Fusion Thruster

From Growing Horizons

The fusion thruster works by expelling plasma through shielded exhaust nozzles to create thrust. All DropShips have a main exhaust nozzle to propel the ship forward at a steady acceleration. The most advanced also have numerous plasma exhaust nozzles dotting their hulls to control steering, but such devices are fragile and expensive, leaving many DropShips equipped with hardier but less efficient chemical rockets to fulfill this role. The plasma exhaust is created as a by-product of nuclear fusion and requires a constant supply of fuel in the form of liquid H2, which is carried aboard in large storage tanks and fed to the drive by one of two systems. The one found on all DropShips is a heat-expansion system where the H2 is fed into a heated chamber; here the high temperature causes it to expand, with the resulting pressure forcing it into the engine core. Military DropShips will also have a series of high-speed pumps which can supply a constant stream of fuel for the engine, allowing for rapid changes in thrust. Unlike the engine core, the fusion plant which provides power for the DropShip is a closed system, reprocessing its own by-products and requiring little additional fuel. It can however tap into the same H2 storage tanks used by the engines when needed.

Compared to the Talaria Fusion Thruster of the Solar nations and similar thrusters of the other species, it is marked by a surprisingly high thrust and specific impulse, allowing it to drive spacecraft at several ten m/s² of acceleration.

Relatively early after contact if the WCDC with the Inner Sphere, scientists and engineers were able to copy the drive system, however it has 15% more bulk and has 20% less efficiency. To slot nicely into existing fuel and propellant infrastructure, the drive was modified to run on Deuterium-Helium³ fusion and utilize common water as propellant.