Mecha and Mufflers

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doghunter1
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Mecha and Mufflers

Post by doghunter1 » Fri May 19, 2017 7:36 am

For mecha with wheels for long-distance travel, are mufflers are a necessity? Refer to the Gundam Leopard from After War Gundam X and the Knightmare Frames of the Code Geass franchise having wheels for long-distance travel.

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Seto Kaiba
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Re: Mecha and Mufflers

Post by Seto Kaiba » Sun May 21, 2017 7:25 pm

doghunter1 wrote:
Fri May 19, 2017 7:36 am
For mecha with wheels for long-distance travel, are mufflers are a necessity? Refer to the Gundam Leopard from After War Gundam X and the Knightmare Frames of the Code Geass franchise having wheels for long-distance travel.
... a muffler has nothing whatsoever to do with having wheels.

Literally the only thing a muffler is for is to reduce the noise produced by an internal combustion engine's exhaust pressure. It works on pretty much the same principles as a suppressor (commonly, if erroneously, referred to as a "silencer") for firearms. If the mecha in question isn't operating on an internal combustion engine, there really is no reason for it to have a muffler because there won't be a combustion exhaust stream.

The GT-9600 Gundam Leopard from After War Gundam X is, as far as I'm aware, using an ultracompact fusion reactor for power and every Knightmare Frame we see in Code Geass save one (YF6-X7K/E Ganymede, which used external power) had a Core Luminous engine powered by a sakuradite-based energy filler which is some kind of either battery or fuel cell. Neither would need any kind of muffler, as both are almost certainly using their far more exotic power systems to run electric motors to drive their wheels. (You wouldn't find a muffler on a purely electric car though, either.)
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Areku
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Re: Mecha and Mufflers

Post by Areku » Sun May 21, 2017 10:05 pm

Perhaps Leopard could use a muffler as an elaborate and hilariously ineffective means to reduce the noise of the hot gases produced by its weapons.

Other than that, see Kaiba's post.

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Arsarcana
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Re: Mecha and Mufflers

Post by Arsarcana » Mon May 22, 2017 8:04 pm

On the off-chance that doghunter meant some kind of sound suppression system for the wheels as opposed to exhaust, well... same response really: There's no point. Even the smallest mecha I can think of with that kind of propulsion (Armored Troopers) are about four meters tall and weigh six tons or more. You're not going to hide the presence of something that large and heavy even if the wheels make no sound when spinning freely. In actual motion they're going to make noise due to friction and in the process of moving that four meter/six ton machine debris will be kicked up which will also make noise.

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Re: Mecha and Mufflers

Post by Seto Kaiba » Mon May 22, 2017 9:03 pm

Arsarcana wrote:
Mon May 22, 2017 8:04 pm
On the off-chance that doghunter meant some kind of sound suppression system for the wheels as opposed to exhaust, well... same response really: There's no point. Even the smallest mecha I can think of with that kind of propulsion (Armored Troopers) are about four meters tall and weigh six tons or more. You're not going to hide the presence of something that large and heavy even if the wheels make no sound when spinning freely. In actual motion they're going to make noise due to friction and in the process of moving that four meter/six ton machine debris will be kicked up which will also make noise.
When you consider that, despite being made of materials that must have the density of packing foam, your average wheeled giant robot is going to have a significantly greater ground pressure than the average car... so the noise the wheels make is going to be pretty substantial as they bite into the ground, pavement, etc.
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Arsarcana
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Re: Mecha and Mufflers

Post by Arsarcana » Mon May 22, 2017 9:45 pm

Yep. Hence the 'noise due to friction' comment.

But now that I've got Votoms and automobiles both in my head at once, a question that's been bothering me for some time: The Berserga SSS-X 'Testarossa'. Why is it not painted red? Missed opportunity there...

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Re: Mecha and Mufflers

Post by JEFFPIATT » Tue May 23, 2017 8:57 am

the3 only ms in the History of gundam to have a muffler would be the MSER-04 Anf From gundam 00 and it's older version the MSJ-04 Fanton both Diesel powered MS http://gundam.wikia.com/wiki/MSJ-04_Fanton

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Re: Mecha and Mufflers

Post by MythSearcher » Sun May 28, 2017 3:23 am

Seto Kaiba wrote:
Mon May 22, 2017 9:03 pm

When you consider that, despite being made of materials that must have the density of packing foam, your average wheeled giant robot is going to have a significantly greater ground pressure than the average car... so the noise the wheels make is going to be pretty substantial as they bite into the ground, pavement, etc.
I always love the packing foam or balloon metaphor.
Considering the ground pressure, it might surprisingly be not very high compared to modern tanks.
Not using wheeled ones as examples, I'd like to draw the attention to The-O, which, has feet larger than the M1.
to scale comparison of The-O, M1 and RX-78-2(Katoki version, smaller feet)
The dalong.net model comparing RX-78 and The-O shows similar size difference.
Given the fact that RX-78-2's density is on the comparitively more reasonable side of the scale (around the density of an average human with a BMI of 18.5, still way too light for an armoured knight) and is about the same weight as the M1, the ground pressure is likely only 0.25 of the M1 when it is on one foot(Walking). If you use the original Kunio version, that will only drop further.
The-O, on the other hand is on the ridiculous side of the scale. I'd give it some advantage of the foot in front is closer to the camera so it is not really to scale, but look at the foot in the back, it can simply have 4 times the area when contacting the ground, compared to RX-78-2, not the M1. AND its only 86.3 tons in weight max, likely light on ground combat since you don't need as much propellant as in space combat. This is some kind of foam structure to be sure.

The Leopard, for the sake of it, is only 8.5 tons empty. We don't have a max number. Structure-wise, it is likely made of aerogel. Assuming its foot is still somewhat of the size of AFVs, the wheels/tracks are not going to be supporting more weight than modern AFVs, but no less than half of that. I see no possible way of minimizing that sound in the wild.

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Re: Mecha and Mufflers

Post by Seto Kaiba » Sun May 28, 2017 7:21 pm

MythSearcher wrote:
Sun May 28, 2017 3:23 am
Seto Kaiba wrote:
Mon May 22, 2017 9:03 pm
When you consider that, despite being made of materials that must have the density of packing foam, your average wheeled giant robot is going to have a significantly greater ground pressure than the average car... so the noise the wheels make is going to be pretty substantial as they bite into the ground, pavement, etc.
I always love the packing foam or balloon metaphor.
Considering the ground pressure, it might surprisingly be not very high compared to modern tanks.
Not using wheeled ones as examples, [...]
I've run a couple simulations based on settings where wheeled mecha are common (e.g. Code Geass) and I've found that the vast majority of them are going to have significantly greater ground pressure when operating using those wheels than a main battle tank. The reason is the size of the contact patch.

The ground pressure of the M1 Abrams is about 1.05kg per square centimeter. Its contact footprint is fairly huge by comparison to an automobile, as it's spread across a pair of tracks that are 635mm wide and a good 7m long, giving the tank a contact patch of about 5.18m^2. I drive a reasonably typical family car, its contact patch is in the vicinity of 950cm^2 and its mass is 1,920kg. That gives it a ground pressure of 2.02kg/cm^2, or about twice what you get from a tank.

Look to a typical Code Geass Knightmare Frame. Its landspinners have one large tyre and one small tyre... but they appear to be either solid rubber or a high-pressure tyre to withstand the significant acceleration which Knightmare Frames are naturally inclined to. Let's be charitable and say that even though the tyre pressure is a good deal higher and the front wheel isn't much larger than a large-ish truck tyre, that it has a contact patch of 2,000cm^2, more than double that of a family car. Something like the RPI-13 Sutherland, which weighs 7,840kg, will have a ground pressure of 3.92kg/cm^2, almost four times that of the tank. The Gundam Leopard's wheels aren't much bigger, and it has even more mass to lug around. The Destroid Cheyenne from Macross Zero's equipped with some pretty big front tyres, but if you run an approximate surface area calculation with respect to contact patch you come back with a number around 3,251cm^2, on which a 25,900kg mecha is riding. It would have a ground pressure just shy of 8kg/cm^2 (which is probably why the Cheyenne's wheels are only really for use on carrier decks, pavement, and starship hulls).
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Re: Mecha and Mufflers

Post by AGF-Antoine » Mon May 29, 2017 2:42 am

Very interesting discussion.

The early Riveni/Savage from Full Metal Panic! might also have had mufflers. I think some flashbacks featured the older diesel ones.

There is one more Gundam unit with wheels I would like to get the math on, Adele Mk-II. I think it might have even more insane ground pressure, considering the size of the wheels and the weight of 42.4 metric ton. It did seem to kind of tear the ground apart in the show.

In the Super Robot part of the spectrum there is Außenseiter from Super Robot Wars.

But yeah, I have always wondered about the realism of inline skates on mecha.


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Seto Kaiba
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Re: Mecha and Mufflers

Post by Seto Kaiba » Tue May 30, 2017 10:22 am

AGF-Antoine wrote:
Mon May 29, 2017 2:42 am
Very interesting discussion.

The early Riveni/Savage from Full Metal Panic! might also have had mufflers. I think some flashbacks featured the older diesel ones.
I'm gonna have to go back and look for those in Full Metal Panic! Σ because I honestly don't remember there being a diesel Rk-series AS. If it's in there, it's gotta be in that post-MITHRIL arc. It probably didn't help much, as they'd depicted Arm Slaves as being kind of inherently noisy things, even with quieter and more efficient gas turbine or palladium cold fusion reactor power.


AGF-Antoine wrote:
Mon May 29, 2017 2:42 am
There is one more Gundam unit with wheels I would like to get the math on, Adele Mk-II. I think it might have even more insane ground pressure, considering the size of the wheels and the weight of 42.4 metric ton
Oh goodness those wheels are SMALL... I've run a rough, back of the envelope bit of math to get the approximate dimensions of the wheel and the front wheel's barely 70cm wide. The rear one's closer to 102cm, but that's still not much for such a large vehicle! The estimated ground pressure's somewhere between 2.7497kg/cm^2 and 3.2667kg/cm^2.
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Re: Mecha and Mufflers

Post by Zeonista » Fri Jun 23, 2017 2:21 pm

For mecha and mufflers, one might reference Blue Gale Xabungle, which has the sort of tech which might make mufflers a good thing.
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