Supercavitation

Supercavitation is a process by which a gas bubble is formed around an object in motion, usually by moving at high speed through a liquid or by rotating in a fluid at extremely high revolutions per minute. This process was first pioneered by the Soviets in the mid 20th century, and has since been improved on, with the invention of more powerful thrusters and motors.
There are several methods used in supercavitating devices as of 2575:
*Several motors spin at approximately 6000rpm in the same direction. Conservation of Angular Momentum causes the projectile to spin at high rpms in the opposite direction, creating the necessary gas bubble. This is only useful in projectiles with a “flight-time” of more than 30 seconds.
*Several Micro thrusters can also be used to spin the projectile. While this method is more expensive, it requires less flight-time to "spin up," usually just a few seconds.
*Tiny holes on the projectile release bubbles of low-density gas around the projectile. This enables the projectile to move faster, which in and of itself sustains the gas bubble. This method was used in tank rounds until the middle of the HCW when a lack of resources prevented the manufacture of these rounds.
*Post-HCW, the humans began mass-producing plasma generators, reducing the cost to the point that they could be mounted in anything from an artillery rounds to tank shells to missiles, and even some tiny, less effective versions for bullets. These would generate a sheath of plasma around the projectile, as well as protecting it with a magnetic field. The plasma had a very low density, and therefore created very low air resistance. The downside to this process is that it left a highly visible trail of plasma behind the projectile, though this was later fixed with a few modifications to the plasma generators.