Why are Honorverse Heavy Industries off Planet?

Galactic Sapper wrote:

TFLYTSNBN wrote:Given Weber's descriptions, Honorverse starships have fusion reactors with power output in the Petawatt or even Exawatt range. In spite of this availability of fusion power, most systems still seem to rely massive solar collectors to power their industries. One can reasonably conclude that system industries require Zetawatt level (1eex21) power levels. This would broil a planet.

Do you have a reference or calculation base for this?

Explosion in EoH.

From an old post I made:

Perhaps you should reread chapter 46 of Echos Of Honor?

How much energy do you need to vaporize a half meter of Honorverse battle cruiser armor at 600 km from an omnidirectional explosion?

Well, we don't really know the characteristics of the armor, but I think it's safe to assume it's at least equal to iron in resisting damage.

A section of iron 1 meter square and .5 meters deep weights about 4 tons. The heat of vaporization of iron is about 6 megajoules per kg. So 4000 kg requires about 24 gigajolues, so it's 24 GJ per square meter. A 600 km diameter sphere has a surface area of 4.5 trillion square meters, so the overall power release was 1x10^23J.

Which is roughly 25,000,000 megatons.

I think that is a tiny bit more than a gigaton.

Galactic Sapper wrote:

TFLYTSNBN wrote:Given Weber's descriptions, Honorverse starships have fusion reactors with power output in the Petawatt or even Exawatt range. In spite of this availability of fusion power, most systems still seem to rely massive solar collectors to power their industries. One can reasonably conclude that system industries require Zetawatt level (1eex21) power levels. This would broil a planet.

Do you have a reference or calculation base for this?

During the account of Honor sneaking up on the State Sec ships at the Battle of Cerbus, Weber indirectly revealed the mass ratio of Hororverse warships. It was about 25% IIRC. From this we can estimate fuel burn rate in Kg/s and hence power rate.

A simpler calculation is to note that the power of a rocket is given by:

Power = (mass flow rate / 2) x (exhaust velocity)^2

Thrust = mass flow rate x exhaust velocity

From the energy density of variouys fusion fuels we can estimate that the exhaust velocity is about 3eex7 m/s.

Requiring the second equation to solve for mass flow rate then substituting for the first equation we get:

Power = Thrust x Exhaust Velocity / 2

I can not recall the acceleration rate during the stealthy fusion rocket burn nor the mass of the ships. I urge you to reread the passage and crunch the numbers.

TFLYTSNBN wrote:I can not recall the acceleration rate during the stealthy fusion rocket burn nor the mass of the ships. I urge you to reread the passage and crunch the numbers.

The problem is you can't assume Newtonian physics, since the acceleration was way more than 1 G and nobody got turned into paste. The grav plates were still working, with unknown physics.

ThinksMarkedly wrote:

TFLYTSNBN wrote:I can not recall the acceleration rate during the stealthy fusion rocket burn nor the mass of the ships. I urge you to reread the passage and crunch the numbers.

The problem is you can't assume Newtonian physics, since the acceleration was way more than 1 G and nobody got turned into paste. The grav plates were still working, with unknown physics.

As I recall, it was a NAMELESSFLY who first offered the calculation many years ago. Weber actually PMed TFLY to ask for more detailed information and clarification. He seemed to eagerly accept the conclusion that a significant fraction but not the majority of ship mass was fuel. The bulk of tankage explained why crew accommodations were somewhat cramped.

The idea that the fuel load on Honorverse ships is significant is consistent with the stated reasons for the development of high power density fission reactors for LACs.

Bottom line is that if multi-million ton warships routinely burn a significant fraction of their own mass as fusion fuel even if it is only every few months, then Honorverse star nations are far more than just class 1 civilizations. Since the Manticore merchant fleet carries an enormous fraction of Silasian, Verge and Solarian League freight, Manticore probably uses more energy than anyone else.

The fact that fision of 11 tons of hydrogen releases about as much energy as fissioning 20,000 tons of putonium tends to suggest that energy usage can’t be that high. Otherwise LACs woudn’t work.

kzt wrote:The fact that fision of 11 tons of hydrogen releases about as much energy as fissioning 20,000 tons of putonium tends to suggest that energy usage can’t be that high. Otherwise LACs woudn’t work.

You made a math boo boo.
Look at this table of binding energy per nucleic:

https://www.physlink.com/education/askexperts/ae534.cfm

The energy density of Deuteroium to Helium fusion is less than ten times higher than the energy density of fissioning uranium, plutonium or Thorium.

Fission fuel is far more compact than fusion fuel.

TFLYTSNBN wrote:

kzt wrote:The fact that fision of 11 tons of hydrogen releases about as much energy as fissioning 20,000 tons of putonium tends to suggest that energy usage can’t be that high. Otherwise LACs woudn’t work.

You made a math boo boo.
Look at this table of binding energy per nucleic:

https://www.physlink.com/education/askexperts/ae534.cfm

The energy density of Deuteroium to Helium fusion is less than ten times higher than the energy density of fissioning uranium, plutonium or Thorium.

Fission fuel is far more compact than fusion fuel.

Hmm.

Another reason: Epsilon Eridani.
All things in space are targets for raids, captures, and conquests. All MILITARY things on/under the ground are Military targets, fair game for raids, etc; no matter how big the city wrapped around/over it.

So, building military and mil-related things in orbit enhances the life expectancy of the people on the ground.

It is foolish, on the scale of neglect of the fragility and vulnerability of life in a hazardous Universe, to have more people working in orbit than you can evacuate to the ground in the time it takes a smash/grab to arrive and smash. Honorverse history shows that Foolishness is still a prime human attribute.

Given the pervasive nature of anti-grav in the Honorverse, I see little reason not to have freighter-sized shuttles lifting ground-orbit (and/or obit-ground) on an hourly basis. Floating glass-bottom cities (that can move/land for adverse weather or season) should be de-regueur.

About tankage: Hydrogen density is not easy to come by. Per litre/Kg, the densest hydrogen storage is not LH2, but CH4 (Methane) NH40H (ammonium compounds) and metallics (chromium Hexahidride). Science being a moving thing that it is, Cr(NH4)6 might be feasible as high-density hydrogen storage.

TheMadPenguin wrote:Another reason: Epsilon Eridani.
All things in space are targets for raids, captures, and conquests. All MILITARY things on/under the ground are Military targets, fair game for raids, etc; no matter how big the city wrapped around/over it.

So, building military and mil-related things in orbit enhances the life expectancy of the people on the ground.

It is foolish, on the scale of neglect of the fragility and vulnerability of life in a hazardous Universe, to have more people working in orbit than you can evacuate to the ground in the time it takes a smash/grab to arrive and smash. Honorverse history shows that Foolishness is still a prime human attribute.

Given the pervasive nature of anti-grav in the Honorverse, I see little reason not to have freighter-sized shuttles lifting ground-orbit (and/or obit-ground) on an hourly basis. Floating glass-bottom cities (that can move/land for adverse weather or season) should be de-regueur.

About tankage: Hydrogen density is not easy to come by. Per litre/Kg, the densest hydrogen storage is not LH2, but CH4 (Methane) NH40H (ammonium compounds) and metallics (chromium Hexahidride). Science being a moving thing that it is, Cr(NH4)6 might be feasible as high-density hydrogen storage.

Pardon the bold to call attention.

Well, something came out of this craaazy thread.

TheMadPenguin wrote:
About tankage: Hydrogen density is not easy to come by. Per litre/Kg, the densest hydrogen storage is not LH2, but CH4 (Methane) NH40H (ammonium compounds) and metallics (chromium Hexahidride). Science being a moving thing that it is, Cr(NH4)6 might be feasible as high-density hydrogen storage.

Water shouldn't be disregarded either.