All ships in Aurora require Fuel to move. The rate of fuel consumption is 1 litre of fuel for every point of engine power applied for one day. For example, a ship with 200 engine power travelling for five days will use 1000 litres of fuel. A ship with 300 engine power travelling for six hours will use 75 litres of fuel. For fuel consumption purposes, engine power is multiplied by the efficiency of the engines (see below). So if an engine had engine efficiency 0.8 and engine power 200, it would be classed as having only 160 power for fuel consumption.

A line of Technology called Engine Efficiency vs Power can be used to increase the overall power of the engines while using more fuel per point of engine power or to decrease the power of the engines and use less per point of engine power.

This line of tech has the following steps (Exp is chance of secondary explosion). The power increase techs are researched separately from the power reduction techs.

Engine Efficiency -10% Power Increase 5%, Exp 7%

Engine Efficiency -20%, Power Increase 10%, Exp 10%

Engine Efficiency -30%, Power Increase 15%, Exp 12%

Engine Efficiency -40%, Power Increase 20%, Exp 16%

Engine Efficiency -50%, Power Increase 25%, Exp 20%

Engine Efficiency -60%, Power Increase 30%, Exp 25%

Engine Efficiency -80%, Power Increase 40%, Exp 30%

Engine Efficiency -100%, Power Increase 50%, Exp 35%

Engine Efficiency 05%, Power Reduction 2.5%, Exp 5%

Engine Efficiency 10%, Power Reduction 5%, Exp 4%

Engine Efficiency 15%, Power Reduction 7.5%, Exp 4%

Engine Efficiency 20%, Power Reduction 10%, Exp 3%

Engine Efficiency 25%, Power Reduction 12.5%, Exp 3%

Engine Efficiency 30%, Power Reduction 15%, Exp 2%

Engine Efficiency 40%, Power Reduction 20%, Exp 2%

Engine Efficiency 50%, Power Reduction 25%, Exp 1%

For example, assume standard ion engine with 60 power. If the Engine Efficiency -20%, Power Increase 10%, Exp 10% tech was applied to the engine, its power would increase to 66. However, due to the less efficient design, it would use fuel as if it had 20% more engine power, which is (66 x 1.2) = 79.2

If the Engine Efficiency 20%, Power Reduction 10%, Exp 3% was applied instead, the engine power would be reduced to 54 but the engine would be more efficient and fuel consumption would be based on engine power (54 x 0.8) = 43.2

A second line of tech called Fuel Efficiency allows a race to get use less fuel overall for a given amount of power, regardless of the efficiency vs power situation, and can considerably reduce the amount of fuel used. When designing a new engine, the available Fuel Efficiency tech is a parameter, along with base engine tech, engine efficiency vs power tech and internal armour tech.

The line of tech is as follows:

Fuel Efficiency 1. Fuel Usage x0.9

Fuel Efficiency 2. Fuel Usage x0.8

Fuel Efficiency 3. Fuel Usage x0.7

Fuel Efficiency 4. Fuel Usage x0.6

Fuel Efficiency 5. Fuel Usage x0.5

Fuel Efficiency 6. Fuel Usage x0.4

Fuel Efficiency 7. Fuel Usage x0.3

Fuel Efficiency 8. Fuel Usage x0.25

Fuel Efficiency 9. Fuel Usage x0.2

Fuel Efficiency 10. Fuel Usage x0.15

Fuel Efficiency 11. Fuel Usage x0.125

Fuel Efficiency 12. Fuel Usage x0.1

For example, an ion engine with no internal armour and standard economy vs power tech has 60 power. If it had a fuel efficiency of 0.8, However, it would now use 43.2 litres of fuel per day (54 x 0.8) compared to 60 litres for the normal engine.

The combination of Fuel Efficiency and Economy vs Power can dramatically reduce fuel use or alleviate the fuel costs normally associated with high powered engines.

For example, if an ion engine had the Engine Efficiency 20%, Power Reduction 10%, Exp 3% tech and also Fuel Efficiency 0.8 tech, the engine power would be reduced to 54 but the fuel consumption would be based on engine power 54 x 0.8 (Engine Efficiency) x 0.8 (Fuel Efficiency) = 34.56

If an ion engine had the Engine Efficiency -20%, Power Increase 10%, Exp 10% tech and Fuel Efficiency 0.8 tech, the engine power would be increased to 66. The fuel consumption would be based on engine power 66 x 1.2 (Engine Efficiency) x 0.8 (Fuel Efficiency) = 63.36. In this case the fuel efficiency tech is allowing a more powerful engine for the same fuel cost as a basic engine.

On a ship design display, the engine efficiency and fuel efficiency rating are combined into a single Engine Efficiency value. If an ship moves at less than its maximum speed, fuel is consumed based on the engine power required to move the ship at that speed (multiplied by the engine efficiency).

Fuel Refineries produce 1000 litres of fuel per ton of Sorium and the base refinery without tech improvements can process ten tons of Sorium per year (producing 10,000 litres of fuel). A new ship system called Fuel Bunkers (1HS) can hold 50,000 litres of fuel. The ship design display now shows both distance and time for the fuel capacity.

Detailed Example

A Themistocles II has six basic ion engines with no modifications and 60 power each, totalling 360 engine power, and has 2 fuel bunkers with 100,000 litres of fuel. It can therefore travel for 100,000/360 = 278 days on a full tank of fuel. With its top speed of 3600 km/s, that equates to a distance of 86 billion kilometers on one tank of gas.

If the Themistocles had ion engines with a Fuel Efficiency 0.8, the 100,000 litre tank of gas would last for 100,000 / (360 x 0.8) = 347 days and its range would increase to 107 billion kilometers.

If the ion engines were designed with both Fuel Efficiency 0.8 and Engine Efficiency 20%, Power Reduction 10%, the engines would have 54 power and an Engine Efficiency of 0.64, giving the freighter engine power of 324 and a top speed of 3240 km/s. Now the 100,000 litre tank of gas would last for 100,000 / (324 x 0.64) = 483 days and its range would increase to 135 billion kilometers.

Fuel Harvesters

Sorium can now be found in gas giants (but no other mineral), which means those bodies need to be surveyed to find it. Because it is in gaseous form it is much easier to mine and refine than the Sorium ore found in planetary cores.

A new ship system has been added called a Sorium Harvester. This acts as a type of combined automated mine and fuel refinery, although it can only be used in orbit of a gas giant and only mines Sorium, converting it directly into fuel as it is mined and added that fuel to the ship?s fuel bunkers. The mining rate of each Sorium Harvester is equal to the current racial mining rate. Each Harvester costs 40BP and is 10HS in size. This may sound cheap compared to the combined cost of an automated mine (240 BP) and a Refinery (120 BP) but an automated mine can mine up to eleven minerals at once while a planet-based refinery can refine Sorium from any source. There are also considerable additional costs for the Harvester as it requires a ship built around it and that ship and the Harvester itself need to be overhauled occasionally.

An example of a Fuel Harvesting ship:

Cypelus class Fuel Harvester 13500 tons 1070 Crew 1355 BP Signature 270-270

1000 km/s Armour 1 Shields 0-0 Sensors 6/0/0/0 Damage Control 0-0

Fuel Harvester: 20 modules producing 320,000 litres per annum

E8 Ion Engine (5) Power 54 Fuel Efficiency 0.8 Armour 0 Exp 5%

Fuel Capacity 500,000 Litres Range 200.0 billion km

High Resolution Thermal Sensor S2-6 (1) Strength 6 Detect Signature 10: 0.6m km

Detect Signature 100: 6m km

Steve