BRP Mecha

[Atgxtg]

I have already reworked the damage bonus table, so no need to worry about that. 10:1 is intuitive when making conversions (well, for non-British at least ) so it is better.

More like non-US. My homeland is probably the last bastion against SI. Personally I can use either, and usually prefer SI for most calaculations, since it make it easier.

]

Of course I am interested. Incidentally, the 60mm rotating vulcan cannon that is standard equipment for Earth Federation mechas is rated by me at 1d4 "mecha" damage (2.5 average vs. your average of 2.8 with 8d6) and has a 2000m max. range. Looks like our ideas converge.

Yeah, looks fairly close. Well within the margin for "wiggle room". I'll put together some files over the weekend with some examples and stats.

My cannon formula for modern cannon is fairly simple, but seems to hold up well so far when comparing to real weapons.

1) Take the square root of the bore (in mm). Refer to this as the Gun Factor (GF).

-For the metric impaired, use the square root of the bore in inches and then mutiply the result by 5 to get the GF.

2) Increase the GF by 10%. This is the number of dice (d6) the weapon ifnlicts. Note that this can vary a bit based on the type of gun and ammo. For instance, a APFSDSDU tank round is probably around 25% higher than it's WWII era predecessor, the APC round, for about 6x the penetrating power.

3) Base Range is equal to the GFx250m. Or, you can just divide the damage dice by 4 to get the range in km. For example, a 406mm (16") naval gun would have a GF of 22 and a base range of 5500m (22x250m), or 5.5km (22/4 km).

4) A gun can shoot to medium and long range just like a small arm. However damage dice should drop off by about 25% at each range band. So a 16" gun would do 22D6 at close range, 17D6 at medium range (out to 11km), and 11D6 at long rangre (out to 22km). Of coruse the chances of hitting anything will probably be low, since few people get a chance to practice with a 16" cannon.

5) Big guns that can elevate can perform indirect fire. This allows them to shoot to extreme range (twice long) at 1/8th skill.

6) For salvos, I been adding 5% to the chance to hit for each additional gun, and then rolling a random die to see how many rounds in the salvo actually hit. For example a three gun turret would get +10% to hit and 1D3 rounds would strike the target on a successful attack.

P.S.

Since average damage works out to about 4xthe GF, it looks like Mecha scale damage would be GF* 0.35 by my method, or GF *.31 for yours. At least based on the 60mm Vulcan. Or we could split the difference and use GF/3.

Hmm, so the main guns on the USS Iowa would do about 2d6 damage, mecha scale. That might even hurt something like Grandizer.

Edited July 18, 2009 by Atgxtg

[RosenMcStern]

Since average damage works out to about 4xthe GF, it looks like Mecha scale damage would be GF* 0.35 by my method, or GF *.31 for yours. At least based on the 60mm Vulcan. Or we could split the difference and use GF/3.

We will see. Most mechas use energy weapons, so fudging a bit with ballistic weapons is not a great problem in any case.

Hmm, so the main guns on the USS Iowa would do about 2d6 damage, mecha scale. That might even hurt something like Grandizer.

In the playtest game I run at Tentacles, we had 280mm rockets (I cannot recall the caliber used by US battleships HE rounds, but it is not very different) doing 2d6 damage, so the two systems are still compatible, in the results.

And Grendizer has Physical resistance 70 (7 on mecha scale) in my stats, published here, so it takes a roll of 12 on 2d6 to really hurt it in a limb (torso hits no way), assuming a battleship can actually hit a moving superobot. On the other hand, if a static cannon like that of a battleship can actually manage to hit a real mecha:

- a Code Geass knightmare gets vaporized (but most of them have force fields)

- a Macross Valkyrie goes BOOM!

- a Universal Century mobile suit loses a limb

[Pilous]

The Uss Iowa was mainly armed by 9x406mm cannons plus 20x120 mm “small” guns :eek: a direct hit of a single 403 mm gun would be capable of obliterate virtually anything...

Ciao

Dario

[Atgxtg]

The Uss Iowa was mainly armed by 9x406mm cannons plus 20x120 mm “small” guns :eek: a direct hit of a single 403 mm gun would be capable of obliterate virtually anything...

Ciao

Dario

Reality-wise, yes. But with certain settings and items, like some giant mecha or Daikaju (i.e. Gojira) it might only get it angry.

[Atgxtg]

We will see. Most mechas use energy weapons, so fudging a bit with ballistic weapons is not a great problem in any case.

True. Engery weapon damage is more of a factor of how much energy you can pump into them.

In the playtest game I run at Tentacles, we had 280mm rockets (I cannot recall the caliber used by US battleships HE rounds, but it is not very different) doing 2d6 damage, so the two systems are still compatible, in the results.

That's not too far off. The rockets could be packing a lot more explosives, vs what is mostly an AP round (the 18 kg burster charge is almost an after through).

Now the HC shell probably wouldn't hurt a big mech as much, but would make a nice 15m crater, and knock down all the trees with 180m. It would make a cool scene.

Guess I'll be all set for when Eva Unit-2 fights from a battleship.

Edited July 19, 2009 by Atgxtg

[RosenMcStern]

The Uss Iowa was mainly armed by 9x406mm cannons plus 20x120 mm “small” guns :eek: a direct hit of a single 403 mm gun would be capable of obliterate virtually anything...

Ciao

Dario

120mm is the standard caliber for a Zaku MG, which is one of the least effective weapons in the Universal Century (think of it as a 37mm AT gun in WW2: good against early war armour, useless against late war tanks).

Rick-DOM RPG launchers shoot 360mm HE rockets instead of 280mm. These are supposed to destroy a mecha with one hit.

Which means that one single Universal Century mecha carries weapons as effective as those used by the biggest capital ships built in the 20th Century.

Note: the 120mm ordnance does 1d8 in BRP Mecha, the 360mm rocket does 2d8, and I would rate a 400mm shell from the Iowa as 3d6.

[Agentorange]

120mm is the standard caliber for a Zaku MG, which is one of the least effective weapons in the Universal Century (think of it as a 37mm AT gun in WW2: good against early war armour, useless against late war tanks).

Rick-DOM RPG launchers shoot 360mm HE rockets instead of 280mm. These are supposed to destroy a mecha with one hit.

Which means that one single Universal Century mecha carries weapons as effective as those used by the biggest capital ships built in the 20th Century.

Note: the 120mm ordnance does 1d8 in BRP Mecha, the 360mm rocket does 2d8, and I would rate a 400mm shell from the Iowa as 3d6.

Not knowing much about mecha ( indeed, nothing would be nearer the mark ) but knowing a little about WW2 naval artillery, I think it's worth pointing out that an HE rocket has little or no armour piercing capability, whereas most naval artillery was designed to fire Semi Armour Piercing (SAP) or Armour Piercing (AP) rounds. I think when dealing with modern weaponry and damage you really need two weapon stats, one for armour piercing and one for damage. Indeed I think someone did exactly that with the Striker/BRP conversion in the downloads section

[RosenMcStern]

Not knowing much about mecha ( indeed, nothing would be nearer the mark ) but knowing a little about WW2 naval artillery, I think it's worth pointing out that an HE rocket has little or no armour piercing capability, whereas most naval artillery was designed to fire Semi Armour Piercing (SAP) or Armour Piercing (AP) rounds. I think when dealing with modern weaponry and damage you really need two weapon stats, one for armour piercing and one for damage. Indeed I think someone did exactly that with the Striker/BRP conversion in the downloads section

Very true. The stats given for Artillery weapons in BRP do not differentiate between HE and AP, not even for the tank guns which usually have at least three types of round available. We might try to provide more detailed rules for this in BRP Mecha, but since most of them will have energy weapons rather than ballistic ones I think we will not go very far with this.

[Agentorange]

The other thing that occurred to me about the ballistic stuff is ammunition supply. You mentioned a while back that the smallest Mecha in the supplement were about 4.5 metres tall, which is what ? about 14-15 ft tall ? Ammunition supply for the kinetic/ballistic stuff is going to be fairly limited, at least for the large calibre stuff. Granted rail guns and such like weapons don't require shell casings/cartridges etc etc so you could probably get away with a larger capacity there, but rockets or missiles are going to take up a fair bit of space.

[Atgxtg]

AP/HE ROUNDS...

've been working on some rules for different types of ammo for vehicles. I've been trying to get the burst radius for shells to mostly closely match real world data. Unfortunately the "shrapnel" rules in the BRP core book don't work very well, so I has to make some adjustments.

I added a "secondary explosion" effect to some shells to help reflect the fact that some round do indeed have a secondary explosion (like the 406mm AP round), or will cause damage though "spauling" and such.

Perhaps some of this might be useful for mecha. I've been meaning to send Rosen some of my notes for consideration, but have been sick lately.

MECHA AMMO CAPACITY

No doubt that there is some truth to this. Then again a lot of mecha shows give the robots "Hollywood Clips" and "regenerating" missiles. I would suspect this depends on how realtic the setting the GM is running-Mechaseries cover a lot of ground. Perhaps Rosen will make this an optional rule for BRP Mecha?

3D6 400mm gun AND SCALING

Hmm, 3D6 might just work for the vehicle stats, too. Especially if we consider that the penetration for those naval guns dropped off over range, and that MEcha tend to fight much close than battleships did.

The major limiting factore is the AP, SIZ and HP ratings of ships in the core rules. With a battleship having around 36 AP and 480 HP, big gun damages can't be too high or too low without making batteships too vulnerable or too tough.

But that assumes the BB Stats in the core rules are being used. Toss those out and it's a whole different story.

[RosenMcStern]

AP/HE ROUNDS...

Better avoid these. They have limited impact on mecha combat and make things more complex.

I would suspect this depends on how realtic the setting the GM is running-Mechaseries cover a lot of ground.

Exactly. In some kind of campaigns you have unlimited (or humongous) amounts of missiles. In others you have realistic ammo supplies: 100 rounds per SMG and 4-10 missiles per launcher.

3D6 400mm gun AND SCALING

Hmm, 3D6 might just work for the vehicle stats, too. Especially if we consider that the penetration for those naval guns dropped off over range, and that MEcha tend to fight much close than battleships did.

The major limiting factore is the AP, SIZ and HP ratings of ships in the core rules. With a battleship having around 36 AP and 480 HP, big gun damages can't be too high or too low without making batteships too vulnerable or too tough.

The battleship in the core book would have 4 APs and 48 HPs on mecha scale (not exactly so, as it would have locations/sections with, say, 16 HPs). A 400mm gun doing 3d6 would disable a section with an average of 3 shots. Attacked by, say, Zakus, it would be hit by SMGs doing 1d8 (need a good roll to pass armor) or missiles doing 2d6. Enough to do some damage and disable some systems. Note that a spaceship would possibly have similar statistics. Char Aznable managed to destroy three spaceships in a battle with a Zaku, which is hardly believable given the average damage above, but Char has at least 90% skill, and SMGs can impale, so it can be done.

All in all, the stats for guns and ships are not too "wrong". Of course energy weapons would blast through those armors in seconds. And spaceships have mostly energy weapons and missiles doing 3d6/4d6 at least.

[Jason D]

Any chance of some giant mecha who sort of resemble the Shogun Warriors?

I hope that the book has a section covering giant monsters, to give the mecha something to fight other than each other.

[Simlasa]

Thumbs up for giant monsters and Shogun Warriors!

[RosenMcStern]

You may have noticed that I already posted the stats for some of the "Shogun Warriors" (name used only in the US) one year ago. No stats for copyrighted materials will be there, of course, but you will be able to build your own versions. Some of the examples in the chapters I have already written are taken from Shogun Warriors anime.

As for giant monsters, the ones that mechas fight are usually mechanical in nature, more cyborgs than Kaiju. The few exceptions are easy to stat for a clever GM. But I could include some stats for cyborg dinos and haniwa genjins.

[Atgxtg]

Better avoid these. They have limited impact on mecha combat and make things more complex.

Fair enough. IMO they are more of a factor when infantry get involved, anyway. Seems like things look compatible enough between my notes and BRP MEcha that someone could port the rules over themselves anyway, if the desired to.

Exactly. In some kind of campaigns you have unlimited (or humongous) amounts of missiles. In others you have realistic ammo supplies: 100 rounds per SMG and 4-10 missiles per launcher.

Sounds good to me.

The battleship in the core book would have 4 APs and 48 HPs on mecha scale (not exactly so, as it would have locations/sections with, say, 16 HPs). A 400mm gun doing 3d6 would disable a section with an average of 3 shots. Attacked by, say, Zakus, it would be hit by SMGs doing 1d8 (need a good roll to pass armor) or missiles doing 2d6. Enough to do some damage and disable some systems. Note that a spaceship would possibly have similar statistics. Char Aznable managed to destroy three spaceships in a battle with a Zaku, which is hardly believable given the average damage above, but Char has at least 90% skill, and SMGs can impale, so it can be done.

You are letting vehicle weapons get "impales"? That can be somewhat problematic, since it will let some weapons penetrate armor that it probably never could. On man-to-man scale, impales made sense, since there are always gaps in the armor, but can be a problem with vehicles, since AP doen't increase as fast as damage does.

All in all, the stats for guns and ships are not too "wrong". Of course energy weapons would blast through those armors in seconds. And spaceships have mostly energy weapons and missiles doing 3d6/4d6 at least.

No, not too wrong. Another factor worth considering is that mecha weapons are almost always going to be more advanced and more powerful than WWII era weapons. The modern 120mm APFSDSDU used in the M1A2 has penetration capabilities comparable to the 406mm cannon-at least out to about 2km or so. Chances are the 120mm cannon used by mecha are probably ever better that the APFSDSDU, and inflict even more damage. SO there is probably a lot of "wiggle room" for weapon stats.

[RosenMcStern]

You are letting vehicle weapons get "impales"?

Not vehicle, mecha. The real advantage of a mecha attacking a ship is that it can circle around it and find the weak spots in the armor - hence the impale.

The modern 120mm APFSDSDU used in the M1A2 has penetration capabilities comparable to the 406mm cannon-at least out to about 2km or so. Chances are the 120mm cannon used by mecha are probably ever better that the APFSDSDU,

Those are SMGs, not cannons. They cannot be as powerful and precise as M1A2 ordnance. Single-shot ballistic weapons are almost non-existent in the anime mecha genre. The dreaded "Autocannon/20" is a Battletech construct that I have no intention to put into BRP Mecha.

[Atgxtg]

Not vehicle, mecha. The real advantage of a mecha attacking a ship is that it can circle around it and find the weak spots in the armor - hence the impale.

I can see that. Come to think of it mcha could probably target a location on a bit ship a bit easier too. Sort of like humans vs. giants. IF the mech is standing right next to a gun turret, it shouldn't be too hard to hit that location.

Those are SMGs, not cannons. They cannot be as powerful and precise as M1A2 ordnance. Single-shot ballistic weapons are almost non-existent in the anime mecha genre. The dreaded "Autocannon/20" is a Battletech construct that I have no intention to put into BRP Mecha.

Well "cannon" isn't a type of gun so much as the size of the gun. For instance we have 40mm autocannons that pump out a lot of rounds. I could certainly see a more technologically advanced culture making a 120mm autocannon/SMG. If the 120mm cannon in BRP does 15D6 (per BRP and CoC) that would work out to about 1.5d6 mecha scale or 1D9, so 1D8 is a good match. Especially if they bleed off some of the gasses to make the weapon fully automatic, and use a smaller barrel to make the weapon more portable.

Just by looking at how much weapons have evolved since WWII can give a good idea of just how much tings could change in a futuristic setting. We don't use battleships anymore because they are obsolete. There are better ways to direct more firepower on a target faster, and with higher accuracy, with only a fraction of the men, materials or cost (and that's a scary thought).

Naturally just how much they do change would depend on the setting. In many mecha series the mecha are so advanced as to make conventional weapons obsolete or even useless. In others humanoid mecha are just another option available to the combatants.

[Trifletraxor]

What's the ETA?

[RosenMcStern]

There is no official ETA, as other projects have a higher priority - like, huh, Merrie England - and need attention. Unfortunately, our BRP production line has slowed down a lot. But it is still planned.

I hope I can provide more details about our planned BRP stuff after Chimeriades. I should be able to make a checkpoint with Charlie (and Jeff) there.

[Atgxtg]

Just wondering, is the slow down something unique to your BRP product line, or a general trend for all your RPG lines?

[RosenMcStern]

Geez! Let us just say that 15 months ago we had just one line (BRP/RQ). Now we have two, with the arrival of HeroQuest in Aug 2010. In one month, we will have four RPG lines, in two different languages.

Is this a good reason for slowing down a bit?

[Agentorange]

Geez! Let us just say that 15 months ago we had just one line (BRP/RQ). Now we have two, with the arrival of HeroQuest in Aug 2010. In one month, we will have four RPG lines, in two different languages.

Is this a good reason for slowing down a bit?

Nah, just means you have to work four times as fast

[Agentorange]

Well "cannon" isn't a type of gun so much as the size of the gun. For instance we have 40mm autocannons that pump out a lot of rounds. I could certainly see a more technologically advanced culture making a 120mm autocannon/SMG. If the 120mm cannon in BRP does 15D6 (per BRP and CoC) that would work out to about 1.5d6 mecha scale or 1D9, so 1D8 is a good match. Especially if they bleed off some of the gasses to make the weapon fully automatic, and use a smaller barrel to make the weapon more portable.

OTO Melara, An Italian arms firm have 76mm auto cannon on the market that can fire upto 120 rpm

http://www.otomelara.it/EN/Common/files/OtoMelara/pdf/business/naval/mediumCalibers/76-62SR.pdf

They also have a 127mm naval gun that they've got to about 60rpm in tests. The main stumbling block with the smaller gun is ammunition supply of the ship it's mounted on. In tests they've achieved over 120rpm ( but not with consistent reliability ), but it's only a matter of time....

EDIT just noticed on their site they have a 40mm gun that can pump out 450 rpm !

Edited October 1, 2011 by Agentorange

[Atgxtg]

They also have a 127mm naval gun that they've got to about 60rpm in tests. The main stumbling block with the smaller gun is ammunition supply of the ship it's mounted on. In tests they've achieved over 120rpm ( but not with consistent reliability ), but it's only a matter of time....

It isn't so much a matter of time, but one of need. Back during WWII the trend was for heavier artillery. But, afterwards it was discovered that lighter, rapidfiring guns are better than bigger, slower, less portable guns.

Even if somebody make a rapid firing 120mm gun, it would be of limited usefulness if there wasn't a way to carry and load enough ammo to make the gun useful. Lots of aircraft have cannon that can toss off thousands of rounds per minute, but only carry a few seconds worth of ammo.

Keep in mind that in the real world, it ususally inst a case of more damage = better. In many cases a 120mm cannon would be overkill. Of coruse, most mecha settings are the exception.

EDIT just noticed on their site they have a 40mm gun that can pump out 450 rpm !

Not surprising. High ROF 40mm guns make great anti-aircraft weaponry.

[RosenMcStern]

Lots of aircraft have cannon that can toss off thousands of rounds per minute, but only carry a few seconds worth of ammo.

Keep in mind that in the real world, it ususally inst a case of more damage = better. In many cases a 120mm cannon would be overkill. Of coruse, most mecha settings are the exception.

A mecha (real robot) is more heavily armoured than a tank (MUCH more) and can actually carry a lot of ammunition. Thus, it needs a Big Gun (120mm is normal for anti-tank weaponry nowadays, whereas the norm was between 75 and 88mm during WWII, the tiger employing an 88) and can afford to have an automatic one.

Standard equipment for a Zaku (the archetypal mass-produced mecha) is a 100mm SMG. It is shaped like a Thompson, and is the equivalent of the 127 described above in firepower. Smaller mechas from Code Geass may employ assault rifles that are the equivalent of an A-10 AT gun.