Thruster mechanics

The Thruster is a mobility block in Space Engineers.

The primary function of a thruster is to provide ships with the ability to move. When turned on, the thruster applies force in the direction opposite to its exhaust. To activate thrusters, either press the movement keys in a cockpit, or activate the thruster's manual override in the control panel.

Each thruster can push ships in only one direction, so for conventional ship designs it's recommended to build thrusters in all 6 directions.

• As a physics simplification in the game, each thruster's force is applied to the Center of Mass, no matter where it actually is located on the ship. Asymmetrical thruster placement will not cause tailspinning.
• Thruster help counteract inertia in zero gravity. Inertia after a thruster burn makes a ship coast (drift). Enable inertial dampeners to slow the ship down by automatically burning the right counter thrusters.
• Thrusters help fight against planetary gravity, so ensure that you have enough lifting thrusters for landers and shuttles.

While thrusters can be placed anywhere on a ship, they require 4-5 blocks of clear space to avoid damaging other objects. Small ship thrusters, do not damage heavy armour blocks. Thruster Damage can be toggled on and off in world settings, allowing for different ship designs.

Thrusters provide only linear movement to the ship (up/down, left/right, backwards/forwards). To rotate (roll, yaw, or pitch), you must build Gyroscopes.

Capacity

When active, inertial dampeners can use 100% of the maximum capacity of all necessary thrusters.

The thrust required to lift your ship takes the Blocks Inventory Size setting into account. The mass of all of the cargo in your ship is divided by the multiplier's setting, so the same number of thrusters will be required regardless of what setting you play with.

Online calculators

Online calculators for easy ship building:

• https://se.analytixresearch.com
• https://se-calculator.com/home

Calculating acceleration

According to physics, we know that force = mass x acceleration. Using algebra, we can then determine that acceleration = force / mass. But what does this mean, exactly?

Units

• Force: Newtons (N), 1 N = 1 kgm/s²
• Mass: Kilograms (kg)
• Acceleration: meters per second per second (m/s²)

Constants

• Inertial dampeners use thrusters' maximum power.
• Small Ion Thruster:
  • Small ship: 18,165 N maximum, 12,110 N on manual burn.
  • Large ship: 150,660 N maximum, 100,440 N on manual burn.
• Large Ion Thruster:
  • Small ship: 218,250 N maximum, 145,500 N on manual burn.
  • Large ship: 1,815,000 N maximum, 1,210,000 N on manual burn.

Equation

To calculate the acceleration of your ship, use the following formula:

$a=\frac{(N_l{F}_l+N_s{F}_s)}{m}$
Where:
$a$	: Acceleration (m/s2)
$N_l$	: Number of large thrusters
$F_l$	: Force of each large thruster (N)
$N_s$	: Number of small thrusters
$F_s$	: Force of each small thruster (N)
$m$	: Mass of the ship (kg)

Example

Let's assume we have a 15000kg small ship with one large thruster and four small ones pointing aft. We want to know how fast we'll accerate when we press 'w'.

Steps:
1.	Calculate small thruster force $N_s{F}_s=4\times 12,110\text{N}=48,440\text{N}$
2.	Add the large thruster. $N_s{F}_s+N_l\times F_l=48,440\text{N}+1\times 145,500=193,940\text{N}$
3.	Calculate acceleration. $a=\frac{193,940\text{N}}{15,000\text{kg}}=12.93{\text{m/s}}^2$

Calculating time to velocity

Sometimes, it may be important to know how long it will take to accelerate to a particular speed. To calculate the amount this, you first need the rate of acceleration calculated above. Then, since we know that velocity = acceleration * time, you can use algebra to find the following equation:

Equation

$t=\frac{\mathrm{\Delta }v}{a}$
$\mathrm{\Delta }v=v_f-v_i$
Where:
$\mathrm{\Delta }v$	: Change in velocity (m/s)
$a$	: Acceleration (m/s2)
$v_f$	: Final velocity (m/s)
$v_i$	: Initial velocity (m/s)

Example

Our ship in the previous example had an acceleration of 12.93 m/s². If we want to know how long it takes to accelerate from a stop up to the game's speed limit, we simply fill in the equation:

Steps:
1.	Get delta-v. $v=105\text{m/s}-0\text{m/s}$
2.	Calculate time. $t=\frac{105\text{m/s}}{12.93{\text{m/s}}^2}=8.1\text{s}$

Distance traveled

Another useful thing to know is how far you'll travel while accelerating. For example, if we plan on docking with a station or carrier, it's good to know exactly how close we can get before we have to start slowing down. For this, we need to know our initial velocity, our acceleration, and the time.

Equation

$d=v_{i}t+\frac{a{t}^2}{2}$
Where:
$d$	: Distance (m)
$v_i$	: Initial velocity (m/s)
$a$	: Acceleration (m/s2)
$t$	: Time (s)

Example

Let's say we've got a small ship up near the speed limit at 100m/s. We want to slow down to about 10m/s in order to dock safely. Our ship isn't really designed for rapid deceleration, so our forward thrusters only generate an acceleration of 15m/s². (Note: since we're decelerating, we use -15m/s².)

Steps:
1.	Calculate how much time it'll take. $t=\frac{10\text{m/s}-100\text{m/s}}{-15{\text{m/s}}^2}$
2.	$t=\frac{-90\text{m/s}}{-15{\text{m/s}}^2}$
3.	$t=6\text{s}$
4.	Then figure out how much distance we need. $d=100\text{m/s}(6\text{s})+\frac{-15{\text{m/s}}^2{6}^2\text{s}}{2}$
5.	$d=600\text{m}+\frac{-15{\text{m/s}}^{2}36{\text{s}}^2}{2}$
6.	$d=600\text{m}+\frac{-540\text{m}}{2}$
7.	$d=600\text{m}-270\text{m}$
8.	$d=330\text{m}$

So we need at least 330m to drop down to our safe speed.

When doing these calculations, it's important to remember that you get more power from inertial dampeners than from manual thrusters. It's even more important to remember your ship can have a different acceleration depending on how many thrusters point away from where you're moving.

Since most ships have more aft thrusters than fore thrusters, you can run into problems if you base all your calculations off aft inertial dampeners. You may well find yourself merging your hull into the side of a station.

Multiple thrust vectors

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