QF9E

I've gone to Duna and back without leaving the (stock) cockpit, which means you cannot use maneuver nodes. It is also possible to go to Duna without doing any steering, see https://imgur.com/a/Y9QpQsg I did use a maneuver node there, but I think it should be possible to do without.

I'm using version 1.12.5.3190 which as far as I know is the current version. I do run a couple of mods, but nothing that should change parts. But to be on the safe side I just tried without mods: my craft still takes off like it should. The impact tolerance for the Girder XL should be 80 m/s, as shown here: https://wiki.kerbalspaceprogram.com/wiki/Modular_Girder_Segment_XL. My SPH shows the same value: In light of all this I don't think it is something on my side. Maybe the girders have been inadvertently changed by some mod or other in your install? Or perhaps there's an issue with your craft. What is the takeoff speed of your craft with normal landing gear? Mine takes off at about 60 m/s, and the girder does explode as expected at 80 m/s if I don't take off in time. And how did you place the girder? It should be placed such that the back end of the girder is only a little behind the center of mass of your craft. Too far back and it will be impossible to pull up the nose during the takeoff run. Not saying you do this, but I see many videos of KSP players who place the main landing gear of their SSTOs (or, in this case, the back end of the girder) so far back that it is impossible to pull up the nose during a take-off run. Many players just run their SSTOs straight over the end of the runway, only pulling up once over the edge. This technique will not work when you're using girders for landing gear as the speed will be too high by then. Thanks for the heads-up. I renamed the craft in KerbalX and I did not realize that this changes the link to the craft. The correct link is https://kerbalx.com/QF9E/Low-part-count-SSTO

9 part SSTO: Craft file: https://kerbalx.com/QF9E/Low-part-count-SSTO I used a girder as a skid rather than a conventional landing gear, which saved me 2 parts compared to @OJT's submission. For the wing I used a single Big-S wing which doubles as a fuel tank, which saves me another 2 parts. And I flew the entire mission on the capsule battery, which saved a further part. To save on electricity I switched off the reaction wheel during atmospheric flight - I didn't need it as the control surfaces offer ample control by themselves. And I carefully balanced my craft so that on re-entry only a small amount of electricity was needed for the reaction wheels. I used the Precise Position mod to position my wing so that its center of mass / lift is eactly on the centerline of the craft. The lack of landing gear means you don't have much control over the craft on the ground, which necessitated a careful approach and landing on the Island Runway, in order not to run out of runway for the subsequent takeoff. And I almost overshot the KSC runway as my speed was a bit high - I knew from testing that the landing skid tends to explode when touching down at over 80 m/s.

You can also replace the 3-part landing gear with a single modular girder segment XL. Or any other part that has a high impact tolerance, forms a relatively stable platform and has limited drag. To prevent excess drag, you could use a Mk2 or Mk3 cargo bay as impromptu landing gear - you can land a craft on their open cargo bay doors. Although the Mk2 and Mk3 form factors may not be the best choice for low part craft.

Three part submission: I mainly used the parachute to turn the craft retrograde so that it can use its rocket engines for a landing burn. Note that I ran out of fuel a second or so before touching down on the KSC runway. If that is sufficient grounds for disqualifying me under rule 1: "running out of fuel", so be it. There's a couple of times in the flight where the flight was less efficient than it could have been, so it should be possible to perform the flight and not run out of fuel. Therefore I hope you will accept my submission as-is.

Rules clarification: nowhere in the current rules does it say that the entire crew must stay with the craft for the duration: Would it be ok for one Kerbal to get out of the craft along the way (and land under their own parachute), as long as at least one Kerbal stays with the craft to complete the flight?

I believe the 2.5m command pod's RCS is only capable of rotating the craft, not translating it.

I have been wondering the same thing.

Pilots can repack chutes in sandbox.

Rayvan Kerman is a pilot:

I made one with 4 parts as well. Who needs wings, landing gear and control surfaces when you have reaction wheels, a thrust vectoring engine and a parachute? Full report here: https://imgur.com/a/bSns1Kg

A variant of this plane with 9 parts (2 extra parts formed a conventional landing gear) was used to fly to the island and back: https://imgur.com/a/JzNqrXl I don't have footage of this 7 part version flying to the island and back but I am confident it can do so. Is that good enough for you?

For a similar challenge a couple of years back I made this monstrosity, with just 7 parts: It's landing gear is just a construction plate, as these have rather high impact tolerances. It would take me a lot of time to find the design in my very messy KSP savegame folder, does a KerbalX link to the craft file also serve as proof of parts count? https://kerbalx.com/QF9E/Low-part-count-plane-c

You can reach orbit in an SSTO with just a single swivel and maximum tech level 4: You must re-enter this craft upside down and with the nose some 40 degrees above the horizon: that way the landing gear is shielded from the re-entry heat by the rest of the craft.

That is amazing! I had no idea that my simple design that I did not spend more than about 30 minutes designing (and which I mostly designed for looks), would be capable of that, if properly optimized. Thank you for all the work you put into this. If I may ask, which mods did you use to design, analyze, optimize and fly this craft?

I noticed some of that as well - when I flew at 10.5 km altitude rather than my original 9 km my craft used significantly less fuel. Good to know that even higher is more efficient still. I'm glad you like it!

Today I built all the necessary ground support equipment to be able to turn a Space Shuttle around and launch it a second time. My shuttle lands and is raised to the vertical position using nothing but gravity and several 100 tons of ore. It is then integrated with a new payload and mated to a new booster stack before being launched into orbit once more.

@Hotel26, that's a neat bit of analysis, thanks for that! Apparently, a double Kerbin circumnavigation is not to be then.

Perhaps ChatGPT can build its own version and perform the experiment by itself? I have little desire to fly this thing for another 3.5 hours.

Neat! Although I think my craft can do better than that: after one circumnavigation of Kerbin it had 779 out of 1600 units of fuel left, and it gets more efficient as it gets lighter. It also accelerated a bit, its speed near the end of my flight was about 15 m/s higher than at the start (305 m/s vs. 290 m/s). Fuel consumption was as follows: hour 1: 258 units (this includes takeoff and getting to altitude); hour 2: 233 units hour 3: 220 units hour 3.5: 100 units for the final half hour of flight, so a projected 200 units for the entire hour if I had continued my flight If the trend that each subsequent hour burns about 10-20 units less fuel continues I would expect fuel consumption to go something like this: hour 3.5 - 4: 100 units hour 5: 190 units hour 6: 180 units hour 7: 170 units At which point it should be able to finish its 2nd circumnavigation, with some 100 - 150 units of fuel left.

Was planning on doing some test missions for the new Space Shuttle v7 challenge, but I got sidetracked: This little flying wing turned out to fly surprisingly well, and since its wings double as fuel tanks, it has quite a long range as well. I just finished flying a 3.5 hour Kerbin circumnavigation, which I flew entirely by hand. I think it will be able to fly around Kerbin twice, but I don't have the patience to find out.

PM sent. Also, I cannot watch the video with more information, as it appears to be set to "private". Intrepid space pioneers Rincewind and Twoflower find themselves in a rather awkward predicament. Can you bring them back to Kerbin safely?

To be fair the challenge does not say in so many words that you have to land on the Mun, only that you have to make a trip to the Mun. It seems to me that a free return trajectory around the Mun would suffice.

My latest SSTO, with just shy of 8 km/s of dv in LKO: I designed this one to do a Vall landing mission without ISRU and without needing gravity assists (the latter not for some noble reason - to say that I am not good with gravity assists would be an understatement) This amount of dv should be sufficient for a direct return to Kerbin, and with two NERVs the TWR on Vall is about 1.8 so this should be a breeze, right? If only it would be possible for this &^$&!! thing to take off from Vall in one piece... Oh well, back to the drawing board it is.

Does it show the incorrect trajectory when doing the burn, or only when planning the maneuver? I once did an IVA only mission to Duna and back from the stock cockpit, without using any maneuver nodes. Not sure if that would work in KSP2 though as I don't yet have it.