Missile acceleration limits

I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

Because, while missiles don't have organic crewmembers, the material out of which they're made still doesn't have infinite strength. It's a hell of a lot stronger than flesh and blood, certainly, but *any* material object will rip itself to shreds under 24 million gees, I don't *care* what it's made out of.

(Also, it's been stated in various backstory dumps that missiles actually do have some kind of partial inertial compensator effect going, which is different from the sort of compensator that regular ships have. Unlike a regular ship compensator it appears to absorb only part of the acceleration forces (obviously making it unusable for manned ships!), but it seems to be able to handle much higher accelerations than the regular kind. Even still, though, it's got to have it's limits, and 24 million gees is probably well beyond them.)

(Edit for context - just for reference, that acceleration of 0.8c in one second is two orders of magnitude higher than that due to gravity at the surface of a white dwarf, which contain the mass of a sunlike star packed into a space roughly the size of the Earth. That acceleration compresses hydrogen enough to cause it to fuse into helium; we see those as novae. NOTHING physical survives that kind of acceleration.)

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

We've been told that RFC's missile drives have some kind of integrated compensator. So presumably if all their acceleration was felt my their internals those would break.

We also know that the impellers that power then have reduced operational lifespan at increased acceleration; hence a missile at half power having three times the operational time. Nodes are theoretical constructs and have to somehow survive linking the physical ship or missile to the theoretically nearly infinity quickly accelerating wedge.

I'd guess that if you tried to get much more than the 130,000g of a current Manty CM/Viper with current drive tech your either burn the impellers out so quickly you'd get far less powers range, or the internals would come apart (probably with catastrophic effects as the capacitor all cascade failed), or both. Or maybe the power required would simply blow out the impellers.
But despite a wedges theoretical performance we've seen enough hints of 'in practice' engineering limitations that I find it totally believable that RFC has missile performance increase in fairly slow steps and that they can't just zip to 24+million g.

MuonNeutrino wrote:

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

Because, while missiles don't have organic crewmembers, the material out of which they're made still doesn't have infinite strength. It's a hell of a lot stronger than flesh and blood, certainly, but *any* material object will rip itself to shreds under 24 million gees, I don't *care* what it's made out of.

(Also, it's been stated in various backstory dumps that missiles actually do have some kind of partial inertial compensator effect going, which is different from the sort of compensator that regular ships have. Unlike a regular ship compensator it appears to absorb only part of the acceleration forces (obviously making it unusable for manned ships!), but it seems to be able to handle much higher accelerations than the regular kind. Even still, though, it's got to have it's limits, and 24 million gees is probably well beyond them.)

(Edit for context - just for reference, that acceleration of 0.8c in one second is two orders of magnitude higher than that due to gravity at the surface of a white dwarf, which contain the mass of a sunlike star packed into a space roughly the size of the Earth. That acceleration compresses hydrogen enough to cause it to fuse into helium; we see those as novae. NOTHING physical survives that kind of acceleration.)

That makes perfect sense to me. Thank you.

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

Because David doesn't want that. A120mm M1 tank fires a proximity fuzed anti-helicopter round and it accelerates at 42,000g going down the barrel. http://proceedings.ndia.org/5560/Thursd ... edberg.pdf

The 155mm Excalibur round has a peak acceleration of something like 15,000 g.

Infinite acceleration has certain structural issues (like infinite stress) but there really isn't any reason why honorverse missiles (with their specified performance) need a compensator other than David says they do. And he does.

A missile using a non-missile propulsion package is an obvious counter to the RMNs MDMs but I don't think it will happen.

kzt wrote:

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

Because David doesn't want that. A120mm M1 tank fires a proximity fuzed anti-helicopter round and it accelerates at 42,000g going down the barrel. http://proceedings.ndia.org/5560/Thursd ... edberg.pdf

The 155mm Excalibur round has a peak acceleration of something like 15,000 g.

Infinite acceleration has certain structural issues (like infinite stress) but there really isn't any reason why honorverse missiles (with their specified performance) need a compensator other than David says they do. And he does.

A missile using a non-missile propulsion package is an obvious counter to the RMNs MDMs but I don't think it will happen.

I should also point out that engineering wise (and biology wise) there is a big difference between survivable point acceleration such as from a gun or in a crash and sustained acceleration such as in a missile or in a high g fighter turn. See https://en.wikipedia.org/wiki/G-force#S ... C_and_jerk for some numbers.

It is quite possible that there are components of the missile (or the M1 anti helicopter round) that can take that level of momentary G force but that would be wrecked under a small fraction of that sustained over a 1 minute flight time.

I understand that the main issue isn't the sustained acceleration, it's the initial acceleration rate that is the big issue. This is the derivative of acceleration and it's called jerk in physics.

So going from 0 to 1.5 km/sec over 10 meters is actually a really big deal. It's much less challenging to keep it running if it can survive the initial jerk.

And in a missile using a ship style impeller drive you can throttle up the acceleration in whatever fashion you need, if this matters. The fact that you can vary acceleration in flight would raise hell with defensive fire control systems in the first few engagements.

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

Acceleration isn't free. There is an energy budget to consider and to gain "Theoretical Infinite Acceleration" would require "Theoretical Infinite Energy."

GabrialSagan wrote:I has been stated more than once that impeller drives can theortically accelerate ships (and by extension, missiles) to the speed of light in an instant, but the thing that prevents such massive accelerations is concern for the effects such acceleration rates have on organic crewmen (turning them into goo). Missiles however, do not have protoplasmic organisms to be concerned about, so what is it that prevents engineers from building missiles with 24,473,469.3878 gees of acceleration that would boost a missile to .8c in a second?

Just because missiles are built much tougher than humans doesn't mean there aren't strength limits.