HG p. 44 Metal hydride storage driving me nuttier

[snrdg121408]

Hello all,

I am having problem wrapping my brain around how the metal hydride storage works.

First, Does metal hydride storage only affect the jump drive, fusion and antimatter power plants fuel tankage?

Second per the metal hydride storage text on p. 42:
"This storage holds 50% less hydrogen fuel than a more normal tank. It is available at TL9 and costs MCr0.2 per ton."

The jump and maneuver drive require 100 dtons in liquid hydrogen fuel tanks.

Would I have to allocate 200 dtons of space if the full fuel load is stored as metal hydride?

If, instead of the whole load I decided to store 50 dtons as metal hydride in order to get the same fuel requiremet my tankage would be 50 dtons of liquid hydrogen and 100 dtons of metal hydride storage right?

 

[AndrewW]

Hello all,

I am having problem wrapping my brain around how the metal hydride storage works.

First, Does metal hydride storage only affect the jump drive, fusion and antimatter power plants fuel tankage?

It effects whatever fuel you use it for.

Second per the metal hydride storage text on p. 42:
"This storage holds 50% less hydrogen fuel than a more normal tank. It is available at TL9 and costs MCr0.2 per ton."

The jump and maneuver drive require 100 dtons in liquid hydrogen fuel tanks.

Would I have to allocate 200 dtons of space if the full fuel load is stored as metal hydride?

Yup.

If, instead of the whole load I decided to store 50 dtons as metal hydride in order to get the same fuel requiremet my tankage would be 50 dtons of liquid hydrogen and 100 dtons of metal hydride storage right?

50 dtons as metal hydride would be 25 dtons of fuel equivalent. So that would be 25 + normal tanks of 75 to equal 100 dtons of fuel.

 

[snrdg121408]

Hello AndrewW,

Thank you for the reply and your attempt to straighten me out on how metal hydride storage works. Unfortunately, I'm still not getting a clear understanding of how the system works.

From my understanding of the text the Reaction M-Drive and Chemical power plant cannot use metal hydride storage since the two systems do not use hydrogen. Did I reach a wrong conculsion?

I'm still not getting an idea on how the to convert the liquid to the solid storage space in spite of the example provided.

The reply appears to have confirmed that converting 100 dtons of liquid hydrogen to metal hydride requires 200 dtons of storage.

Unfortunately, the reply still did not clear up the amount of storage required when only a portion of the total fuel loadout is in metal hydride form. If storing all 100 dtons of fuel as metal hydride requires 200 dtons of space then, if I understand the text, storing 50 dtons of fuel as metal hydride should require 100 dtons of space.

I am really missing the point here and this may be one option that probably won't be used anytime soon.

Again thank you for the reply and my apologies for not understanding something that appears to be simple and straight forward.

Hello all,

I am having problem wrapping my brain around how the metal hydride storage works.

First, Does metal hydride storage only affect the jump drive, fusion and antimatter power plants fuel tankage?

It effects whatever fuel you use it for.

Second per the metal hydride storage text on p. 42:
"This storage holds 50% less hydrogen fuel than a more normal tank. It is available at TL9 and costs MCr0.2 per ton."

The jump and maneuver drive require 100 dtons in liquid hydrogen fuel tanks.

Would I have to allocate 200 dtons of space if the full fuel load is stored as metal hydride?

Yup.

If, instead of the whole load I decided to store 50 dtons as metal hydride in order to get the same fuel requiremet my tankage would be 50 dtons of liquid hydrogen and 100 dtons of metal hydride storage right?

50 dtons as metal hydride would be 25 dtons of fuel equivalent. So that would be 25 + normal tanks of 75 to equal 100 dtons of fuel.[/quote]

 

[AndrewW]

From my understanding of the text the Reaction M-Drive and Chemical power plant cannot use metal hydride storage since the two systems do not use hydrogen. Did I reach a wrong conculsion?

It's not actually specific about that but doesn't say you can't.

I'm still not getting an idea on how the to convert the liquid to the solid storage space in spite of the example provided.

The reply appears to have confirmed that converting 100 dtons of liquid hydrogen to metal hydride requires 200 dtons of storage.

Unfortunately, the reply still did not clear up the amount of storage required when only a portion of the total fuel loadout is in metal hydride form. If storing all 100 dtons of fuel as metal hydride requires 200 dtons of space then, if I understand the text, storing 50 dtons of fuel as metal hydride should require 100 dtons of space.

Take how much is stored in normal form subtract that from how much total fuel you want and then multiply the remaining by 2.

 

[snrdg121408]

Hello again AndrewW,

I've been doing a little more research on the chemical power plant and reaction drive. Looking through HG you are right that the reaction mass for the reaction drive is not specified in the text. However, on p. 57 of the Small Craft design sequence states under the Power section that a chemical plant uses petrochemical or synthetic fuels.

A hydride is stablized hydrogen which, at least for small craft, appears to mean a chemical power plant cannot use metal hydride storage.

Okay let me see if I correctly translated the process of "Take how much is stored in normal form subtract that from how much total fuel you want and then multiply the remaining by 2."

100 dtons of liquid fuel storage. I am leaving 50 dtons of the total storage for holding liquid fuel and converting the remaining 50 dtons to metal hydride for storage. To store 50 dtons of metal hydride I will need 50 X 2 or 100 dtons of space. Total fuel storage is 50 liquid dtons + 100 metal hydride dtons or 150 dtons of space.

Have I finally gotten a glimmer of how the system works yet.

Again I want to thank you for the help that you have been giving me.

From my understanding of the text the Reaction M-Drive and Chemical power plant cannot use metal hydride storage since the two systems do not use hydrogen. Did I reach a wrong conculsion?

It's not actually specific about that but doesn't say you can't.

I'm still not getting an idea on how the to convert the liquid to the solid storage space in spite of the example provided.

The reply appears to have confirmed that converting 100 dtons of liquid hydrogen to metal hydride requires 200 dtons of storage.

Unfortunately, the reply still did not clear up the amount of storage required when only a portion of the total fuel loadout is in metal hydride form. If storing all 100 dtons of fuel as metal hydride requires 200 dtons of space then, if I understand the text, storing 50 dtons of fuel as metal hydride should require 100 dtons of space.

Take how much is stored in normal form subtract that from how much total fuel you want and then multiply the remaining by 2.

 

[AndrewW]

Hello again AndrewW,

I've been doing a little more research on the chemical power plant and reaction drive. Looking through HG you are right that the reaction mass for the reaction drive is not specified in the text. However, on p. 57 of the Small Craft design sequence states under the Power section that a chemical plant uses petrochemical or synthetic fuels.

A hydride is stablized hydrogen which, at least for small craft, appears to mean a chemical power plant cannot use metal hydride storage.

Right, I was getting at the text isn't clear if this works for a case like the chemical power plant fuel or not.

Okay let me see if I correctly translated the process of "Take how much is stored in normal form subtract that from how much total fuel you want and then multiply the remaining by 2."

100 dtons of liquid fuel storage. I am leaving 50 dtons of the total storage for holding liquid fuel and converting the remaining 50 dtons to metal hydride for storage. To store 50 dtons of metal hydride I will need 50 X 2 or 100 dtons of space. Total fuel storage is 50 liquid dtons + 100 metal hydride dtons or 150 dtons of space.

Have I finally gotten a glimmer of how the system works yet.

That will do it.

Again I want to thank you for the help that you have been giving me.

You are welcome.

 

[Gaidheal]

The implication is that 'chemical' powerplants don't use hydrogen, however it's a Referee call, reallly, like anything else (they are obviously intended to be an alternative to H-fuel but hydrogen is a chemical, of course, hehe!).

For a reaction drive, there's nothing to stop you using anything - in point of fact any real drive would rely on the reaction but we're into the realms of Science Fiction, so whatever works for your game, really.

Your understanding was correct, wrt the amounts, I think you confused Andrew with the phrasing. I.E. 1 dt of H => 2 dt mH.

 

[snrdg121408]

Yipee I finally got the idea :lol:

Again thanks for all the help and patience.

Hello again AndrewW,

I've been doing a little more research on the chemical power plant and reaction drive. Looking through HG you are right that the reaction mass for the reaction drive is not specified in the text. However, on p. 57 of the Small Craft design sequence states under the Power section that a chemical plant uses petrochemical or synthetic fuels.

A hydride is stablized hydrogen which, at least for small craft, appears to mean a chemical power plant cannot use metal hydride storage.

Right, I was getting at the text isn't clear if this works for a case like the chemical power plant fuel or not.

Okay let me see if I correctly translated the process of "Take how much is stored in normal form subtract that from how much total fuel you want and then multiply the remaining by 2."

100 dtons of liquid fuel storage. I am leaving 50 dtons of the total storage for holding liquid fuel and converting the remaining 50 dtons to metal hydride for storage. To store 50 dtons of metal hydride I will need 50 X 2 or 100 dtons of space. Total fuel storage is 50 liquid dtons + 100 metal hydride dtons or 150 dtons of space.

Have I finally gotten a glimmer of how the system works yet.

That will do it.

Again I want to thank you for the help that you have been giving me.

You are welcome.

 

[snrdg121408]

Howdy Gaidheal,

I was fairly sure that a chemical power plant met something other than hydrogen. The fuels I was thinking something along the lines of metal/LOX or some other fuel.

Okay, now I'm a little confused are we talking about power plant fuel or reaction mass?

So what you are saying is that I had grasped the idea of how to handle metal hydride storage before misdirecting poor AndrewW with my replies? :shock:

Thank you and AndrewW for clearing up my confusion with metal hydride storage.

The implication is that 'chemical' powerplants don't use hydrogen, however it's a Referee call, reallly, like anything else (they are obviously intended to be an alternative to H-fuel but hydrogen is a chemical, of course, hehe!).

For a reaction drive, there's nothing to stop you using anything - in point of fact any real drive would rely on the reaction but we're into the realms of Science Fiction, so whatever works for your game, really.

Your understanding was correct, wrt the amounts, I think you confused Andrew with the phrasing. I.E. 1 dt of H => 2 dt mH.

 

[Gaidheal]

"In the real world" 'chemical fuel' would be anything which you can make react exothermically with another reagent - we tend to use oxygen from the atmosphere and any number of compounds (especially petrochemicals, of course) which are exothermically reactive in its presence. In SF you can invent all sorts of weird fuels, as you see fit, of course.

In strict terms, for any 'engine' in space, you're talking reaction mass, really. That is not how Traveller postulates it, though, for the default setting and options, so 'power' is the same as 'thrust' since you have some magic box that turns energy into kinetic force, but I am not sure what your question really is.

Aye, you had the arithmetic of the storage just fine.

 

[snrdg121408]

Hello again Gaidheal,

I am a science fiction nut and have read enough to know that there are a wide range of fuels that are used for propulsion or motive force and to run an power generation plant. However, I try to use materials that are already present in the particular universe.

In Traveller there is a difference between the maneuver drive and the power plant, though you get more information from TNE Fire, Fusion, and Steel on the how the drives work. Of course, in my opinion, GT: Starships and GURPS Vehicles help with the real world drive systems.

I think I see where communications got out of whack. I was working under the gravitic M-drive propulsion system that does not require reaction mass. The power plant requires fuel the is converted into electrical energy to power the jump drive and other systems.

Again thank you for the assistance.

"In the real world" 'chemical fuel' would be anything which you can make react exothermically with another reagent - we tend to use oxygen from the atmosphere and any number of compounds (especially petrochemicals, of course) which are exothermically reactive in its presence. In SF you can invent all sorts of weird fuels, as you see fit, of course.

In strict terms, for any 'engine' in space, you're talking reaction mass, really. That is not how Traveller postulates it, though, for the default setting and options, so 'power' is the same as 'thrust' since you have some magic box that turns energy into kinetic force, but I am not sure what your question really is.

Aye, you had the arithmetic of the storage just fine.

 

[Gaidheal]

I know all about how Traveller does it ;¬)

If they're both using hydrogen as a fuel though and you're sticking with the default 'reactionless' drive, all there is to it is "How much fuel? Where do I put it?" - Hence I wasn't sure what you were asking about. I only talked about 'real' reaction drives because they were mentioned above.

If you want to, for some reason, have a powerplant that uses another fuel and a drive which still use hydrogen, then obviously you need two separate storage solutions and perhaps even locations (tactically wiser). That's pretty obvious, though, aye?

 

[snrdg121408]

Hello Gaidheal,

I guess I was basically asking about storing either the total or a part of hydrogen fuel loadout as metal hydride regardless of the fuel being used by the M-Drive, J-Drive, and/or power plant.

I thought just popped up that there is never any mention of storing fuel for carried small craft and/or vehicles. I think that I might have included small craft fuel storage in a design many years ago. To be honest I had not given any thought about the subject until now.

Should there be a rule concerning fuel storage for carried small craft?

I know all about how Traveller does it ;¬)

If they're both using hydrogen as a fuel though and you're sticking with the default 'reactionless' drive, all there is to it is "How much fuel? Where do I put it?" - Hence I wasn't sure what you were asking about. I only talked about 'real' reaction drives because they were mentioned above.

If you want to, for some reason, have a powerplant that uses another fuel and a drive which still use hydrogen, then obviously you need two separate storage solutions and perhaps even locations (tactically wiser). That's pretty obvious, though, aye?

 

[Gaidheal]

I confess immediately that I've really not looked hard at the small craft rules, there is a thread with that title though, might be useful. In my own games small craft are never explored in very much detail and I've certainly not use the rules to actually build any, I am afraid - they are just there and work according to whatever dramatic needs I have. Sorry.

 

[AndrewW]

Could just add extra fuel storage if you need to store more fuel for small craft. They can have full tanks of their own while stored.

 

[Ishmael]

instead of metal hydrides to store hydrogen, why not use liquid anhydrous ammonia?
you can get 105Kgs of hydrogen per cubic meter instead of only 71Kg's for liquid hydrogen. ( nearly half again as much )
We already know how to handle it in fairly large bits of infrastructure and its not nearly as difficult to handle as liquid hydrogen although it is toxic.
It IS more massive though... but not a problem for Trav ships that ignore mass in design sequences... but something to remember when figuring mass in FFS1 type design sequences ( .625Kg/m^3 , or about 8.8 times the density of liquid H2 )
for us noodniks that prefer reaction drives, most of it becomes reaction mass.

The relatively small amounts of hydrogen needed for actual fusion can be extracted using catalysts
We are already working on hydrogen fuel cells that run on ammonia

 

[Gaidheal]

Because there are rules for 'metal hydride', for one ;¬)

 

[EDG]

Hm. I wonder how much hydrogen actually is in 1 displacement ton. TNE is the only version that I can recall that assigns a mass to liquid hydrogen (FF&S p63) - it says that it's 0.07 metric tons per cubic metre. So that's 70 kg/m³ - which sounds a lot but it's really 0.07 kg per litre. BUT... that assumes it's stored cryogenically at 20K (see http://en.wikipedia.org/wiki/Liquid_hydrogen ).

So... can you store even more hydrogen if you compress it more? How much can you compress it by before it turns into weird liquid metallic or solid metallic phases? (Hrm, seems that we're talking about gigapascals of pressure (hundreds of thousands of atm) before we get even to liquid metallic phases, so that's probably not going to happen in a spaceship!).

Still, I'm sure it can be compressed further by several times in order to store more hydrogen in the ship (yummy - pressurised cryogenic liquid hydrogen... that's probably about as dangerous as it gets!). Then you can fit twice, or thrice, or four times or more times the amount of fuel in the ship. It's not like Traveller generally cares about the mass of the ship, does it.

That said, liquid hydrogen is insane anyway - as soon as you got hit in combat and the fuel tanks breached inside the ship, they'd mix with the oxygen therein and then *boom*.

 

[Gaidheal]

We have magic storage for the liquid hydrogen, rendering it inert! :¬)

 

[snrdg121408]

Hello again Gaidheal,

No need to be sorry since I've overlooked the fact that small craft have fuel requirements the same as a system ship or starship. For merchants refueling can be made before departing a star system which would minimize the need to have additionally fuel for them. Mordern naval assets that carry fighters, helicopters, landing craft, or anything needing fuel has storage tanks for the equipment. I don't recall any of the design systems mentioning needing fuel storage for subordinate small craft or vehicles.

Of course by including small craft fuel storage space is taken away from the stuff that blows the opposition into itty bitty pieces. Or the stuuf that helps prevent the opposition from blowing me into itty bitty pieces.

Looks like I'm starting to over engineer another aspect of Traveller.

I confess immediately that I've really not looked hard at the small craft rules, there is a thread with that title though, might be useful. In my own games small craft are never explored in very much detail and I've certainly not use the rules to actually build any, I am afraid - they are just there and work according to whatever dramatic needs I have. Sorry.