Hey all fascinating stuff!
I've got some related queries and speculations about drives and ship design.
I've been trying to work out exactly how much ships weigh. We design vessels using displacement tons, and this displacement is of L-hyd, therefore 14 cubic metres per ton. However, the actual components will be much denser than L-hyd; so what would be average ship density? water at 1 bar? That would mean vessels mass 14 times their displacement.
The design tools are tied to this 14m3/dton ratio: so a stateroom is 4.5x3m and there's 1.5x3m in communal area. If you change the fuel to H2O, density changes too, unless you increase the mass requirements by 14.
There's also the fact that if the M-drive is a fusion reaction drive, then its drive plume will be very large. A 100k dTon (so massing much more than 100ktons) 6G battleship's drive plume will be absolutely enormous, to the point where a spinal mount may be superfluous.
Now I don't know the physics or engineering well (no more than I gleaned from Jerry Pournelle's 'A Step Farther Out') but IMTU I work on the assumption the M-drive is an ion engine in concert with MRT, using heavy metal atoms as the source of the ion stream. This would negate the need for lots of reaction mass, and tie M-drive into the powerplant. Query: how often would the hvy metal need to be replenished. Also, does a PGMP require 'refuelling' for its plasma stream?
As far as the J-drive is concerned, the THB states somewhere that to open the jump bubble requires a crash burn of the fuel in a very inefficient reaction to achieve the vast energy requirement, and this is why all this fuel is required. Perhaps L-hyd is particularly useful in jump operations, perhaps some special quality - after all it is the primordial element. Peter F Hamilton uses He3 for his fusion reactors in his Confederation trilogy, and I assume he's got his reasons, so there has to be a particular reason for L-Hyd.
Now I get to the point!
I've been thinking about batteries to store extra power for either emergency operations or for limited use of lasers on low power vessels like the Far Trader. When discussing black globe generators the THB mentions capacitors, 1 ton holding up to 36 EP, but does not specify whether this can be used to power other systems. I've postualted that these capacitors are rapid charge/discharge but cannot stay charged for a significant length of time: otherwise ships could precharge the jump capacitors in port and therefore need less fuel. The capacitors act as a sort of buffer between the crash reaction and the J-drive. The max time a capacitor could hold this energy is the j-drive in hours (this should be enough for a ship combat to finish one way or the other...).
There are some interesting numbers this throws up. A far trader has 3 tons of capacitors, therefore can hold 108 EP. Its PP can produce 4 EP, therefore supposedly 27 rounds to power up its j-drive. If this was all that was required, it wouldn't need 40 dtons of L-hyd. This energy stored may be required just to contain the super-reaction that uses the fuel. Maybe the L-hyd is pumped into the anti-matter universe to be annihilated, and this is actually the energy required to get into jump.
This is where I start to get confused in relation to batteries. A capacitor is 1 dton, and holds 36EP. 1 dton is 14000 vlitres. A TL9 basic vehicle battery of 14000vl would hold 140000EP at the vehicle scale. So what is the relationship between vehicle EP and spaceship EP?
Now these are for the jump capacitors, which as I said before are high charge/discharge and cannot store energy for proper lengths of time. I'd assume something more like 1dton of long-term battery gives 10-20EP at up to 2-4EP/round, though this power is unavailiable for M or J drive operations (but maybe for agility).
I think this might become a problem (I know rpg rules can't and shouldn't have to stand up to scrutiny like physical laws). If you replaced that far traders main L-hyd fuel tank with TL11 batteries you'd get 14 million vehicle EP's stored. Is this enough for a 2 parsec jump?
As a final note, if we assume efficient conversion from heat into electricity or whatever, then batteries or capacitors would also make perfect heatsinks.
hope that was worth tuppence.
I've got some related queries and speculations about drives and ship design.
I've been trying to work out exactly how much ships weigh. We design vessels using displacement tons, and this displacement is of L-hyd, therefore 14 cubic metres per ton. However, the actual components will be much denser than L-hyd; so what would be average ship density? water at 1 bar? That would mean vessels mass 14 times their displacement.
The design tools are tied to this 14m3/dton ratio: so a stateroom is 4.5x3m and there's 1.5x3m in communal area. If you change the fuel to H2O, density changes too, unless you increase the mass requirements by 14.
There's also the fact that if the M-drive is a fusion reaction drive, then its drive plume will be very large. A 100k dTon (so massing much more than 100ktons) 6G battleship's drive plume will be absolutely enormous, to the point where a spinal mount may be superfluous.
Now I don't know the physics or engineering well (no more than I gleaned from Jerry Pournelle's 'A Step Farther Out') but IMTU I work on the assumption the M-drive is an ion engine in concert with MRT, using heavy metal atoms as the source of the ion stream. This would negate the need for lots of reaction mass, and tie M-drive into the powerplant. Query: how often would the hvy metal need to be replenished. Also, does a PGMP require 'refuelling' for its plasma stream?
As far as the J-drive is concerned, the THB states somewhere that to open the jump bubble requires a crash burn of the fuel in a very inefficient reaction to achieve the vast energy requirement, and this is why all this fuel is required. Perhaps L-hyd is particularly useful in jump operations, perhaps some special quality - after all it is the primordial element. Peter F Hamilton uses He3 for his fusion reactors in his Confederation trilogy, and I assume he's got his reasons, so there has to be a particular reason for L-Hyd.
Now I get to the point!
![](/proxy.php?image=http%3A%2F%2Fsmile.gif&hash=1cfd60796e07197b75d7b7de95fa9177)
There are some interesting numbers this throws up. A far trader has 3 tons of capacitors, therefore can hold 108 EP. Its PP can produce 4 EP, therefore supposedly 27 rounds to power up its j-drive. If this was all that was required, it wouldn't need 40 dtons of L-hyd. This energy stored may be required just to contain the super-reaction that uses the fuel. Maybe the L-hyd is pumped into the anti-matter universe to be annihilated, and this is actually the energy required to get into jump.
This is where I start to get confused in relation to batteries. A capacitor is 1 dton, and holds 36EP. 1 dton is 14000 vlitres. A TL9 basic vehicle battery of 14000vl would hold 140000EP at the vehicle scale. So what is the relationship between vehicle EP and spaceship EP?
Now these are for the jump capacitors, which as I said before are high charge/discharge and cannot store energy for proper lengths of time. I'd assume something more like 1dton of long-term battery gives 10-20EP at up to 2-4EP/round, though this power is unavailiable for M or J drive operations (but maybe for agility).
I think this might become a problem (I know rpg rules can't and shouldn't have to stand up to scrutiny like physical laws). If you replaced that far traders main L-hyd fuel tank with TL11 batteries you'd get 14 million vehicle EP's stored. Is this enough for a 2 parsec jump?
As a final note, if we assume efficient conversion from heat into electricity or whatever, then batteries or capacitors would also make perfect heatsinks.
hope that was worth tuppence.
![](/proxy.php?image=http%3A%2F%2Fsmile.gif&hash=1cfd60796e07197b75d7b7de95fa9177)