Impulse Engines

The impulse engines are used to move the ship at sub-light (non warp) speeds. They provide large amounts of thrust in only one direction. Impulse power is the normal method for navigating around star systems.

Impulse engines produce thrust measured in Newtons. A Newton accelerates 1kg of mass by 1 metre per second per second.

So a small impulse engine that generates 1 MegaNewton (1,000,000 Newtons) can accelerate a 500 tonne ship (500,000 kg) at 2 metres per second per second. After 60 seconds of thrust it will be travelling at 120 metres per second (or 432 km/hour).

After one hour of thrust the speed will be 7,200 metres per second (or 25,920 km/hour). The speed of light is 1,080 million km/hour. To reach this speed would take 41,666 hours of acceleration (or just under 5 years). In shows like Star Trek ships could accelerate much faster than this, so it stands to reason that some very powerful impulse engines will be available.

In order to accelerate a 1,000,000 tonne ship (e.g. a large battle cruiser) to light speed in one hour we would need engines that produce 300 MegaNewtons per kg or 300,000,000 MegaNewtons. 

Of course acceleration like this would kill anyone inside the ship, so internal field dampening technology has to be installed to counteract the forces inside the ship.

If converted with no loss in energy 1 Watt of power produces 1 Newton of Force. Technology levels for the game allow for power conversion with 90% efficiency. Therefore to accelerate our large battle cruiser it would need to produce 333,333,333 MegaWatts (333 TerraWatts) of power for the engines. This is a crazy large number - so in all practicality a ship of this size would just have to take much longer than an hour to accelerate up to light speed. 

So when designing a ship the player has to balance power generation capabilities with the engine size to get the most out of them.

As with all ship components impulse engines can be damaged and repaired. The amount of damage sustained may cause each engine to operate at reduced efficiency or fail completely.

 The impulse engines do not provide any maneuverability (that is provided by the thrusters), they simply apply thrust in one direction.

To further complicate matters, larger engines are more inefficient at lower power levels. So a large engine might operate at 90% efficiency when producing 100 MegaNewtons of thrust, but only be 50% efficient when producing 10 MegaNewtons of thrust. This makes scaling the engine for the size of ship even more important. 

Another issue here is that as objects approach the speed of light, time dilation starts to take effect. 

Note: Time is measured as local time on the ship. As the ship approaches the speed of light (e.g. c=0.99) the time dilation hypothesised in Einstein’s Special Theory of Relativity will become very large. That is, although only a day may have passed on the ship, a year may have passed for an external observer on Earth. Therefore instead of having only travelled the distance light travels in a day (one light day), the ship would actually have travelled a light year. Therefore to the observers on the ship they would be traveling faster than light, but to an external observer they would not have exceeded the speed of light. This will start to get very complex, so we will limit the ship to 0.95 of the speed of light in normal operation.

Antimatter can be injected into the impulse engines to increase efficiency. This obviously uses up anti-matter reserves, however it can be used to provide either extra speed or to reduce the amount of energy required.

Due to the incredibly volatile nature of anti-matter, this injection process can only be used when there is no damage to the anti-matter injectors on the engine. When used the injectors will use 0.0001 kg of anti-matter per second for every TerraWatt of power being drawn, and will provide a 25% boost to the engine thrust. 

Normally the engine output will be controlled automatically by the navigation computer, however they can be placed into manual mode and controlled directly from the bridge.

Putting one engine into manual and the others into automatic will cause the automatic engines to attempt to maintain the desired speed from the navigation computer. i.e. If the ship is travelling at the desired speed of 0.25c and a manual engine is turned on, then the automatic engines will be backed off to compensate and attempt to maintain the 0.25c speed. Only when all engines are in manual can the ships speed be truly manually controlled.

An "Emergency Stop" command from the bridge will switch all of the engines off regardless of whether they are in manual mode or not. Note: The ship will continue to move at the current speed with inertia.

The engines can also be overloaded by as much as an extra 15%. Doing so will increase the efficiency of the engine, but will also use a commensurate amount of extra power and cause damage to the engine itself. This damage may result in a failure of the engine.

Reliability

For each hour of use each engine suffers a 0.1% reduction in efficiency. This can be rectified with scheduled maintenance from the engineering crews. Like all other systems, engines can also be damaged by hostile attacks or by collisions.  

If an engine falls below 50% in health then it will be unusable until repaired.

Power Requirements

As discussed engines have differing efficiency levels. These are defined as low power efficiency (engine at 0% power) and high power efficiency (engine at 100%).

A typical engine might have a low power efficiency of 55% and a high power efficiency of 90%. If the engine is capable of using 10 TerraWatts of power, then at full power this would produce 9 TerraNewtons of thrust. However if only 5 TerraWatts of power is supplied to the engine, then the efficiency drops to 55 + ((90-55) * 0.5) = 77.25% so only 3.86 TerraNewtons of thrust would be produced.

Research Improvements

Scientists carrying out research for the player can improve the lower and upper band efficiencies (though never more than 100%), the efficiency of the anti-matter injectors, the overload capabilities of the engine and the reliability of the engine.

 

Dev Notes

According to various sources the impulse engines can drive the Enterprise up to almost the speed of light. In reality this would cause massive time dilation (time moving slower on the ship than in the outside universe) and one assumes this is therefore normally avoided. Such a system could be easily applied by using the time acceleration feature of the simulator however it would not work with multiple ships in the simulation. Therefore the impulse speed will be restricted to a slower speed in the simulator. Probably about 0.95c

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If the ship is using its tractor beam to lock onto another object, then the mass of that object will have to also be included in the calculations. For example: If a starship is using it's tractor beam to tow another starship of roughly the same mass it will have to provide twice as much thrust to the engines as it would normally to achieve a particular acceleration/deceleration rate.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

For every 1% over 100% that each engine is overloaded there is a 1% chance per minute of damage being done to the engine. This damage is calculated by a random number of 0-100.
0-25 - 1% damage to the engine
26-90 - 2% damage to the engine
91-100 - 50% damage to the engine (engine failure).