Mass

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Mass is one of the crucial statistics of a robot, determining its stability, speed, maneuverability, and most importantly, ability to fly.

The Basics[edit | edit source]

The mass of your robot is expressed in kilograms and grows as you add more and more cubes onto it. All cubes have mass. See Armored cubes for a table of weights of cubes, prisms, and tetras. The more mass you have, the more powerful the various movement cubes have to be to move your robot.

Center Of Mass Location[edit | edit source]

Mass balance becomes EXTREMLY important in hovering, flying, and skiing robot types. Generally you want your center of mass to be the lowest level possible so that moving forward or turning does not (never) flip your craft. All of the mass of a cube regardless of the shape or size is applied to the attachment location, not the cube you attach it to but the empty cube space next to the adjacent cube the new cube now fills.

Balance[edit | edit source]

A more important aspect of weight is balance. Distribution of mass on your robot determines how it steers and how stable it is. While this might seem like a concern primarily for asymmetric robot designs, it is a major problem for all robots. A top-heavy tank will tumble when going over terrain. Likewise, a top-heavy hovercraft will flip often, sometimes even at the beginning of a round. Poorly balanced satellites will behave erratically. However, that's not all. A rear-heavy design will tend to drag the tail and cause oversteering when making turns.

One caveat is in the case of robots with tracks. Since tracks are usually an order of magnitude heavier than the armor on top of them, it is possible to place tracks away from the center of armor mass and not run into the risk of the bot constantly tipping forward. The overstearing remains, but that can be useful when making 180 degree turns.

The game uses a fairly simple method for calculating mass and can be simulated with basic graph paper. Ideally, you want the center of mass to be the center of your robot and place your thrusters and Armored Helium cubes around that point. Otherwise you run the risk of the above problems manifesting. As stated, graph paper is great for designs.

Pendulum Rocket Fallacy[edit | edit source]

Pendulum Rocket Fallacy demonstration from Kerbal Space Program

The physics model in Robocraft is realistic enough that it will suffer from the pendulum rocket fallacy, which means that moving thrusters or hoverblades to the top of a tall bot will not make it more stable, as they cannot adjust their orientation freely with respect to the bot. This phenomena is correct behavior for the physics engine to model the real world and will not be "fixed".

Difference between weight and mass[edit | edit source]

Weight is a force (W = m·g) so objects weigh about ⅓(0.38g) on Mars(3.7 m/s²) compared to Earth(9.8 m/s²). Currently all maps are placed on Mars and GJ 1214b but the system does support having planets with another gravity leading to the possibility of weights being different from map to map as speculated in Game Forces. This point is illustrated by thrusters and Armored Helium having their lift denoted in force (Newton) rather than weight.

Trivia[edit | edit source]

  • Many masses were not given by robocraft so they had to be found with such bots as the Precision scale. As of the Respawned and overclocked update, all masses are given.