Ships move through ordinary space using maneuver drives. Power for the drives is provided by the ship's power plant . Tech Level restrictions for maneuver drives are imposed to cover the grav plates integral to most ship decks, and which allow high-G maneuvers while interior G-fields remain normal. See Gravity Generation and Acceleration Compensation System.
Maneuver drives are made up of thruster plates. Thrusters are very advanced, reacting with both the strong and weak nuclear force to create a reactionless drive usable even outside of a gravity well. Thruster plates have vectored thrust which allow ships high maneuverability while within a gravity well.
Main thruster plates are usually mounted in the aft end of a ship, as they tend to build up a slight ionization field around them. This is generally bled off into space. Early thruster plates released a substantial amount of residual energy in the form of heat and radiation, making their use hazardous. Modern thrust plate designs release only a slight amount of waste energy provided engines are properly maintained and control systems are properly configured.
Modern Manuevering Engines are capable of delivering thrust in any direction, even forward. Such thrusters work underwater and safely in the atmospheres of gas giants. Even the most water boyant vessel can become a submarine by using a portion of its vectored thrust to push it beneath the ocean.
The acceleration provided by thruster plates in manned spacecraft is limited by the ability of gravity compensation technology to nullify the effects of the acceleration on living beings. The best environmental gravity control systems top out at 6G. Governors prevent pushing the systems past this. Standard Missiles top out at over 10G's and the military has weapons that use even higher acceleration plates (although exact specifications are classified.)
Most ships have an auxiliary vectored thruster system designed to provide attitude control while in a gravity well or to assist in docking. These consist of sets of computer controlled, low powered thruster plates which are often linked to the contragrav system and allow small unstreamlined ships to safely land on planet. On ships smaller than 10,000 dtons power for this system is provided by the main reactor. On larger ship and most military craft a separate auxiliary power system provides power for this system. Even ships smaller than 10,000 dtons sometimes have power cells to provide emergency vector drive power.
Only spacecraft designed for landings on planetary surfaces have contrgrav systems. Contragrav neutralizes the effects of a planet's gravitational field upon the craft. To launch, a vessel with contragrav will slowly reduce the effective weight of the spacecraft while using the vector maneuvering drive to set the attitude of the craft. The main drive may then be engaged to accelerate the spacecraft away from the planet.
A spacecraft with contragrav can land by slowly descending into the planet's atmosphere making it unnecessary to shed velocity through atmospheric friction. Most streamline spacecraft can land without contragrav if the system is down. The armored hull of most ships is quite capable of withstanding the resulting friction and the ship's maneuvering drive able to provide propulsion allowing a heavy landing. Unstreamlined ships, such as the Broadsword, must have a working contragrav system to land on a planet with an atmosphere.
Using contragrav even extremely large vessels can safely land on a planet possessing an atmosphere. Ship's above a certain size will usually land at special facilities or only in oceans, because of their great weight. Such craft will usually have special power systems for the contragrav generators. Even small craft will sometimes have power cells to provide emergency or backup power to the contragrav generators. More on the contragrav system can be found in the gravity systems section.