 do lasers have recoil? |
  |
 Aug 24 2004, 09:23 PM
Post
#51
|
|
|
Shooting Target  Group: Members Posts: 1,665 Joined: 26-April 03 From: Sweden Member No.: 4,516  |
Anyone of the enlightened people here want to take a shot at this:
Imagine a combination of a regular rifle and a gauss rifle - a bullet is fired using normal explosion (causing recoil etc) and then accelerated using a coil along the barrel. And could recoil reduction be accomplished using the same coil/rail technology? (Replacing the spring in an automatic weapon with a rod and reverse coil that slows the firing rod down and then propels it back toward the next round? (And does anyone even understand what I mean?) :grinbig: |
 |
 
|
|
Aug 24 2004, 09:30 PM
Post
#52
|
|
|
Manus Celer Dei Group: Dumpshocked Posts: 17,013 Joined: 30-December 02 From: Boston Member No.: 3,802 |
It'd either be very energy-expensive or minimally useful.
~J |
|
|
|
|
Aug 24 2004, 09:34 PM
Post
#53
|
|
|
Immortal Elf Group: Members Posts: 11,410 Joined: 1-October 03 From: Pittsburgh Member No.: 5,670 |
errr... shut up, austere! you're stupid! shut up! (hah! i win.)
what would the utility be, snowRaven? i can't see any advantage to that, off-hand. |
|
|
|
|
Aug 24 2004, 09:50 PM
Post
#54
|
|
|
Target Group: Members Posts: 31 Joined: 23-August 04 Member No.: 6,583 |
Man, I leave for a couple hours, and this thread blows up...
Also, continuing the Star Wars blaster thing: My "Star Wars: The Essential Guide to Weapons and Technology" (Shut up, its old and I'm a nerd, I know) states that the blaster fires high energy particles in a 'bolt' (from the excited gas) and that the light is a 'harmless by-product" of the process. I could draw you a diagram if you wanted me to ;) But seriously, Thats just what this book said, and is a reason the bolts travel slower than the speed of light. Someone must have thought at one point: "Well, people will be more interested in these things if we call them 'recoilless rifles' instead of 'reduced-recoil rifles'" ;) |
|
|
|
|
Aug 24 2004, 10:34 PM
Post
#55
|
|
|
Street Doc Group: Admin Posts: 3,508 Joined: 2-March 04 From: Neverwhere Member No.: 6,114 |
Just to play the devils advocate (as if this debate needs another side) many physisists now believe that you can't apply classical physics (newtonian laws and whatnot) on a quantum scale (photons), because there is evidence that all kinds of screwy chaotic stuff takes place. For example, theres Quantum Tunneling (maybe not the best link) wherein a particle can pass through an energy field (or even solid masses) if the conditions are just so that it is more energetically favorable for the particle to be on the other side. And as far as gauss weapons go (bear with me... its been awhile since i took physics), is it possible that the magnetic coil could exsert force on the projectile in such a way that the recoil force (opposite and equal) occures at a tangential angle to the spiral? Over a very short time interval (miliseconds) this would effectively create recoil in all directions simultaneously (for all intents and purposes) which would cancel each other out for a net recoil force of zero. Just a thought.... |
|
|
|
|
Aug 24 2004, 10:42 PM
Post
#56
|
|
|
Moving Target Group: Members Posts: 942 Joined: 13-May 04 Member No.: 6,323 |
According to Newton's laws, the sum total of the forces in the system must be 0. Thus, the force out of the magnetic coils (the projectile's force) must be equal to the force going back (recoil). There's no way to just turn that force outwards.
JaronK |
|
|
|
|
Aug 24 2004, 10:48 PM
Post
#57
|
|
|
Manus Celer Dei Group: Dumpshocked Posts: 17,013 Joined: 30-December 02 From: Boston Member No.: 3,802 |
Unfortunately, you don't hit quantum mechanics with that sort of thing. The Newtonian model of physics is still very accurate at that scale.
~J |
|
|
|
|
Aug 24 2004, 11:28 PM
Post
#58
|
|||||
|
Running Target Group: Members Posts: 1,428 Joined: 9-June 02 Member No.: 2,860 |
It takes 3,624,433 kilowatts (3.6 gigawatts) of light to generate 5 pounds of thrust on a solar sail. I'm not going to lose sleep over the lack of recoil compensation in anything smaller than an 18 gigawatt laser.
No. If you shove mass forward, some mass will go backward. |
||||
|
|
|
||||
|
Aug 24 2004, 11:31 PM
Post
#59
|
|
|
Manus Celer Dei Group: Dumpshocked Posts: 17,013 Joined: 30-December 02 From: Boston Member No.: 3,802 |
Not if you stick two of them together :grinbig:
~J |
|
|
|
|
Aug 25 2004, 12:19 AM
Post
#60
|
|
|
Running Target Group: Members Posts: 1,049 Joined: 24-March 03 Member No.: 4,323 |
Mmmm... 18 gigawatt laser... tasty...
|
|
|
|
|
Aug 25 2004, 12:42 AM
Post
#61
|
|
|
Beetle Eater Group: Dumpshocked Posts: 4,797 Joined: 3-June 02 From: Oblivion City Member No.: 2,826 |
As Cray74 says, recoil from the beam will be minute. However, recoil from the generation process may not be. The three "plausible" methods of beam generation includes one that may cause recoil. This method involves jetting unimaginably highly compressed gasses though the resonator chamber which, according to the white paper I read, gives 90lbs of recoil per shot. Recent technology has shown we can generate a beam using "motionless" sealed gasses and RF instead of the typical turbine driven resonators. However, the sealed lasers have not yet gone beyond 600 watts. Turbine driven have reach over 1 mWatt and compressed gass lasers have supposedly gone beyond that. If you think SR lasers used compressed gass they may well have a recoil, and it requires a turbine to recompress the gasses. Both turbine and compressed also make noise.
I've always assumed SR lasers used an awakened rodent: pulling the trigger flips up the reflectors over its eyes and a laser beam shoots out. |
|
|
|
|
Aug 25 2004, 12:50 AM
Post
#62
|
|||
|
Target Group: Members Posts: 29 Joined: 15-August 04 From: Columbia, PA Member No.: 6,562 |
"There is no escaping. The bullet is enormous. Jumping is useless." |
||
|
|
|
||
|
Aug 25 2004, 12:51 AM
Post
#63
|
|||
|
panda! Group: Members Posts: 10,331 Joined: 8-March 02 From: north of central europe Member No.: 2,242 |
well there are 3 options, either the gun moves and the bullet stands still or the bullet moves and the gun stays still or they both moves according to mass. ie gun moves a small bit as more energy is needed to move the mass while the bullet goes flying as the same amount of energy work on less mass. while i belive that a gauss gun would have recoil it would not act in the same way as the recoil of a normal gun. rember that the force of an explotion pushes in all directions at the same time while a gauss gun works on the prinsiple of pulling and pushing at set times +-+-+-+-+-+ and so on. therefor the energy all works in one direction, the way the bullet is supposed to travel instead of the direction of least resistance (that happens to be the direction of the barrel in the case of a gun). there is allso the fact that in a normal handgun there is physical mass pushing while in a gauss setup its a electromagnetic effect so there isnt realy any physical object between the back of the gun and the bullet. except air that is :) (vacume would lead to insane amounts of air pressure acting on the bullet so there have to be ports so that air can be sucked in as the bullet travels)... there is allso the effect of the reload system on most propellant based guns to take into account as they work by useing some of the force to move parts of the gun. as those parts hit the end of thier movement the force will transfer to the gun proper and allso the fact that some of the mass of the gun have now moved into a diffrent posision, ever so slightly changeing the center of gravity of the gun (unless your fireing a revolver that is). this isnt that big a thing in a rifle but in a handgun that can play its part in the effects of recoil. so while recoil can be distilled down to newtons law i belive its not the whole picture. |
||
|
|
|
||
|
Aug 25 2004, 01:18 AM
Post
#64
|
|
|
Immortal Elf Group: Members Posts: 11,410 Joined: 1-October 03 From: Pittsburgh Member No.: 5,670 |
the main part of recoil still comes from newton's law. will there be a difference between the way a given gauss pistol and a given chem-propellant pistol handle recoil for a bullet of the same mass? yes, of course--but the difference isn't going to be much more than the difference between two different model chem-propellant pistols of the same caliber and load.
|
|
|
|
|
Aug 25 2004, 01:58 AM
Post
#65
|
|||||||||||
|
Running Target Group: Members Posts: 1,428 Joined: 9-June 02 Member No.: 2,860 |
The gases aren't compressed - they're just burned in a reactor not unlike a rocket engine. Selective redirection of the exhaust gases should cancel the issue. And SR lasers do not seem to produce clouds of toxic chlorine oxide (or whatever), so if they use a chemical approach, they don't vent at all and thus produce no (effective) recoil. As for "sealed lasers," multi-kilowatt welding lasers are off-the-shelf items, and the Navy has been playing around with 10kW free electron (Sealed) lasers.
No, there are not 3 options. If the gun moves as a result of reacting against the bullet, the bullet will move, too. And vice versa. Basically, there's only the third option: both recoil.
The multi-directional push of a gunpowder explosion is moot: most directions are canceled by equal and opposite pressure on the opposite side of the barrel. What ends up happening is that, like the gauss rifle, all that matters is that a mass (bullet+propellant gases) leave one end of the barrel, while the gun recoils in the opposite direction. The equations (see: conservation of momentum) are exactly the same in both situations, the difference being the velocity and mass spat out the barrel. That some gauss rifles might use an on/off means of propelling the projectile is also irrelevant to the total felt recoil. The triggering of the electromagnetics occurs so rapidly that even a wired human won't notice it - it'll be one shove, just like with a single-charge gunpowder weapon.
Irrelevant. The magnets push forward on the bullet while pushing back on the barrel. The net forces are basically the same: one mass goes forward, the other goes back. Trying to focus on little details like where the exchange of momentum occurs will just get you bogged down - as you are - in misleading details.
No, it's still M1V1 = M2V2. One mass goes one way, the other mass goes the other way. Details like how many masses are involved (separate recoil mechanisms, gun weights, projectile weights, etc.) and velocities are just details to be plugged into the same mechanism. Newton's laws do cover everything - you just need to plug them in correctly. |
||||||||||
|
|
|
||||||||||
|
Aug 25 2004, 02:21 AM
Post
#66
|
|||||
|
Beetle Eater Group: Dumpshocked Posts: 4,797 Joined: 3-June 02 From: Oblivion City Member No.: 2,826 |
SR lasers do not use up the gas, thus they cannot be that type of laser. They must be sealed or recycled. The gasses are not "burned," they work like a florescent light bulb and are excited by either RF or Electricity. The gas does not escape the laser and thus causes some kind of rocking motion as the gas shoots though the resonator chamber.
The first is not effective against organic matter, as SR lasers clearly are. I haven't heard of the second. |
||||
|
|
|
||||
|
Aug 25 2004, 02:29 AM
Post
#67
|
|
|
panda! Group: Members Posts: 10,331 Joined: 8-March 02 From: north of central europe Member No.: 2,242 |
hmm, i recall reading something about a particle "laser" ones. instead of light ut was useing atoms or molecules or something to create a beam.
there could be that the sr lasers are useing a diffrent part of the em spectrum, maybe microwaves to cook the target. what would the range of a microwave gun be? and i see now that i screwed up the stuff above, i dont know where i had my head when i typed it... |
|
|
|
|
Aug 25 2004, 02:48 AM
Post
#68
|
|
|
Moving Target Group: Members Posts: 128 Joined: 26-February 02 From: Winston Salem, NC Member No.: 1,359 |
Those would be particle accelerators. Accelerating electrons as a beam weapon. Not sure about the physics about that.
As far as Microwave, they use photons, and the term generally used for a microwave laser has been Maser in most sci-fi settings. It would have different properties as far as handling air density, humidity, and so on, but it is still a laser. |
|
|
|
|
Aug 25 2004, 03:57 AM
Post
#69
|
|||
|
Target Group: Members Posts: 51 Joined: 26-February 02 From: Reinbek, Germany Member No.: 72 |
The gun uses magnets or coils with electrical current running through them which basically function just as magnets at that moment. and magnetic force always works both ways - on the object you try to pull/push and on the magnet itself. So absolutely no difference to force-projection through solid levers or compressed gases or whatever - "actio = reactio" still stays in effect, has something to do with being a basic law of nature. @littlesean: microwave lasers are called Maser not only in SF settings but in RL as well. |
||
|
|
|
||
|
Aug 25 2004, 04:47 AM
Post
#70
|
|
|
Runner Group: Members Posts: 2,901 Joined: 19-June 03 Member No.: 4,775 |
As laser (Light Amplification by Stimulated Emission of Radiation, for the unfamiliar) is an acronym, you can swap out the L and replace it with any section of the electromagnetic spectrum. Actually doing it, of course, is another matter entirely.
|
|
|
|
|
Aug 25 2004, 04:56 AM
Post
#71
|
|
|
Manus Celer Dei Group: Dumpshocked Posts: 17,013 Joined: 30-December 02 From: Boston Member No.: 3,802 |
MASERs being the fundamental technology of the atomic clock, yeah, I'd say they've actually been done.
~J |
|
|
|
|
Aug 25 2004, 05:20 AM
Post
#72
|
|
|
Grand Master of Run-Fu Group: Dumpshocked Posts: 6,840 Joined: 26-February 02 From: Tir Tairngire Member No.: 178 |
IIRC, the guy who invented lasers was trying for a Maser in the first place, but gave up and went with light because it was easier.
|
|
|
|
|
Aug 25 2004, 05:49 AM
Post
#73
|
|
|
Target Group: Members Posts: 33 Joined: 7-August 04 From: Las Vegas, NV Member No.: 6,549 |
:cyber:
Take the energy output in J/s (joules per second) and divide by c^2 (speed of light, squared). The result of this calculation would be the equivilant mass of the energy being projected from the laser (photons have no rest-mass, so this is releative or effective mass only). Does this help? EDIT/ Example: Say you have a laser that outputs 10 kW of energy via LASER (aka, photons). 1 kW = 1,000 J 10,000 J / c^2 = 6.747E-14 kilograms /or/ 6.747E-2 picograms /or/ about 67 femtograms (Metric conversion may be wrong, I am more used to Imperial) (c (speed of light) = 385,000,000 km/s) ... Going with the weight given above (67 femto-grams), I can virtually garantee the recoil is un-noticable on a human scale. You would need something a lot more powerful to even start to have a pressure you could feel. This post has been edited by SunRunner: Aug 25 2004, 06:10 AM |
|
|
|
|
Aug 25 2004, 08:41 AM
Post
#74
|
|
|
Great Dragon Group: Members Posts: 5,889 Joined: 3-August 03 From: A CPI rank 1 country Member No.: 5,222 |
Could someone please clear up this issue: If you've got a 10kW laser, does that actually mean it generates 10kJ of kinetic energy per second through launching photons?
Anyway, either you typoed the speed of light, or your figures are screwed. c = 299,792,458 m/s |
|
|
|
|
Aug 25 2004, 09:03 AM
Post
#75
|
|||||
|
Target Group: Members Posts: 33 Joined: 7-August 04 From: Las Vegas, NV Member No.: 6,549 |
If it is a laser with a 10 kW input per second it has an output of 10 kJ per second; assuming perfect efficiency. I do not know of a laser that is 100% efficient, so I approximate.
My apologies. Let me re-run the numbers for you. 10 kJ output per second, divided by c^2 = 1.113E-13 kg of mass 1.113E-13 kilogram mass = 1.113E-1 picograms, or 11.13 femtograms of mass. I still garantee you will not feel the recoil from that. |
||||
|
|
|
||||
|
|
Lo-Fi Version | Time is now: 9th March 2026 - 10:56 PM |
Topps, Inc has sole ownership of the names, logo, artwork, marks, photographs, sounds, audio, video and/or any proprietary material used in connection with the game Shadowrun. Topps, Inc has granted permission to the Dumpshock Forums to use such names, logos, artwork, marks and/or any proprietary materials for promotional and informational purposes on its website but does not endorse, and is not affiliated with the Dumpshock Forums in any official capacity whatsoever.