Flight time and deuterium consumption in Inter-War are not fixed values. They depend on distance, the slowest ship in the fleet, the selected speed percentage, drive research, speed bonuses and the fleet-speed setting of the current universe.
How is distance calculated?
The game uses a different formula depending on the route:
- different galaxy:
20,000 × |galaxy difference|, - different system in the same galaxy:
95 × |system difference| + 2700, - different position in the same system:
5 × |position difference| + 1000, - the same coordinates: base distance
5.
For example, position 8 to 9 in one system gives distance 1005, system 100 to 110 gives 3650, and two neighbouring galaxies give 20,000.
How is flight time calculated?
Each ship first receives an effective speed. In simplified form: effective speed = base speed × (1 + 0.10 × drive level) × (1 + speed bonus). The slowest ship determines the fleet speed.
Base duration in seconds is calculated as (10 + (35000 / speed %) × √(distance × 10 / slowest speed)) / universe fleet speed and rounded to whole seconds. Moving from 50% to 100% therefore shortens a flight strongly, but not as a simple linear division.
How is deuterium consumption calculated?
Every ship type has its own consumption and effective speed. For one ship profile the mechanic is approximately count × consumption × distance / 35000 × ((speed % × √(Vmin / Vship))/10 + 1)². Costs from all ship types are added and rounded.
Lower speed percentages usually reduce fuel use sharply. As a mathematical example, one hypothetical ship with consumption 20, effective speed 10,000 and distance 1005 costs about 69 deuterium at 100%, 21 at 50% and 2 at 10%. Your actual fleet result depends on its real ship profiles.
What has the biggest effect?
Distance, the slowest ship and the selected speed percentage matter most. Officer or other fleet-speed bonuses may reduce travel time, while the universe fleet-speed multiplier divides the base duration. A single slow ship can therefore slow down the whole mission.
Additional drive and bonus rules
Some ships can switch to a second propulsion profile. A ship with drive profile 4 uses Combustion until Impulse Drive level 5; from that point the game uses its speed2/consumption2 values and Impulse research. Profile 5 switches from Impulse to Hyperspace at Hyperspace Drive level 8. Fleet-speed bonuses include Admiral (+5% per level), General (+10% per level), Resort Officer (+2% per level) and avatar bonuses.
Time reductions are applied after the base duration, while an active fleet-speed event divides the resulting duration by its multiplier. Interplanetary missiles are a special case: speed is fixed at 30,000, fuel cost is 0 and normal fleet modifiers are not used. Fuel-efficiency bonuses and avatar effects can reduce normal fleet consumption by at most 95%, because the final fuel factor cannot fall below 0.05.
Practical consequence: a research level can change both speed and consumption at once when it activates the alternate drive. This is why two apparently identical fleets may show a different flight time or fuel bill after Impulse 5 or Hyperspace 8.
FAQ — fleet flight
Does 50% speed use exactly half as much deuterium?
No. Fuel consumption uses a nonlinear squared speed factor, so the reduction is not proportional one-to-one.
Does improving a ship drive always shorten the flight?
Only if it changes the speed of the slowest unit in the fleet, because that unit controls the base pace of the mission.
Related FAQ: How do fleet and expedition slots work? · How do expeditions work?