DFW said:
I'm just digging into HG to look at capital ship design. Sorry if this is a question that has been asked and answered.
From the book: "Instead of storing the ship’s hydrogen in liquid form at extremely low temperature with a high risk of explosion if a leak occurs into the inhabited spaces of the ship,"
It only stores a fraction of the hydrogen vs. pure LHY. Why not just store it as liquid ammonia that would hold 170% of H at the same tank volume containing LHY? I would require such a ship to have fuel purifiers to do so.
Two points here.
Number one being the fact that storing via a matrix of metallic hydride doesn't explosively release as a result of combat damage. No big balls of burning hydrogen when you take a fuel hit. You get hydrogen release because the temp to release depending on the nature of the metallic part can be 120 °C (248 °F) - 200 °C (392 °F) which is easily possible with weapon hits but only the local area subject to that temp will release rather than an entire storage tank with a hole in it.
In game terms this reduces the loss of fuel from a fuel tank hit but doubles the volume of fuel, a fact which seems to have escaped the people who did the ship plans for ships with Metallic Hydride storage. Liner OO from Merchant Prince for example would take 312 Dtons to hold 156 Dtons of fuel in Metallic Hydride stores and cost Mcr62 which would consume the ships entire cargo allocation.
Secondly. Biiiiig can of worms here with Traveller fuel. You need fuel for two reasons, the jump bubble and power. Fusion power requires Deuterium to either fuse with itself or with Tritium.
A fusion reaction with D+D requires a significant expenditure of energy to ignite but once running produces energy happily as long as the D holds out. D+T is a more efficient energy producer but the difficulty here is the Tritium which is very rare naturally and needs to be manufactured.
It is also mildly radioactive (12 year half-life) and a D+T fusion reaction gives off free neutrons which will over time and build-up leave your power plant radioactive.
Allowing higher techs to be able to improve fusion reactions to the point where D+D is the one used you just need a source of the Deuterium. Deuterium is found naturally, most often with Hydrogen in the form of Hydrogen Deuteride or HD.
This can be scooped straight off a gas giant but needs to be filtered out from the mass of hydrogen around it then cracked to separate the Hydrogen from the Deuterium.
Deuterium exists as roughly 0.015% of Hydrogen and in a pure D+D fusion reaction you can find enough of the stuff in a gallon of seawater to produce the energy equivalent of 300 gallons of petrol (theoretically).
Buying refined power plant fuel at a starport or just cracking the stuff yourself will result in a Dton of hydrogen producing 0.15 litres of Deuterium which you use for fusion. Filtering the fuel load of even small ships will produce several cubic litres of D for the power plant and all the remaining H can be used for the jump bubble. Either Traveller fusion plants scoop and purify and then burn entire Dtons of Deuterium which is an insane amount of power generation or a single Dton of Deuterium will fuel your power plant of months or years. To produce a single Dton of
Deuterium would require scooping and filtering 6666 Dtons of Hydrogen which would take years for your 20 Dtons a day purification plant. It is more likely that a ships entire fuel load would be filtered to provide the Deuterium with everything else apart from the H then vented to space and what is left being the jump bubble H.
For the jump bubble part of the use you need a gaseous volume of H which can be released quickly to maintain the bubble volume as needed. If you have a jump event and burn off 10% of your jump bubble volume due to contact with a jump space matter or energy field then you need to be able to dump enough gaseous H into the jump field to make up for the loss in seconds.
You don't have the time for fancy cracking of chemicals to release the Hydrogen. It is entirely possible to have multiple tanks with one being the gaseous ready for use jump H and others holding the Hydrogen slush or liquid H or Ammonia etc. But then you are using Dtons for multiple tanks with several types of stored H which defeats the point.
