His_Most_Royal_Highass_Donkey
07/25/08 09:01 PM
70.0.222.238
|
I have been thinking about something.
Why does machine guns and flamers not have the -2 to hit like pulse lasers do?
OK you may now start dumping on me again.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
07/26/08 12:38 PM
157.157.83.10
|
Hm, let's see..
Game balance
And the fact those two don't work like pulse lasers do
Yup, that would be reason enough for me.
|
Cray
07/26/08 04:00 PM
68.205.198.74
|
Quote:
I have been thinking about something.
Why does machine guns and flamers not have the -2 to hit like pulse lasers do?
Because pulse lasers and machine guns have different mechanisms. Pulse lasers are not "machine gun lasers."
Non-pulse lasers are already the epitome of "point and shoot" weaponry. You don't need to give your target any "lead" for their movement; the laser burst is instantaneous or nearly so (so you as soon as your laser briefly lines up with the target, you can fire and hit); there's no time-of-flight delays or ballistic arcs to compensate. Point and shoot.
But lasers still "miss." A problem with even welding lasers (to say nothing of battlefield, armor-blasting lasers) is that they deliver energy so quickly, the thinnest surface layers of the target burn off first and form a light-absorbing plasma that prevents the laser from continuing to burn into the target. So, a lot of the time, they'll find their energy wasted literally burning off the paint.
Pulse lasers, though, give that plasma a chance to disperse, so each subsequent pulse can burn away fresh armor. Pulse lasers are much more likely to dig into armor than standard lasers. Hence, a -2 to-hit bonus.
Machine guns are entirely different. In the time it takes to get one bullet out the barrel of an MG, a pulse laser (or standard laser) could be done with their burst(s) of light. That a machine gun sprays a bunch of bullets doesn't make it light a pulse laser at all. MGs have their own targeting problems, like getting enough damage in one spot for their small (20-30mm) bullets to dig into the magical materials of 'Mech armor.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
|
His_Most_Royal_Highass_Donkey
07/26/08 10:06 PM
70.6.6.6
|
Quote:
Quote:
I have been thinking about something.
Why does machine guns and flamers not have the -2 to hit like pulse lasers do?
Because pulse lasers and machine guns have different mechanisms. Pulse lasers are not "machine gun lasers."
Non-pulse lasers are already the epitome of "point and shoot" weaponry. You don't need to give your target any "lead" for their movement; the laser burst is instantaneous or nearly so (so you as soon as your laser briefly lines up with the target, you can fire and hit); there's no time-of-flight delays or ballistic arcs to compensate. Point and shoot.
But lasers still "miss." A problem with even welding lasers (to say nothing of battlefield, armor-blasting lasers) is that they deliver energy so quickly, the thinnest surface layers of the target burn off first and form a light-absorbing plasma that prevents the laser from continuing to burn into the target. So, a lot of the time, they'll find their energy wasted literally burning off the paint.
Pulse lasers, though, give that plasma a chance to disperse, so each subsequent pulse can burn away fresh armor. Pulse lasers are much more likely to dig into armor than standard lasers. Hence, a -2 to-hit bonus.
Machine guns are entirely different. In the time it takes to get one bullet out the barrel of an MG, a pulse laser (or standard laser) could be done with their burst(s) of light. That a machine gun sprays a bunch of bullets doesn't make it light a pulse laser at all. MGs have their own targeting problems, like getting enough damage in one spot for their small (20-30mm) bullets to dig into the magical materials of 'Mech armor.
Is that from some source book or just your opinion? That explanation is so full of holes one can fly a jump ship though it with its solar sails deployed. Lafeel's answer was better.
Quote from Battletech Compendium page 120
The pulse laser uses a raped-cycling, high energy pulse to generate multiple laser beams, creating an effect comparable to machine gun fire.
Since that book says that pulse lasers act like machine guns, machine guns should act like pulse lasers. aka the -2 to hit.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
07/26/08 10:27 PM
157.157.83.10
|
Nope, if only for the game balance bit. The machine guns would be too good if you did that, they already are the most heat efficient weapon out there (the only battlemech weapon in the entire game with a heat of 0)
|
His_Most_Royal_Highass_Donkey
07/26/08 10:48 PM
70.6.6.6
|
Ya, but who gets that close for them to be used? How often do you get that close to an enemy mech?
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
07/26/08 10:58 PM
157.157.83.10
|
Now that would depend on how you play your cards, would it not? After all machine guns do their best work on very fast mech's, or battle armor.
Fast 'mech+ stealth armor+ a gaggle of machine guns=not a nice combination.
|
His_Most_Royal_Highass_Donkey
07/26/08 11:13 PM
70.6.6.6
|
I like staying at range. Its easier to wipe out light mechs that way.
Not that my personal mech is at all bad with being in point blank range. 10 med lasers with 16 double heat sinks ant something to take lightly.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
07/26/08 11:16 PM
157.157.83.10
|
Nope, but neither is the to hit penalty to try to hit a foe that just moved 10 hexes or more.
|
His_Most_Royal_Highass_Donkey
07/26/08 11:20 PM
70.6.6.6
|
With 10 lasers theres a good chance that one or two will hit. And with some light mechs thats all that is needed.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
07/26/08 11:25 PM
157.157.83.10
|
Indeed, but we have gone somewhat off topic again, haven't we?
|
His_Most_Royal_Highass_Donkey
07/26/08 11:33 PM
70.6.6.6
|
I do have a problem of doing that.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Greyslayer
07/30/08 07:31 PM
216.14.198.53
|
Quote:
Hm, let's see..
Game balance
Not really much of an issue. 1 or 2 MGs are very much useless on most mechs and are rather an ammo explosion waiting to happen. Apart from the Pirannah which fields many many MGs the weapon is far from worthy of mention though I am yet to try MG arrays yadda yadda yadda.
|
Cray
08/01/08 11:16 PM
68.205.198.74
|
Quote:
Quote:
Quote:
I have been thinking about something.
Why does machine guns and flamers not have the -2 to hit like pulse lasers do?
Because pulse lasers and machine guns have different mechanisms. Pulse lasers are not "machine gun lasers."
Non-pulse lasers are already the epitome of "point and shoot" weaponry. You don't need to give your target any "lead" for their movement; the laser burst is instantaneous or nearly so (so you as soon as your laser briefly lines up with the target, you can fire and hit); there's no time-of-flight delays or ballistic arcs to compensate. Point and shoot.
But lasers still "miss." A problem with even welding lasers (to say nothing of battlefield, armor-blasting lasers) is that they deliver energy so quickly, the thinnest surface layers of the target burn off first and form a light-absorbing plasma that prevents the laser from continuing to burn into the target. So, a lot of the time, they'll find their energy wasted literally burning off the paint.
Pulse lasers, though, give that plasma a chance to disperse, so each subsequent pulse can burn away fresh armor. Pulse lasers are much more likely to dig into armor than standard lasers. Hence, a -2 to-hit bonus.
Machine guns are entirely different. In the time it takes to get one bullet out the barrel of an MG, a pulse laser (or standard laser) could be done with their burst(s) of light. That a machine gun sprays a bunch of bullets doesn't make it light a pulse laser at all. MGs have their own targeting problems, like getting enough damage in one spot for their small (20-30mm) bullets to dig into the magical materials of 'Mech armor.
Is that from some source book or just your opinion?
Interesting question. It's from pg226 of the Tech Manual, but pg226 of Tech Manual codifies my research into older canon and some research into lasers (both welding and military). If you looking into the keyholing effects of welding lasers, you'll see where I was coming from when Tech Manual was written.
Quote:
That explanation is so full of holes one can fly a jump ship though it with its solar sails deployed. Lafeel's answer was better.
As you like. How do you explain the reaction of light to plasma in a laser welding "keyhole" if my explanation doesn't work? And what do you think of the canon explanation of pulse lasers' performance in the Blood of Kerensky trilogy, where the chance to disperse ablation products factors highly in their accuracy?
Quote:
Quote from Battletech Compendium page 120
But how did the "Blood of Kerensky" trilogy explain the accuracy of pulse lasers before the Compendium was printed? And how did the Tech Manual reprint that old canon?
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
|
His_Most_Royal_Highass_Donkey
08/01/08 11:34 PM
68.26.156.30
|
I know how lasers work. A pulse laser would be no more accurate than a standard laser. Also the reason that lasers are not used as weapons is that fact that they can be reflected away from a target way to easily doing no damage. About the only use they are on a battle field is rendering people blind. And that is ageist international law.
As for the books "Blood of Kerensky" its been some years since I read them. I vaguely remember the plot let alone some finite detail.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Cray
08/01/08 11:56 PM
68.205.198.74
|
Quote:
I know how lasers work.
And yet you're talking about the reflection of battlefield lasers. Once again, I strongly urge you to look into the laser-absorbing behavior of plasmas in high energy laser welding. The keyhole effect pretty much explains how BT lasers work.
Quote:
A pulse laser would be no more accurate than a standard laser. Also the reason that lasers are not used as weapons is that fact that they can be reflected away from a target way to easily doing no damage.
Lasers of sufficient strength to burn armor do not "reflect" off targets unless they are absolutely clean (class 1000+ clean room), perfectly optimized mirrors for that wavelength of laser light.
The paint jobs of BattleTech war machines are neither sufficiently clean, sufficiently mirrored, or correctly optimized for all laser wavelengths to reflect battlefield lasers.
A little haze of battlefield dust on a target's surface is enough to absorb the leading edge of a laser beam, generate a light-absorbing plasma, and end all thoughts of "reflection" from a target's surface. You end up with a ferocious surface explosion that doesn't really care how perfectly mirrored the target's surface is.
Battlefield lasers are not laser pointers - they are machines that deliver so much heat that even 99.99% reflection means enormous heating, sufficient heating to destroy the reflection properties of the target. It also means a serious surface explosion - basic undergraduate thermodynamics. Look up what happens when you deliver more than 100,000 joules per second per square centimeter to...well, pretty much any substance. "Reflection" is not the correct word. Neither is "melting" or "evaporation." Only "explosion" suffices.
When you get done researching welding lasers, keyholes, and plasma laser absorbtion, you should better understand why pulse lasers have an advantage in accuracy.
Quote:
As for the books "Blood of Kerensky" its been some years since I read them. I vaguely remember the plot let alone some finite detail.
The Compendium gave the extremely dumbed-down, sensationalized cinematic version of pulse lasers that the Blood of Kerensky captured more accurately. Tech Manual took the time to do its home work.
"The pulse laser uses rapid-cycling, high-energy pulses to generate multiple
laser beams, creating an effect comparable to machine-gun fire. But
because the staggered pulses give the protective ablation products from
combat armor a chance to disperse—to expose fresh armor to subsequent
pulses—the result is a burst of fire that is more effective and accurate." --p. 225 TM
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Edited by Cray (08/02/08 12:24 AM)
|
His_Most_Royal_Highass_Donkey
08/02/08 01:59 AM
68.26.156.30
|
Quote:
And yet you're talking about the reflection of battlefield lasers. Once again, I strongly urge you to look into the laser-absorbing behavior of plasmas in high energy laser welding. The keyhole effect pretty much explains how BT lasers work.
Thats in a controlled environment not a battle field.
Quote:
Lasers of sufficient strength to burn armor do not "reflect" off targets unless they are absolutely clean (class 1000+ clean room), perfectly optimized mirrors for that wavelength of laser light.
The paint jobs of BattleTech war machines are neither sufficiently clean, sufficiently mirrored, or correctly optimized for all laser wavelengths to reflect battlefield lasers.
A little haze of battlefield dust on a target's surface is enough to absorb the leading edge of a laser beam, generate a light-absorbing plasma, and end all thoughts of "reflection" from a target's surface. You end up with a ferocious surface explosion that doesn't really care how perfectly mirrored the target's surface is.
The same happens with dust in the air it absorbs the heat generated by the beam. But that still does not increase the accuracy. All you need to do is throw up a lot of smoke or dust both of which are quite plentiful on battle fields and the laser is stopped.
Quote:
Battlefield lasers are not laser pointers - they are machines that deliver so much heat that even 99.99% reflection means enormous heating, sufficient heating to destroy the reflection properties of the target. It also means a serious surface explosion - basic undergraduate thermodynamics. Look up what happens when you deliver more than 100,000 joules per second per square centimeter to...well, pretty much any substance. "Reflection" is not the correct word. Neither is "melting" or "evaporation." Only "explosion" suffices.
When the first damaging lasers are being built for the battle field. Armor to stop it will also be developed. Why do you think we have no battle field damaging lasers today? We know that countermeasures will be developed at the same time and lasers will. So lasers will be rendered useless. If that was not the case we would have battle field damaging lasers today. No one wants to wast the money on pointless weapon technology.
Quote:
When you get done researching welding lasers, keyholes, and plasma laser absorbtion, you should better understand why pulse lasers have an advantage in accuracy.
Any movement of the weapon or target that will give the laser fresh armor to absorb it. To really increase accuracy you will need a laser that stays active for long periods of time. *Correct human error* That will do one of two things you need to have a laser creating a great amount of heat and power use over a short burst laser. Which in game terms does not do if it did pulse lasers would generate hundreds of heat points for the heat sinks to get rid of. Or do a great amount of lesser damage. Pulsing does nothing to help anything. In truth it hurts. A long steady beam would help the most in hitting. Again correcting human error. but at the cost of damage. You will over heat the laser its self if it stayed on. A very short burst would be the most efficient to do damage. So you can have one but not both. accuracy or penetrating damage.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Cray
08/02/08 11:17 AM
68.205.198.74
|
Quote:
That will do one of two things you need to have a laser creating a great amount of heat and power use over a short burst laser. Which in game terms does not do if it did pulse lasers would generate hundreds of heat points for the heat sinks to get rid of.
The energy transfer rate of any laser sufficiently powerful to damage metal is way beyond mere melting and thermal conduction limits. A battlefield laser's discharge will be done and over before heat soaks through armor to the heat sinks. The surface armor will be ablated before the heat reaches the heat sinks.
Again, PLEASE, look up what happens when you deliver more than 100,000 joules per second per square centimeter to...well, pretty much any substance. If you're thinking in terms of melting and heat conduction then you need to update your thermodynamics information. Those are very slow processes compared to the energy input rates battlefield lasers deliver.
Quote:
Quote:
And yet you're talking about the reflection of battlefield lasers. Once again, I strongly urge you to look into the laser-absorbing behavior of plasmas in high energy laser welding. The keyhole effect pretty much explains how BT lasers work.
Thats in a controlled environment not a battle field.
I did not mean keyholes formed on battlefield armor targets. I was asking you to brush on your basic thermodynamics of very high energy transfer rates and the interaction of lasers with the plasmas they generates. Keyholes in laser welding have some handy descriptions of all that in one place and are a good start for understanding battlefield lasers. Actually, so is laser peening. I gave you a direct link on peening below.
If you'd prefer the more academic approach to deciphering high energy, high power lasers and the ablation/surface explosions they generate, look into "Thermodynamics: An Engineering Approach," 4th ed., by Cengel. Chapter 2 (subsections on phase changes) and Chapter 3 (Energy transfer) will get you about where you need to be. I'll dig up my heat transfer notes Sunday or Monday if you want some more specific example home work problems to learn this stuff.
Quote:
The same happens with dust in the air it absorbs the heat generated by the beam.
The difference is dust is not backed by solid, opaque armor. A few motes of dust in the air do not have sufficient mass to absorb the whole beam that's going to burn off 62.5kg of armor per point of damage, and the products of superheated air disperse without an armor wall to trap them (leading, btw, very neatly to plasma dispersion advantages of pulse lasers - they can strobe smoke and fog out of the way before the beam's spent).
Quote:
Quote:
Battlefield lasers are not laser pointers - they are machines that deliver so much heat that even 99.99% reflection means enormous heating, sufficient heating to destroy the reflection properties of the target. It also means a serious surface explosion - basic undergraduate thermodynamics. Look up what happens when you deliver more than 100,000 joules per second per square centimeter to...well, pretty much any substance. "Reflection" is not the correct word. Neither is "melting" or "evaporation." Only "explosion" suffices.
When the first damaging lasers are being built for the battle field. Armor to stop it will also be developed. Why do you think we have no battle field damaging lasers today?
Because we can only build weak lasers. The giant USAF Airborne Laser mounted on a 747 only delivers 1 megawatt, 1 megajoule per second. 1 megajoule per second will take minutes to burn through a sheet of armor steel. The BT small laser delivers *at least* 185 megajoules (based on the mass of armor it ablates), preferably in a burst of much less than a second.
I mean, when your best laser, the end product of decades of chemical laser development, fills a 747, burdens a 747 with its ammo load for just 20 shots, and would only burn the paint off an Abrams' nose, I think the answer to why there's a lack of battlefield lasersis pretty clear: we don't have the technology to build a laser powerful enough to defeat armor in 2008AD.
Quote:
Any movement of the weapon or target that will give the laser fresh armor to absorb it
Or fresh paint, depending how squarely you get the beam to hit the target. The same plasma generation that can stymie a laser at one point will work at other points if you're not careful. Hence, again, the value of pulse lasers in BT.
Quote:
To really increase accuracy you will need a laser that stays active for long periods of time. *Correct human error*
Keeping a laser beam active for a long time gives more time to wastefully disperse laser energy across the target due to beam jitter, and it most definitely wastes the efficient surface explosion effect of a short-period beam discharges. For a real world example, look up laser peening.
http://en.wikipedia.org/wiki/Laser_peening#Mechanics_of_LSP_superficial_treatment
"When a metallic sample is irradiated by in intense Nd:YAG laser pulse spot 5-15 GW/cm², 10 to 30 nanoseconds long, having a wavelength of 1.06 μm, with an energy per pulse of 50 joules or more and range from 5mm to 1 mm in diameter, it forms high-pressure plasma on the surface of the part, causing a shock wave to travel through the depth and plastically deforming material."
Scale that up to megajoules on the same ultra-short time scale and just imagine. Substitute that real world laser for whatever science fiction cartoon laser in your mental laser model and imagine what happens when you go from 50 Joules to 150 Megajoules.
It's that sort of efficiency from high energy delivery rates that lets a couple of SRM warheads with just a few megajoules of energy do more damage than a small laser with 187 megajoules.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Edited by Cray (08/02/08 11:20 AM)
|
His_Most_Royal_Highass_Donkey
08/02/08 01:02 PM
70.6.90.94
|
If you want to continue this contact me privetly. People will start seeing this as flaming.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Cray
08/02/08 02:26 PM
68.205.198.74
|
Quote:
If you want to continue this contact me privetly. People will start seeing this as flaming.
I'd prefer to keep this discussion public. There shouldn't be any flames from citations of real world physics and canonical quotes of laser behavior; it's a matter of facts, not opinions. We should both have the same information resources available at our fingertips, via Google or another search engine, to present a credible position.
And you should also now have more than enough key words and topics to get those counter arguments well-founded.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Edited by Cray (08/02/08 02:56 PM)
|
Lafeel
08/02/08 06:01 PM
157.157.83.10
|
I'd have to agree with Cray. Just because we disagree with you it does not mean that there is any flaming involved (in fact, as disagreements go, this one's been very cordial)
|
His_Most_Royal_Highass_Donkey
08/02/08 07:27 PM
70.6.90.94
|
Putting aside that the cutting lasers that you have been talking about are not true lasers but more like PPCs. And they would not be effective at any real range.
I would like to know how this 100,000 joules per second laser will be made into a tight beam. Considering that any lens would be melted in less than a millionth of a second.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
08/02/08 08:09 PM
157.157.83.10
|
"Considering that any lens would be melted in less than a millionth of a second"
First of all you realize that this is supposed to be the 31st century, right? And while we might not be able to make a lens strong enough to survive that with our tech (more on that later), they might.
Oh, and I want a source on that bit about lenses not being able to take the heat, please.
|
His_Most_Royal_Highass_Donkey
08/02/08 11:45 PM
70.0.168.213
|
Quote:
"Considering that any lens would be melted in less than a millionth of a second"
Oh, and I want a source on that bit about lenses not being able to take the heat, please.
I would like a source saying that there is one that can. If the lenses have any impurities at all or damage even some that could barley be seen via a electron microscope it will absorb that heat from the laser. That is if something could be found that could let the laser pass throe the lenses with out absorbing any of the beam in the first place.
Why argue if the glass is half full or half empty, when you know someone is going to knock it over and spill it anyways.
I was a Major *pain* before
But I got a promotion.
I am now a General *pain*
Yay for promotions!!!
|
Lafeel
08/03/08 12:06 AM
157.157.83.10
|
Quote:
Quote:
"Considering that any lens would be melted in less than a millionth of a second"
Oh, and I want a source on that bit about lenses not being able to take the heat, please.
I would like a source saying that there is one that can. If the lenses have any impurities at all or damage even some that could barley be seen via a electron microscope it will absorb that heat from the laser. That is if something could be found that could let the laser pass throe the lenses with out absorbing any of the beam in the first place.
Great way of ignoring at least six centuries of technology advances there..
|
Christopher_Perkins
08/03/08 11:36 AM
24.125.201.167
|
Quote:
Pulse Lasers, though, give that plasma a chance to disperse, so each subsequent pulse can burn away fresh armor. Pulse lasers are much more likely to dig into armor than standard lasers. Hence, a -2 to-hit bonus.
There has got to be some additional Equipment in the Pulse Laser... Probably a targeting system...
The increased damage is from allowing the vapor to disperse... but it is unlikely that the targeting bonus is from the vapor dispersal as well.
caveat...
are they saying that the vapor from the dispersal makes it more likely that the subsequent energy will be wasted enough that it drops below some threshold...
Targeting systems in the pulse laser make more sense... they need to rework that one
Quote:
MGs have their own targeting problems, like getting enough damage in one spot for their small (20-30mm) bullets to dig into the magical materials of 'Mech armor.
Fluff has 7.62 mm (Phoenix Hawk - Ghost of Christmas Present, and other places), and 12.7 (TR3026, and other places) and 20 mm (Bulldog - TR3026) where the real world has MG in 5.56 mm - 20 mm. 7.62 mm and above have access to AP rated ammo. Some Russian 30 mm guns are called "MGs" as well, but most places call weapons with calibers higher than 20 mm "Cannon"
The Bear Hunter is probably a 20 mm MG like the BullDog's MG but the majority of BattleTech MGs are going to be 12.7 mm
Christopher Robin Perkins
It is my opinion that all statements should be questioned, digested, disected, tasted, and then either spit out or adopted... RHIP is not a god given shield
|
Christopher_Perkins
08/03/08 12:07 PM
24.125.201.167
|
Quote:
The energy transfer rate of any laser sufficiently powerful to damage metal is way beyond mere melting and thermal conduction limits.
Agreed
Quote:
Because we can only build weak lasers. The giant USAF Airborne Laser mounted on a 747 only delivers 1 megawatt, 1 megajoule per second. 1 megajoule per second will take minutes to burn through a sheet of armor steel. The BT small laser delivers *at least* 185 megajoules (based on the mass of armor it ablates), preferably in a burst of much less than a second.
How Many Minutes?
How Thick is the Sheet of Armour Steel?
*re 185 Megajoules*
What Mass of armour?
the Equivelent of a Single Point of (Barrier 10 Tech D) BattleTech Standard Armour would be 125 - 126 kg of steel armour (2 points Tech B Bar 5)...
How thick is the plate of Steel Armour?
What is the Diameter of the Hole Being Drilled by the Laser?
a Machine Gun burst or Cannon Shell / Burst of Cannon Shells or Missile Hit is not assumed to totally vaporize that amount of Armour, so why do you say that the Laser Has to vaporize the full amount?
The Other types of weapons only reduce the effectiveness of the armour to the point that it does not provide adequate protection holding lasers to "full vaporization" is a bit of a double standard.
Quote:
It's that sort of efficiency from high energy delivery rates that lets a couple of SRM warheads with just a few megajoules of energy do more damage than a small laser with 187 megajoules.
thats why I say that the Lasers are not required to be as powerful as your assume that they are... mainly because the power / energy delivered requirements are so much more than by other means...
what does that do to your calcs if you assume that the same energy delivered by any means (flamer, Laser, missile, machine gun, cannon, particle cannon) will have the same amount of impact on the effectiveness of armour and therefore the same amount of Damage in the BattleTech Game to Table * 2 points of Bar 5 Tech B Armour (for the sake of argument, assume one point of Tech B Bar 5 Armour is a plate of modern day standard Steel Armour that weighs 62.5 kg)...
Christopher Robin Perkins
It is my opinion that all statements should be questioned, digested, disected, tasted, and then either spit out or adopted... RHIP is not a god given shield
|
Cray
08/03/08 06:58 PM
97.97.243.184
|
Quote:
I would like to know how this 100,000 joules per second laser will be made into a tight beam. Considering that any lens would be melted in less than a millionth of a second.
Those are good questions in that they aim exactly at problems lasers must deal with, but you might want to look into something first: what is 100,000 joules per second?
100,000 joules is sufficient energy to warm a 1-liter bottle of water by 23.88C, enough to bring from room temperature to boiling in 3 seconds (followed by 22.6 seconds actually boiling the whole bottle as the enormous heat of vaporization of water was met.)
100,000 joules per second (~130 horsepower) is about the maximum power output of my car's 4-cylinder engine, as dynamo-tested at the wheels. (At the same time, it'd be dumping about 100,000 joules per second out the radiator and 100,000 joules per second out the tail pipe in the form of waste heat.) At ~130 horsepower (100,000J/s), I don't drive a powerful car.
What's more relevant to laser performance was 100,000 joules per second per square centimeter.
While 130 horsepower takes half a minute to heat and boil a liter of water, applying that same energy to a very small patch of metal (or any other substance) found in a square centimeter target area produces very different results. Instead of dealing with a kilogram of water, you're dealing with milligrams of materials, upwards of 6 orders of magnitude in difference in mass.
Add into this the fact that most materials have about 1/4th to 1/10th the heat capacity of water and even lower heats of vaporization, and you'll see that small patch of surface heating by at least hundreds of thousands of degrees per second.
There's obvious limits to the peak temperature (the rate of cooling by radiation increases by the fourth power of the temperature), but at that concentration of energy input you'll blow past nucleate boiling, past film boiling, and straight into plasma generation. There's simply no time for conduction to soak the heat into the bulk of the material. Heck, once you're flash-heating the surface material above about 100C beyond its boiling point, the Leidenfrost effect will help insulate the bulk of the material. (And that's where you start seeing the value of pulse lasers.)
Quote:
Considering that any lens would be melted in less than a millionth of a second.
A very good question, if a bit exaggerated.
A lens or mirror encountering 100,000 joules per second per square centimeter would be in a world of trouble. The trick used in the likes of the Airborne Laser is: don't let the optics handle that power density. If you use a final aiming mirror that's 11.3 centimeters in diameter to generate that 1 square centimeter spot, the mirror is only dealing is 1000 joules per second per square centimeter (1/100th the concentration that the target endures).
To draw from a familiar example, a magnifying glass used to concentrate sunlight to burn paper or ants does not itself burn - the magnifying glass handles a much smaller power density than the target.
Military lasers generally work with very large, aggressively cooled mirrors; Reagan's SDI sometimes considered diamond mirrors for diamond's epic thermal conductivity and melting point. The Airborne Laser, for example, uses very large mirrors to handle a "mere" megawatt (1 million joules per second) without water cooling, while BT lasers are much more powerful.
http://findarticles.com/p/articles/mi_m0ICK/is_1_15/ai_75578155
http://www.airpower.maxwell.af.mil/airchronicles/apj/apj94/fal94/coulombe.html
http://www.boeing.com/defense-space/military/abl/news/2004/010004_mirrors.html
http://en.wikipedia.org/wiki/Boeing_YAL-1 (This article has links to other, modern battlefield laser projects.)
(Too bad BT can't match the accuracy of the ABL. It's designed to keep its beam jitter within an area the size of a basketball at 200 miles range with sub-micron pointing accuracy during a shot 3- to 5- seconds long. It's a continuous beam alright, but it most definitely does not spray-and-pray with its beam.)
As a fun little laser factoid, the National Ignition Facility gave up trying to beat plasma generation in its final optics assemblies. The aluminum mirrors that aim into the fusion chamber actually perform the reflection with plasma evolved on their surfaces by the passing laser pulse. (Of course, those 192 mirrors are each, I think, several square feet while their targets are smaller than a pea.) If you want to see the extreme end of ultra-fast deliveries of modest energy quantities (1.8 million joules), read the whole wiki article on the NIF.
http://en.wikipedia.org/wiki/Image:Fusion_microcapsule.jpg
Back to BT: 100,000 Joules per second per square centimeters is just a trip point for some of the more exciting laser effects. Consider what happens to a target when you dump 187 million joules (equivalent to 187 sticks of dynamite) from a small laser into a square foot on a target in a 1/10th second discharge, or 1/1000th second discharge (I'll discount the crazy nanosecond shots of the NIF as not being practical for battlefield use.) With 187 megajoules** even a modest 1-second burn, which opens the opportunity to waste a lot of the beam on the landscape, will generate ferocious surface explosions.
**187 megajoules is the amount of energy needed to melt half of 187.5 kilograms of cheap carbon steel with a low melting point. The small laser destroys 187.5kg of armor, which is most definitely not cheap carbon steel. Depending on your assumptions about beam power (rate of energy delivery) and various inefficiencies (reflection from the target, energy wasted trying to hose the beam onto target, etc.), you could very well need much more energy from a small laser to destroy 3 points of armor.
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
Edited by Cray (08/03/08 07:06 PM)
|
Prince_of_Darkness
08/03/08 07:37 PM
71.215.57.179
|
Quote:
Putting aside that the cutting lasers that you have been talking about are not true lasers but more like PPCs. And they would not be effective at any real range.
I would like to know how this 100,000 joules per second laser will be made into a tight beam. Considering that any lens would be melted in less than a millionth of a second.
Wow, first post and I say this...
Cutting lasers, such as plasma cutters (note I said PLASMA) are not like PPC's. PPC's are basically an electron gun like the ones in older TV's, just colandesed into a beam of electrons (and, perhaps even positrons). If they were like PPC's, they would actually have range- it would just be a matter of how much power was put into firing the electrons.
The laser and plasma tools used for cutting are not BUILT for range- they are built for power so they can CUT metal precisely. It is why they are not used for any form of weapon these days.
Now, on the concept of lenses; the first thing you must understand is that not all lenses are made of glass. In fact, industrial cutting lasers do not use anything like a glass lens, but more like like a focusing crystal, normally made of factory-made diamond (like for steel-cutting saws) which, are much tougher than glass (and can aim the light for the laser much better).
You might want to ask Cray for some links to this data (I've known him for awhile on Solaris 7).
|
Cray
08/04/08 08:41 AM
147.160.136.10
|
Quote:
Cutting lasers, such as plasma cutters (note I said PLASMA) are not like PPC's. PPC's are basically an electron gun like the ones in older TV's, just colandesed into a beam of electrons (and, perhaps even positrons).
Or protons, or a mix. The BT weapon known as "PPCs" covers a range of machinery that emits different particles. The Manticore tank's PartiKill PPC fires a plasma bolt, for example.
And the advantage of PPCs over lasers is that these particles tend to penetrate some distance into the target due to their radiation-like behavior, instead of being caught in surface effects. With proper tuning of particle energies, you'll get a nice Bragg spike in the middle of an armor plate rather than lost on the surface.
Quote:
Now, on the concept of lenses; the first thing you must understand is that not all lenses are made of glass. In fact, industrial cutting lasers do not use anything like a glass lens, but more like like a focusing crystal, normally made of factory-made diamond (like for steel-cutting saws) which, are much tougher than glass (and can aim the light for the laser much better).
You might want to ask Cray for some links to this data (I've known him for awhile on Solaris 7).
All sorts of materials get used in laser optics. Glasses do figure prominently in windows...
http://www.msnbc.msn.com/id/11961673/
And mirrors:
http://www.boeing.com/defense-space/military/abl/news/focus/MayJun99.PDF
(Though I was expecting copper, aluminum, or beryllium for the mirror of ABL for their rapid cooling capacity. I guess the power density is low enough that the ABL's main mirror can be ultra-low expansion glass, and air cooled at that.)
Welding lasers, particularly IR lasers, can use some real oddball stuff like Zinc Selenide glass, Germanium, or (for water-cooled mirrors) copper.
http://www.iiviinfrared.com/products/diamond-turned_optics.html
Mike Miller, Materials Engineer
Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.
|
Christopher_Perkins
08/10/08 01:33 AM
24.125.201.167
|
Quote:
What's more relevant to laser performance was 100,000 joules per second per square centimeter.
Thats good... That is what i have been driving at in a way..
The Laser is delivering the energy to a square centimeter of the targets armour to burn through or otherwise render Hors De Combat an unknown thickness of the magical clarkeian armour... or a determinable thickness of standard steel plate armour (unadulterated with things like carbon fibers, reactive blocks, etc...)
1 cm * 1 cm = 3.14 * x 0.56 cm * x 0.56 cm quiaff?
a plate of Standard Armour Steel of thickness X with a surface area of Y weighing Z
Z is the mass of armour defeated by a small laser
Given
62.5 kg per Tech B Bar 5 Armour Point
Number of Tech B Bar 5 Armour Points required to be roughly equal to Tech D Bar 10 is 2
Small Laser renders Hors De Combat 3 Points of Standard Tech D Bar 10 Armour.
Z = 62.5 kg * 2 * 3 = 375 kg of standard plate steel armour...
X = the thickness of the Armour with a Mass of Z and a surface area of Y
Solve For: a 1.12 cm diameter beam cutting through a thickness X plate of armour massing 375 kg of armour would only have to defeat what mass of armour?
And key holing & Penetrating that thickness of steel with an entry point 0.56 cm in diameter would require what amount of energy to melt a 0.56 diameter hole through the armour in approximately 0.2 seconds?
Alternately...
if Tech B Bar 5 Armour requires 4 points (250 kg Tech B Bar 10 / 62.5 Tech B Bar 5 = 4) to be equivalent to Tech D Bar 10 Armour, then 750 kg of Standard Steel Plate Armour would be the equivalent to 187 kg of Standard Tech D Bar 10 armour
And key holing & Penetrating that thickness of steel with an entry point 0.56 cm in diameter would require what amount of energy to melt a 0.56 diameter hole through the armour in approximately 0.2 seconds?
Quote:
**187 megajoules is the amount of energy needed to melt half of 187.5 kilograms of cheap carbon steel with a low melting point. The small laser destroys 187.5kg of armor, which is most definitely not cheap carbon steel. Depending on your assumptions about beam power (rate of energy delivery) and various inefficiencies (reflection from the target, energy wasted trying to hose the beam onto target, etc.), you could very well need much more energy from a small laser to destroy 3 points of armor.
humm, interesting...
What level of energy is needed to do the same to 187.5 kg of homogenous plate armour steel?
Christopher Robin Perkins
It is my opinion that all statements should be questioned, digested, disected, tasted, and then either spit out or adopted... RHIP is not a god given shield
|
|
|
Extra information
|
1 registered and 59 anonymous users are browsing this forum.
Moderator: Nic Jansma, Cray, Frabby, BobTheZombie
Print Topic
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is enabled
UBBCode is enabled
|
Topic views: 16403
|
|
|
|
|
|
|