Optimization Of Battlemech Mass For The Planned Mission

Battlemech designers have operated for centuries on the basic assumption that making a battlemech heavier increased its ability to carry armor and weaponry, and therefore its performance in toe-to-toe combat. This also comes with the assumption that certain weight classes of battlemech are sufficiently better at certain missions than other weight classes - that light mechs make better scouts, for example - that it overrides the reduced combat potential.

When considered in more depth, however, it becomes apparent that the key feature of the battlemech in these cases is not its weight class, but its mobility. An Ostscout makes a better scout than an Atlas, not because of its lighter weight, but because of its superior speed and jump-capability.

As a result of this, we end up with mech designers increasing a mech's weight to increase its combat potential, while keeping the speed the same to maintain the machine's appropriateness for its mission. At the extreme of this mentality, we have the CGR-1A1 Charger, which is classified as an "assault mech" by weight, but, in combat, is barely a match for most light mechs.

The reason for this is that all components of the machine either remain the same weight (as the cockpit does) or scale linearly with increasing mech weight (as the internal structure does), with one exception - the power plant. A quick examination of engine power/weight ratios reveals that an engine's weight increases exponentially with the amount of power it produces, and hence, its ability to drive a mech of linearly increasing weight at a constant speed. Because of this, there comes a point where increasing a mech's weight results in a greater increase in the weight of the engine, and thus a net loss of useful mass.

Dissection of the the Charger design confirms this. Over 84% of the Charger's mass is in the engine, internal structure, and other unavoidable subsystems that do not directly contribute to the combat performance of the machine, leaving only 12.5 tons for weapons and armor. Compare this to the DRG-1N Dragon, which is 20 tons lighter overall and has the same maximum speed. The Dragon's engine, skeleton, et cetera, occupy slightly under 52% of its mass, leaving 29 tons for arms and armor - 16.5 tons more than the 20-ton-heavier Charger has available. Comparison of the combat records and reputations of the Charger and the Dragon reveals that this is more than just a paper advantage.

These figures lead to the startling conclusion that it is possible, in some cases, to increase the combat potential of a mech by reducing its overall mass. The question, then, becomes exactly where the break-even point is, beyond which increasing the mech's mass is no longer a profitable endeavour. Examination of the tonnage required for for each combination of mech weight and speed results in the following table. Cross-referencing the desired mech speed with the tonnage reveals the tonnage that remains after addition of all the essentials. The maximum of this value for each speed is highlighted in red. Any mech lighter than the weight that results in this value can be profitably increased in weight. Any mech heavier should have either its mass or its speed reduced.

Note that reducing speed will always, except in trivial cases where the mech is already extremely light and relatively slow, result in a increase in available mass, but carries with it its own combat penalties in reduced maneuverability. Determination of the appropriate speed for a mech should be based on its intended mission, which is beyond the scope of this document, but the information in the tables can be used to make decisions on this as well.

Speed/Weight Optimization Walking Movement (x10.6kph) 1 2 3 4 5 6 7 8 9 10 11 12 13 M

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e 5: 0.0 0.0 0.0 0.0 0.0 10: 4.5 4.5 4.0 4.0 3.5 3.5 3.0 2.5 2.0 2.0 0.5 0.0 15: 9.0 8.5 8.5 8.0 7.5 6.5 5.0 4.5 4.0 3.0 2.5 1.5 0.5 20: 13.5 13.0 12.5 11.5 11.0 9.0 8.0 7.0 6.0 4.5 2.0 0.5 25: 18.0 17.0 16.5 15.5 13.5 12.0 10.5 9.0 6.5 4.0 1.0 30: 22.0 21.5 20.0 18.0 16.5 15.0 12.0 9.5 6.5 2.0 35: 26.5 25.5 23.0 21.5 19.5 16.5 13.5 9.5 3.0 40: 31.0 29.5 27.0 25.0 22.5 18.5 14.0 6.5 45: 35.5 33.5 31.0 28.5 24.5 20.0 12.0 0.5 50: 39.5 38.0 34.5 31.5 26.5 20.0 8.5 55: 44.0 41.0 38.5 33.5 28.0 18.0 60: 48.5 45.0 42.0 36.5 29.0 14.0 65: 52.5 49.0 45.5 39.0 28.0 5.5 70: 57.0 53.0 48.0 41.0 26.5 75: 61.5 57.0 51.5 42.5 22.0 80: 65.5 61.0 54.5 42.5 12.5 85: 70.0 65.5 57.5 42.5 90: 74.0 69.0 60.5 41.0 95: 78.5 73.0 63.0 37.5 100: 83.0 76.5 65.0 30.5

There are some pieces of data in this table that should be taken note of. The first is that our example mech, the Charger, is well over the ideal weight for a 50 kph-walking-speed mech. At the other extreme, we have to drop the mech weight clear down to 20 tons before we find another mech with as little tonnage available at that speed as the Charger has. This would imply that the 20-ton FOX-1A Fox is an even match for the Charger in combat. Anecdotal evidence seems to indicate that this is, in fact, the case. The Dragon, on the other hand, and not coincidentally, is exactly at the ideal weight at that speed.

Another interesting datum is that the ideal weight at 40 kph, the standard speed for most heavy and assault mechs, is actually a plateau across the 75, 80, and 85 ton ranges. This would imply that a BattleMaster's 10-ton weight advantage over a Marauder is nearly irrelevant, as both have the same available mass for weapons and armor. Frequent matchups between the two in real-world situations and in testing has also proven this true.

The introduction of extralight engines and other advanced construction materials alters this picture somewhat. Because the masses of most of the advanced materials scale linearly with mech tonnage, the effect of their use is minimal, though not non-existent. XL engines, like their heavier counterparts, scale exponentially in weight, however, and their effect is outlined in the next table.

Speed/Weight Optimization with XL Engines Walking Movement (x10.6 kph) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 M

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5: 0.25 0.25 0.25 0.25 0.25 0.00 0.00 0.00 0.00 10: 4.75 4.75 4.50 4.50 4.25 4.25 4.00 3.75 3.50 3.50 2.25 2.00 1.75 1.50 1.25 1.00 1.00 0.50 0.25 15: 9.25 9.00 9.00 8.75 8.50 8.00 6.75 6.50 6.25 5.75 5.50 5.00 4.50 3.00 2.50 1.75 1.00 0.25 20: 13.75 13.50 13.25 12.75 12.50 11.00 10.50 10.00 9.50 8.75 7.00 6.25 5.25 4.00 2.50 25: 18.25 17.75 17.50 17.00 15.50 14.75 14.00 13.25 11.50 10.25 8.75 7.00 3.75 0.75 30: 22.50 22.25 21.50 20.00 19.25 18.50 16.50 15.25 13.75 11.50 7.75 3.50 35: 27.00 26.50 24.75 24.00 23.00 21.00 19.50 17.50 13.75 9.75 2.75 40: 31.50 30.75 29.00 28.00 26.75 24.25 22.00 17.75 12.50 2.75 45: 36.00 35.00 33.25 32.00 29.50 27.25 22.75 17.00 4.25 50: 40.25 39.50 37.25 35.75 32.75 29.50 23.25 11.75 55: 44.75 42.75 41.50 38.50 35.75 30.25 20.75 60: 49.25 47.00 45.50 42.25 38.50 30.50 9.75 65: 53.50 51.25 49.50 45.75 39.75 28.50 70: 58.00 55.50 52.50 49.00 41.25 18.75 75: 62.50 59.75 56.50 52.00 41.25 80: 66.75 64.00 60.25 53.75 38.75 85: 71.25 68.50 64.00 56.00 28.75 90: 75.50 72.50 67.75 57.50 6.25 95: 80.00 76.75 71.25 58.00 100: 84.50 80.75 74.50 56.75

The experimental, super-light XXL engines, like the XL engines, have the effect of shifting the curve of optimal weights further out, making faster, heavier mechs practical, as outlined in the next table. Again, the effects of other experimental materials is negligible for our purposes here.

Speed/Weight Optimization with XXL Engines Walking Movement (x10.6 kph) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 M

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5: 0.33 0.33 0.33 0.33 0.33 0.17 0.17 0.17 0.17 0.00 0.00 0.00 10: 4.83 4.83 4.67 4.67 4.50 4.50 4.33 4.17 4.00 4.00 2.83 2.67 2.50 2.33 2.17 2.00 2.00 1.67 1.50 1.17 0.00 15: 9.33 9.17 9.17 9.00 8.83 8.50 7.33 7.17 7.00 6.67 6.50 6.17 5.83 4.50 4.17 3.67 3.17 2.67 2.00 1.17 20: 13.83 13.67 13.50 13.17 13.00 11.67 11.33 11.00 10.67 10.17 8.67 8.17 7.50 6.67 5.67 3.50 2.00 0.00 25: 18.33 18.00 17.83 17.50 16.17 15.67 15.17 14.67 13.17 12.33 11.33 10.17 7.67 5.67 2.67 30: 22.67 22.50 22.00 20.67 20.17 19.67 18.00 17.17 16.17 14.67 11.83 9.00 4.67 35: 27.17 26.83 25.33 24.83 24.17 22.50 21.50 20.17 17.33 14.67 10.00 40: 31.67 31.17 29.67 29.00 28.17 26.17 24.67 21.50 18.00 11.50 45: 36.17 35.50 34.00 33.17 31.17 29.67 26.33 22.50 13.67 50: 40.50 40.00 38.17 37.17 34.83 32.67 28.17 20.50 55: 45.00 43.33 42.50 40.17 38.33 34.33 28.00 5.67 60: 49.50 47.67 46.67 44.17 41.67 36.00 21.83 65: 53.83 52.00 50.83 48.00 43.67 36.17 0.50 70: 58.33 56.33 54.00 51.67 46.17 30.83 75: 62.83 60.67 58.17 55.17 47.67 15.00 80: 67.17 65.00 62.17 57.50 47.50 85: 71.67 69.50 66.17 60.50 42.00 90: 76.00 73.67 70.17 63.00 28.50 95: 80.50 78.00 74.00 64.83 100: 85.00 82.17 77.67 65.50

It may be noted that even the greatly improved efficiency of the XXL engine leaves the Charger overweight, though only by 5 tons, with a mere 175 kilograms less available mass than the 75-ton ideal weight. A margin that small could be made up by utilizing Endo Steel or other advanced construction materials that would provide a slightly larger advantage for a heavier mech.

This report is a classified document produced by the Confederate Armed Forces Division of Research and Design. If you are not cleared to view this document, you might as well just shoot yourself now and save CAFALL the trouble.