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Akita T
Caldari Navy Volunteer Task Force
Posted - 2011.06.01 13:41:00 - [241]
 

Originally by: Furb Killer
And again you are ignoring the time factor that is a huge issue if you want to look at recoil.
Lets say your railgun is 50m in length, and you have a normal constant acceleration, then with your example shooting the railgun takes 0.1ms. (tbh longer than i expected). Now a laser in eve fires for several seconds, but lets say 1 second. Then we got another factor 10000 difference in force applied (which would cause the recoil). So from your factor 600 weaker we got to a factor 6 million times weaker. Which is completely negligble.

If you have 1 billion newtons force acting for 10 microsecons, or a 1 million newtons force acting for 10 milisecond, or a 1 thousand newton force acting for 0.1 seconds, as long as the COUNTER-RECOIL ELASTIC FORCES IN THE WEAPON MOUNTS ARE STILL NOTICEABLY SMALLER THAN THE FORCE OF THE RECOIL, the recoil will be very similar in look and feel in all those three cases.

Yeah, sure, if you have an extremely stiff mount, counter-recoil forces increase extremely fast as distance from "pre-fire position" increases, so you do need a rather large impulse delivered in the shortest time possible to generate a visible recoil, since the counter-force quickly increases, so the impulse dissipates very fast.
But if you have a very soft mount, even the tiniest impulse can generate a visible recoil, since the counter-forces build up much slower, dissipating the impulse at a much greater distance from the pre-fire position.

Nobody said the mounting springs of a railgun barrel have the same elasticity coefficient as the ones on a laser firing assembly - for all we know, if the springs are 600 times weaker, the recoil might be very well visually almost identical (the "build-up time" to max firing assembly recoil speed would differ, but not much else).

Daedalus II
Helios Research
Posted - 2011.06.01 13:41:00 - [242]
 

It could be like this:

Consider that there is significant heat created when firing the laser. This would heat the laser crystal, shifting its focus point. By quickly moving the turret backwards the same focus point is kept through the entire fire cycle even though the crystal gradually heats up.

I think that is an explanation as good as any Very Happy

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.01 16:15:00 - [243]
 

Originally by: Daedalus II
It could be like this:

Consider that there is significant heat created when firing the laser. This would heat the laser crystal, shifting its focus point. By quickly moving the turret backwards the same focus point is kept through the entire fire cycle even though the crystal gradually heats up.

I think that is an explanation as good as any Very Happy


apart from the fact that your suggesting your correcting the focus point of a laser shooting at sometimes over 200km by moving the barrel back 10~20 yards.

NinjaSpud
Posted - 2011.06.01 16:50:00 - [244]
 

Originally by: Akita T
Originally by: Furb Killer
And again you are ignoring the time factor that is a huge issue if you want to look at recoil.
Lets say your railgun is 50m in length, and you have a normal constant acceleration, then with your example shooting the railgun takes 0.1ms. (tbh longer than i expected). Now a laser in eve fires for several seconds, but lets say 1 second. Then we got another factor 10000 difference in force applied (which would cause the recoil). So from your factor 600 weaker we got to a factor 6 million times weaker. Which is completely negligble.

If you have 1 billion newtons force acting for 10 microsecons, or a 1 million newtons force acting for 10 milisecond, or a 1 thousand newton force acting for 0.1 seconds, as long as the COUNTER-RECOIL ELASTIC FORCES IN THE WEAPON MOUNTS ARE STILL NOTICEABLY SMALLER THAN THE FORCE OF THE RECOIL, the recoil will be very similar in look and feel in all those three cases.

Yeah, sure, if you have an extremely stiff mount, counter-recoil forces increase extremely fast as distance from "pre-fire position" increases, so you do need a rather large impulse delivered in the shortest time possible to generate a visible recoil, since the counter-force quickly increases, so the impulse dissipates very fast.
But if you have a very soft mount, even the tiniest impulse can generate a visible recoil, since the counter-forces build up much slower, dissipating the impulse at a much greater distance from the pre-fire position.

Nobody said the mounting springs of a railgun barrel have the same elasticity coefficient as the ones on a laser firing assembly - for all we know, if the springs are 600 times weaker, the recoil might be very well visually almost identical (the "build-up time" to max firing assembly recoil speed would differ, but not much else).


Interesting theory, Akita, but here's my problem with that:

You're ideas sound good until I put them on paper, I didn't see the anomaly until I tried to cross reference the Coefficient of Friction with the recoil...*HEAD VIOLENTLY EXPLODES*


Crewman Jenkins
Caldari
Malicious Demi-Lancers
Posted - 2011.06.01 16:55:00 - [245]
 

They don't have noticeable recoil, but they do have to retract the mechanism into a cooling chamber after every shot.

Akita T
Caldari Navy Volunteer Task Force
Posted - 2011.06.01 17:46:00 - [246]
 

Originally by: NinjaSpud
Interesting theory, Akita, but here's my problem with that:
You're ideas sound good until I put them on paper, I didn't see the anomaly until I tried to cross reference the Coefficient of Friction with the recoil...*HEAD VIOLENTLY EXPLODES*

Ah, come on, it's basic physics.

Impulse is speed difference time mass. I=Dv*m
Speed difference is acceleration multiplied by time that acceleration is applied. Dv=a*t
Acceleration is total force applied divided by mass. a=F/m
Total force is the sum of all forces acting on the object - in this case, the object is a firing assembly, and there are two big sets of forces acting on it in opposite directions : the recoil force (from propelling something forward, be it an explosively fired projectile, a stream of particles, a beam of photons) and the counter-recoil force (initially static then dynamic friction with any bearings or similar limiting/guidance devices and a constantly increasing resistance from the spring assemblies which dampen the recoil the farther away from the initial position it goes).

What we know is the most likely value for the total impulse imparted on the firing assembly by the firing of stuff.
What we don't know is the time in which that impulse is being discharged, nor the mass of the firing assembly, which means we don't have a clue as to the force being applied on the firing assembly. We also don't know how high or low any frictional forces inside the recoiling firing assembly might be, be it initially or afterwards. We don't even know the elasticity coefficient of the springs for the counter-recoil mechanism which brings the firing assembly back in position after the shot.
Even if we make educated guesses regarding the time of the shot and the mass of the recoiling firing assembly, and even if we neglect any friction forces, we still don't know how rigid the springs are, which means we can't know for sure how much distance does the barrel recoil, and depending on that, it could recoil like crazy or it could barely budge.

Ghoest
Posted - 2011.06.01 18:04:00 - [247]
 

Originally by: Akita T
Originally by: NinjaSpud
Interesting theory, Akita, but here's my problem with that:
You're ideas sound good until I put them on paper, I didn't see the anomaly until I tried to cross reference the Coefficient of Friction with the recoil...*HEAD VIOLENTLY EXPLODES*

Ah, come on, it's basic physics.

Impulse is speed difference time mass. I=Dv*m
Speed difference is acceleration multiplied by time that acceleration is applied. Dv=a*t
Acceleration is total force applied divided by mass. a=F/m
Total force is the sum of all forces acting on the object - in this case, the object is a firing assembly, and there are two big sets of forces acting on it in opposite directions : the recoil force (from propelling something forward, be it an explosively fired projectile, a stream of particles, a beam of photons) and the counter-recoil force (initially static then dynamic friction with any bearings or similar limiting/guidance devices and a constantly increasing resistance from the spring assemblies which dampen the recoil the farther away from the initial position it goes).

What we know is the most likely value for the total impulse imparted on the firing assembly by the firing of stuff.
What we don't know is the time in which that impulse is being discharged, nor the mass of the firing assembly, which means we don't have a clue as to the force being applied on the firing assembly. We also don't know how high or low any frictional forces inside the recoiling firing assembly might be, be it initially or afterwards. We don't even know the elasticity coefficient of the springs for the counter-recoil mechanism which brings the firing assembly back in position after the shot.
Even if we make educated guesses regarding the time of the shot and the mass of the recoiling firing assembly, and even if we neglect any friction forces, we still don't know how rigid the springs are, which means we can't know for sure how much distance does the barrel recoil, and depending on that, it could recoil like crazy or it could barely budge.


No gun with a spring is going to be with out a damper. And chances are there wont be a spring. More probable is either a pneumatic type, or even magnetic, system to reset the gun.




Akita T
Caldari Navy Volunteer Task Force
Posted - 2011.06.01 18:18:00 - [248]
 

Edited by: Akita T on 01/06/2011 18:33:54
Originally by: Ghoest
No gun with a spring is going to be with out a damper. And chances are there wont be a spring. More probable is either a pneumatic type, or even magnetic, system to reset the gun.

It doesn't really matter what device it uses for the "spring action", the equivalent mechanical device is some form of spring either way.
The important thing is that the "spring-like device(s)" acts with a certain force in the opposite direction.

LHA Tarawa
Posted - 2011.06.01 18:28:00 - [249]
 

I am not going to read the whole thread to see if anyone else has pointed it out....

Momentum = mass * velocity is a simplified version of the formula. Remember, that mass and energy are interchangable using the formula E = m * C ^ 2 where C is the speed of light.

Using the energy version of the formula for momentum, we see that indeed massless energy in the form of electormagnetic radiation (light) does have momentum.

The law of conservation of momentum states that if you are sending a large amount of momentum off in one direction (whether that be mass based momentum, or pure energy based momentum) you must have equal and opposite momentum. Call it recoil if you choose to.


polerbear
Posted - 2011.06.01 18:28:00 - [250]
 

Originally by: Mister Smithington

No, they're definitely recoiling.

Here's an attempt at an explanation:
When the Amarrian engineers were designing the laser systems for their ships, they realized they would look so much cooler with a "recoil" effect. So they built them with a mechanism that pulls the barrel back to make it look like it's recoiling. Because, I mean, God damn! Look at it. It's awesome.

Dang, beat me to it - without doubt it was jealousy that made them PUT a recoil-simulating-mechanism into the turrets.

Akita T
Caldari Navy Volunteer Task Force
Posted - 2011.06.01 18:36:00 - [251]
 

Originally by: polerbear
Dang, beat me to it - without doubt it was jealousy that made them PUT a recoil-simulating-mechanism into the turrets.

They only need to have very light firing assemblies with very weak springs, and the photons themselves provide the recoil force, no need to simulate anything Razz

Ghoest
Posted - 2011.06.01 19:51:00 - [252]
 

Edited by: Ghoest on 01/06/2011 19:52:17
Originally by: Akita T
Edited by: Akita T on 01/06/2011 18:33:54
Originally by: Ghoest
No gun with a spring is going to be with out a damper. And chances are there wont be a spring. More probable is either a pneumatic type, or even magnetic, system to reset the gun.

It doesn't really matter what device it uses for the "spring action", the equivalent mechanical device is some form of spring either way.
The important thing is that the "spring-like device(s)" acts with a certain force in the opposite direction.


Well if you have a damper involved(Which you will) the resetting mechanism can be unrelated to the firing action.

Daedalus II
Helios Research
Posted - 2011.06.01 22:24:00 - [253]
 

Originally by: Soden Rah
Originally by: Daedalus II
It could be like this:

Consider that there is significant heat created when firing the laser. This would heat the laser crystal, shifting its focus point. By quickly moving the turret backwards the same focus point is kept through the entire fire cycle even though the crystal gradually heats up.

I think that is an explanation as good as any Very Happy


apart from the fact that your suggesting your correcting the focus point of a laser shooting at sometimes over 200km by moving the barrel back 10~20 yards.

And you of course know that future laser crystals will change their focus point more than 10-20 yards when they get hot? A change of 20 yards (which I think is a bit excessive btw) over 200 km would result in roughly 0.01% change in the focus point when the laser crystal gets hot. Sounds reasonable enough I think, given that we're wildly speculating.

This is so speculative it's just stupid Very Happy

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.01 22:37:00 - [254]
 

Originally by: Daedalus II
Originally by: Soden Rah
Originally by: Daedalus II
It could be like this:

Consider that there is significant heat created when firing the laser. This would heat the laser crystal, shifting its focus point. By quickly moving the turret backwards the same focus point is kept through the entire fire cycle even though the crystal gradually heats up.

I think that is an explanation as good as any Very Happy


apart from the fact that your suggesting your correcting the focus point of a laser shooting at sometimes over 200km by moving the barrel back 10~20 yards.

And you of course know that future laser crystals will change their focus point more than 10-20 yards when they get hot? A change of 20 yards (which I think is a bit excessive btw) over 200 km would result in roughly 0.01% change in the focus point when the laser crystal gets hot. Sounds reasonable enough I think, given that we're wildly speculating.

This is so speculative it's just stupid Very Happy


The trouble is that the focal 'point' is simply the place at which the beam width is minimised and the energy density per unit area is maximised. At the kind of ranges at which these lasers operate the focal 'point' from all practical perspectives will be of the order of kilometres long. Thus recoiling a few yards will have absolutely no impact, and would in fact make holding the beam on the same location on the target hull (far more important) harder.

Andr Katelo
Caldari
Dromedaworks inc
Test Alliance Please Ignore
Posted - 2011.06.01 22:51:00 - [255]
 

Edited by: Andr Katelo on 01/06/2011 22:51:45
When the Stormtroopers fired they rifles, they seemed to feel the kick.
The Protoss recoiled after firing photon based energy projectiles.
Phasers set to "****" seemed to push even Worf's hand back.

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.01 23:01:00 - [256]
 

Originally by: Andr Katelo
When the Stormtroopers fired they rifles, they seemed to feel the kick.
The Protoss recoiled after firing proton based energy projectiles.
Phasers set to "****" seemed to push even Worf's hand back.


That's cos the Stormtroopers rifles were actual guns with blanks in them, (as opposed to the 'new' star wars films where they went all CG which is why they look rubbish.) made by a firm on the outskirts of London. Who have a little museum with famous weapons that have appeared in film's that they made, Blades steak gun, Sigorny weavers pulse rifle (alien), And in a little glass cabernet by the entrance, that you miss on your way in, Han solo's original blaster (A WW2 Luger with bits stuck on)... I geeked out sooo much. And that was 'before' the behind the scenes tour of the workshop where they were working on the actual working guns. "This is Harrison Fords revolver he uses in Indiana Jones... these are Pierce Brosnen's guns from the latest bond film... This is the Bonds original walta ppk... That was a good day... Anyhow what were we talking about?

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.01 23:22:00 - [257]
 

Originally by: CCP Spitfire
Good question, actually. I'll check with the storyline team and get back to you; meanwhile a quick search (but please do not take it as an "official" answer) suggests that sci-fi laser weapons may indeed have recoil according to the conventional laws of physics.




BTW is anyone at CCP still watching this thread?
And has storyline had any brainwaves on the subject?
Just as you said you would get back to us Razz Wink

I personally would recommend going with something along the lines of...
"The recoil force is enough to distort the adaptive optics inside the laser and so the gun housing recoils to lessen that stress allowing for more accurate targeting and focusing."

Thus also explaining why the turret is so light, if it was heavier it wouldn't recoil enough to protect the optics.

Diomedes Calypso
Aetolian Armada
Posted - 2011.06.01 23:28:00 - [258]
 

I heard that if your used a rail gun to hurl a concrete telephone pole at the earth from the moon you'd make a crater of destucion on the scale of an asteroid and subsequent particle cloud enough to change the earth's weather for 50 years.

(or maybe I mixed up two stories)

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.01 23:41:00 - [259]
 

Originally by: Diomedes Calypso
I heard that if your used a rail gun to hurl a concrete telephone pole at the earth from the moon you'd make a crater of destucion on the scale of an asteroid and subsequent particle cloud enough to change the earth's weather for 50 years.

(or maybe I mixed up two stories)


If you used a mass driver of great enough power you could impart enough energy to the mass being fired to deal that kind of damage. However to fire a projectile with enough energy to replicate the KT event, you would have to generate at least that much energy (assuming rail gun 100% efficient, whereas efficiency likely to realistically be significantly less than 50%) and channel it all into your coil(no rails would be able to handle the power) gun.
Thus you need a gun capable of handling energys in the order of tens of thousands of times the total destructive power of every single one of the planets nuclear weapons detonating at once. To build such a weapon on the moon would likely require the coil gun to loop completely around the moon (thus requiring incredibly powerful magnets thus using even more power), and require more power than the entire current power generating capability of the planet by orders of magnitude.

So while you could make a coil gun that powerful, it would be simpler to deflect an actual asteroid of the required size onto a collision course, and just sit back and watch.

Ghoest
Posted - 2011.06.01 23:58:00 - [260]
 

Originally by: Soden Rah
Han solo's original blaster (A WW2 Luger with bits stuck on)...


It was a Broom Handle Mauser, not a Luger. And it was primarily a WW 1 weapon.

LHA Tarawa
Posted - 2011.06.02 16:01:00 - [261]
 

Originally by: Soden Rah
If you used a mass driver of great enough power you could impart enough energy to the mass being fired to deal that kind of damage. However to fire a projectile with enough energy to replicate the KT event, you would have to generate at least that much energy (assuming rail gun 100% efficient, whereas efficiency likely to realistically be significantly less than 50%) and channel it all into your coil(no rails would be able to handle the power) gun.


Wrong.

The beauty of a mass driver is that the object you would be hurling already has its own energy in the form of potential and kinetic energy.

If you grab a rock in space that is already orbiting a planet, then just alter its trajectory enough that it falls out of orbit, its current kinetic energy plus the potential energy converted to kinetic as it accelerates toward the planet due to gravity... Well... Boom.

stoicfaux
Gallente
Posted - 2011.06.02 16:35:00 - [262]
 

Originally by: Diomedes Calypso
I heard that if your used a rail gun to hurl a concrete telephone pole at the earth from the moon you'd make a crater of destucion on the scale of an asteroid and subsequent particle cloud enough to change the earth's weather for 50 years.

(or maybe I mixed up two stories)


At 0.1c It would probably burn up in the atmosphere and explode with 0.19 megatons of force.

Asteroid Impact Calculator


Hauling Hal
The Black Ops
Posted - 2011.06.02 22:21:00 - [263]
 

I reckon the guns recoil to put the barrel in coolant as it gets so hot.

'nuff said.

Yuki Kulotsuki
Posted - 2011.06.02 22:41:00 - [264]
 

This thread. Rolling Eyes

What's next? Airplanes on a treadmill? Everyone knows that the reason the Earth has an elliptical orbit is because the suns rays are pushing it further out during the summer. So of course lasers will have recoil.

Nuhm DeAra
Posted - 2011.06.02 23:08:00 - [265]
 

Originally by: Calathea Sata
stupider.


Even though it was added to the dictionary a little over a decade ago, it still doesn't make you sound intelligent.

Jeune
The Scope
Posted - 2011.06.02 23:27:00 - [266]
 

Assuming the lens is at the tip of the barrel.... maybe it's not recoil. Perhaps it's just changing focus for one of the following reasons:

~ To compensate for material between the lens and the target
~ It's a two-stage laser... stage 1 for target verification laser, stage 2 for primary beam.

Both of these are currently used in present day weapons in development, though usually it's the mirror that adjusts to compensate for air density changes not the lens. Yes, I know there's no atmosphere in space, but it's not totally devoid of matter either.

~ Jeune

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.03 00:33:00 - [267]
 

Originally by: LHA Tarawa
Originally by: Soden Rah
If you used a mass driver of great enough power you could impart enough energy to the mass being fired to deal that kind of damage. However to fire a projectile with enough energy to replicate the KT event, you would have to generate at least that much energy (assuming rail gun 100% efficient, whereas efficiency likely to realistically be significantly less than 50%) and channel it all into your coil(no rails would be able to handle the power) gun.


Wrong.

The beauty of a mass driver is that the object you would be hurling already has its own energy in the form of potential and kinetic energy.

If you grab a rock in space that is already orbiting a planet, then just alter its trajectory enough that it falls out of orbit, its current kinetic energy plus the potential energy converted to kinetic as it accelerates toward the planet due to gravity... Well... Boom.



The object you suggested firing was the size of a lamp post.
The KT event was caused by an object the size of mount Everest.
To give the lamp post the same energy as the mountain, It has to go faster...
MUCH faster...
and that speed will not come from Earth or even the Sun's gravitational well.
So you have to impart almost all of it yourself, which takes energy...
and we get back to my original post.

Also a mass driver is just another name for coil gun,
(rail guns don't cut the mustard at high energies... the rails vaporise)
and while shooting down into Earth's gravity well will speed up the inbound projectile
(by up to a max of 11km/s) the velocity required for a lamppost sized lump of mater to rival the KT event is so much larger than that, that its pretty much irrelevant.

Soden Rah
Gallente
EVE University
Ivy League
Posted - 2011.06.03 00:40:00 - [268]
 

Edited by: Soden Rah on 03/06/2011 00:50:07
Originally by: stoicfaux
Originally by: Diomedes Calypso
I heard that if your used a rail gun to hurl a concrete telephone pole at the earth from the moon you'd make a crater of destucion on the scale of an asteroid and subsequent particle cloud enough to change the earth's weather for 50 years.

(or maybe I mixed up two stories)


At 0.1c It would probably burn up in the atmosphere and explode with 0.19 megatons of force.

Asteroid Impact Calculator




The velocities required to make a lamppost (I simplified to 3 meter wide sphere) hit with the energies required to simulate the KT event are relativistic... and that website doesn't use relativistic equations to calculate impact yield.

EDIT: I know this cos if you put in a speed of 299700km/s (99.9691593%c) it still only gives an impact of 1.21exp6 MT TNT which is big I grant you but not in the same league as the KT event.

Meldorn Vaash
Caldari
Posted - 2011.06.03 01:06:00 - [269]
 

*Blink*

I think I just found the epicenter of high level nerd pvp!!! Shocked

So long as it looks cool, does it really matter what the math says?

Carry on...

Tippia
Caldari
Sunshine and Lollipops
Posted - 2011.06.03 12:33:00 - [270]
 

Originally by: Yuki Kulotsuki
This thread. Rolling Eyes

What's next? Airplanes on a treadmill? Everyone knows that the reason the Earth has an elliptical orbit is because the suns rays are pushing it further out during the summer. So of course lasers will have recoil.
You forgot standing an egg on the spring equinox!

But yes, of course lasers have recoil.


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