Some or all of the parts and/or features on this page require the Parts Expansion in-app purchase.
Engines are a vital and necessary component of any rocket. Engines produce thrust, which allows for rockets to fight the pull of gravity and ascend through the skies.
Spaceflight Simulator features various engines that can be used to power one's rocket, ranging from liquid-fuel engines to solid-fuel engines to precision maneuvering engines. All engines consume some version of fuel to operate, a fact that must be considered in the creation of any a rocket.
Types of engines[]
There are seven liquid fueled engines in the game. They are named Titan, Hawk, Peregrine, Frontier, Valiant, Kolibri and Ion. The odd one is the RCS Thruster; its name doesn't end with "Engine", but "Thruster", unlike the other six do. The engine thrusts on 4 vectors, unlike other engines, which expel fuel out of the nozzle, and the ion engine, that do some process to expel the fuel out.
Here are the types of engines:
| Name | Appearance | Mass | Thrust | Efficiency (Isp) | Description |
|---|---|---|---|---|---|
| Titan Engine |  |
12 tons | 400 tons | 240s | The largest engine in the game. Titan has very high thrust but low efficiency, making it best suited for the first stages of rockets where the atmosphere is thicker. It is the larger variant of the Hawk Engine. |
| Hawk Engine |  |
3.5 tons | 120 tons | 240s | The smaller version of the Titan Engine. Hawk has high thrust but lower efficiency, making it ideal for the first stages of rockets. |
| Peregrine Engine |  |
2 tons | 75 tons | 180s | A basic engine that is only available for Career Mode and can be used for lower stages of a rocket. It has very low efficiency, but medium thrust. It is the first liquid fueled engine player unlocks in Career.
This engine likely uses kerolox (kerosene and liquid oxygen) for fuel, that's why it burns out an opaque orange plume. |
| Frontier Engine |  |
6 tons | 100 tons | 290s | A large engine with high efficiency and moderate thrust best suited for the upper stages of rockets in a vacuum regime. Despite this fact, decent thrust allows for use in atmosphere for smaller rockets and launch vehicles. |
| Valiant Engine |  |
2 tons | 40 tons | 280s | A basic engine that can be used for upper stages of a rocket. They have high efficiency, but low thrust. They can also used as landing engines, due to their high efficiency and low thrust. merging a lot of engines would recreate the real life Raptor engine.
This engine uses methalox or hydrolox (liquid methane and liquid oxygen or liquid hydrogen and liquid oxygen) for fuel, that's why it burns out a purple-pink plume. |
| Kolibri Engine |  |
0.5 tons | 15 tons | 260s | This engine is small, but terrible.
This engine has moderately-high efficiency, but low thrust of only 15 tons. The engine can be used as a landing engine on the Moon, Phobos and Deimos due to its extremely low thrust. This engine uses methalox or hydrolox (liquid methane and liquid oxygen or liquid hydrogen and liquid oxygen) for fuel, that's why it burns out a purple-pink plume. |
| RCS Thruster |  |
0.05 tons | 1.5 tons | 120s | The least efficient liquid fueled engine in game. This engine can be used for orbital maneuvering but not for rocket engines at launch of the rocket.
It fires on 4 vectors, but appears to be 3 because the game is 2 dimensional. The engine can be place on upper stages of the rocket. The engine uses all fuel, unlike all other engines in the game. |
| Ion Engine |  |
0.5 tons | 1.5 tons | 1200s | The engine, along with the RCS Thruster, are the smallest engines in the game, only occupying a 2×1 array of tiles.This engine is also the lightest of all engines in the game. The engine can be used on satellites and orbiters due to its extremely low thrust, to change their trajectory. The engine has very low thrust, but VERY HIGH efficiency at 1200s. This engine cannot work well on thick atmospheres due to its very low thrust.
It can be used as landing engines, for long interplanetary transfers and a replacement for RCS. This engine uses xenon or krypton fuel. |
Vitalness[]
They are very important parts of the rocket. Engines are used to launch rockets, correct trajectories, transfer burns and many more.
How engines work?[]
There are mainly two types of engines, liquid fuel engines and solid fuel engines (more commonly known as solid rocket motors or solid rocket boosters (SRMs and SRBs) and they work differently.
Solid fuel engine[]
There are two types of solid fuel engines in game, but as of 1.5.5.2 beta they are exactly like Peregrine Engine available only in Career Mode. As of January 29, 2022, they both have the same in-game name, but in blueprints they are named Booster Tut 1 and Booster Tut 3. They have lowest efficiency of all the engines with Isp of only 60 seconds.
Solid rocket engines are used on air-to-air and air-to-ground missiles, on model rockets, and as boosters for satellite launchers. In a solid rocket, the fuel and oxidizer are mixed together into a solid propellant which is packed into a solid cylinder. A hole through the cylinder serves as a combustion chamber. When the mixture is ignited, combustion takes place on the surface of the propellant. A flame front is generated which burns into the mixture. The combustion produces great amounts of exhaust gas at high temperature and pressure. The amount of exhaust gas that is produced depends on the area of the flame front and engine designers use a variety of hole shapes to control the change in thrust for a particular engine. The hot exhaust gas is passed through a nozzle which accelerates the flow. Thrust is then produced according to Newton's third law of motion.
Source from NASA
Liquid fuel engine[]
There are, of course liquid fuel engines in the game. Four out of six engines are liquid fuel engines. They are:
- Titan Engine
- Hawk Engine
- Frontier Engine
- Valiant Engine
- Kolibri Engine
This is how it works:
Liquid rocket engines are used on the Space Shuttle to place humans in orbit, on many un-manned missiles to place satellites in orbit, and on several high speed research aircraft following World War II. In a liquid rocket, stored fuel and stored oxidizer are pumped into a combustion chamber where they are mixed and burned. The combustion produces great amounts of exhaust gas at high temperature and pressure. The hot exhaust is compressed at the smallest point of the nozzle, making it reach supersonic speed. To accelerate further, the exhaust rushes into a widening nozzle. Thrust is produced according to Newton's third law of motion. This is very similar to when a balloon filled with air is let go.
Source from NASA
Odd engines[]
The odd engines, RCS and Ion Engine work differently than solid or liquid fuel engines. They have some process of pumping fuel out of the tanks. Here is how they work:
RCS thrusters[]
Reaction control systems often use combinations of large and small (vernier) thrusters, to allow different levels of response. Spacecraft reaction control systems are used for:
- attitude control during re-entry;
- stationkeeping in orbit;
- close maneuvering during docking procedures;
- control of orientation, or 'pointing the nose' of the craft;
- a backup means of deorbiting;
- ullage motors to prime the fuel system for a main engine burn.
Source from Wikipedia
Ion engines[]
An electrostatic ion engine works by ionizing a fuel (often xenon or argon gas) by knocking off an electron to make a positive ion. The positive ions then diffuse into a region between two charged grids that contain an electrostatic field. This accelerates the positive ions out of the engine and away from the spacecraft, thereby generating thrust. Finally, a neutralizer sprays electrons into the exhaust plume at a rate that keeps the spacecraft electrically neutral.
Source from New Atlas
Optimality[]
When aerodynamic drag isn't accounted for (ie. in the sphere of influence of a body with no atmosphere) and assuming they are being fired opposite to gravity, the non-engine (payload+fuel) mass per engine can be adjusted to maximise efficiency, measured in delta-v (from thrust minus that from gravity throughout their operation) divided by fuel consumption. Being too high will lead to accelerating too slowly and operating for too long in the gravity well, but being too low will lead to the engines comprising too high a proportion of the rocket's mass and spend unnecessary fuel lifting themselves. An optimal ratio exists between either extreme, the non-engine mass per engine to achieve it is plotted with respect to gravity for each type in the first image, and the efficiency resultant of this in the second.
Trivia[]
- In 1.5.4, you cannot clip engines together. Stef said it's too unchallenging if you do this and he received tons of hate for removing that feature. However, he re-enabled it in 1.5.4.1, but engines now heat each other, causing them to explode.
