[Spaceships] Antimatter Plasma Torch fuelled by Water?

[malloyd]

Originally Posted by Figleaf23

Makes sense, but I can't see where that's spelled out in the book.

Probably because it's unnecessary detail. The mixture is never significantly variable, so it's simplest to have one system with the weighted average statistics rather than two different sized fuel tanks, which you can't really do with the Spaceships system anyway.

Almost all reaction engines require you to mix things inside the engine - though one of them may be energy - there are a few exceptions, called monopropellants, but they aren't used much. They tend to have fairly low performances, and they're *dangerous*. You don't want a single/premixed "fuel", because the thing that makes it a good fuel is it easily converts to an extremely hot pressurized gas. Having that happen accidentally somewhere other than in the engine would be really really bad.

[Bruno]

All the fun long-chains-of-nitrogen compounds that like spontaneously reverting back to elemental nitrogen gas (and some other less exciting stuff), for example.

Which is why saying "That stuff is like rocket fuel" isn't a complement most of the time.

[Anthony]

Originally Posted by Bruno

Which is why saying "That stuff is like rocket fuel" isn't a complement most of the time.

Most stuff that's described as 'like rocket fuel' is just ferociously flammable. And isn't necessarily all that much like rocket fuel, kerosene is only considered 'moderately flammable' on its MSDS.

[starslayer]

Originally Posted by lostrobertsandwich

Hey guys,

Just a quick question:

The Antimatter Plasma Torch [Spaceships 1, pp.23], normally powered by Antimatter-Boosted Hydrogen, has the option to 'replace hydrogen with water (3x Thrust, 1/3 Delta-V)'.

Does this mean it can run on 'pure' water, or does it require antimatter-boosted water?

I'm trying to build a smuggler/free-trader ship as cheaply as possible for a TL10 (limited super-science) setting.

The other option, of course, is the Fusion Torch which would be more expensive to buy but cheaper to fuel (with water).

Ok, others have pointed out that yes, the antimatter is required.

What are you trying to accomplish, by answering that you might receive responses more along the line of what you are seeking. (IE- I am trying to figure out the cheapest way to operate the torch)

[Fred Brackin]

Originally Posted by Anthony

Most stuff that's described as 'like rocket fuel' is just ferociously flammable. And isn't necessarily all that much like rocket fuel, kerosene is only considered 'moderately flammable' on its MSDS.

I think the most comon monopropellant is Hydrogen Peroxide at about 95# purity. It's massibly corrosive and induces fores in other substances more than catches fire itself.

[malloyd]

Originally Posted by Fred Brackin

I think the most comon monopropellant is Hydrogen Peroxide at about 95# purity. It's massibly corrosive and induces fores in other substances more than catches fire itself.

These days it's surely some sort of hydrazine derivative - monomethylhydrazine or unsymmetrical dimethylhydrazine. Those are merely poisonous, flammable and occasionally spontaneously explosive, much safer than concentrated H2O2....

[Fred Brackin]

Originally Posted by malloyd

These days it's surely some sort of hydrazine derivative - monomethylhydrazine or unsymmetrical dimethylhydrazine. Those are merely poisonous, flammable and occasionally spontaneously explosive, much safer than concentrated H2O2....

H2O2 is still used in all of the contemporary jetpacks I know of.

It was alos going to be used in the rocket Armadillo Engineering was going to enter in the X-Prise competition. I dom't think that ever got beyond basic tests.

[Anthony]

Originally Posted by Fred Brackin

I think the most comon monopropellant is Hydrogen Peroxide at about 95# purity.

Sure, but relatively little 'rocket fuel' is monopropellant.

[jacobmuller]

Precedent for cheaper antimatter - Vorkosigan Saga pg201.

[Ulzgoroth]

Originally Posted by jacobmuller

Precedent for cheaper antimatter - Vorkosigan Saga pg201.

Or Spaceships p46, if for some reason you needed a precedent.