71 replies to this topic

[Strum Wealh]

Nightwish, on 21 February 2012 - 09:38 AM, said:

New Info:
I was reading the wiki article on charged particle cannons (don't ask) and it turns out that realy heavy duty lasers like those on a mech cause recoil both to the target and weapon due to the super fast expansion of air around the beam. Also the metal directly under the beam expands causing further recoil.

That isn't really recoil.

The first effect you're describing - the dispersal of a directed energy weapon's energy into the local medium (the atmosphere) - is a result of "blooming", an effect that is one of the main problems with regard to implementing DEWs.

Quote

Laser beams begin to cause plasma breakdown in the air at energy densities of around a megajoule per cubic centimeter. This effect, called "blooming," causes the laser to defocus and disperse energy into the atmosphere. Blooming can be more severe if there is fog, smoke, or dust in the air.

The second effect - explosive vaporization of armor - would cause some rocking to the target, but is also a problem to the attacker because the airborne material would absorb some of the energy of the beam (discussed here) as well as cause both refraction and reflection of the beam (thus reducing the energy that can continue to reach the target after the initial strike).

That being that... it's already been done.

Strum Wealh, on 11 February 2012 - 06:59 PM, said:

Recoil is a function of momentum and energy conservation.

Strum Wealh, on 09 February 2012 - 10:57 AM, said:

Lasers fire photons, which have no rest mass.
Photons in motion, however, do have momentum represented as p = h/λ.
The "h" represents the Planck Constant, equal to 6.626x10^(-34) Joule-seconds (J*s).
The "λ" represents the wavelength of the beam (3.80x10^(-7) to 7.40x10^(-7) meters for visible light).
Recoil for a laser would be so small (values on the order of 10^(-27)) as to be negligible.
(Moreover, the beam, however, would exert some radiation pressure on the target. However, the effect of such radiation pressure on a multi-ton machine in a planetary gravity well would be negligible, so lasers would also have negligible/no "knock".)

The laser itself would produce neither noticable recoil nor knock in the same manner as, say, an autocannon or a Gauss Rifle.
The rapid loss of material from one area of the targeted 'Mech, on the other hand, would cause a rapid and substantial shift in said 'Mech's balance, which may cause it to fall. This, however, is not unique to the DEWs; the ballistic weapons do this too, in addition to the knock to the target and the recoil on the attacking 'Mech that result from momentum conservation

Nightwish, on 21 February 2012 - 09:38 AM, said:

Also it turns out PPC's exist in real life as prototype weapons.

Not PPCs per se, but DEWs like the electrolaser may mimic their effects.

Quote

An electrolaser is a type of electroshock weapon which is also a directed-energy weapon. It uses lasers to form an electrically conductive laser-induced plasma channel (LIPC). A fraction of a second later, a powerful electric current is sent down this plasma channel and delivered to the target, thus functioning overall as a large-scale, high energy, long-distance version of the Taser electroshock gun.

Nightwish, on 21 February 2012 - 09:38 AM, said:

A 2cm hole has 4 times the surface area of 1cm hole, bring this into the third dimension and a 2cm sphere has 8 times the volume of a 1cm sphere, pretty basic right?. Therefor an AC10 round being twice the size of an AC5 round would have 8 times the mass. Therefor 3 AC5's would still only deliver 3/8 of the mass and energy of an AC10. So if we want true realism an AC10 should cause 8 times more knockback than an AC5, and an AC20 should cause 64 times more knockback than an AC5.

http://en.wikipedia....Particle_cannon

Not quite.

Again, recoil is a function of momentum and energy conservation. The same is true of knock.
(momentum, p) = (mass, m) * (velocity, v)
(Kinetic Energy, E) = 0.5 * (mass, m) * (velocity, v)^2 = (p^2)/(2*m)

For m1 = 1.0 kg, v1 = 100 m/s, m2 = 0.5 kg, and v2 = 200 m/s:

p1 = 1.0 * 100 = 100 N-s
E1 = 0.5 * (1.0) * (100^2) = 5,000 J

p2 = 0.5 * 200 = 100 N-s
E2 = 0.5 * (0.5) * (200^2) = 10,000 J

Depending on the differences in mass and velocity, a low-mass, high-velocity projectile can have equal momentum and equal or greater kinetic energy to a high-mass, slow-moving projectile.

Additionally, BT ACs normally fire HEAP (high-explosive, armor-piercing) shells - cylindrical or ogive-elliptical in shape, with relatively thick solid walls, and a cavity filled with an explosive charge.
("Shell" is used in contrast to "shot", "slug" and "bullet"; the former-most often carry an explosive or fragmenting payload, while the others are generally solid projectiles.)

Depending on shell thickness and the densities of both shell and charge materials, the relationship between volume and mass may not be as consistent as that of ideal spheres.
That variation, combined with different muzzle velocities, actual calibers (AC-20s' canon calibers include the 185 mm models used on the Demolisher and the 203 mm UAC model used on the Ebon Jaguar/"Cauldron-Born"), and number shells fired per salvo (and that doesn't even begin to account for the variable fire rates of UACs and RACs), makes the relationships between ACs of different classes - or even ACs of the same class - not so clear-cut...

[Trogusaur]

First of all, I love how this thread became a huge quoting party! This is most interesting.

Solis Obscuri, on 21 February 2012 - 05:07 PM, said:

Can you back this up with facts, or is it just supposition?

Actually, there was a thread that was on here quite a while ago, including a poll asking for BT fan ages. This came out when these forums were still fresh, so I have quite a few threads to sift through to find support. I will definitely get back to you on that one, though.

Solis Obscuri, on 21 February 2012 - 05:07 PM, said:

We had PPCs and Gauss rifles back in 1984? Why was I not informed, I'd have definitely asked Santa for one!

That isn't quite what I meant. I was saying that BT first came up with the PPC in fiction, meaning that is still entirely hypothetical. Notice how my poll includes nothing about PPCs specifically, as that weapon is still open to interpretation. As for Gauss Rifles, have you ever heard of Carl Friedrick Gauss? Yeah, he discovered the properties of magnets in the early 1800s. He may not be directly responsible for making the first rifle, but the properties he discovered immediately brought about the fruition of the gun itself. One may assume it is even older than today's conventional missles. So yes, Gauss Rifles existed even before BT made it popular.

Edited by Lord Trogus, 21 February 2012 - 09:31 PM.

[Jess Hazen]

Kael Tropheus, on 09 February 2012 - 11:30 AM, said:

4 LRM5s have the same number of missiles as an LRM20. Why wouldnt it cause the same impact jolt?

It all depends on rate of fire and i'm not talking about refire rate here. If 4 LRM 5's get 5 missiles launched faster than 1 LRM 20 can launch 20 missiles. This is the time that it takes for 20 missiles to fire from a single LRM 20 module vs 5 missiles firing from an LRM 5, just in the case of of LRM 5's it's happening 4 times simultaneously. All we are talking about here is physics and should scale the same for all weapons. Now the rate of fire for multi salvo weapons can be tweaked but I think the physics of all of it should be left alone.

[Trogusaur]

Alright, I believe Pht and Solis Obscuri were asking about my comment concerning average fanbase age. I managed to dig up one of the older ones asking about years playing BT.
http://mwomercs.com/...etech-universe/
Although this poll does not directly state ages, one may rationally assume most to all people that fall under the 16+ years brackets are older than 25. On a further stretch, it is also safe to assume that most from the 11+ years bracket are above twenty, seeing how otherwise they would have began playing as ages under double digits. Add that together, you have approximately have 80% for the 20+ y/o age bracket. I am aware that I had originally said that the mean age was older than 25 years, but this was extremely close nonetheless, considering how I made that approximation without citing anything.

This is not ideal, but my search isn't over. Regardless, this does prove my initial point that the majority of the fanbase has been here for a very long time, and that there are few people playing now that didn't play in the beginning. I rest my case.

Edited by Lord Trogus, 21 February 2012 - 10:12 PM.

[FACEman Peck]

Whoever voted for NO for the missiles dealing more and more knockdown doesn't have a clue about physics 101.

[rctechnologies]

weight of projectile x velocity = energy of projectile (how hard it will hit)
this is directly proportional to knockback.

The same is for missiles. An LRM is an LRM. It is larger and heavier than and SRM. Let us not forget that the differece is in the number of warheads fired.

Example. an LRM 20 is fired at say, a Cougar. This pilot is very skilled at evasive maneuvers. He takes 1 hit, and is knocked somewhat. He is able to evade and recover in less than 1 second and dodges the next warhead. Unfortunately he then takes a wrong turn and receives 10 hits in rapid succession, knocking him on his face. the remaining 8 warheads are unable to compensate and miss, doing no further damage or knockback/disorientation.

SRMs being smaller may not deal as much impact per missile, but hit in a faster succession. All ammunition based weapons should work on this principle, as well as the PPC.

MW4 Vengeance dealt with this perfectly.

Edited by rctechnologies, 22 February 2012 - 05:57 AM.

[Strum Wealh]

rctechnologies, on 22 February 2012 - 05:56 AM, said:

weight of projectile x velocity = energy of projectile (how hard it will hit)
this is directly proportional to knockback.

(mass of projectile) x (velocity of projectile) = momentum of a projectile
kinetic energy of a projectile = 0.5 x (mass of projectile) x (square of velocity of projectile)

Momentum and kinetic energy are NOT the same thing, nor are they interchangable.

Also:

Quote

Though popularized in television and movies, and commonly referred to as "true stopping power" by novice or uneducated proponents of large powerful calibers such as .44 Magnum, the effect of knockback from a handgun and indeed most personal weapons is largely a myth. The momentum of the so-called "manstopper" .45 ACP bullet is approximately that of a 1 pound (0.45 kg) mass dropped from a height of 11.4 feet (3.5 m). Such a force is simply incapable of arresting a running target's forward momentum. In addition, bullets are designed to penetrate instead of strike a blunt force blow, because, in penetrating, more severe tissue damage is done. A bullet with sufficient energy to knock down an assailant, such as a high-speed rifle bullet, would be more likely to instead pass straight through, while not transferring the full energy (in fact only a very small percentage of the full energy) of the bullet to the victim.

The "knockback" effect is however commonly "seen" in real-life shootings, and can be explained by physiological and psychological means. Humans encountering a physical hit, be it a punch or a bullet, are conditioned to absorb the blow by moving in the same direction as the force. The physical effect against a non-penetrating weapon is to reduce the force felt by the blow, and in addition, retreating from an attack increases the distance such an attack must cover, which in the case of non-projectile weapons such as fists or a knife, places the target out of range of further attack. In addition, there is a theoretical sociological explanation, that in modern civilization, with far greater separation by most individuals from violence, hunting, and combat, normal individuals may simply recoil, buckle, or fall backward when hit by a bullet, even when in pure physiological terms they are perfectly capable of continuing to charge.

Although knockback is not possible with a handgun bullet, it can be an actual effect occurring in reaction to being hit by a massive slug, such as a rubber bullet or sandbag fired from a shotgun. The dynamics of a slug round are quite different than penetrating bullets; the projectile is here designed not to penetrate but instead to strike a hard, blunt force blow, and as the momentum carried by a shotgun cartridge is greater than practically any production handgun cartridge, the force imparted is comparable to a hard punch and is capable, by physics, of affecting a person's forward motion. In any case, due to conservation of momentum, the gun's recoil is always larger than the bullet's knockback, as some momentum of the bullet is lost during flight, and if the bullet penetrates through the target it will not have imparted all its momentum into the target.

In general, knock delivered to the target should generally be less - perhaps even substantially less - than recoil imparted on the firing 'Mech.
Though, it should be noted that ACs normally fire explosive (specifically, high-explosive armor-piercing) shells, so the damage mechanism is not wholly dependent on the transfer of momentum or kinetic energy (as would be the case with MGs or Gauss Rifles).

rctechnologies, on 22 February 2012 - 05:56 AM, said:

The same is for missiles. An LRM is an LRM. It is larger and heavier than and SRM. Let us not forget that the differece is in the number of warheads fired.

Example. an LRM 20 is fired at say, a Cougar. This pilot is very skilled at evasive maneuvers. He takes 1 hit, and is knocked somewhat. He is able to evade and recover in less than 1 second and dodges the next warhead. Unfortunately he then takes a wrong turn and receives 10 hits in rapid succession, knocking him on his face. the remaining 8 warheads are unable to compensate and miss, doing no further damage or knockback/disorientation.

SRMs being smaller may not deal as much impact per missile, but hit in a faster succession. All ammunition based weapons should work on this principle, as well as the PPC.

MW4 Vengeance dealt with this perfectly.

Actually, it's quite the opposite - standard LRMs are actually smaller and lighter than standard SRMs.

Standard LRMs come in sets of 120 missiles per one-ton (1000 kg, or ~2204.62 lbs), 1-critical ammo bin.
Standard SRMs come in sets of 100 missiles per one ton (1000 kg, or ~2204.62 lbs), 1-critical ammo bin.

Standard LRMs have a mass of 1/120 of one-ton (that is, 1/120 of 1000 kg), or 8.33 kg (or ~18.36 lbs) per missile.
Standard SRMs have a mass of 1/100 of one-ton (that is, 1/100 of 1000 kg), or 10.0 kg (or ~22.05 lbs) per missile.

A standard SRM is about three-and-two-thirds pounds heavier than a standard LRM, and both are in the same weight range as modern shoulder-fired missiles like the FIM-92 Stinger (10.1 kg per missile) and the FIM-43 Redeye (8.3 kg per missile).
As more LRMs fit into the same volume (one critical space), it stands to reason that 1.) LRMs are physically smaller than SRMs and/or 2.) the SRM bins are not filled to capacity, in order to maintain the one-ton increment.

Like standard AC shells, the damage mechanism for LRMs and SRMs is explosive in nature (specifically, an explosive warhead), rather than being wholly dependent on the transfer of momentum or kinetic energy
Standard SRMs also carry a larger warhead, and cause more damage per missile - 2 units of damage per missile, versus 1 unit of damage per missile for standard LRMs.

If anything, SRMs - larger, heavier missiles with bigger warheads per missile - should impart more impact on a target per missile, with LRMs making up the difference in impact per missile by firing more missiles per salvo (which they typically do anyway)...

[Pht]

Kraktzor, on 20 February 2012 - 01:09 PM, said:

Uh, actually yes they do. TT rules say that if you take enough damage at once, you need to make a Piloting roll or fall down. And it only takes 20 points to do it (I think), so a couple AC/10's is all you needed to (possibly) knock a Mech over.

No, they don't; and the rule you're citing does not give any explanation as to how the damage causes a piloting skill roll; it does not cite knock, nor does it cite anything else. It just says "psr here when x damage taken."
You have to look elsewhere to see why this PSR is given; and the other sources that speak clearly on the topic show that the PSR is due to the unbalance caused by the nearly instant loss of weight; which the 'Mechs stabilization systems cannot compensate for (the gyro, the Diagnostic Indicator & Battle computers controlling the actuators, etc). What's this source? The Techmanual writeup on page 31, & the older version of that writeup in classic Battletech companion. The novels as well do not consistently speak of battlemechs suffering from recoil effects that affect the ability of the 'Mech to aim from anything other than a heavy gauss (and than only when shot on the move); and ditto on the other side of the equation. The amount of fire required to generate enough kinetic based fire at any one instant to knock a target 'mech's aim off will slag that target 'mech.

[Trogusaur]

Not that it matters anymore, but I did find the two polls I was referring to earlier in the thread. The majority of BT players really are at least 22+ years of age, as stated here:
http://mwomercs.com/...ch__1#entry9082

And most BT fans are diehards, having been around for many a year. Note the lack of numbers in the newer categories.
http://mwomercs.com/...etech-universe/

Just keeping the credibility of my statement
I would also like to add that times have changed, and some weapons could use a good remodeling. This doesn't mean that canon has to be thrown out the door, it means some unstated rules need clarification. Regardless, it seems the recent ingame video will clear up many of our previously unanswered questions.

Edited by Lord Trogus, 10 March 2012 - 09:14 PM.

[Intikam]

i mean realy a Atlas hit by chain firing ssrm2... that should tickle an Atlas but not more... also a ak2... thats a joke right now. I mean its not the same been hit by a ak2 or ak20.... also heavyer mechs should be shaken less FAR LESS!

[Reoh]

In TT I believe the amount of damage done by a single strike mattered. Doing over 20 damage at a time caused a piloting skill check which could result in losing balance. Missiles have a strange rock factor currently in MWO. They seem to all rock for the same amount no matter if fired in a single flight, or stream (from a smaller launcher hole point on the mech). Chain firing them also shakes the cockpit around like crazy making it difficult to see what's going on even though the missiles themselves may only be firing 2 at a time for somewhat minimal damage.

[Reoh]

Also I've had this idea about piloting skill rolls. This would seem to apply for large volumes of damage, and crashing into things (like other mechs).

When you run into something (or suddenly take a lot of damage in a single strike) there's a chance for a piloting skill roll. to simulate this, the mech would start to wobble about and the player had to counter the wobble by moving in the appropriate direction and twisting their torso to try and keep it centered (if your'e falling to the right, you'd need to step to the right and so on). The more severe the knock (faster the impact, or larger the damage) the more severe the wobble and shorter the duration required to counter-act it before falling. It wouldn't resolve just after one such incident but would rock back and forth a bit getting easier if you succeeded until you were back to normal.

This way players get a chance to avoid falling, and instead might only lose a little speed or change direction (rebounding off where they were hit). Very small knocks would be quite simple to counter but larger impacts would become quite difficult to react to and thus more likely to result in falling to a prone position.

Edited by Reoh, 21 November 2012 - 09:07 AM.