

 

[MongooseMatt]

TL 5 ships? Getting into Flash Gordon territory there. Does it look like an old flatiron?

You probably don't want to spend much time in it!