Internal Structure of Mortar Headd
Mortar Headd Frame = Keel
"Frame" must be one of the most commonly heard mortar headd (MH) terms. The Frame is the principal part of the internal skeleton, namely the solid and durable spinal parts, the shoulders that mount the arms (shoulder blade and collarbone), and the hips that take most of the weight and impact. This large spine, shoulder, and hip assembly is called the "Frame", and termed the "Keel". It has the same meaning as the keel running down the center of a ship’s frame.
A MH with the moving parts of its joints and skeleton assembled is called a "Setting Frame (Exoskeletal Stage)", but as this includes some armor Sopp and others may also refer to it as "Primary Armoring". The Jagd Mirage under construction in volume 2 is at the Primary Armoring stage. Hence, arms and legs are not counted in the Frame category.
A MH’s Frame refers to just the keel, and the length of the keel determines the size of the MH. Among MHs, Hathuha’s A-Toll and the various Sirens carry some of the longest, heaviest keels and are called Large Frame MH. Keel dimensions are decided by the individual Meights, so there is no standardization. On the other end of the scale, the Engage series use a rather short keel resulting in a small, compact unit.
LED Mirage units use a larger keel, but maintain a unit height similar to the Engage. The LED Mirage needs a heavier keel to accommodate the paired Twin Ezlazer Bypass units. A large frame therefore does not necessarily imply a taller MH.
Frame Settings ~ Cheetah Type and Lion Type
Frame settings are frequently related to wild animals. The spine’s toughness becomes a beast’s power, and is reflected thereby. The small cheetah has a bigger spine than its body would imply to provide explosive power to its limbs and absorb impacts, making it capable of reaching speeds over 100km/hr. The lion capitalizes instead on brute strength and the power of his jaws, trading the cheetah’s high speed for the limb and jaw strength to take down large game the cheetah couldn’t possibly hunt.
This theory then is transferred directly over to develop the MH’s spine and skeleton. Accordingly, MH built with heavy keels for their armor and unit weight are "Cheetah Type", while ones with a keel balanced for armor and unit weight are "Lion Type".
Cheetah type settings prioritize speed and agility, with a slender armored appearance. Colus’s Engage series and the Electroknights’ KAN are examples. These frames are powerful and nimble, but lack the Lion type’s capability for different armor variations. Essentially they have the disadvantage of a lack of versatility.
The majority of MH are built with Lion type settings, that proportion including such noted MH as the Black Knight, the Berlin, and the Ashura Temple’s Temple series, adding up to more than 90% of all MH. Lion types balance power with stability, and with the versatility of supporting variant armor configurations can be said to be the standard frame settings for a MH.
While these settings are also affected by the power settings of the limb and torso tissue systems, this is not an indication that the keel is specifically light or heavy. All this is saying is that the final power balance of the frame can be Cheetah type or Lion type. The frame alone cannot provide a cheetah’s speed or a lion’s strength. Engine power must be balanced against armor weight, and a strong engine puts its own stress on the frame, affecting durability and reliability. Adding a management system to the frame to control engine power and the keel’s tissue system improves durability but reduces speed and agility, which then requires the reduction of armor and equipment to restore. Balancing all these is incredibly difficult.
Rather than pushing for just "running fast" or "jumping high", meights are constantly worrying about multiple factors. It’s about how much to tune mobility and defense and attack power.
The Siren has an abnormally wide tolerance; everything from the tough Arcana Siren to the slender Neptune all share the same main Siren Frame. Rather, the fact that an armor monster like the Arcana Siren can be moved, with its heavy weight and the corresponding shock absorbed by the same frame that the Neptune is using for its high-speed strikes and movement show just how super first-class the Siren Frame is.
The new MH Phantom is based on streamlining this frame to support only heavy and standard combat equipment. There aren’t likely to be as many variations as the Siren, but general-purpose and destroyer types are quite possible. It will likely be used alongside the Siren for some time.