Drop Tanks

[Carlobrand]

IMTU they can only hold water, ammonia or the like. J-fuel is then refined from them during jump so it is in the main tanks by the time you arrive in system.

Some math problems there since you then have to calculate how much hydrogen the thing delivers but a very good idea since it means more cargo space for the freighter, as well as being safer - well, as safe as you can get barring combat damage that leaves several dTons of water on the floor of your cargo hold, but it beats several dTons of a cryogenic fluid freezing everything as it boils and mixing with air to create a potentially explosive mix. I'd prefer water as being both easier to get and less dangerous than ammonia.

 

[Marcatlas]

Some math problems there since you then have to calculate how much hydrogen the thing delivers but a very good idea since it means more cargo space for the freighter, as well as being safer - well, as safe as you can get barring combat damage that leaves several dTons of water on the floor of your cargo hold, but it beats several dTons of a cryogenic fluid freezing everything as it boils and mixing with air to create a potentially explosive mix. I'd prefer water as being both easier to get and less dangerous than ammonia.

The math is pretty simple. For instance, every cubic meter of water contains 111 kg of hydrogen whereas a cubic meter of liquid hydrogen contains only 71 kg of hydrogen. So, 1.56 times as much hydrogen per displacement ton. Yes, ammonia I only mention because it is the one other liquid that is easier to store in that type of container. Water would be the best.

 

[Badenov]

The math is pretty simple. For instance, every cubic meter of water contains 111 kg of hydrogen whereas a cubic meter of liquid hydrogen contains only 71 kg of hydrogen. So, 1.56 times as much hydrogen per displacement ton. Yes, ammonia I only mention because it is the one other liquid that is easier to store in that type of container. Water would be the best.

Ammonia would be OK, because if it spilled out, you'd get a very clean cargohold.

 

[Grav_Moped]

IMTU they can only hold water, ammonia or the like. J-fuel is then refined from them during jump so it is in the main tanks by the time you arrive in system.

Not a bad idea.

 

[Condottiere]

Spacecraft bunkerage is actually more complex, than at first sight.

 

[AnotherDilbert]

No, I was just misunderstanding drop tanks. I had imagined they were flexible, weightless bags and imagined them as inflatable when you want to fill them and deflatable when empty because the drop tank itself has no mass.

No extra mass for fuel tanks is the default. Regular tanks, demountable tanks, and drop tanks, they are all the same size as the fuel they contain.


TCS = Trillion Credit Squadron, there is a version for CT and a version for MgT1.

That is my understanding also: if not jettisoned, they count against you full or empty, as all editions of Traveller seems to Jump and Thrust by volume rather than mass. This hurts my TL7 brain, but is how the game world is described.

I would say that is just a simplification to be able to design ships with paper and pencil. In TNE FF&S, where you do keep track of mass and thrust, you have to recalculate the drives for every change of the ship... Even there, there is a short-cut.

The same as grav vehicles in CT Striker, MT, and TNE, where mass and thrust are calculated realistically, and have to be recalculated for every change you make.