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Old 02-19-2019, 06:41 PM   #1
Agemegos
 
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Default [Ultra-Tech] HEDM batteries and explosives

Spaceships presents as a possible TL9 technology "HEDM chemical" rockets, using "high energy-density materials such as metallic hydrogen or metastable helium for fuel". The fuel tanks of HEDM rocket fuel are "volatile systems", that is they may explode if violently damaged.

The delta-vee that HEDM rocket fuels provide suggests that they contain at least eleven times as much energy as a like mass of ordinary chemical rocket fuels such as liquid oxygen + liquid hydrogen. And they are explosive….

Now the useful relative effectiveness factor of an explosive depends on more than just energy density. But energy density does establish a limit.

So consider a TL9 or TL10 setting that is using HEDM chemical rockets. Or one that has has abandoned HEDM rockets in favour of fission or fusion propulsion but doesn't want to use nuclear explosives in quarrying, demolitions, and tactical weapons. What sort of REF might the explosives have that are based on the same sort of chemistry as HEDM rocket fuel?

Also, what about batteries? Is HEDM chemistry a promising source of controllable [electric] power for high-current devices such as laser weapons? Is it at all possible that such batteries might be rechargeable?
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Old 02-19-2019, 06:57 PM   #2
Anthony
 
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Default Re: [Ultra-Tech] HEDM batteries and explosives

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Originally Posted by Agemegos View Post
So consider a TL9 or TL10 setting that is using HEDM chemical rockets. Or one that has has abandoned HEDM rockets in favour of fission or fusion propulsion but doesn't want to use nuclear explosives in quarrying, demolitions, and tactical weapons. What sort of REF might the explosives have that are based on the same sort of chemistry as HEDM rocket fuel?
It would use the statistics of existing Ultratech explosives -- REF 4 at TL 9, REF 6 at TL 10 -- with the possibility of higher REF if you don't care about safety.
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Old 02-19-2019, 07:02 PM   #3
Fred Brackin
 
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Default Re: [Ultra-Tech] HEDM batteries and explosives

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Originally Posted by Agemegos View Post
What sort of REF might the explosives have that are based on the same sort of chemistry as HEDM rocket fuel?

Also, what about batteries? Is HEDM chemistry a promising source of controllable [electric] power for high-current devices such as laser weapons? Is it at all possible that such batteries might be rechargeable?
First a technical note that HEDM is not really "chemical". We're talking about phase transition materials rather than chemical bonds.

Second is that canonically the TJ10 default explosives in UT use metallic Hydrogen explosives at REF 6. It is noted that this REF is a result not only of the high energy materials but "stabilzers" too. Pure Metallic Hydrogen would have a predicted REF of over 30. Metastable Helium would be more than that but that's an even less well know material than Metallic Hydrogen.

As a power source these HEDM materials would need some way to convert high energy gasses or plasmas into elctricity such as a turbne or an MHD tunnel. Not a good target for miniturization and certainly not running in reverse.
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Old 02-19-2019, 07:08 PM   #4
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Default Re: [Ultra-Tech] HEDM batteries and explosives

HEDM materials like metallic hydrogen have around 216 MJ of energy per kilogram (around 50x as much as TNT). They are so energetic that researchers are worried that they could be used as alternatives to nuclear weapons for triggerind fusion weapons (one metric ton of metallic hydrogen could trigger a one megaton fusion detonation). They are also highly unstable, so they will likely have a stabilizing agent added (one-sixth of the mass) to keep them from becoming an unintended explosion (reducing their energy density to 180 MJ/kg).

As for batteries, I think that they would make very intensive nonreusable power cells. I would say that they would have ten times the endurance of reusable power cells, though they would also detonate with a force equal to 20x their mass in TNT if hit by an attack that pierced their housing. They would likely also need to vent the hydrogen produced as the metallic hydrogen releases energy by becoming gaseous hydrogen.
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Old 02-19-2019, 07:30 PM   #5
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Default Re: [Ultra-Tech] HEDM batteries and explosives

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Originally Posted by Fred Brackin View Post
First a technical note that HEDM is not really "chemical".
Yes, but "HEDM chemical" is what GURPS Spaceships calls it. I can't go on using scare quotes forever.
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