SSTO C-9 Payroll Mk.1
by Val
uploaded 2015-12-14
(updated 2015-12-14)
stock spaceplane
#SSTO #Monster #Heavy #Cargo #Mk3


The C-9 Payroll is a toned down version of an unsubmitted entry I made for the Stock Payload Fraction Challenge.

It originally had 34 RAPIERs, lifted more than 400 t payload and had a takeoff weight of 780 t, but the part count was so high it was a slideshow to fly it. This version is still quite hard on the physics engine, so expect a reduced frame rate.

There’s also an issue with cargo bay occlusion. Sometimes, after time/physics warp and quickload, some of the control surfaces will become unresponsive. Double tap Action Group 9 to open-close the Cargo Bay doors, to make the control surfaces respond again.

  • When loading cargo, be sure to place the Center of Mass above the front half of the landing gear bay.

For a half size version check out SSTO S-108 Long

  • Front external docking port
  • No RCS
  • Propulsion: 24 RAPIERs.
  • Liquid Fuel: 13780
  • Oxidizer: 8580
  • Dry Weight: 115.7 t.
  • Wet Weight: 318.7 t.
  • Max Payload (LKO): 216 t.
  • Max Take-off weight: 535 t.


  • Type: SPH
  • Class: spaceplane
  • Part Count: 140
  • Pure Stock
  • Built in the SPH
  • KSP version 1.0.5
  • Cost: 361,560

Ascent Profile

  1. SAS on, Full throttle, Stage and start your takeoff roll.
  2. Just before reaching the end of the runway activate the Takeoff Flaps and lift off. (RCS Action Group)
  3. You should be able to lift the nose 5-10° and just barely avoid crashing the rear of the craft into the ground.
  4. Deactivate the Takeoff Flaps and build up speed to 400 m/s at sea level. (Below 300 m)
  5. Pitch up to 15° above horizon.
  6. At 5 km pitch down to 10° above horizon.
  7. At 8 km pitch down to 5° above horizon.
  8. At 11 km pitch up to 10° above horizon, again.
  9. At 22 km switch RAPIER Mode. (Action Group 1)
  10. Pitch down slightly to midway between 10° and the prograde marker.
  11. At 30 km pitch down to follow prograde marker.
  12. Throttle down when AP is at 82 km altitude.
  13. Circularize at AP.

Descent Profile

  1. 80 km orbit. In Map mode, focus Kerbin and turn camera so KSC is facing towards you right above the Navball.
  2. Time warp until your spaceplane is right behind Kerbin.
  3. Put a maneuver node right where you orbit appears from behind Kerbin on the left side.
  4. Pull the retrograde handle until the maneuver is ~100 m/s dV.
  5. Move the maneuver node until the planned orbit intersects the surface through KSC.
  6. Pull the prograde handle until the maneuver is ~80 m/s dV.
  7. Perform the maneuver.
  8. Turn Prograde and time warp till you enter atmosphere.
  9. Keep nose ~30° above horizon. (May need to move fuel around to keep stable)
  10. At 36 km altitude pitch down to 10° above the horizon.
  11. When you pass over the coast of the landmass where KSC is pitch down 5°-10° below horizon.
  12. Adjust pitch to pass the mountains at 10 km, at 650-750 m/s.
  13. When you’ve passed the mountains aim for a point about half the runway length in front of the runway.
  14. At 200 m, flare and aim for the runway.
  15. Touch down with 70 m/s and less than 3 m/s vertical speed.

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