StarDestroyer.Net BBS

Hi there. This is my first thread so be kind
I have been reading the technical essays on the main page of this website, and been impressed with the well thought out reasoning and arguments.

However there is one piece of technology that is evidently present that has some consequences that I don't think are dealt with.

This has to do with calculating the structural strength of the ships, and how hard they can accelerate.

In the essay size matters http://www.stardestroyer.net/Empire/Science/Size.html
There is a case study of the Executioner class ISD looking at the structural strength required and concluding that it "It must be constructed out of impossibly strong materials or it must incorporate some sort of force fields in order to hold it together. "

I concur that it must incorporate some sort of forcefields... and we can deduce from watching the films what kind of forcefields and roughly how they work.

We know from watching the films that in the SW universe they have artificial gravity and inertial dampening.

These technologies are, I believe, intimately linked and work on similar principles.

Acceleration is in effect equivalent to a gravitational field and thus an inertial dampening system that intends to compensate for acceleration will almost certainly do so by creating a gravitation field.
Technology we know they have, because of their wide use of artificial gravity throughout their starships.

Now when accelerating a body MUST be being acted on by a force.
There is no technobabble handwavyness that gets you out of this.

If you want your ship to accelerate at many g's then both it and all the people in it must have a force acting on them large enough to cause that acceleration.

So what inertial dampening does is not remove the force acting on the people/equipment in the ship, otherwise they wouldn't accelerate at all.
What it must therefore do is change the WAY that force acts on the people in the ship.

Inertial dampeners must work by spreading the force out exactly evenly throughout the object being accelerated so that every atom in it is being pushed
Equally in the same direction resulting in no stress (mechanical) on that object.
This would be in effect like being in free-fall in orbit, where gravity is constantly acting on every atom in your body to accelerate you towards the earth and changes your velocity so that you curve around the earth, while experiencing no mechanical stress whatsoever.

This property of gravitational fields, of acting on each atom in your body to accelerate each equally is exactly what you need to spread out the forces needed to accelerate and prevent you being laminated over the rear bulkhead of whatever cabin you are in when someone decides to put the foot to the pedal.

However, this field doesn't just work on the people inside the ship; it works on the ship as well.

It would seem to me to be much easier to create one monolithic inertial dampening field covering the entire ship (especially since gravitational fields go through solid matter perfectly easily) than to individually create fields for each cabin and hold space that didn't encompass any of the structure of the ship.

In fact it seems perverse to try to ONLY initially dampen the internal volumes of the ship and not just the entire ship.

This means that the entire ship would be encompassed by the inertial dampening field.

This means that as long as you are within the tolerances of your inertial dampening field it doesn't matter how hard you accelerate, the structural strength of the ship is irrelevant. The forces are all evenly distributed over the entire ship by the inertial dampening field.

This is fantastic, because it means that you can now build extremely large starships that can perform high-speed manoeuvres without having to discover/invent a materiel umpteen orders of magnitude stronger than anything yet discovered.


However it goes beyond that.

Using good engineering practice, we want to make this system as safe as possible.
And bearing in mind that we are using this technology to get around needing as yet undiscovered (and probably impossible) super materials to build our starships, we can conclude that they cannot withstand the forces generated by their engines without these inertial dampening fields.

Which brings up the fairly horrifying concept, that in the event of a failure of the inertial dampening system, (say because someone just fired a turbo laser blast into it) your own engines, if on, are likely to tear their way strait through your own ship.
Instantly turning you into an expanding cloud of superheated wreckage.

However, we don't (to my knowledge) observe this ever happening in SW, and I can think of a potential reason why.

The problem is to do with how the engines interact with the inertial dampening system.

The normal way of picturing this is that the engines are physically attached to the ship and transfer their thrust to the ship via these mechanical connections.
The Inertial Damping system then magically stops all the people getting turned into pancakes.

However as we have deduced, the Inertial Damping system acts on the entire ship and it is the inertial damping system that makes it accelerate.
Not the physical connections to the engines.

So we could think that the engines are physically connected to the inertial damping systems, and that they push those, which produce the inertial field, which pushes the ship.

However this would risk the aforementioned problem of the engines ploughing strait through the ship in the event of a failure of the inertial damping system.
You can't guarantee/rely on the engines shutting down fast enough in the event of a failure. Remember these engines are producing an enormous amount of thrust.
And you also need to make your engines and inertial dampening systems capable with withstanding the thrust they generate, and we have already concluded that they don't have materials capable of doing this.

My postulate is this.

The Inertial dampeners ARE the engines. Or more properly the engines are inertial dampeners... but not the only ones. Others are needed to cope with turning forces and countering shocks from enemy weapons hits and such.

Just as the ship is accelerated forward by the inertial dampeners, the propellant is accelerate backwards (for our Newtonian equal and opposite reaction) by inertial fields. This means that you don't have to make the engines out of some magic materiel that can take the immense forces involved.
It means that a failure of the inertial dampening system automatically cuts the engines, as the engines are powered by that same system.
And it might also explain the off axis location of many drives on SW ships.

Also...

As the inertial dampening field is what moves the ship, it might well be possible to generate this field asymmetrically around the engines...

In fact as each engine must generate its own field to compensate for its own thrust and all engines are not located dead centre in the middle of a symmetrical ship we must conclude that inertial dampening fields must be able to be generated asymmetrically.

Thus the centre of thrust of an engine will always be through the centre of mass of the ship regardless of engine placement.

Which explains why SW ships don't need to have their engines places symmetrically around the centre of mass.

Well dude, I don't understand most of that so... two thumbs up on your first thread.

Nah, I get it. It's an interesting thought if I am understanding what you are saying.

One question you don't answer is how the Ifield generates a directional field that is seen or felt at pushing downward on a person or object. If the Ifield is all encompassing then it would make bulkheads and overhead the same as the deck we do not see this in sw rather we see what we can approximate as earth standard, similar to what is produced in a centrifugal machine.

Tldr: you don't answe the question of artificial gravity

Zwinmar wrote:One question you don't answer is how the Ifield generates a directional field that is seen or felt at pushing downward on a person or object. If the Ifield is all encompassing then it would make bulkheads and overhead the same as the deck we do not see this in sw rather we see what we can approximate as earth standard, similar to what is produced in a centrifugal machine.

Tldr: you don't answer the question of artificial gravity

While the Inertial dampening and artificial gravitation systems work on similar principles and with similar technology, they would and should be separate systems.
(They do different jobs, and thus would be optimised differently, as well as the security of redundancy)

The Primary inertial dampening would be generated by the engines themselves to counteract the linear acceleration they generate.
This is generated by each of the engines and is designed to exactly counteract each engines acceleration so there is no delay between engine firing and inertial damping. And the loss of an engine cuts both its thrust and its inertial compensation, exactly cancelling out.

The Secondary inertial dampening would be independently generated and used to counteract turning forces.
This is designed to handle non-uniform/non-linear but predictable forces caused by the turning and manoeuvring of the ship.

The Tertiary inertial dampening systems would also be independently generated and would be used to counteract shocks caused by collisions and weapons fire.
This is optimised to deal with sudden unexpected shocks and pulses caused by collisions and weapons fire, and to cover any deficiencies in the other two systems.
This would also be the most likely system used to counteract any gravity based weapons fire, as it's designed to react to and generate rapid unplanned and unexpected gravitational fields.

Of course all of the above should and would be independently and multiply redundant.



The artificial gravity system would be independent of the inertial damping systems and would maintain a 1 g 'downwards' force against whatever external gravitational field the ship is currently experiencing.

As gravitational fields pass through each other and add these systems can work independently of one another without issues of competing goals.

The Inertial dampening systems are set to maintain effective 0g internal environment regardless of any manoeuvres the ship is performing, as well as handling unexpected forces due to collisions and weapons fire.

While the artificial gravity system overlays a steady (net when combined with any external gravitational fields, caused by massive celestial bodies or interdictors) 1g downwards acting gravitational field that allows for the easy habitation and optimal working conditions for the human/humanoid crew.




This of course all depends on the accuracy of my observations and arguments as laid out in the OP.


My main point in the OP was that an inertially dampened star ship should (unless the designers are being truly perverse, or there is some non-obvious 'physics' relating to the functionality of inertial damping and artificial gravitation systems) be able to accelerate at any rate it's engines can handle, without having to worry about the physical strength of the starships structure. As the structure is effectively being maintained in a microgravity environment by the inertial damping system.

In a manned ship it simply has to support it's own weight, the stress of the artificial gravity (which is 1 g not tens of thousands), and the stresses of weapons fire, both incoming and outgoing.


This seemed to me to be a reasonable conclusion based on the observed properties of the SW (and other) starships, and what we know of physics.

If you don't damp the structure of the ships in this manner, using inertial dampeners which we observe that they must have, then you have to use structural reinforcing forcefields and/or as yet unknown super-materials which introduce even more handwavium into the equation.

It seems that an application of Occam's razor would apply. IF it's a logical conclusion of the consequences of inertial dampening and artificial gravity systems that they would naturally remove all acceleration stresses from the starship hull allowing any acceleration your engines can produce without the use of any other 'magic'.
Then my proposed explanation is and must be simpler and less reliant on sci-fi physics than an explanation that requires additional 'magic' to work.



How inertial damping relates to FTL drive is a separate question, presumably IF that generates any kind of internal acceleration forces they would be compensated for by inertial damping built into the FTL system itself. This would be included in the Primary damping by inertial dampeners in the engines, this time in the FTL drive.

Artificial gravity cold be a separate mechanism than that of his engine/inertial dampener.

This isn't sci fi physics; speculative, yes, extremely so, but basically this is a Mach-Lorentz thruster being described- articles

http://nextbigfuture.com/2009/09/mach-e ... march.html

http://nextbigfuture.com/2009/09/mach-e ... rt-ii.html

http://nextbigfuture.com/2009/09/path-u ... ivity.html

http://nextbigfuture.com/2009/09/mach-e ... swers.html

http://www.talk-polywell.org/bb/viewtop ... sc&start=0

http://en.wikipedia.org/wiki/Woodward_effect

The short version is that inertia is (if Mach's Principle is right) essentially the random quantum burbling of the universe's gravitational field, and the hardware lets you selectively blank out (through quantumelectrodynamic effect, where the Lorentzian part comes in) part of the background enabling you to accelerate against the rest of it; no relative stresses within the field effect, all in freefall relative to each other, and absurd, absurd propulsive efficiencies- oh, and inertialess, and reactionless. Bring enough reactor food and you're sorted.

It does sound too good, and far too wierd- or the other way around- to be true, but there are definitely people out there taking it seriously. That may only put it into "men who stare at goats" territory, doubly appropriate because government money has been handed out on the strength of this, but at least it should be interesting to figure out why it's wrong, and it does sound like what's being described by CultureClash, except better.


Two in universe issues I have; somebody somewhere may be using something like it, but it's not the galactic mainstream, because what we see as that mainstream is nothing like a Mach- Lorentz Thruster, which for one thing can be a sealed box and doesn't need visible jet/rocket-looking things on the back of your spaceship- and anyhting which could produce thrust like that would be obviously an engine in its' own right. The general assumption from day dot is that it's some kind of electromagnetic thruster, uses a much more straightforward process (I reckon plasma wake-field accelerator coils myself, you could at least make something out of those that looks like the cross section of an ion turbine) to chuck out probably quite small amounts of ejecta at near- c velocity.

The problem here is explaining why the relative inertial field doesn't produce thrust in its' own right and you still need the engines- when our best guess at what could do relative inertials most certainly does, and may (if you play around with weird things like negative gravity) be an FTL drive to boot.

The other one is that you need the extremely tough materials anyway for the giving and taking of fire. Well, turbolaser bolts anyway. Even if most of it is done by forcefields, still need to anchor the forcefield generators to something that can at least hold them together relative to one another.

If I am reading this right, the only problem with the Mach-Lorentz type engine device is that even though it may make an object reactionless and inertialess it does not make it massless which means that a large engine of some sort would have to be utilized in order to get any sort of velocity up. I don't have time to do more than skim the Mach-Lorentz link at the moment, so this is just speculative.

I'd say it's more a matter of careful synchronization between sensors, computers, engines, gravity generators, and the inertial compensators. The ship makes a maneuver - either through its own power or as a result of external forces, (including being attacked), and the computer decides how best to protect those inside, (i.e. maintain a stable 1G environment), via the various resources at its disposal. Since using the engines or thrusters themselves would likely maneuver the ship in a manner contrary to the user desired, (if it used them as part of the internal homeostasis mandate), it uses the inertial compensators/gravity generators as the main go-to system.

Sometimes external forces act faster or too unpredictably for the computer to adjust for, or they're just too powerful to fully counter, and that's why the passengers feel the jolts when they're hit.

I'd also say that if this system could maintain such a state within the ship, it could also theoretically reduce the stress of maneuvers to the point where materials only a few degrees better than what we have now, could handle the loads.

Indeed, this could account for why ships whose systems do totally fail exhibit such severe structural collapses.

CultureClash, what you said does make sense.

To summarize:
Instead of the massive engines being merely structurally connected to the rear of the ship's superstructure, the engines are instead pushing a set of "field generators". The engines push these field generators, and in turn the field generators exert force onto every particle in the entire ship (including its contents), thus the superstructure itself is not under any stress whatsoever during linear acceleration. Essentially, the ship and its contents effectively remain an inertial frame of reference even when the engines are accelerating the ship.
For the lateral acceleration incurred by non-linear maneuvers, or acceleration due to outside forces, you have a separate set of inertial dampening field generators.

That pretty much is what Curtis Saxton meant by "[ships like the Executor] must be constructed out of impossibly strong materials or it must incorporate some sort of force fields in order to hold it together", just worded in a different way.
I suppose it logically follows that engine thrust should be applied to the mechanism where the fields originate from, which you pointed out, but I hadn't thought of that either. Nice.

Meh, I didn't see this thread earlier.