Modern tank vs Mobile Suit, serious calcs included.

[Darth_Shinji]

Yeah you right.... lets quitly forget the fact that the mech is made with advanced technology we haven't elclisped to this day.

Then why do low velocity 120mm rounds blow the shit out of it? They've
never answered those questions....

I notice you do this alot too. Change the subject.

[Howedar]

Proof of round going 5km/s:

10km engagement range, 2 second observed travel time = average velocity of 5km/s
Procedure: We see muzzle flash, we count 2 seconds, we see impact.
10km was quoted by character on screen and believable in scene (pilot had to use maximum zoom and the visuals were still iffy, etc)
2 seconds was counted by me, SAMAS and somebody else independently (SylasGaunt?) on both DVD and VCD

A round hitting something at 5km/s is not going to be effective, as it will not remain intact and therefore will be a poor penetrator. Meanwhile, it still has too little kinetic energy to be used as a blunt-force penetrator.

If you don't believe that KE penetrators are rendered ineffective by physical damage, take note that special ERA is now made soley to damage KE penetrators before impact.

Ground Pressure:

MKSheppard, you keep going on and on about ground pressure, about how MSs would apply more pressure to the ground than a T90 and thus sink when tanks can go. BAD NEWS!

T90 stated ground pressure = .938kg/cm^2 or 9380kg/m^2

Zaku has two feet, each of which are roughly 5m x 2.5m size (measured from 1/100 MG Zaku model kit I own), or 25m^2 total area, so a weight of 60 tons would give 60000/25 or 2400kg/m^2

Or in other words, 3.9 times less!

OK, tell me again with a straight face, WHICH ONE'S GONNA SINK INTO THE GROUND FIRST?

Yes, the Mech has lower ground pressure when its standing still. Now, what happens when it takes a step? Thats right, your advantage is down to about 2x. Now, what happens when that foot comes down onto the ground? Do you think that the pressure is going to be magnified even more?

Suffice to say that while a Mech may have superior ground pressure while standing still, it loses this advantage while moving.

Now, thats not all. To get this impressive ground pressure figure (for a mech), you're utilizing a mass thats pretty damn low. 60 tons is about right for a typical tank (T-90 weighs 47 tons). Guess what? Thats coming back to bite you.

Your funky Mech thing is about 17 meters tall . Lets say, just for laughs, that you're only armoring the front of it. Moreover, lets say the mech is only 8 meters wide. Lets say the T-90 is about 7x4x2.5 meters (this is high). Lets say that the tank is equally armored over the whole top, sides, front, and rear. Finally, let say that both the 60 ton Mech and the 47 ton T-90 both are 1/2 armor by weight (the number really doesn't matter if we use the same number for both). Guess what we get? 136m^2 to be armored on the Mech, versus 83m^2 on the Tank. We get .22 tons armor per square meter on the Mech, about .3 tons armor per square meter on the T-90. Now, this means the Tank is better protected than the Mech. Now, before you point out how close that is, let me remind you of a few things:

Mech has only the front armored.
Tank has [/i]ever surface armored equally[/i] (save the bottom).
Mech estimate uses conservative dimensions.
Tank estimate uses liberal dimensions.

What does this tell us about the armament of the Mech? Completely regardless of its speed, caliber, or pretty effects, it tells us that it is roughly equivilent to T-90 main guns, since the Mech is stated to use a variety of steel for armor (actually inferior to the T-90's armor, but I digress).

We don't care about your bullet speed, or caliber, or pretty explosions. What we do care about is that it demonstrates effects against armor less impressive than the T-90's.

Proof of speed:

In the series we saw a Gouf Custom running for all it's worth.
Count of 4 strides per second, 6m per stride (scaled from foot size), giving 24m/s or roughly 86km/h, fully loaded.
So a Zaku going at 90km/h isn't outrageous, the Gouf had shitloads more equipment on it as well

This is about double that of a T-90, whose max cross-country speed is 45kph (By the way, was said Gouf Custom able to mantain that speed for any distance?).

Of course, it is vastly inferior to the speed of, say, a Mi-24 Hind.

Proof of capability of no shattering at 5km/s

Quite easy, energy needed to shatter projectile is supplied entirely by the projectile's motion and its weight. So the 5kg DU core of the M1A1 which doesn't shatter at 1.8km/s can be matched by a .648kg DU round at 5km/s, and it will still not shatter. This is a minumum though, you realise. DU should still have much headroom, so round shattering isn't really a problem, it can be compensated for!

Can you rephrase this? Are you saying that you're going to have a little tiny penetrator moving at 5km/s? And you think this will make it magically less likely to be deformed on impact?

Proof of round being NOT ultralight:

We assume that all KE generated by round is absorbed by the thing that fires it in the form of recoil.

M1A1:
KE = 1 / 2 * m * v ^ 2 = .5 * 5 * 1800 ^ 2 = 8.1MJ
Magella:
FOR SAME RECOIL
m = KE / (.5 * v ^ 2) = (8.1 * 10^6) / (.5 * 5000 ^ 2) = .648kg (!)
For your proposed recoil, I would assume 1/10 to be reasonable?
By same method, the round would weight .0648kg, or roughly 65g...

If your theory's right, and that the Magella's firing HE, well, dude, 65g of MSG HE = 3500g of T90 HE, as you people keep saying that the effects of this shell has to be HE. Insane, inane, and obviously, unworkable.

F = m * a
F, force from crosswind
m, mass of the shell, is in contention
a, acceleration (in this case lateral to path), is what we're looking at.
If your shell is small (small m), then obviously for a given F your a will be high, and that will mean bigger discrepancy between aim point and actual landing point. Say for a 20km/h crosswind, 4000 metre range

M1A1 round:
Force from wind
= Cd * (.5 * density of air * wind cross sectional area of round * wind velocity ^ 2)
Cd obtained from Drag coefficient table, after calculation of Reynold's Number, assume round is similar to smooth circular cylinder
Re = (wind velocity * diameter of round) / Kinematic viscosity of air
= (5.56m/s * .05m) / (14.6 * 10 ^ -6)m^2/s
= 19041
Hence Cd ~ 1.1
Force from wind = 1.1 * (.5 * 1.2 * (.3 * .05) * 5.56 ^ 2) = .306 N

F = m * a
a = F / m = .306 / 5 = .06m/s^2, or with a 4000 metre range, it would have a 'to hit' circle of 14cm diameter. That's quite ok.

Your proposed Magella round:
Same principle, substitute the 1/10 recoil round in place of 5kg
a = F / m = .306 / .0648 = 4.72m/s^2 or with the observed 10000 metre range, it would have a to hit circle of 9.4m in diameter! That's insane! The Zaku pilot wouldn't have fired at the Gundam in 'that' scene, he'd have put his hands up and go "I surrender" since he would have had NO chance! Furthermore, we have never seen this kind of scattering before in any of the weaponery as demonstrated in MSG.

Christ only knows what you're babbling about here. I don't care about round weight: said rounds demonstrate capability similar to a T-90's 125mm cannon, but against inferior armor. Let me make this real clear to you, in case you're slow:

T-90's 125mm cannon has x effect on certain thickness of armor.
Mech weapons have same effect on less armor (of same quality).

Therefore, 125mm > Mech weapons

Recoil and toppling:

Here is where everybody says there's a problem, and the toughest nut to crack, so I looked at it last. Unfortunately, as I'm rather short on time as I am in the middle of university end exams over here in Australia, I can't do justice to this section. However, some preliminary stuff would probably be interesting.

In a free standing rigid object, there is a physical property called Centre of Percussion. If you apply a force not at this point/level/height, the object will tend to topple, but if you apply the force at this point/level/height the object will not topple but will be shoved backwards. The problem with calculating this is that I do not know the weight distribution of the Zaku, so I cannot model the Zaku as multiple cylinders, find their Moments of Inertia, combine them using the Transfer of Axis theorm, and then calculate the Centre of Percussion, all in 3D!

However, it boils down to this, you can argue this one either way. Since the weight distribution is unknown, it is possible that the Zaku has been balanced so that the force left over from firing goes through this point/level and thus the Zaku would be shoved back and not toppled, or it could be extremely low weight projectiles because all the weight's bunched right up, but that has been shown to be highly unlikely from visuals in the series and from my previous calculations.

And as for shoving backwards, well, assuming no toppling (which Centre of Percussion DOES allow for, and Zakus and tanks can be treated as a rigid object, I'm sure it can lock its servos/treads!), the tank and the Zaku would give equivalent resistance to the recoil as frictional forces work by the formula F= (Coefficient of Friction) * (Normal force)
Normal force is about the same for both, and as for coefficient of friction, well, steel treads on ground = steel treads on ground at the very least, and surface contact area surprisingly for non-engineers doesn't come into it at all.

All irrelivent; see above.

Conclusions

To sum it all up in simple words:

1- Magella cannon fires with average velocity of 5km/s

Thats nice. Magella cannon demonstrates inferior capabilites than a T-90 125mm round, regardless of muzzle velocity, caliber, number of pink bunnies inside, or anything else.

- It does not need to elevate to ridiculous levels, simple analysis indicates less than a degree's worth of elevation

Doesn't matter worth a damn, but this is against Shep, not me.

3- Tanks would get sink in soft ground faster than MSs would

Until Mechs start to move, in which case they're in deep shit (mud).

4- MSs are FAR faster than tanks, to the tune of at least 21km/h, or nearly a third faster!

Twice as fast, if we're looking at cross-country speed.

5- A DU projectile can perform the same at 5km/s as 1.8km/s, simply by paring down the weight. No shattering, ma!

Ignoring the fact that paring down the weight means paring down the size and penetrating ability, if you hit RHA with a DU slug, it is going to deform or break.

6- If the Magella's projectile really is HE and it really does have a low recoil, damn, that's some HE! 65g of it can SHAKE THE GROUND, feck! As the old saying goes, that just ain't right.

Doesn't matter, said weapon demonstrates inferior capabilities to 125mm cannon of T-90.

7- Also, if the Magella's round was so light, it would be useless at range from random drifting and WE DO NOT SEE THAT IN THE SERIES ANYWHERE.

Thats nice. Its also irrelivent.

8- There is a physical explaination for how a Zaku can take the same recoil a M1A1 experiences when it is standing up, thus reinforcing the idea that the Magella IS powerful.

Doesn't matter.

In light of all these factors, I think I can safely say that since a Gundam was able to take a point blank Magella shot to the chest without a problem, and the Magella can be just as powerful as a contemporary tank cannon, Mobile Suits in general can be effective against T90s.

You're looking at that backwards. Since Mech armor must be thinner than T-90 armor, and this Mech armor can take a hit from x weapon to its chest at point-blank, then the Tank would withstand the hit easily, as it has more armor.

[The Yosemite Bear]

That DOES IT!

I am officially asking for a Tread/Heavy Armor group (Like BOTM & ATJ)

Of the points, I will raid the Bolo Pages, Email Drake's Son, and do what evere else is nessarry to get a perminate set of calcs (Material Thickness, Force Pressure, etc.

Oh well you can see.

[MKSheppard]

Good work Howedar.....now this is for Darth_Shinji, data_link, and Dendrobius:

[Vympel]

Wish he would stop beating the dead horse. And he repeats his ridiculous claim that the round was transonic even against the mountain of evidence Yosemite has posted. The best thing about the whole thing is that, as Howedar demonstrated- it's irrelevant anyway.

[Pablo Sanchez]

That DOES IT!

I am officially asking for a Tread/Heavy Armor group (Like BOTM & ATJ)

Sounds good.

[Darth Wong]

Mod, please at least look at this before locking it, I did my homework and there is serious calculations in here and not just conjecture and crap.

I appreciate the effort, but most of your calculations evade or ignore the most serious criticisms of the underlying points and assumptions.

10km engagement range, 2 second observed travel time = average velocity of 5km/s. Procedure: We see muzzle flash, we count 2 seconds, we see impact.

Was it a continuous one-angle camera shot?

T90 stated ground pressure = .938kg/cm^2 or 9380kg/m^2

Zaku has two feet, each of which are roughly 5m x 2.5m size (measured from 1/100 MG Zaku model kit I own), or 25m^2 total area, so a weight of 60 tons would give 60000/25 or 2400kg/m^2

Actually, the T-90's ground pressure is 87 kPa, not 94 kPa. And as Howedar pointed out, each time a mech raises a foot off the ground, it must support its entire weight on one foot, not two. In fact, it must support MORE than its entire weight on one foot, because there is a reaction force associated with the upward movement of the other foot and leg. And is the length of each foot seriously almost a third of the mech's height? Can someone confirm this?

In the series we saw a Gouf Custom running for all it's worth.
Count of 4 strides per second, 6m per stride (scaled from foot size), giving 24m/s or roughly 86km/h, fully loaded.

OK, now can it aim worth shit when it's running? Remember that when running, a biped is bouncing up and down, while a tracked vehicle is rolling along the ground. Also note that a running mech will have far greater ground pressure than a walking mech or a stationary mech, so it won't be running for long.

Quite easy, energy needed to shatter projectile is supplied entirely by the projectile's motion and its weight.

Irrelevant. In any collision, the weaker object will shatter/deform while the stronger object will not. If the round is weaker than the target, it will absorb all of its own energy. When you fall from 800 feet and hit the ground, what gives? The ground, or you?

We assume that all KE generated by round is absorbed by the thing that fires it in the form of recoil.

I thought you said you were studying engineering. You ARE aware that recoil/collision kinematics are dictated by MOMENTUM, not KE, right? Please re-do your calculations without this monstrous error. Momentum is conserved in collisions; KE is not, unless it's elastic (and since we're not talking about rubber shells bouncing off rubber mechs, I think we can safely say that it's not an elastic situation).

Recoil and toppling:

Here is where everybody says there's a problem, and the toughest nut to crack, so I looked at it last. Unfortunately, as I'm rather short on time as I am in the middle of university end exams over here in Australia, I can't do justice to this section. However, some preliminary stuff would probably be interesting.

In a free standing rigid object, there is a physical property called Centre of Percussion. If you apply a force not at this point/level/height, the object will tend to topple, but if you apply the force at this point/level/height the object will not topple but will be shoved backwards. The problem with calculating this is that I do not know the weight distribution of the Zaku, so I cannot model the Zaku as multiple cylinders, find their Moments of Inertia, combine them using the Transfer of Axis theorm, and then calculate the Centre of Percussion, all in 3D!

However, it boils down to this, you can argue this one either way. Since the weight distribution is unknown, it is possible that the Zaku has been balanced so that the force left over from firing goes through this point/level and thus the Zaku would be shoved back and not toppled, or it could be extremely low weight projectiles because all the weight's bunched right up, but that has been shown to be highly unlikely from visuals in the series and from my previous calculations.

And as for shoving backwards, well, assuming no toppling (which Centre of Percussion DOES allow for, and Zakus and tanks can be treated as a rigid object, I'm sure it can lock its servos/treads!), the tank and the Zaku would give equivalent resistance to the recoil as frictional forces work by the formula F= (Coefficient of Friction) * (Normal force)
Normal force is about the same for both, and as for coefficient of friction, well, steel treads on ground = steel treads on ground at the very least, and surface contact area surprisingly for non-engineers doesn't come into it at all.

In other words, after saying you would perform scientific calculations, you decided to post an excuse not to perform the necessary calculations on this key point. The fact remains that an off-centre recoil will have far greater effect than a centred recoil, and a mech holds its gun in one hand. Furthermore, the fact remains that a high centre of gravity will topple more easily than a low centre of gravity, and your attempts to evade this simple truism smell like a whole lot of bullshit to me.

8- There is a physical explaination for how a Zaku can take the same recoil a M1A1 experiences when it is standing up, thus reinforcing the idea that the Magella IS powerful.

There is? Then why didn't you provide one? All you provided was an attempt to make the situation ambiguous.

Lord Wong, if you do read this, could I ask of you a favour, that is if you do find something wrong, even if it's drastically wrong and will change the findings significantly, could you PM it to me if Sea Skimmer, MKSheppard, Vympel etc have not replied yet? Since I was accused of not knowing my physics, I would like to let this be a demonstration of who really knows his/her physics/mechanics better, not how well can we shoot our mouths off and rely on Lord Wong to back us up.

Too late; everyone's already replied. There was one major omission and one glaring error. Please re-do the calcs for recoil and add the missing calcs for toppling.

[MKSheppard]

Now that darth wong has added his input.....

The Mecha Fanwhores got......



AGAIN!

[Sea Skimmer]

Knew I should have come online sooner, now theres nothing to add except a list of Videos of what's going to be crushing the mecha...

http://www.rusarm.ru/video/t90s_1.wmv
http://www.rusarm.ru/video/t90s_2.wmv
http://www.rusarm.ru/video/t90s_3.wmv
http://www.rusarm.ru/video/khriz.wmv
http://www.rusarm.ru/video/khriz_dual.mpg
http://www.rusarm.ru/video/mi35_1.wmv
http://www.rusarm.ru/video/mi35_2.wmv

[Sea Skimmer]

And a few things to deal with those pesky aerial cruisers.

http://www.rusarm.ru/video/torm1.wmv
http://www.rusarm.ru/video/s300v.wmv
http://www.rusarm.ru/video/s300pmu.wmv
http://www.rusarm.ru/video/bukm1.wmv
http://www.rusarm.ru/video/tungm1.wmv

[Evil Sadistic Bastard]

Skimmer, what exactly is inside? My connection's a bit flaky and transfers quite slowly.

[Sea Skimmer]

That DOES IT!

I am officially asking for a Tread/Heavy Armor group (Like BOTM & ATJ)

Sounds good.

I'm in. Die Mecha DIE!

[Sea Skimmer]

Skimmer, what exactly is inside? My connection's a bit flaky and transfers quite slowly.

Each ones a video from http://www.rusarm.ru/main.htm, the web site for ROSOBORONEXPORT, the Russian state corporation reasonable for arms exports among other things. Each one is a 2-5 meg video of whatever weapon system is noted at the end of the URL.

The T-90's at the minimal are worth it. Though I downloaded every single one via 56K from this page and it was worth it.

http://www.rusarm.ru/video.htm

[Evil Sadistic Bastard]

Hmmm... I see..

Thanks Skimmer.

If nothing else, they will make excellent material for plotting the destruction of various idiotic instituutions.

[Sea Skimmer]

Hmmm... I see..

Thanks Skimmer.

If nothing else, they will make excellent material for plotting the destruction of various idiotic instituutions.

Forgot this little part. As they are, the video download are formatted in a stupid annoying way to prevent direct downloads it seems. However someone has already gotten all the URL's. You need to scroll down some for the naval ones though.

http://www.whq-forum.de/cgi-bin/iB3/iko ... f=1;t=2302

[Typhonis 1]

Hmmm mecha vs tanks again welll Tanks rule specially if one is hull down and cammoflaged plus a hellfire AT missle would most likely gut a mech since there armor ton for ton is thinner than a tanks.BTW the armor is thickest on front .thin on the sides mybe60% frt rear my be 30% frts and top and bottoms are maybe 10% if that

[Howedar]

Yes, I know. I was being exceedingly generous.

[SAMAS]

Here's the scene of the Zaku firing the Magella Attack's 175mm cannon.

http://samas.freehosting.net/Zakushot1.jpg
00:20:16 -- After just missing getting it's arm shorn off by a Beam Rifle, the Zaku takes aim in the direction of the shot, and returns fire.

http://samas.freehosting.net/Zakushot2.jpg
00:20:16 -- The scene switches to Karen's view as the Zaku tries to find her.

http://samas.freehosting.net/Zakushot3.jpg
00:20:17 -- The shot passes by Karen.

I know, I know. Not necessarily a continuious shot. Luckily, the Zaku fires twice in this shot.

http://samas.freehosting.net/Zakushot4.jpg
00:20:18 -- The Zaku fires again(yes, I know that it looks the same as the second pic. The Zaku didn't move).

http://samas.freehosting.net/Zakushot5.jpg
00:20:19 -- The second shot impacts, a little closer to Karen.

[SAMAS]

Oh, and for the person who claimed that the Magella Attacks can easily blow Gundams apart, here's an example of how the Gundams fared against Magella Attack cannons attached to actual Magella Attacks.

The exchange begins when the Gundam's detect metallic objects 2km away, and Shiro accidentially backs into a mine. They begin by firing HEAT rounds into Terry's RX-79[G]. Two rounds impact, causing little damage, but shake the Gundam.

http://samas.freehosting.net/Magella1.jpg

The tanks switch to Penetrator rounds, and this time manage to hit Terry in the leg as he tries to jump back. This manages to put him down for a second, as he manages to land badly on the leg and damage it further.

http://samas.freehosting.net/Magella3.jpg

And what about those HEAT rounds?

http://samas.freehosting.net/Magella5.jpg

The didn't do much to him. In fact, it later takes two HEAT shots in the same area to damage Shiro's shield, and he later takes a HEAT round to the chest at point-blank range. This is Mirrored in MSG when the Gundam takes two such rounds to the back.

http://samas.freehosting.net/Magella4.jpg

[MKSheppard]

Here's the scene of the Zaku firing the Magella Attack's 175mm cannon.

Did I hear something in the background? Sounded like a baby crying.

[Howedar]

What pretty pictures you've provided us with, SAMAS. Are they in some way applicable to the discussion?

[Illuminatus Primus]

Count me in for a heavy armor group.

I hate Mecha so much its undescribable.

[SAMAS]

Proof of round going 5km/s:

10km engagement range, 2 second observed travel time = average velocity of 5km/s
Procedure: We see muzzle flash, we count 2 seconds, we see impact.
10km was quoted by character on screen and believable in scene (pilot had to use maximum zoom and the visuals were still iffy, etc)
2 seconds was counted by me, SAMAS and somebody else independently (SylasGaunt?) on both DVD and VCD

A round hitting something at 5km/s is not going to be effective, as it will not remain intact and therefore will be a poor penetrator. Meanwhile, it still has too little kinetic energy to be used as a blunt-force penetrator.

If you don't believe that KE penetrators are rendered ineffective by physical damage, take note that special ERA is now made soley to damage KE penetrators before impact.

Well, we've shown that the Penetrators can do some damage, even to Gundarium "super" armor.

Proof of speed:

In the series we saw a Gouf Custom running for all it's worth.
Count of 4 strides per second, 6m per stride (scaled from foot size), giving 24m/s or roughly 86km/h, fully loaded.
So a Zaku going at 90km/h isn't outrageous, the Gouf had shitloads more equipment on it as well

This is about double that of a T-90, whose max cross-country speed is 45kph (By the way, was said Gouf Custom able to mantain that speed for any distance?).

The Gouf was engaged with two RX-79[G]'s, the EZ-8, and three Mass Production Guntanks.

It started by jumping out of an elevator, dropping into a building, altering his rate of descent as to not get shot, Destroyed one Guntank, used his gun to kick up some dust by blasting at the street around his nex target, and runs around them to take out the Gundam's Beam Rifle, and use his sword to splatter the crew of the second Guntank over the front of his suit. He jumps onto a highway, and runs down that to the third Guntank.

After getting the road shot out from under him, he uses one arm to push a massive section of road off of him. http://samas.freehosting.net/Goufpush.jpg

After that little act of intimidation, the Gouf's pilot engages Shiro in combat. He essentially plays with the three Gundams the entire time, and only allows himself to be killed because of his respect for Shiro's girlfriend. Of course, he makes sure that his final act also kills the last Guntank.

Of course, it is vastly inferior to the speed of, say, a Mi-24 Hind.

True, but that's running speed against an aircraft.

When that sucker takes to the air, however, is another matter.

Proof of capability of no shattering at 5km/s

Quite easy, energy needed to shatter projectile is supplied entirely by the projectile's motion and its weight. So the 5kg DU core of the M1A1 which doesn't shatter at 1.8km/s can be matched by a .648kg DU round at 5km/s, and it will still not shatter. This is a minumum though, you realise. DU should still have much headroom, so round shattering isn't really a problem, it can be compensated for!

Can you rephrase this? Are you saying that you're going to have a little tiny penetrator moving at 5km/s? And you think this will make it magically less likely to be deformed on impact?[/quote]

I realized that you missed this part, that disproves the round shattering, and thus capable of imparting it's force to the target.

Proof of round being NOT ultralight:

We assume that all KE generated by round is absorbed by the thing that fires it in the form of recoil.

M1A1:
KE = 1 / 2 * m * v ^ 2 = .5 * 5 * 1800 ^ 2 = 8.1MJ
Magella:
FOR SAME RECOIL
m = KE / (.5 * v ^ 2) = (8.1 * 10^6) / (.5 * 5000 ^ 2) = .648kg (!)
For your proposed recoil, I would assume 1/10 to be reasonable?
By same method, the round would weight .0648kg, or roughly 65g...

If your theory's right, and that the Magella's firing HE, well, dude, 65g of MSG HE = 3500g of T90 HE, as you people keep saying that the effects of this shell has to be HE. Insane, inane, and obviously, unworkable.

F = m * a
F, force from crosswind
m, mass of the shell, is in contention
a, acceleration (in this case lateral to path), is what we're looking at.
If your shell is small (small m), then obviously for a given F your a will be high, and that will mean bigger discrepancy between aim point and actual landing point. Say for a 20km/h crosswind, 4000 metre range

M1A1 round:
Force from wind
= Cd * (.5 * density of air * wind cross sectional area of round * wind velocity ^ 2)
Cd obtained from Drag coefficient table, after calculation of Reynold's Number, assume round is similar to smooth circular cylinder
Re = (wind velocity * diameter of round) / Kinematic viscosity of air
= (5.56m/s * .05m) / (14.6 * 10 ^ -6)m^2/s
= 19041
Hence Cd ~ 1.1
Force from wind = 1.1 * (.5 * 1.2 * (.3 * .05) * 5.56 ^ 2) = .306 N

F = m * a
a = F / m = .306 / 5 = .06m/s^2, or with a 4000 metre range, it would have a 'to hit' circle of 14cm diameter. That's quite ok.

Your proposed Magella round:
Same principle, substitute the 1/10 recoil round in place of 5kg
a = F / m = .306 / .0648 = 4.72m/s^2 or with the observed 10000 metre range, it would have a to hit circle of 9.4m in diameter! That's insane! The Zaku pilot wouldn't have fired at the Gundam in 'that' scene, he'd have put his hands up and go "I surrender" since he would have had NO chance! Furthermore, we have never seen this kind of scattering before in any of the weaponery as demonstrated in MSG.

Christ only knows what you're babbling about here. I don't care about round weight: said rounds demonstrate capability similar to a T-90's 125mm cannon, but against inferior armor. Let me make this real clear to you, in case you're slow:

T-90's 125mm cannon has x effect on certain thickness of armor.
Mech weapons have same effect on less armor (of same quality).

Therefore, 125mm > Mech weapons

Actually, the armor of the Mobile suits have shown to be able to take quite a few hits. Even against the rounds of the Machineguns of other Mobile Suits, it takes several rounds to penetrate and do damage.

Recoil and toppling:

Here is where everybody says there's a problem, and the toughest nut to crack, so I looked at it last. Unfortunately, as I'm rather short on time as I am in the middle of university end exams over here in Australia, I can't do justice to this section. However, some preliminary stuff would probably be interesting.

In a free standing rigid object, there is a physical property called Centre of Percussion. If you apply a force not at this point/level/height, the object will tend to topple, but if you apply the force at this point/level/height the object will not topple but will be shoved backwards. The problem with calculating this is that I do not know the weight distribution of the Zaku, so I cannot model the Zaku as multiple cylinders, find their Moments of Inertia, combine them using the Transfer of Axis theorm, and then calculate the Centre of Percussion, all in 3D!

However, it boils down to this, you can argue this one either way. Since the weight distribution is unknown, it is possible that the Zaku has been balanced so that the force left over from firing goes through this point/level and thus the Zaku would be shoved back and not toppled, or it could be extremely low weight projectiles because all the weight's bunched right up, but that has been shown to be highly unlikely from visuals in the series and from my previous calculations.

And as for shoving backwards, well, assuming no toppling (which Centre of Percussion DOES allow for, and Zakus and tanks can be treated as a rigid object, I'm sure it can lock its servos/treads!), the tank and the Zaku would give equivalent resistance to the recoil as frictional forces work by the formula F= (Coefficient of Friction) * (Normal force)
Normal force is about the same for both, and as for coefficient of friction, well, steel treads on ground = steel treads on ground at the very least, and surface contact area surprisingly for non-engineers doesn't come into it at all.

All irrelivent; see above.

Conclusions

To sum it all up in simple words:

3- Tanks would get sink in soft ground faster than MSs would

Until Mechs start to move, in which case they're in deep shit (mud).

Only assuming the ground it muddy, but even Zakus have been shown to move around in mud with little effect.

6- If the Magella's projectile really is HE and it really does have a low recoil, damn, that's some HE! 65g of it can SHAKE THE GROUND, feck! As the old saying goes, that just ain't right.

Doesn't matter, said weapon demonstrates inferior capabilities to 125mm cannon of T-90.

In what? In Speed, Range, and Power, it's been shown to be comparable, if not superior.

Yes, I saw those clips you showed. The T-90's gun shows little, if any, power greater than those of the Zeon's Guns. In fact, the MA cannon, and any of their bazookas can outdo that.

In light of all these factors, I think I can safely say that since a Gundam was able to take a point blank Magella shot to the chest without a problem, and the Magella can be just as powerful as a contemporary tank cannon, Mobile Suits in general can be effective against T90s.

You're looking at that backwards. Since Mech armor must be thinner than T-90 armor, and this Mech armor can take a hit from x weapon to its chest at point-blank, then the Tank would withstand the hit easily, as it has more armor.

Unless the armor provides equally, if not greater, amount of protection for it's size than modern armor.

[Darth Wong]

Hey SAMAS, if you want to prove that a fictional vehicle can trash a real one, it does you no good to compare it to another fictional vehicle from the same universe.

By this "logic", we can prove that Jem'Hadar can kick US Marine ass by showing that they're pretty good at killing Starfleet pajama-clad Mama's boys.

[Sea Skimmer]

So Wong, what about our new user group?