[SSTO] LR-133 'Sabertooth'
by Fulgora
uploaded 2016-09-22
mod spaceplane
#far #ssto #duna


  • Type: SPH
  • Class: spaceplane
  • Part Count: 221
  • Mods: 7


  • B9 Aerospace Parts Pack
  • B9 Procedural Wings Modified
  • Ferram Aerospace Research
  • KAL9000
  • MechJeb 2
  • RealChute Parachute Systems
  • Squad (stock)

[SSTO] LR-133 ‘Sabertooth’

An interplanetary SSTO which has been built with 221 parts using mostly stock parts except for wings, airbrakes, main sabre-engines, parachutes (and Mechjeb / kOS controls).

Built with KSP version 1.1.3.

Built for the HotTips Duna challenge

Challenge completion in pictures (with comments/info)

  • Transports up to 20 Kerbals and a rover (technically 21 if one Kerbal volunteers for an indefinite stay on Duna)
  • Can get into orbit with around ~3400 deltaV left.
  • Can go to Duna without an obital insertion burn (heavy aerobreaking)
  • Can place a rover on Duna that has every stock science experiment on board
  • Can get back into a low Duna orbit
  • Can get back to a low Kerbin orbit from Duna (again lots of aerobreaking)
  • Can land anywhere at Kerbin - including the runway at the KSC
Launching with kOS:
  • Go to the GitHub repository
  • Read the Github readme and follow its (very short) instructions.

It is faster to launch this with a script and also a lot easier because it is impossible for things to go wrong if you don’t change the craft or the default FAR settings.

Manual launch at Kerbin:
  • After carefully taking off (plane will lose a few meters after the runway) disable the nukes (AG 4)! (very important for maximum deltaV)
  • Pitch up to about 20° until you reach 10000m
  • Pitch down to 0° (horizon) and stay at roughly the same altitude until you are going 900m/s - 950 m/s
  • Pitch back up to 20° - 30° until you reach an altitude of ~ 26000m
  • Manually toggle Sabre-Mode (AG 3), close air-intakes (AG2) and enable the nukes (AG4)
  • Switch Sabre-Mode again at an apoapsis of > 70000m and finish the circularisation with the nukes (if possible)
Duna landing:
  • Shallow descent with a periapsis of ~20k at the atmospheric reentry
  • Set SAS to point prograde (and enable brakes of course)
  • Make sure you are above the Lowlands or Midlands - if not disable airbreaks and glide while maintaining an altitude of more than 10k above ground
  • If you are satisfied with the terrain ahead open the cargo bays (AG 5) at 6 - 10k altitude (above terrain!) for a safe landing
  • Landing preparations (be quick with that):
    • Stage the vertical thrusters (Don’t actually let them burn - just activate them)
    • Disable nukes AG 4 - important
    • Your sabre engines should be either at airbreathing mode or disabled which is what you want - double check just to be sure
    • Toggle gear
    • Open and lock the action window for the first and last fuel tank in the center so you are ready to transfer fuel if needed
    • Open and lock the action window for the center ‘Dart’ engine in the back and one of the ‘Thud’ engines inside the cargo bay. It does not matter which ‘Thud’ engine you choose. (to balance thrust if needed)
  • Stage drogue chutes and set SAS to normal stability control
  • When pointing at -10° (can also be sooner) toggle the first stage of the main chutes
  • Wait ~ a second or two and stage the next set of main chutes
  • Wait ~ a second or two and stage the next last set of main chutes
  • You should be somewhat level now and have a vertical velocity of < 20m/s (after all chutes are fully deployed)
  • Balance fuel so you are pointing at the horizon with an error margin of < 5° (if not at 0 let it point slightly up rather than slightly down if it doesnt want to zero out perfectly…)
  • Set throttle to max (with ‘Z’) for a fraction of a second and see if the craft starts pointing more upwards or downwards. Adjust max throttle accordingly
  • Start buring off most of the vertical velocity when <150m above groundlevel - go full throttle close to the ground unless your craft starts turning in which case thrust balancing wasn’t sufficient…
  • Enable RCS if needed for stability assist

Piece of cake am i right? :D
Seriously though - this list sounds more complicated than it actually is…

After the touchdown (when standing still) don’t forget to hit stage to release the rover!

Duna ascent:
  • Point at the 270° marker
  • Retract solarpanels etc. if extended (AG 1)
  • Set sabre engines to closed cycle (AG 3)
  • Enable nukes (AG 4)
  • Close cargo bays (AG 5)
  • Disable vertical thrusters (AG 6) - unless you need an almost vertical takeoff because you are looking at a steep hill
  • Disable breaks (obviously)
  • Throttle up and fly away!
  • Pitch up to ~30°
  • When almost out of Oxidizer (<200) cut thrust
  • Switch sabre mode (AG 3)
  • Circularise with the nukes
Landing at Kerbin (with almost no fuel left):
  • Shallow descent with a periapsis of ~40k at the atmospheric reentry
  • Set SAS to point prograde (and enable brakes of course)
  • Pitch gently up (while SAS is set to prograde) to avoid deadly vertical velocities (its a plane after all!)
  • If your prograde starts to drop below -10 at low altitudees (~15.000m) or your speed drops well below 1000 m/s disable the brakes and start gliding
  • When safe stage the drogue chutes and open the cargobays with AG 5 b[/b]
  • Shortly after (max. 3 seconds) stage the main chutes
  • You should be somewhat level now and have a vertical velocity of < 10m/s which makes for a nice bumpy touchdown.

There should be one final parachute-stage left at the end - this is reserved for an emergency to save the crew. Staging it will cause the plane to point the engines to whatever is beneath and further slow it down.
Landing like this will cause the plane to take damage but reduce the chance of Kerbals being subjected to deadly forces.

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