SSTO Challenge

[digitaleyes]

The goal of this challenge is to make an SSTO that has to refuel before making it to a stable orbit. The rules are pretty simple: the SSTO can't have the capacity to make it to a stable orbit without docking, no mod parts, no cheats, and no ARM claw. This will require a rendezvous craft of sorts to dock with the SSTO in the sub-orbital path, as well as a decent docking ability.

Scoring

• 5 points for every km below 200,000 m for the SSTO's apogee
  
• 1 point for every part under 50 for the SSTO
  
• 1 point for every part under 300 for the rendezvous craft at launch
  
• 100 points if you can return to rendezvous craft to a stable orbit
  
• minus 20 points if the rendezvous craft pushes/pulls the SSTO in orbit
  
• 20 points if the SSTO doesn't have RAPIER engines
  
• 5 points for every 500 m above Kerbin's atmosphere the docking is achieved
  

[KissSh0t]

How do you dock with something in orbit if you are not in orbit?

[John Crichton]

If you dock with something in a stable orbit...don't you have to match velocities and therefore end up in a stable orbit before docking too?

[digitaleyes]

Send up the refueling vessel and park it around 150,000 m over Kerbin. Launch the SSTO and try to get the apogee in the ballpark of the refueler's orbit, then switch to the refueler and maneuver to match the SSTO's sub-orbital path. Proceed to dock like normal. I managed to dock these on my own save but I launched the SSTO too late and the intercept was on the SSTO's descent, so they were then greeted by atmosphere.

[Keldaria]

How do you dock with something in orbit if you are not in orbit?

I'd guess that you'd have to push your fueling vehicle into a suborbital trajectory that matched your rocket. How you would match up and close distance in time before reentry into the atmosphere I don't know.

I'm trying to think about how to accomplish this with a craft that can't make it to stable orbit on its own. Any entry for this would rely on a craft being nearly perfectly balanced on fuel vs consumption so that a perfect launch would leave it just a 100 m/s or so shy of a stable orbit, that way you could have enough time to use another craft to link up and dock to transfer fuel. Timing is literally everything on this challenge tho, if you are off by to much you'll never be able to correct, and without Mods like MechJeb I'm not sure how you'd ever get this timing down.

I do have 1 thought on this challenge that appears to be within the rules but ultimately defeats the purpose of the challenge, And that would be to have your craft rendezvous on the ground and use the extra power from the rendezvous craft to push your SSTO into a full orbit. As such I'd recommend you add on to your rules that both craft must be off the ground when they rendezvous.

[TJPrime]

SSTO stands for 'Single Stage To Orbit'. Does this make sense? Because I'm not too sure

[digitaleyes]

If the fuel pod makes it back to a stable orbit, nothing is wasted and a shuttle can refill later to prepare for another SSTO launch.

Edited April 6, 2014 by digitaleyes

[cantab]

Scoring

• 5 points for every km below 200,000 m for the SSTO's apogee
  
• 5 points for every 500 m above Kerbin's atmosphere the docking is achieved
  

Are these two scorings not a problem together? The points you gain for a higher docking will be lost twice over for a necessarily higher apoapsis.

Or is it deliberate that higher apoapses are always penalised, but they're penalised less if you make the docking later?

[digitaleyes]

The second one, the higher the apoapses, the more likely the SSTO doesn't need the pit stop. Also a side note, my current docking altitude record is 70,000 from an intercept of 1 km and intercept altitude of around 115,000m descending. I hope that isn't confusing.

Edited April 6, 2014 by digitaleyes

[Kasuha]

First, it is not an SSTO if it cannot make it to orbit. "rocket", "ship" or "craft" are all fitting names for it, SSTO is not.

I assume the refueling station is in stable orbit. In order to dock to it, the ship needs to match its position and velocity, i.e. reach stable orbit. So the station must change its trajectory to dock with the ship instead. That however means it will be on suborbital trajectory itself and it will fall back on Kerbin instead of our ship unless it returns to stable orbit instead.

The apoapsis points and docking altitude points go against each other.

[digitaleyes]

First, it is not an SSTO if it cannot make it to orbit. "rocket", "ship" or "craft" are all fitting names for it, SSTO is not.

I assume the refueling station is in stable orbit. In order to dock to it, the ship needs to match its position and velocity, i.e. reach stable orbit. So the station must change its trajectory to dock with the ship instead. That however means it will be on suborbital trajectory itself and it will fall back on Kerbin instead of our ship unless it returns to stable orbit instead.

As long as it doesn't decouple any parts, it is still an SSTO because it hasn't actually dropped anything. Otherwise an SSTO docking with anything is no longer an SSTO. And yes the station (I'm using a fuel pod) does have to put itself on a suborbital path, honestly the only part I have trouble with is docking before the apoapsis because I suck at docking. My fuel pod can still return to orbit after docking, but I have yet to dock soon enough to fill up the Spaceplane enough to reach orbit.

[700NitroXpress]

It's an SSTS (Single Stage To Space)

[Kasuha]

Okay, here's my entry.

Apoapsis 343 km so there are 0 km below 200 km -> 0 points

3 parts -> 47 points

rendezvous ship is 120 parts -> 180 points

no "return" to the rendezvous ship -> 0 points

rendezvous ship pushes to orbit -> -20 points

no RAPIER -> 20 points

rendezvous at 319605 m, atmosphere ends at 69078 m, 501 times 500 m -> 2505 points

total 2732 points

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