you're almost 90 degrees off. :) "A body in motion will remain in motion..." You're thinking of a body wanting to "move [i]Forward[/i] in a straight line" but that straight line is actually "Down", away from the center of rotation, the tangent to the center of gravity or rotation is very small. The floor of a station is not constantly pushing you forward around in a circle. Once you're moving, you keep that momentum. To expand on your example of the Frictionless Rotating Ring; What would happen if you start out with friction that lasts just barely long enough to give you that simulated gravity, but then all friction is eliminated? You wouldn't stop moving or even slow down because you've already matched the speed of the ring. You would continue to feel the effects of the simulated gravity. Here's a fun question; What happens if you run against the rotation of the ring at exactly the same speed the ring is traveling? ;) http://www.calctool.org/CALC/phys/newtonian/centrifugal

Here's a link I found with an example of coriolis vs centrifugal force calculations: http://www.bogan.ca/physics/coriolis.html http://www.artificial-gravity.com/sw/SpinCalc/SpinCalc.htm Here you can calculate the ratio coriolis vs. centrifugal/centripedal depending on body speed, but you're limited to 1g only: http://jsbin.com/ukike3/6 Eclipse Phase has toruses at 190 meters in diameter at .38g equivalent, so the ratio of coriolis force to centrifugal force is going to be a lot less than in the first link. Edit: EP has 1g spinning stations gemerally at 500 meter diameters plus, .1g at 50 meters diameter plus etc.

Interesting... Good links. Maybe there is a case for laser weapons here. Might have to start upping my beam weapons skill.

NewtonPulsifer wrote:

I think homing bullets would do the trick just fine?

Don't know if 35g figure is correct, but if it, I doubt homing bullets have enough propulsion power to offset 35g sideways acceleration. But I don't think that 35g is realistic - after all, how bullet differs from person jumping up? Wouldn't everything be smashed against walls, like OP suggests ?

250 m radius is a fairly small habitat I think, and most likely at that size it'll function on 0.5g instead in order to have lower rotational speed and less coriolis force. As RustedPanthress says, there is no sideways acceleration, there is only sideways speed. The corebook mentions Hamiltoncylinders with 4 km radius. Even though your velocity would be very high in a such a system (operating at 1g), the effect of the coriolis force will be lower since the floor will only be very tinily curved. As far as game mechanics go, as long as the habitat is large enough, you can more or less ignore the effect.

Revinor wrote:

NewtonPulsifer wrote:

I think homing bullets would do the trick just fine?

Don't know if 35g figure is correct, but if it, I doubt homing bullets have enough propulsion power to offset 35g sideways acceleration. But I don't think that 35g is realistic - after all, how bullet differs from person jumping up? Wouldn't everything be smashed against walls, like OP suggests ?

The coriolis effect is proportional to the speed of the object, that's why it is so large for the bullet.

In other words, any gun training in EP is going to include how to shoot at people on a rotating station.

Regarding whether 35 gravities is too much, here's a rough calculation: A homing bullet leaves a SMG going 500 meters per second. The target is 20 meters away. The homing bullet needs to pull a .5 meter correction. Assume the correction starts immediately as the bullet exits the barrel and accelerates continuously. How many gravities of acceleration must the bullet achieve? We have 1/25 of a second (time it takes to go 20 meters). We need to go .5 meters. Average velocity needs to be 12.5 meters per second - that means final velocity needs to be 25 meters per second (a we're starting from zero). We have 1/25 of a second to achive a final velocity of 25 meters per second, so our acceleration needs to be 625 meters per second. About 94 gravities.

I wholeheartedly agree, but that's the logical consequence of allowing that +10 homing bonus even at short ranges. A more self-consistent in game bonus might be the the negation of range penalties, but we have a smart bullet that does that already. Perhaps just don't allow the homing bonus at short range. Also, the homing bullet might not have enough fuel to pull a .2 second burn. EDIT: With the rulebook talking about homing and laser-guided bullets being used in indirect fire like seeker rounds, it seems the developer's intent of these rounds may be for them to act more like seeker missiles than bullets?

In vacuum they need it and the description says something about tiny nozzles, if I am not mistaken.

By nozzles I assumed they meant tiny thrusters. I wouldn't always want to increase muzzle velocity, often precision is worth more than the ability to cause (collateral) damage. Hm.. Is it correct that these delta v budgets are a result of the .5 correction at 20m distance? Because 0.5m seems quite a lot for +10. But even 10cm are a bit too much after 20m I guess. So no bonus at short distance. In any case it would be better to let the weapon fire itself when it detects that is on target, as it seems to know better where the target is than the shooter does. They try to do this in reality by the way: http://www.gizmag.com/sandia-self-guided-bullet/21286/

NewtonPulsifer wrote:

I think homing bullets would do the trick just fine?

Or you could just let the dice decide. A success means the character successfully accounted for the Coriolis force and the shots hit. A failed roll means they did not.

NewtonPulsifer wrote:

Seeker micromissiles are already scramjets? delta v was 25 m/s in the example, acceleration was 625m/s/s

Wow that was a serious error of reading comprehension thanks for the correction. I am not a multi-tasker I was working on a bid proposal and browsing the forums. [sighs] Now I've got to wonder what mistakes I made on the bid. Hope I didn't spec 65000 psi concrete! :D No, I didn't say that seeker missiles were scramjets. I was ragging on the game Rifts for their "ramjet" rounds which are regular bullets with tiny rockets that do x100 damage. My ability to play rifts (and enjoy it for a little while), means that EP really doesn't "jump the shark" for me. But I do prefer that it doesn't become cartoonish like rifts and fantasy games. I'm too tired for maths right now, Can someone figure the I-sp for the proposed slug accelerating at 625m/s^2? I'll give you all my R-rep.

Even transhuman habitats are certainly not firefight-proof except in HiSec areas, and anybody using something other than low-velocity flechette or energy stunners would punch holes in the habitat, causing a vacuum suction/decompression effect that would destroy the habitat and everything in it like a coke can that is stomped upon. Aiming and negating the coriolis effect is nearly impossible, because with every arc-centidegree the weapon's aim is moved, the acceleration and coriolis forces alter. To shoot straight along a corridor you would need to aim either the corner between floor and wall or wall and ceiling, and be sure that you shoot spinward (or was it *not* spinward?!), or otherwise the projectile will very likely drop at your feet or hit yourself.

NewtonPulsifer wrote:

rekuli wrote:

Even transhuman habitats are certainly not firefight-proof except in HiSec areas, and anybody using something other than low-velocity flechette or energy stunners would punch holes in the habitat, causing a vacuum suction/decompression effect that would destroy the habitat and everything in it like a coke can that is stomped upon. Aiming and negating the coriolis effect is nearly impossible, because with every arc-centidegree the weapon's aim is moved, the acceleration and coriolis forces alter. To shoot straight along a corridor you would need to aim either the corner between floor and wall or wall and ceiling, and be sure that you shoot spinward (or was it *not* spinward?!), or otherwise the projectile will very likely drop at your feet or hit yourself.

Just....no.

Structural integrity does not work that way! Or conservation of momentum. And even if it did, have a look at the given armour ratings for habitat hulls. Page 203, 'Advanced Composites'. Armour of 50. To even push into a habitat hulls durability (do damage) you need to use high-grade explosives. Like, really high-grade. Shooting a HEAP minimissile right at it will only sometimes make a dent.

I was more going for the whole 'Guns in space stations are bad!' part. There is only a pressure difference of ~1 atmosphere within your space station compared to the vacuum of space. Probably less, because habitats can get away with running at a lower pressure. 1 atmosphere of pressure difference is only ~15psi. A bullet hole is only a few cm/squared. With those numbers all you are going to feel is a light breeze while near the hole. It might be quite noisy, and you will experience atmospheric loss in line with the one-one-ten-hundred rule, but your space station will not suddenly rip itself apart, and given that a fair majority of the larger habitats have self-repairing hulls, even that will not be that large of an issue.

rekuli wrote:

...would punch holes in the habitat, causing a vacuum suction/decompression effect that would destroy the habitat and everything in it like a coke can that is stomped upon.

You're confusing explosions (perhaps you're thinking of explosive decompression) with implosions (stomping on a coke can). [/quote]

rekuli wrote:

Aiming and negating the coriolis effect is nearly impossible, because with every arc-centidegree the weapon's aim is moved, the acceleration and coriolis forces alter. To shoot straight along a corridor you would need to aim either the corner between floor and wall or wall and ceiling, and be sure that you shoot spinward (or was it *not* spinward?!), or otherwise the projectile will very likely drop at your feet or hit yourself.

How is aiming nearly impossible? A computer can calculate this without any problem whatsoever. I'm well aware of the limitations of straight shooting weapons, hence the thread digression into homing rounds. Could you please write up the math on how somebody could shoot themselves or have a projectile drop at their feet?

rekuli wrote:

Structure integrity: That would assume nobody cares about the cost of building habitats, and I am sure the corporations would save money wherever possible. One of the last things of mankind to ever die is greed and lust for power. Where light construction and shielding suffices, they wouldn't waste better ones or ultra-durable composite materials that are much more difficult to manufacture, or more complex building methods.

Why would additonal structural integrity be so expensive? Pig iron is like $100/ton. It would likely be cheaper if mined in space. Even in EP a cheap replacement for pig iron is probably bulk metallic glass steel alloys. If you space 10,000 corporate people with "stuff" (morphs and possesiosn) each costing 100k, you've just blown 1 billion credits worth of value. For a one-time cost of 1k per person (10 million credits), you could have 100,000 tonnes of EP pig iron equivalent, if credits=dollars. To give you an idea of how "thick" that would be - if every person on that hab lived in an approximately 4x4x4 meter cube and contributed none of their steel mass to the hab structure as a whole, they would have walls approximately 14.6 millimeters thick of bulk metallic glass steel alloy. That would stop a .50 caliber BMG round.

Quote:

Momentum: If you look at physics of atmospheric friction and rotation momentum, there is the fact that a projectile in motion at an angle, no matter how small, to the spin direction takes a part of the spin into its movement and thus flies an elongated curve, the form of which is depending on the projectile's own velocity, the spin speed, the angle at which the projectile was launched, and the atmospheric density and temperature. Ask any astronaut. Ask the people that calculate the ballistic flight trajectories of satellites or the drones sent to Jupiter, Mars, Saturn, Halley, and whatever. The same applies inside a rotating habitat, especially when you are standing on the „ground” and not levitating in micro-gee. If you still don't believe it, that's not my problem. What I explained here is called „Coriolis effect”, and I believed you knew all that.

I'd say most readers of this thread that read it from the beginning are aware of the Coriolis effect. You're asking us to "look at the physics". You haven't shown any. Show me the math where a shooter shoots himself.

rekuli wrote:

The bigger ones just blast you out. Tinies crush you by suction-implosion into that hole. Don't get deceived by hollywood movies where the heroes have time enough to tin can themselves and go EVA to plug that hole, that is pure nonsense.

No. Just... no. That isn't how pressure works. The forces involved with small punctures in space are tiny. Enough so that you could easily put your finger over the hole and stop the majority of the air flow. You also seem to demonstrate an opposite understanding of what the majority of sci-fi Hollywood movies show when it comes to hull breaches. In that a large proportion of them demonstrate the exact mechanism you are falsely claiming as true. Spaghettification of people through micro-fractures is a physical impossibility. At least at atmospheric values that people are comfortable in. Again, 1 atmosphere differential. That is 15psi of force. Very small.

rekuli wrote:

and of the arrogance of people who believe their opinion is the only measure, regardless of real-life fact or freedom of speech

The irony! It burns! Edit: I am also throwing up the bat signal for any of our resident space scientists to chime in here, because I am close to 100% certain that I am correct here. I know that you guys are out there.

Rekuli obviously has major problems with quantifying the forces involved. It's a common problem. People trust their intuition even though it sucks at getting quantities right, and that's what matters. Do the math or refer to credible sources. At a pinch you can do back of the envelope calculations.

rekuli seems to think that that the pressure differential between 1atmo and 0atmo is huge. Also, they seem to have confused centrifugal force with acceleration. You could only stand on the walls of a rotating hab (presumably walls that are perpendicular to the direction of rotation) if it's accelerating. And even then, the pseudo-gravity would force you into the corner at the junction of the wall and the floor. Fun fact: If you live part A of a torus hab and your school is in part B, this means that if you walk, your journey is uphill both ways. Now, let's not get into what rekuli thinks of material sciences and structural stresses. And, rekuli, I am very sorry to tell you this, but tin-can habs are not actually built out of tin cans. We're talking here about some pretty tough materials, with layers between the outer hull and the interior space. Those layers are also pretty thick, as they hold water pipes and tankage (clean water, gray water, sewage), recyclers and filters for the water, pumps for the water, power cables, fiberoptic cables for hardwired computer networks, air tanks, ventilation trunks, air pumps, air filters, you get my point. In a tin can, each can has all of these. Even in a cluster hab, each can is going to have, at the minimum, power, fiber optics and minimal life support equipment, even if they're not in the amount found in a tin can. (this is because cluster habs have dedicated cans for several life support functions). So, your bullet has a lot to punch through. Oh, let's get into the spin habs! All that equipment? It's between the floor and the outer hull. And did we mention the couple meters or so of dirt and such? Most spin habs have those for recreating an earth-like environment where plants grow around a lot. And don't get any fancy ideas about the windows or side walls. Engineers in EP planned for bullets and micrometeorite impacts. And that's why rekuli is an idiot: because they assumed that anybody would be willing to build a hab that can heavily damaged by a micrometeorite impact. What, you thought those things were rare?

So let us use a real world example of habitat puncture, shall we? Please explain to me how the Spektr module of the Mir space station remained un-crunched after its collision with the Kvant-1 module in 1997? Or how the rest of the station (which prior to the crews shutting of locks was open air to the Spektr module) also remained uncrunched?

[Raymond Terrific][B]All right boffins, LET'S GET THIS SORTED![/B][/Raymond Terrific] No, I have nothing useful to contribute.

rekuli wrote:

1: pressure decomposition inside an environment with external pressure that partly softens the depressurizing effects is completely different from compression into a vacuum, where suction is much stronger until the equilibrium is reached. If there is a vacuum involved, it does not matter if the pressure is 1 bar or 0.5 bar or 200 bar, the effects don't differ much.

You're right that the effects don't differ much. That's because the air flow at the hole will be capped at the speed of sound. And at the speed of sound (which at the hole will be lower due to lower air density in the hole), air isn't going to evacuate that quickly. A bullet sized hole will take over 30 minutes to drop the air pressure to 1/10th in a 10x10x10m space, as per the one-one-ten-hundred rule.

Quote:

Ever had a lab experiment where you had a pressurized tin can inside a vacuum and perforated the can? It crunches together.

I believe you're thinking of the experiment where you suck air out of a can and the atmospheric pressure crushes the can.

Quote:

2: if you stand on a moving surface and throw something in the air, or shoot, you move on along with the ground, while the item gathers its momentum from your throw and the momentum you had while throwing. So if you throw it spinward, the item will stay relatively close to you

No. If you throw something spinwards, the coriolis force will accelerate it downwards (in the rotating frame of course), but otherwise it will behave as if thrown in non-rotation frame.

rekuli wrote:

Momentum: If you look at physics of atmospheric friction and rotation momentum, there is the fact that a projectile in motion at an angle, no matter how small, to the spin direction takes a part of the spin into its movement and thus flies an elongated curve

I assume you mean drag, not friction. Friction is a part of drag, and not the most important factor. Most of the drag comes from having to push away the air the object is moving through. The coriolis effect is zero when moving parallel to the rotation axis, not the spin direction as you write.