Thruster's effects on a ship
Thrusters are the last mechanical part of the power chain, the physical output point of the engine. They influence the ship's features in many different ways:
Thrusters can be set to exhaust the burned fuel at different rates. This directly influences the amount of thrust (or force) they exert on the ship which translates to the amount of acceleration or deceleration the ship gets.
Another consequence of the burning rate of the thrusters (actually the rate at which they propel the burned fuel) is the range how far the ship can fly. If the burning rate is slow, the ship can fly slowly for a longer distance. At a higher burning rate the ship flies quicker but only at a close distance (cf. Bingo fuel).
Radar profile and visibility
The quicker you burn and exhaust fuel, the bigger will be the plume (or trace) the thrusters produce. This makes your ship easier to detect on a radar (signature) or visually. If you want to fly stealthily, you might want to pay extra for “silencer” thrusters which don’t give off such a large drive plume.
You can modify the appearance of your ship by selecting different nozzle sizes for your thrusters or modify the color of their exhausts.
Thrusters are defined by two values: thrust rating and Articulation type.
Thrusters are manufactured in various sizes and performance classes. Thrust rating (TR) is a classification system for this. The smallest of thrusters, e.g. the maneuvering thrusters of small ships have a thrust rating of 1 (TR1). Maneuvering bigger and heavier ships needs more powerful thrusters (e.g. TR3 on the Constellation). The main thrusters of a ship have generally a higher thrust rating, usually starting at TR4 (M50, 300i, Hornet) although for the very light and small ones like Aurora TR3 is used. A cruiser's main engines are commonly equipped with a TR10 while even big carrier ships like the Bengal carrier use a cluster of high-rated thrusters (TR10, TR8, TR7) as their main engines.
A ship can only mount thrusters of a thrust rating not higher that it has slots for. A slot for TR4 can hold one thruster of TR4 or lower. Most ships have a combination of a few higher rated thruster slots for the main engine thrust and at least four, but more usually eight lower-rated thruster slots for the maneuvering and retro thrusters.
|“||Each thrust rating actually describes a range of force capacities, so while multiple thrusters may be classed as "TR1", each of those thrusters may in fact output different amounts of force. This is analogous to modern cars in that many cars have 4-cylinder engines, but not every 4-cylinder engine has the same horsepower. Conversely, it's also true that no TR1 thruster will match the output of a TR2 thruster, just as no inline-4 engine will match the output of a V8 engine. How closely the output of the highest thrust TR1 gets to the lowest thrust TR2 remains to be seen, of course.||”|
–Chris Roberts on November 11, 2013
Thrusters are manufactured with one of these articulation types:
- fixed (thrusters don't move)
- jointed (thrusters have rigid nozzles that can rotate on one or two axes)
- flex (thrusters can articulate on one or two axes but aren't rigid)
- vectored (thrusters have nozzles with flaps that direct the stream of exhaust)
Depending on where a thruster is mounted on a ship we can generally distinguish between following thruster types by their usage:
Main thrusters are usually the most powerful ones on a ship. They are the ship's main means of propulsion. The ship's maximum velocity, range, and radar signature is directly affected by its main thrusters.
The maneuvering thrusters are used to change the ship’s orientation or to adjust its overall velocity vector. They are small thrusters that provide the majority of the pitch, roll and yaw control. The better they perform the quicker will the ship respond to maneuvering actions. An intelligent flight control system (IFCS), can help the maneuvering thrusters to correct the ship’s velocity vector to be in the direction it’s pointing.
Retro thrusters arrest the ships velocity (deceleration). Frequently a front mounted maneuvering thruster will also perform retro fire duties. The performance of the retro thrusters should not be underestimated. Especially explorers flying through asteroid belts appreciate a powerful retro thruster which allows them to reduce the speed quickly when it matters.
A ship can sport thrusters of different ratings with various types of articulation. The Anvil Aerospace Hornet has one 4-rated vectored main engine thruster, four 2-rated flex maneuvering jets (with the front two also performing retro duties) on the top and four 2-rated jointed thrusters on the bottom.