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Scale Rules

PostPosted: Tue May 02, 2006 7:35 pm
by adamsderk

In an effort to delegate some of the art effort, I am adding a series of topics that will be wrapped up into an instruction set.

Mech Scale Equations
    Height = ( ((mass-20)/5) / (16/6) )+10
    Type Multiplier:
      Man Leg 1.0
      Dog Leg 0.9
      Chicken Leg 0.8
      Quad 0.6
    Final Height = Height * Multiplier

Ex. Catapult:
Height = ( ((65-20)/5) / (16/6) )+10 = 13.375
Final Height = 13.375 * 0.8 = 10.7 meters

Vehicle Scale Equations
    Height = (mass/50)+1
    Length = (mass/10)+2.5

Ex. Rotunda:
Height = (20/50)+1 = 1.4 meters
Length = (20/10)+2.5 = 4.5 meters

Now, the vehicles use the height or the length. For the Rotunda, using the length would result in a car that was under 1 meter high; not very probable. So I used the height as the value and let the length get larger than listed.

These values are directly used in MilkShape to set the size. Since BTS is a half scale game, the model is multiplied by 0.5 in the exporter to make it the correct size for the game. But real values are used in MilkShape.


PostPosted: Wed May 03, 2006 1:56 pm
by Ben
Seeing an unsimplified equation offended my engineering sense, so here's a bit cleaner version :wink:

Height = (0.075*mass) + 8.5


PostPosted: Wed May 03, 2006 2:49 pm
by adamsderk

I totally agree, but I didn't simplify it so people could understand where the numbers came from. A simplified equation would have people asking how I came up with those numbers.


PostPosted: Wed May 03, 2006 3:10 pm
by Stormwolf
Good equation, but there's one tiny problem, what about mechs that are designed a bit shorter then mechs of similar tonnage?

Mechs like like; the Nova, Linebacker or Crab come to mind.

Making a Linebacker just as high as a Hellbringer doesn't quite feel right.

PostPosted: Wed May 03, 2006 5:04 pm
by adamsderk

There is no height data, only speculation and some "comparisons."

There has been much discussion on the topic:
Mech Height IS:3028
Mech Height Revisited MekTek

It came down to a decision on my part that the Mechs would follow an equation based on their tonnage, hence above. It won't be perfect, but it will be consistent.


PostPosted: Wed May 03, 2006 6:29 pm
by Ben
Wouldn't things like the Crab and the Linebacker get the 0.8 'chicken leg' multiplier? That'd make them shorter then comparable tonnage mechs.


PostPosted: Wed May 03, 2006 9:19 pm
by Faolan_Conall
I'm sure that AD merely posted his general system for Mech height. Obviously, some will be slightly taller or shorter than others, and thats a discretionary thing. If a Mech is broad, it'll probably be slightly shorter than other mechs of the same tonnage, since reasonably it'd need to be to still remain that tonnage.

Also there are fluff descriptions for these mechs, and a few specifically say things like they're the tallest mech on the battlefield, etc.

PostPosted: Wed May 03, 2006 9:55 pm
by adamsderk
Ben and FC,

I might as well get this over now...

No, because of the discontinuity in the fluff description, I have decided to not use any of it. The Mechs follow the equation. As I said before, it's not perfect, but it works. If and when FanPro comes out with a definitive guide to Mech sizing, I will redo them, but in the mean time, the equation is king.


No, the multipliers are to deal with the leg bend. If you took a chicken leg and straightened it up, it would be close to the man leg height for the same weight.


As discussed in the MekTek link, volume and tonnage do not relate to each other, at least not in the BT universe. Think of broader Mechs as having lighter materials than skinny Mechs.


PostPosted: Sun Jul 06, 2008 5:14 am
by elitewolverine
i was wondering about the tank dimensions it seems abit "small"...

our current m1-a abrahams at only 7tons stands almost 90" tall or 2.5m..

the lrm carrier is a big tank at 60tons...but with the current calculator it would be shorter than a 7ton abraham at just 2.2m

now its length is abit odd vs its height, the abraham is about 4.2m long so its almost a 1 to 2 ratio of length and height, where with the lrm carrier it would be 8.5m long...

making it look like a pancake, especially since its lrm launchers occupy more than half its height leaving a mere 3ft for crew and ground clearance...

and again just for comparison the m1 is a mere 7.5 tons, where as the lrm is 60tons....

and when compared side by side it looks extremely funny for a 60ton tank to be lower than a 7 ton tank

PostPosted: Sun Jul 06, 2008 5:24 am
by SandMan
elitewolverine wrote:i was wondering about the tank dimensions it seems abit "small"...

our current m1-a abrahams at only 7tons stands almost 90" tall or 2.5m..

the lrm carrier is a big tank at 60tons...but with the current calculator it would be shorter than a 7ton abraham at just 2.2m

An Abrams weighs 70 tons.

PostPosted: Sun Jul 06, 2008 5:33 am
by Smoking_Mirror
Maybe the length calculation for the tanks is OK (who knows what they are made of) but the height calculation is much too small.

No tank is five times longer than it is tall. Three times maybe. between 2 and 2.5 would be more accurate.

Yeah I thought the Abrams was heavier than 7 tons.

PostPosted: Sun Jul 06, 2008 5:54 am
by adamsderk

Check the bold word in the vehicle equation... "or"

I calculate the height and length and then shrink the model to fit into one of them. Usually, the model will fit one of the numbers and go over the other.

Based on the discussion, the Abrams would be either 2.4m high or 9m long. It would fit one and go over on the other, so depending on the model, it could be say 9m long and 3m tall, or 2.4m tall and 10m long.

If someone can come up with a tonnage based equation that works from 5 tons to 100 tons, I'd be happy to hear it.


PostPosted: Sun Jul 06, 2008 10:24 am
by elitewolverine
that was my typo guys i had two webpages up....didnt mean to refer to the m1a as 7tons...that just under 70 at ~67...

i ment the m-1, built in the 1920's well 1928...

but at the same rate, the m1-a, just a tad not much bigger is 54-70tons (depending on model)...and is still the same size...

but at the same rate when looking at modern tanks ie anything from ~30 to 70 tons all fall within, a ratio of 3m tall, 8m long, and 3.5m wide...

maybe we could define tank size by class, ie, L-W-H

Small(<30tons): 6.5-2.5-2.2
Medium(30-70tons): 8-3.5-2.6
Heavy(>70tons): 9.5-5-3

make those estimates so that you have a tad of leway between sizes for artistry...

PostPosted: Sun Jul 06, 2008 2:32 pm
by Smoking_Mirror
I did see the or, but guessed that the only reason for allowing two calculations would be to allow for either extremely long and thin vehicles (like the long tom Carrier) or short and tall ones (like the vedette).

That should still leave an area open for an intermediate shape, where the height and length are in proportion to each other.

Sometimes when I see the minatures, the tanks are really really big, like a prone assault mech, other times they are really tiny. Much smaller than a prone light mech. There doesn't seem to be much of a coherent strategy.

PostPosted: Sun Jul 06, 2008 4:10 pm
by Hana Yuriko
I don't think you can rely on tonnage and height. A 30t Javelin is about 8m tall and a 30t Spider is 12m tall (according to various art depictions). The Banshee is supposedly 12m tall and the Atlas has been stated to be the tallest at 16m. With those sizes, a 30t Spider is the same height as a 95t Banshee. Even the size chart in the back of TRO 3039 it has this note on pg. 303.

NOTE: Although size varies individually among units, this scale shows the relative size difference in each weight class.

If you look at the chart, you'll notice a 3-5m difference in height between each weight class for 'mechs. The tanks seem easier to scale since they are based on human proportions. The Schrek PPC carrier looks to be about 2.5m in height, Rommel at 2m, Hetzer Wheeled Assault Gun at 2m, and the J. Edgar Hover Tank at 1.5m.

These are all based on the Human figure in this chart which I guess is around 183cm (or 6ft).