Flight model

Setup time, acceleration and maximum speed: how your fleet's flight time comes about – and why short and long trips feel so different.

In SpaceInvasion 2 ships do not simply fly at a fixed speed. Every flight starts with the setup time, during which the fleet gets ready to launch. Then it accelerates to its maximum speed, cruises at full speed for a while and brakes again before reaching the target.

The three flight values

Setup time: a fixed preparation time before launch, no matter how far you fly. A fleet always needs the longest setup time of all its ships.
Acceleration: how quickly a ship gets up to speed – and slows down again. The lowest acceleration in the fleet counts.
Maximum speed: the cruising speed on long trips. Here, too, the slowest ship sets the pace.

How the flight time comes about

The game splits every flight into four stages:

Setup: the fleet waits for the longest setup time of its ships – no matter how far away the target is.
Accelerating: then it picks up speed until it reaches its maximum speed. The lowest acceleration and the lowest maximum speed in the fleet count.
Cruising: it covers the middle part of the route at maximum speed.
Braking: before the target it brakes for exactly as long as it accelerated.

If the route is so short that the fleet never reaches its top speed, it accelerates up to the halfway point and then brakes straight away – there is no cruising stage. That is why twice the distance never takes twice as long: setup, speeding up and braking only happen once.

The distance is the straight line between the start and target planet on the map (Galaxy map). The fleet window shows it to you in kilometres.

Short and long trips

On short trips a fleet often never reaches its top speed – setup time and acceleration decide the flight time. On long flights the start-up hardly matters and the maximum speed is what counts. That is why the Phoenix, for example, is faster than the Battle ship on short trips, while the battleship overtakes it on long ones.

Example flight times

The table shows how big the differences are: this is how long a single ship of each type needs for typical routes – from the neighbouring planet to a distant galaxy.

Unit	Same system 150 million km	Neighbouring system 750 million km	A few systems away 3,750 million km	Half the galaxy 22,500 million km	Neighbouring galaxy 45,000 million km	Distant galaxy 112,500 million km
Small transport ship	21 min 1 s	31 min 40 s	1 h 9 min	5 h 9 min	9 h 56 min	1 d 18 min
Large transport ship	17 min 46 s	28 min 25 s	58 min 33 s	4 h 2 min	7 h 43 min	18 h 45 min
Transmitter	15 min 17 s	24 min 30 s	50 min 8 s	3 h 25 min	6 h 32 min	15 h 53 min
Small fighter	14 min 7 s	23 min 20 s	46 min 3 s	2 h 56 min	5 h 32 min	13 h 21 min
Warship	16 min 11 s	26 min 50 s	54 min 1 s	3 h 33 min	6 h 45 min	16 h 19 min
Star cruiser	17 min 46 s	28 min 25 s	59 min 9 s	4 h 7 min	7 h 53 min	19 h 12 min
Phoenix	15 min 26 s	26 min 5 s	51 min 17 s	3 h 10 min	5 h 56 min	14 h 16 min
Colony ship	21 min 40 s	32 min 25 s	1 h 26 min	7 h 2 min	13 h 45 min	1 d 9 h 55 min
Spy probe	24 s	42 s	1 min 21 s	3 min 3 s	4 min 15 s	6 min 37 s
Recycler	22 min 3 s	41 min 28 s	1 h 29 min	6 h 7 min	11 h 40 min	1 d 4 h 20 min
Battle ship	25 min 35 s	36 min 35 s	1 h 1 min	2 h 51 min	5 h 4 min	11 h 42 min
Stealth bomber	18 min 5 s	29 min 30 s	59 min 49 s	4 h	7 h 38 min	18 h 30 min
Destroyer	19 min 35 s	31 min	1 h 4 min	4 h 30 min	8 h 38 min	21 h
Imperial star base	48 min 35 s	1 h 12 min	3 h 14 min	15 h 51 min	1 d 7 h	3 d 4 h 27 min
Jammer probe	24 s	42 s	1 min 21 s	3 min 3 s	4 min 15 s	6 min 37 s
EMP-Bomb	32 s	1 min	2 min 2 s	4 min 44 s	6 min 37 s	10 min 22 s
Scanner ship	14 min 7 s	23 min 20 s	46 min 3 s	2 h 56 min	5 h 32 min	13 h 21 min

A single ship at 100% speed, drive research level 0, setup time included. With drive research, a lower speed or in mixed fleets the times change – the fleet window always shows you the exact flight time.

Engine research

Every ship flies with the Rocket engine, the Diffusion engine or the Warp engine. Each level of the matching engine adds +5% maximum speed and +10% acceleration. The setup time stays the same. Which ship uses which engine is listed on every ship page and in the Ships overview.

Speed and fuel

In the fleet window you choose a speed between 10 and 100% in steps of ten. Lower speed reduces both acceleration and maximum speed: the flight takes longer but costs much less Spice. Fuel use also depends on the distance and on the number and type of ships – a base amount is due even on short flights.

The fuel has to be available on the start planet and takes up part of the cargo space. A fast ship flying along in a slower fleet burns less fuel than it would on its own.

A universe in motion

Planets orbit their suns and move a little further along their path every day. That is why the distance between two planets changes from day to day – the same route can be shorter or longer tomorrow than today (Planets). Before launch, the fleet window always shows you the current distance, flight time and fuel costs. Once the fleet has launched, its flight time is fixed.