Strum Wealh, on 22 March 2012 - 08:41 PM, said:
Well, what I posted was supposed to represent the high-end of each weapon's per-shell damage capability in terms of raw energy.
The numbers could easily change due to a variety of factors - higher or lower muzzle velocities, higher or lower percentages of explosive material vs total shell weight, use of different explosive material (those that I cited are among the most powerful, but are still in the experimental/developmental stages).
For example, the AC-20 shell I described (20 kg mass, ~600 m/s velocity, explosive charge is ~15% of shell mass, charge has a
R.E. Factor of 2.7 (representing Octanitrocubane)) should have a total energy output (KE + explosive energy) of about
37.49 MJ.
By contrast, a different AC-20 shell (20 kg mass, ~600 m/s velocity, explosive charge is ~4% of shell mass, charge has a R.E. Factor of 1.0 (representing TNT)) should have a total energy output (KE + explosive energy) of about
6.95 MJ.
And even then, not all of the shells' energy is going to be transferred to the BattleMech instantaneously - there would be losses and inefficiencies.
Also, as BattleMech armor is ablative, a large portion of that energy (mainly the explosive component) would be carried away by the ablating armor material, sparing the 'Mech from most of its effects, yes?
So, for most cases, we'd probably be looking at ~3-4 MJ being transferred to the target 'Mech per AC-20 shell, yes?
Assuming 10 such shells (from, say, a
Hetzer's gun) struck a 100-ton (100,000 kg)
Atlas, the ~40 MJ being transferred to the
Atlas - together with the loss of over a ton of armor - should produce a noticeable but reasonable effect...
(Though, the lower energy outputs for high-damage weapons do make 'Mech armor seem so much less impressive...
)
Your thoughts?
My physics training is insufficient to deal with assumptions of nonelastic collisions and/or explosion effects, only enough to deal with basic momentum calculations. So I can't comment on something of this level confidently.
Lord Trogus, on 23 March 2012 - 12:51 AM, said:
From the results, it seems people don't like knockback on lasers much. Maybe that inspired the following:
CCC_Dober, on 23 March 2012 - 12:36 AM, said:
To both of you gents:
The good thing about BT is the adherence to basic physics. I take it that you have a good enough grasp on them to understand how energy weapons can cause knockback in MW. They do it indirectly by making the target shed armor layers and thus offset the center of gravity, as opposed to ballistic weapons that cause direct knockback on top of the indirect knockback effects. I have given you the clue and if you don't take them, I'm fine with that.
Given the way this thread is driven it would appear that certain unnamed people want energy weapons not to cause knockback and claim that physics don't allow for that (breaking news: they do!). If that is indeed so, come out and show your true colors. I've seen my share of 'lobbying' on forums and this thread is no different.
To which I have nothing new to add except to repeat that the loss of balance via armour loss on the front side will lead to a knockforward. And no, I'm not a lobbyist, applying assumptions you've formed on others on me works rarely since I don't function like most people do, though your theory might be true on some of the other posters who hold the same view as me. To avoid derailing the topic by describing what motivates me to do stuff in general, let's say that I'm only interested in finding out what would be the most physically realistic effect, and I would support whatever that effect is, if: A. there is a good argument for it or B. there is real-world experimental data for it. The armour melting one doesn't make any logical sense to me due to the
opposite direction of movement it would cause, though I have no doubt you will disagree with me on that since you already have. But I don't want to start drawing diagrams, ASCII or otherwise to illustrate why.
I don't
personally care whether or not lasers actually get knockback, knockforward, or just damage in the final product, as long as whatever is most accurate is reflected. It is entirely up to you whether or not you wish to believe me.
Nik Van Rhijn, on 23 March 2012 - 03:07 AM, said:
Given that the consensus of opinion is for knockback what are your views on knockdown, which is actually in the rules. I started a thread quite a while back
http://mwomercs.com/...e-of-knockdown/.
Looking at Strums figures the bottom end, ie 20 points would appear likely to be mostly affecting light mechs. Its equivalent to 1.25 tons of armour lost.
Knockdown will occur on a strictly physical sense if the moment exerted by the weapon on the 'Mech on its impact site exceeds the momentum imparted to the 'Mech in general to a sufficient extent that its centroid of gravity is no longer contained within the base area in contact with the ground. To be more specific, if I shoot a Jenner in the head, it should fall down. If I shoot it in the arm, it should swing away from the impact, and if this twisting effect is large enough it may cause it to fall down. If I shoot it in the leg, it should not fall unless the leg itself flies off. And of course, a Catapult will be less likely to fall over than a Jenner. Gyro factors also matter in retarding the movement of the centroid of gravity towards/over the edge of its base area, so 'Mechs with better gyros should be more stable. Crouching 'Mechs should not be easily knocked over. 'Mechs that are already descending a slope should be more easily knocked over if shot from behind.
I didn't like the way in which MW4 handled it, i.e. that damage to tonnage ratio alone determined the knockover potential, regardless of where I shot the 'Mech, but I've no objections to knockover in general, if well-executed.
Wild Cat, on 23 March 2012 - 12:39 AM, said:
I don't recall playing any game including the MechWarrior games on the PC where when you got hit, your aim got screwed up. The only thing I've see was camera shake, and that screws around with your mind more than it actually does with your true aim.
I'm really interested in actually seeing this in action and see how things balance out.
MW4 implemented this. In low levels it moves your targeting reticle. In higher levels it can move your torso. At the highest levels it can knock your 'Mech over. In MW4, knock effects are determined by combined damage potential of the strike vs the tonnage of the target. The quad-PPC and triple LBX AC-20 arrangements I used knock over every light mech in the game, and most mediums up to an Argus.
Togg Bott, on 22 March 2012 - 10:14 PM, said:
to set the rcord straight, yes lasers have knockback.
not from the kenetic energy transfer of solid objects impacting each other.
BUT from the release of energy in the reaction of metal being transformed from a solid to a gas. thats alot of energy being released ,and in the span of milli-seconds would feel similar if not exactly like a solid impact.
yes. i have the engineering background to say this with confidence. if you need a reference then here is one you MIGHT trust..
http://en.wikipedia....rm_dense_matter this is the action created by hitting a object with a laser
Firstly, I should state the first two things:
- The usage of heat to change phase is an absorptive reaction, not a release reaction; unless we're talking internal ammo explosions, the effect of the laser on the armour absorbs, not releases, heat.
- The above is irrelevant to your main assertion, as explosions are not a result of heat (a misconception so common it's quite sad really). Explosions only occur because of rapid volume expansion down the pressure gradient due to a vastly larger amount of gas formation relative to its components and can thus occur even with benign components like flour and air.
If the armour melts off a 'Mech this would definitely not be a factor, but if it vapourises, then it would depend on how much of the armour vapourises and at what speed. At a high enough vapourisation speed, this mechanism you mentioned can possibly explain a laser-based knockback. Sadly, Wikipedia was unable to provide much information as to this WDM phenomenon you mentioned, nor could its attached links. Do you have any other information on this topic? It seems rather intriguing.
StaIker, on 22 March 2012 - 11:27 PM, said:
Cutting lasers are a different thing. While they do vaporise material as well, the quantities are so small that the gas and particulates floats away into the atmosphere without any noticable effect. Some materials vaporise completely and others also throw off melt, it's all a matter of material, cutting speed, laser power, cooling and so on. But to turn a giant hunk of metal into a hole in 100ms requires a staggering amount of energy. The process will be explosive.
On the same topic as the previous post by Togg, is there any source I can view as to this effect? I've seen many cases of lasers melting stuff down before, but never a vapourisation process fast enough to cause an explosion, even a small one. This is not to say that I don't believe you right off the bat; rather, I'd like to see this for myself, or at least an article to the same effect.
If there's something like this, you'll have convinced me at least. Though I can't speak for any of the other posters.