How to Build an SSTO in Kerbal Space Program

An SSTO is a vehicle that can reach orbit without any staging events. This means that the entire vehicle is recovered and can be reused when it returns from space. SSTOs are currently (as of 2016) considered impossible in real life on Earth, but they are a possible and viable option in the virtual gameplay of Kerbal Space Program, and provide a good way to recover funds to build more spaceships.


  1. 1
    Go to the Spaceplane hangar.
  2. 2
    Start with a Mk2 cockpit.
  3. 3
    Add a liquid fuel fuselage behind the cockpit. Don't use the rocket fuel fuselage, as it contains oxidizer as well as liquid fuel.
  4. 4
    Optionally, swap the liquid fuel fuselage for a liquid fuel short fuselage and a cargo bay (cargo delivery). Make sure you use the short cargo bay. Alternatively, swap the liquid fuel fuselage for a monopropellant short fuselage and a Mk2 docking port, suitable for transporting crew to a space station.
  5. 5
    Add a liquid fuel short fuselage behind the liquid fuel fuselage, followed by a Mk2 Bicoupler. Leave the oxidizer in the bicoupler, you'll use it later.
  6. 6
    Add a LV-N nuclear engine to each part of the bicoupler, using symmetry mode. Use the offset tool to move the engines inside the plane, so that just the engine bell is sticking out.
  7. 7
    Add a Wing Connector Type A to the sides of your plane, still using symmetry mode. To the side of this, add a Structural Wing Type A. Add a second Structural Wing Type A to the front of the wing connector. You should now have a triangular wing on either side of your plane. These are your main wings.
  8. 8
    Tweak the positions of the wings using the offset tool. The centre of lift should be in the same place, or slightly behind, the centre of mass.
  9. 9
    Add a Mk1 Liquid Fuel Fuselage to each wing using symmetry mode. Half of the tanks should be sticking up above the wing, and half below. Use the offset tool to move these tanks next to the bicoupler.
  10. 10
    Add an FL-T200 fuel tank to the front of each Mk1 Liquid Fuel Fuselage. Add a R.A.P.I.E.R. engine to the back. Add a shock cone intake to the front, and two radial intakes to the top. Use the offset tool to move the whole setup (tanks, intakes and engines) forwards or backwards until the ends of the R.A.P.I.E.R. engines are in line with the ends of the nuclear engines.
  11. 11
    Add an AV-R8 winglet to the front of the plane, one on either side (symmetry mode again, if you haven't sussed it out yet). Right-click on it and disable pitch and yaw control.
  12. 12
    Add an AV-R8 winglet on top of each Mk1 Liquid Fuel Fuselage. These winglets should be vertical, not horizontal. Right-click and disable pitch and roll control.
  13. 13
    On the end of each main wing, add an elevon. Right-click and disable yaw and roll control.
  14. 14
    Add a wheel on the bottom of each Mk1 fuselage. Add a third wheel at the front, under the cockpit.
  15. 15
    Use the offset tool to move the main wings backwards or forwards until the centres of mass and lift are aligned.
  16. 16
    Set up some action groups. Since an SSTO, by definition, has no staging, this is how your spaceplane will be controlled. You need to set up these action groups:
    • 1 - toggle shock cone intakes and radial intakes
    • 2 - toggle R.A.P.I.E.R. engines on and off.
    • 3 - toggle R.A.P.I.E.R. engines fuel mode.
    • 4 - toggle nuclear engines on and off.
    • 5 - toggle cargo bay/docking port (if applicable)
  17. 17
    Add some RCS thruster blocks. Add one on either side, either in front of the winglets or between the winglets and the main wings. Add a second pair on top of the bicoupler, and a third on the bottom of the Mk1 fuselages, behind the wheels.
  18. 18
    Save and launch! There is a bit to learn about flying an SSTO:
    • Press Z to turn up the thrust.
    • Press 2 to activate the R.A.P.I.E.R. engines. Taxi down the runway and take off.
    • When airborne, press G to stow the wheels.
    • When the R.A.P.I.E.R. engines flame out, press 1 to close the intakes and 3 to activate rocket mode.
    • When your apoapsis is at the desired height, press 2 to deactivate the R.A.P.I.E.R. engines.
    • Use 4 to toggle the nuclear engines. Use these to complete orbital insertion.
  19. 19
    Just remember: once you're in orbit, you have to get back...


  • Don't be afraid to change things up a bit! For example, if you can squash in an extra pair of engines, swapping the R.A.P.I.E.R. engines for a pair of dedicated air-breathing engines and a pair of dedicated rocket engines is highly recommended, as the R.A.P.I.E.R. engines aren't very efficient. A good set would be a pair of J-X4 ramjets and a pair of Toroidal Aerospike engines.
  • Twiddle with the setup until it flies. Don't be scared if you crash on your first go.
  • Rocket mode engines aren't needed when returning. Just wait until you are low enough in the atmosphere (below ~20km on Kerbin) then use the air-breathing mode.


  • Once you're in orbit, make sure that you have enough fuel to return and to land.
  • You're probably going to crash on your first go.
  • Use the rocket mode engines as little as possible. Rocket mode engines are very inefficient (Isp ~ 300) compared to the nuclear engines (Isp = 800) and air-breathing engines (4000 < Isp < 8000).

Article Info

Categories: PC Games