68 replies to this topic

[MechaBattler]

What is engine rating representative of? It doesn't increase in volume, which is what I take slot size to be representative of. But it goes up in weight. What are they putting in there that doesn't require expanding the reactor?

[Karl Streiger]

volumetric scaling - the whole mech scales with the engine = power plant and power drive.

and the real answer to have different scales would have blew the "useability" of a mech lab of the 80s.
you can build a mech witb sheet of paper and a mech.

[MechaBattler]

So it was for simplicity sake most of all.

Are there rules for what a mech's engine limits are? I never understood what they based that on in MWO. Wonder if it's different in TT.

[Nightbird]

MechaBattler, on 11 June 2019 - 11:49 AM, said:

What is engine rating representative of? It doesn't increase in volume, which is what I take slot size to be representative of. But it goes up in weight. What are they putting in there that doesn't require expanding the reactor?

Like horse power for ICE except in MW

Karl Streiger, on 11 June 2019 - 01:03 PM, said:

volumetric scaling - the whole mech scales with the engine = power plant and power drive.

and the real answer to have different scales would have blew the "useability" of a mech lab of the 80s.
you can build a mech witb sheet of paper and a mech.

The engine doesn't get bigger when you take it out of a light mech and put it into an assault. That's MWO's problem

[FupDup]

MechaBattler, on 11 June 2019 - 01:29 PM, said:

So it was for simplicity sake most of all.

Are there rules for what a mech's engine limits are? I never understood what they based that on in MWO. Wonder if it's different in TT.

In terms of a "hard" limits you have to take an engine that is a multiple of your mech's maximum tonnage.

In terms of "soft" limits, depending on what rules you're playing under you may need certain level refit kits or other logistical stuff to change the engine. Or you might be playing with people that just let you take whatever you want without having to worry about the logistics.

Note that Omnimechs can have their engines changed, but they lose their Omnipod powers in exchange. They become a standard Battlemech.

[MechaBattler]

I mean I get the rating means more power. But is there an in universe technological explanation? Or is it just hand waved away as space magic boogaloo?

[Nightbird]

FupDup, on 11 June 2019 - 01:42 PM, said:

In terms of a "hard" limits you have to take an engine that is a multiple of your mech's maximum tonnage.

In terms of "soft" limits, depending on what rules you're playing under you may need certain level refit kits or other logistical stuff to change the engine. Or you might be playing with people that just let you take whatever you want without having to worry about the logistics.

Note that Omnimechs can have their engines changed, but they lose their Omnipod powers in exchange. They become a standard Battlemech.

that hard limit is only because you could only move in discrete hexes lol

[FupDup]

Nightbird, on 11 June 2019 - 01:50 PM, said:

that hard limit is only because you could only move in discrete hexes lol

I know.

MechaBattler, on 11 June 2019 - 01:48 PM, said:

I mean I get the rating means more power. But is there an in universe technological explanation? Or is it just hand waved away as space magic boogaloo?

It's basically space magic AFAIK because I've never come across any specific explanation of what the ratings mean. It's purely a simplified game mechanic similar to missile and AC ratings.

[Half Ear]

https://mwomercs.com...y-an-education/

Information garnered from several locations, noted in the thread. Rating vs Mech weight ratio acted more as a governor.

Quote

In the early days some BattleMech designers experimented with using fusion engines that produced more power than a particular chassis needed. The idea was that the extra power produced would provide some nebulous benefits in combat. This idea turned was not only false, but the oversized engines actually generated too much waste heat and would either cook off explosive ammo stored in the BattleMech; or the engine safeties would cut in and automatically shut down the engine. A BattleMech can only use so much power... trying to force it to use more provides no extra benefits and simply does not work.

And with Canon max weight 100 tons, the largest engine available is the 400 engine rating, thus allowing a 100 tonner move a max 4 walk/6run. Advanced rules have sprinting, which is 2x walk points so 4 walk/ 6 run/8 sprint

While sprinting the unit can not perform any attacks nor spot for indirect attacks
The Unit can not move backward nor can it enter water with a depth of 1 or more
Attacks made on the sprinting unit gets a +1 to hit (pilot focusing on going fast and not dodging)
And any piloting skill role has a +2 to it.
And at least in Battletech (lore) successful sharp turns all the time at high speeds do not happen...especially

Edited by Half Ear, 11 June 2019 - 03:50 PM.

[Alex Morgaine]

Nightbird, on 11 June 2019 - 01:35 PM, said:

The engine doesn't get bigger when you take it out of a light mech and put it into an assault. That's MWO's problem

Mechanically true but from what I read in lore, a 300std in an atlas is not the same size as a 300std from a marauder. While one or the other could donate an engine, it would need kludging to fit,
Also about sub 250 engines and external heat sinks:
The reason for this instead of just running with less then 10 was 2fold
1: mechanically it was a way to balance lighter Mechs having the same build space as a mech 3x heavier.
Additional:
There are lv3 rules for creating armless Mechs with no arm slots, and removing slots from light, medium and heavy Mechs but they don't apply to canon Mechs, unless your GM is insane or lives in perpetual 3025 no retro tech or advanced tech ever to allow less slots without invalidating canon builds.
2: In lore the external heat sinks represented the smaller mechs with smaller engines as taking up more space forthe engine and it's cooling system. Rarely would anything medium or larger have a sub 100 engine so outside the urban mech's std60 which is technically 8 to 9 slots larger due external cooling systems.

[Karl Streiger]

Nightbird, on 11 June 2019 - 01:35 PM, said:

The engine doesn't get bigger when you take it out of a light mech and put it into an assault. That's MWO's problem

No of course not - the fusion engine in its core will hardly change. The difference is the movement system.

I used once some calculation (using Corps)
The results is a Wolfhound need ~6MW of energy for its "drive", as did the Atlas with 6MW for movement.
On top of that come the weapons that need to be recharged - not so a big changer as you might think, at least not with the punny battle technology values - 3MJ for a Medium Laser and 8MJ for a PPC is not a real problem as long as you only shoot them once in 10sec.

So when we would ignore all the other stats of Corps (heat, acceleration, mobility, fuel (yes even fusion engine need fuel thats the killer - fuel for our 6MW engine for a single year would mass as much as the whole engine core)

TLDR
when correctly scaled - the Awesome with its smaller engine need to be the smallest of all 80ton Mechs, while the Gargoyle or the Charger need to be the largest - of course this would make it necessary to have dynamic scaling based on the engine the player chooses.
The slots if you keep that system would scale accordingly - so a slot on the Awesome might be equal to 1000cf (0.28m³), and on the Charger its equal to 1500-2000cf.

[FupDup]

Alex Morgaine, on 11 June 2019 - 07:40 PM, said:

1: mechanically it was a way to balance lighter Mechs having the same build space as a mech 3x heavier.

I don't really see how that would be necessary given the armor and tonnage drawbacks of the lighter mechs. Lights wouldn't be suddenly OP if all 10 base heatsinks were allocated inside of the engine.

[jss78]

MechaBattler, on 11 June 2019 - 01:29 PM, said:

So it was for simplicity sake most of all.

Are there rules for what a mech's engine limits are? I never understood what they based that on in MWO. Wonder if it's different in TT.

The way engine engines worked in TT is, the maximum distance a 'mech can walk, in hexes/turn, is engine rating divided by 'mech tonnage. So a 55-ton Shadowhawk with a 275-rated engine can walk 275/55=5 hexes, and a 35-ton Panther with a 140-rated engine can walk 140/35=4 hexes.

In OP you ask what engine rating is representative of. So from the above we learn: each unit of engine rating represents the power needed to move 1 ton at a speed of 1 hex/turn. Because a TT hex is 30 meters and a turn 10 seconds, that speed of 1 hex/turn equals 3 meters/second or 10.8 kilometers/hour.

The above are walking speeds, running speed is always 1.5x as many hexes, rounded up, so that Panther runs 6 hexes and the Shadow Hawk 8 hexes (gaining half a hex from rounding).

In MWO things basically derive from the TT logic, but with some twists. In TT an engine rating always needs to be a multiple of mech tonnage, because anything in between wouldn't give you a full extra hex of movement. So most Cicadas are 320-engined, while the down-engined CDA-3C goes down to exactly 280, losing one hex of walk move.

In MWO we can freely fine-tune engine size, because movement is not constrained by hexes. As far what the engine limits (lowest and highest allowed rating), these also don't derive from TT. In TT, you generally never replaced an engine with a different rating (I don't recall if the rules even allow it), and this also is enforced in HBS's BattleTech and I believe also MW5:M. I believe the upper and lower engine limits are just decided by PGI to allow a reasonable customization, and I think also considering MWO balance, so that some 'mechs that really need it get a higher max engine rating.

But what's cute in MWO even PGI-original hero 'mechs have engine ratings as an exact multiple of 'mech weight, so while the 'mechs have only existed in MWO, PGI has made them backwards-compatible with TT...

[Koniving]

MechaBattler, on 11 June 2019 - 11:49 AM, said:

What is engine rating representative of? It doesn't increase in volume, which is what I take slot size to be representative of. But it goes up in weight. What are they putting in there that doesn't require expanding the reactor?

Fluff-wise the reactors aren't necessarily the same size even across different iterations of the same size.

In general the only real difference is speed. In some cases its fluffed to be more than it is.

For example the Long Tom is a tracked vehicle with a 110 engine. Sarna calls it a meager engine which it is. But the original entry mentions that it has a powerful engine that's weighed down significantly by the multiple trailers that make up the long train-like vehicle and the necessity to be slow to avoid damaging the system.

Another good one is the Savannah Master versus the other 5 ton hovercraft. One has the Omni 25, which is apparently "one of the most compact and efficient engines ever created" and naturally no longer in production. The other uses another 25 engine. They're both the same slot count, but in visual appearance the Savannah Master is 1/3rd the length of the barge-like Gabriel, a chunk of the Gabriel's size is to encompass the larger engine (that's the same weight and same size on the crit-slots table) and a turret housing.
Savannah Master (ML mounted under cockpit, forward only)

Gabriel (note the cockpit's much shorter size in length, admittedly this one's more of a shoulder-low glass to peer out with your head rather than a full canopy seat like the Savannah Master.) Medium laser on turret.


On a similar note: the Defiance B3M on the Savannah Master is so small it fits neatly under the cockpit (though the length of it goes all the way to the engine on the back)
The Gabriel's Maxwell TR medium laser is significantly larger. Now part of this is the turret and its automatic targeting system. But even so even its girth of the smallest diameter of its barrel is easily triple that of the Savannah Master's tiny "headlight"-like visible laser lens.

Also if you read the Atlas D, the mech is so tightly packed it has a 5 tube LRM-20 on the hip with 'all the space consumed' across the entire mech Yet there's many slots left.

So slots do not equal space fluff-wise... is the takeaway to uh...takeaway.

Afterall, you could have a 6 meter Locust and a 13.6 meter Atlas and they have the same number of slots. And on tanks an AC/2, 5, 10, 20 are all 1 slot each. Heavy Gauss Rifle? 1 slot. Machine gun? 1 slot. Machine gun array with 5 MGs? 1 slot. Ultra/2? 1 slot. Rotary AC/5? 1 slot. MRM-40? 1 slot. Arrow VI? 1 slot. And what does the motor take up? 0 slots.

Edited by Koniving, 13 June 2019 - 03:05 AM.

[Horseman]

jss78, on 12 June 2019 - 01:31 AM, said:

In TT, you generally never replaced an engine with a different rating (I don't recall if the rules even allow it)

They do, but as a Grade F refit it requires access to mech production facilities.

[Nightbird]

Horseman, on 13 June 2019 - 05:29 AM, said:

They do, but as a Grade F refit it requires access to mech production facilities.

Does a 300 rating engine weigh differently on a 50 tonner than a 100 tonner for its size difference though?

[Horseman]

Nightbird, on 13 June 2019 - 05:38 AM, said:

Does a 300 rating engine weigh differently on a 50 tonner than a 100 tonner for its size difference though?

No, the engine mass is only a function of engine rating and type.

[Nightbird]

Horseman, on 13 June 2019 - 08:51 AM, said:

No, the engine mass is only a function of engine rating and type.

Which is why unless it's a different engine type, ICE, LFE, what have you, I think it's a writer's mistake if they suggest it's not the same size.

[Koniving]

Nightbird, on 13 June 2019 - 05:38 AM, said:

Does a 300 rating engine weigh differently on a 50 tonner than a 100 tonner for its size difference though?

No, but it costs differently (for example an XL 300 for a 50 tonner is half the price as an XL 300 for a 100 tonner, which the engine alone is 12 million cbills for a 100 ton mech... for a 50 ton mech it's a bit over 6 mil.)

They're also not compatible, unless your GM's basically saying an engine's an engine. In Megamek it's doing them as entirely separate parts. 300 XL for a 30 ton mech is actually dirt cheap at somewhere around early 3 mil.

Similar is true for standard engines but I'd have to actually look up their costs.
They're also different brand names by default for different mech sizes. (Edit, least in Skunkwerks I think it was; the quickest example of identical engines I can think of both use Nissan 200).

Here we go:
Dragon and Quickdraw 4G use standard VLAR 300.
Quickdraw 5M uses standard Magna 300

Might not be a function of weight difference and default names.
Megamek doesn't make a brand name distinction sadly.

Edited by Koniving, 13 June 2019 - 10:41 AM.

[Nightbird]

Koniving, on 13 June 2019 - 10:32 AM, said:

No, but it costs differently (for example an XL 300 for a 50 tonner is half the price as an XL 300 for a 100 tonner, which the engine alone is 12 million cbills for a 100 ton mech... for a 50 ton mech it's a bit over 6 mil.)

They're also not compatible, unless your GM's basically saying an engine's an engine. In Megamek it's doing them as entirely separate parts. 300 XL for a 30 ton mech is actually dirt cheap at somewhere around early 3 mil.

Similar is true for standard engines but I'd have to actually look up their costs.
They're also different brand names by default for different mech sizes. (Edit, least in Skunkwerks I think it was; the quickest example of identical engines I can think of both use Nissan 200).

Here we go:
Dragon and Quickdraw 4G use standard VLAR 300.
Quickdraw 5M uses standard Magna 300

Might not be a function of weight difference and default names.
Megamek doesn't make a brand name distinction sadly.

Even cost doesn't mean different sizes does it? If the weight is the same? One can be more cube shaped, another more rectangular.

If the 300 engine on the 100 tonner produces more power than on the 50 tonner, I think it has to be larger and heavier. That's just common sense.