ERIM

@Relax: the data your quoting doesn't mean what you think it means.

Quite simply put this is a mostly hard sci-fi setting. Conservation of energy must be maintained.

The energy to accelerate a 300Kt cruiser to 0.8C and back down again, assuming the ship has to supply 40% of the energy at 100% efficiency as your using the provided data to specify would require 6Mt of hydrogen bunkerage.

Given going to 0.8C and back down again is treated as a pretty minor thing we know that this value must be in error.

Your claim also does not fit with the idea that the higher a ships acceleration the more powerful it's impeller signature and thus the harder to hide under stealth it is.


Fortunately there's another way to read the bit your quoting.

At rest the wedge draws 40% of it's power from the object generating it, and as the ship accelerates the amount of energy drawn from the generating object as an absolute value does not change, (which satisfies he wording of what you're quoting). But the amount drawn from hyperspace does increase, (which satisfies the conservation of energy aspect).

Realistically at full acceleration the percentage of total energy drawn from the generating object must be in the fraction of a fraction or one percent range.

munroburton wrote:IIRC, those canisters didn't have any drives of their own. They relied on the shipboard launcher to impart enough velocity to get clear of the wedge and then deployed.

Not exactly ideal for extended range interceptions.

Canisters, no. Canister in place of the warhead in a "MIRV" configuration, maybe. ["MIRV" is "Multiple Independent Re-entry Vehicle" which isn't exactly correct; it would be more "Multiple Independent Targeted Counter-missile" or "MITC"]

The problem, despite Relax's refusal to accept Honorverse limitations, is providing an acceptable command and control loop for each counter-missile and/or finding a way to extend counter-missile range without usurping attack missile tubes or pods...

Bill Woods wrote:

kzt wrote:I don't think acceleration in the honorverse is mass based at all. Empty freighters don't accelerate faster then full freighters. I think it's all based on the shape and depth of the field.

So why are warships always being characterized by their mass, instead of, say, length or usable volume? (Or is tonnage a measure of volume, as it is in contemporary surface ships?)

Because that's the terminology used. Basically, the "ship mass" is a measure of volume, based on the idea that an average ship has a specific density.

In part, this goes back to the Great Resizing, when David and Ad Astra changed the sizes of various ships to match a specific volume. It had been pointed out previously that, if you assumed the "mass" of the ships really was its mass, and divided by the volume, superdreadnoughts turned out to have the density of smoke. So all ships were assigned new lengths and widths, to match a specific density (0.25 tons per cubic meter, if I recall correctly). This also clarified something that David had already assumed in his text but had never made explicit--that a ship accelerate the same whether it is fully laden or has empty holds. Thus, the "mass" of a ship is a constant based on its size. It can be used as an estimate of the actual mass, but is more accurate as a measure of volume.

David has since explained that it is the volume enclosed by the inertial compensator, combined with the strength of the wedge, which determines the maximum acceleration. And ships are generally designed to utilize as much of the compensated volume as possible.

Carl wrote:@Relax: the data your quoting doesn't mean what you think it means.

Quite simply put this is a mostly hard sci-fi setting. Conservation of energy must be maintained.

The energy to accelerate a 300Kt cruiser to 0.8C and back down again, assuming the ship has to supply 40% of the energy at 100% efficiency as your using the provided data to specify would require 6Mt of hydrogen bunkerage.

Given going to 0.8C and back down again is treated as a pretty minor thing we know that this value must be in error.

Worse than that, I think. The kinetic energy of a mass m at 0.8c is 2/3 mc2. Hydrogen fusion is 0.007 efficient at turning mass into energy. So it would take 95m to accelerate ... if the hydrogen fuel didn't need to be accelerated along with the ship. And then the same amount to decelerate, with the same caveat.

Obviously this energy has to be coming from somewhere outside the ship, just as sailing ships of the Napoleonic War era got their energy from the wind rather than from fuel carried onboard.

Carl wrote:@Relax: the data your quoting doesn't mean what you think it means.

Quite simply put this is a mostly hard sci-fi setting. Conservation of energy must be maintained.

The energy to accelerate a 300Kt cruiser to 0.8C and back down again, assuming the ship has to supply 40% of the energy at 100% efficiency as your using the provided data to specify would require 6Mt of hydrogen bunkerage.

Given going to 0.8C and back down again is treated as a pretty minor thing we know that this value must be in error.

Your claim also does not fit with the idea that the higher a ships acceleration the more powerful it's impeller signature and thus the harder to hide under stealth it is.


Fortunately there's another way to read the bit your quoting.

At rest the wedge draws 40% of it's power from the object generating it, and as the ship accelerates the amount of energy drawn from the generating object as an absolute value does not change, (which satisfies he wording of what you're quoting). But the amount drawn from hyperspace does increase, (which satisfies the conservation of energy aspect).

Realistically at full acceleration the percentage of total energy drawn from the generating object must be in the fraction of a fraction or one percent range.

While that is a useful measure of energy in many contexts, it is not appropriate in this one. In this context, the energy consumed is the energy necessary to run the impeller wedge, not the energy to accelerate the ship. David has made clear that much of the energy to accelerate the ship (or missile) is actually drawn from the hyperspace interface itself. So the missile does not have to store enough energy to accelerate itself to 0.8 c--it only has to store enough energy to run the impeller wedge; the impeller wedge accelerates the ship, using energy from hyperspace.

So when David said that maintaining the impeller wedge takes only 60% of the energy to start the impeller wedge, he was only talking about how much energy needed to be stored or generated on board the missile.

SWM wrote:

Bill Woods wrote: So why are warships always being characterized by their mass, instead of, say, length or usable volume? (Or is tonnage a measure of volume, as it is in contemporary surface ships?)

Because that's the terminology used. Basically, the "ship mass" is a measure of volume, based on the idea that an average ship has a specific density.

In part, this goes back to the Great Resizing, when David and Ad Astra changed the sizes of various ships to match a specific volume. It had been pointed out previously that, if you assumed the "mass" of the ships really was its mass, and divided by the volume, superdreadnoughts turned out to have the density of smoke. So all ships were assigned new lengths and widths, to match a specific density (0.25 tons per cubic meter, if I recall correctly). This also clarified something that David had already assumed in his text but had never made explicit--that a ship accelerate the same whether it is fully laden or has empty holds. Thus, the "mass" of a ship is a constant based on its size. It can be used as an estimate of the actual mass, but is more accurate as a measure of volume.

So it would be more accurate to describe, e.g., an Invictus-class ship as 35 gigaliters than as 8.8 megatonnes?

While that is a useful measure of energy in many contexts, it is not appropriate in this one. In this context, the energy consumed is the energy necessary to run the impeller wedge, not the energy to accelerate the ship. David has made clear that much of the energy to accelerate the ship (or missile) is actually drawn from the hyperspace interface itself. So the missile does not have to store enough energy to accelerate itself to 0.8 c--it only has to store enough energy to run the impeller wedge; the impeller wedge accelerates the ship, using energy from hyperspace.

So what your saying is that the total energy used to both initiate and maintain the wedge over it's lifetime is 160% the initiation energy?

the impeller wedge accelerates the ship, using energy from hyperspace.

This was what i was trying to say with all that math.

@Bill Woods: I'm aware that KE does not at relativistic values of speed equal 0.5*m*v^2. But since that will always return a low result it makes it perfectly fine for such a patently non-working example as the one i wanted to address.

For the love of... Can NO ONE READ?

I even gave the relevant quote.

Kinetic Energy means NOTHING in the honorverse.

If you have a wedge up, energy required to accelerate is NO DIFFERENT than not moving at all.

PS. If you cannot figure out how to dump a CM out of a cannister... Got issues. RFC does not have such an issue either.

Carl wrote:

While that is a useful measure of energy in many contexts, it is not appropriate in this one. In this context, the energy consumed is the energy necessary to run the impeller wedge, not the energy to accelerate the ship. David has made clear that much of the energy to accelerate the ship (or missile) is actually drawn from the hyperspace interface itself. So the missile does not have to store enough energy to accelerate itself to 0.8 c--it only has to store enough energy to run the impeller wedge; the impeller wedge accelerates the ship, using energy from hyperspace.

So what your saying is that the total energy used to both initiate and maintain the wedge over it's lifetime is 160% the initiation energy?

Something like that, yes.

Carl wrote:So what your saying is that the total energy used to both initiate and maintain the wedge over it's lifetime is 160% the initiation energy?

No. It says what the author said it says.

When an impeller drive is up, any impeller drive, no matter its duration, for its entire duration requires 40% of said power from internal sources. So, initiation, for however LONG that takes, requires 150% power levels above "normal".

So, if you want to calculate TOTAL power consumed you must multiply startup time times power level and then ADD flight duration times flight power level to get your Total power availability.

Effectively, RFC created an infinite(perpetual motion) energy machine.