Starships in Atmosphere

[Infojunky]

Hi,

Although Mongoose Traveller doesn't really appear to address space ship weight, other versions of Traveller have, and that info could be of use here.

A generally rule of thumb from FF&S is 10 metric tons per 1 displacement ton.

i.e. 100 dTon scout boat weighs in about 1000 metric tons.

 

[PFVA63]

Hi,

I was using the GURPS Traveller: Interstellar Wars rules and in them a Warship weighs about 8 tons per dton, a semi-warship (like a picket ship or commerce raider) weighs about 6 tons per dton, and a merchant ship about 4 tons per dton. Scouts are little different because the 100dton scout is a little over 7 tons per dton, but a 200dton fast courier that they provide data on has a weight of about only 3.2 tons per dton.

Regards

PF

 

[AKAramis]

Hi,

I was using the GURPS Traveller: Interstellar Wars rules and in them a Warship weighs about 8 tons per dton, a semi-warship (like a picket ship or commerce raider) weighs about 6 tons per dton, and a merchant ship about 4 tons per dton. Scouts are little different because the 100dton scout is a little over 7 tons per dton, but a 200dton fast courier that they provide data on has a weight of about only 3.2 tons per dton.

Regards

PF

GT and GTIW have very different fundamental assumptions about drive masses from MT, FF&S, and Striker.

From MT, unloaded masses
The Type S, under MT, masses some 840 metric tons
The 200Td Free Trader is 1130 metric tons
The 200Td Far Trader is 1180 metric tons
The 400Td Type R Subbie is 2060tons
The 400Td Patrol Craft is 3540tons

None of the above are significantly armored. I've seen armored warships with masses of more than 15tons per Td.

Note that, under FF&S, the peak armor mass is about 27tons per cubic meter for the high end... and at 14 times that, about 370 tons per Td...

Steel, by the way, is about 112 tons per Td....

 

[Infojunky]

Guys all I was posting was the Rule of Thumb put forth in FF&S, it wasn't a end all figure just a ball-park number for figuring out rough masses.

In general I use a lot of cargo related rules of thumb;

Max cargo load is 700 kg per 1 cubic meter

the standard Vacuum rated container is 3x3x7 meters or 63 cubic meters with a maximum gross weight 45 tons. (why 3x3x7? Well it is the approximate size of a HO scale twenty foot container rescaled into 1:100/15mm)

 

[Xoph]

:idea: Since Fuel is hydrogen, it would be pretty light even compressed. Might even make your ship lighter, it does make blimps float. Perhaps you'd want to land with a full tank.

 

[PFVA63]

Hi,

I don't think anyone is trying to say that there is a definitive answer, I think its more just that we all have different data from different sources that might be of use to anyone trying to decide if it make sense that a RV-like starship can land at a non-prepared spot on a planet in their game.

As such, I'd suspect that any and all references, rules-of-thumb, and/or guesses would be of interest. I know that I'm finding what others have posted of a lot of use to me.

Regards

PF

 

[Infojunky]

:idea: Since Fuel is hydrogen, it would be pretty light even compressed. Might even make your ship lighter, it does make blimps float. Perhaps you'd want to land with a full tank.

Well, the tanks in Traveller assume hydrogen in cryonic storage, i.e. ice. it is quite a bit denser than the gaseous form you are thinking about. The Displacement ton is in those terms also. So your typical ship will float in water but not air.

 

[zozotroll]

The most important two questions are, do you want your players to do it, and how hard do you want your science? If you want as close to real science as you can get, then it will be very hard to go RVing. If you are a bit more lax, or dont mind that your players do that, then go for it.

Ground preasure is always a pain to deal with, particularly in real life.

 

[SSWarlock]

If you want as close to real science as you can get, then it will be very hard to go RVing.

Actually, it'll be difficult to travel even the distance from Earth to Mars within an economically useful time and impossible to travel faster than light. Real science doesn't support Traveller..don't let reality ruin fun.

 

[zozotroll]

Well yeh, other than all the FTL Grav plates and all that others stuff without which it isnt much fun to play sci-fi.

Besides I have found most of my players over the years are able to forgive things they are not familiar with, like hperdrive, but expect thoings they do know about, like mud to work largely as they expect.

But of course every group has its own set of expectations.

 

[AKAramis]

If you want as close to real science as you can get, then it will be very hard to go RVing.

Actually, it'll be difficult to travel even the distance from Earth to Mars within an economically useful time and impossible to travel faster than light. Real science doesn't support Traveller..don't let reality ruin fun.

Wrong. A relatively sustainable 0.1G (The recent electroplasma drives should be able to generate this with a useful load after round trip fuel of about 5% of overall volume; IE, 95% is drives, fuel, power and control systems), and 0.1G puts martian close approach at about 3 weeks each way; 4 weeks if you meet before closest approach and return just after, with up to a month of on station time.

Even 0.01G continuous thrust drive (ala the Deep SPace One mission's ion thruster) puts mars only 6-8 weeks per leg for the same month at world. This is FAR less than the 6-8 months for current drive motifs.