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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.

Could you please clarify the points system for me? Assume I have constructed a crewed 12 ton rocket that is able to reach Minmus. With this rocket, I can do either a Minmus flyby or a Kerbin orbit to Minmus orbital altitude without doing a Minmus flyby. Now, according to your rules this nets me the following amount of points: * For the Minmus flyby: base multiplier of 5, to which 4 is added for Minmus, for a total multiplier of 9. The rocket itself is worth 1200 points, for a total score of 1200 * 9 = 10800 * For the orbit to Minmus orbital altitude (at approximately 47 000 km above Kerbin): base multiplier of 5, and 0.5 bonus point for each km that my apoapsis is above Kerbin's atmosphere. Total score is approximately 1200 * 5 + 0.5 * 47000 = 29500. Did I do this correctly? And was it your intent that a high Kerbin orbit that is essentially the same as the transfer orbit needed to do a Minmus flyby yields a lot more points?

I did the same a while ago for KSP1, and my thought process was identical to yours: I never succeeded in getting a more or less circular orbit, I'm impressed that your mission has PE and AP so close together.

Sorry to gatecrash this challenge with a KSP1 entry (I haven't bought KSP2 yet), but I thought this too funny not to share. Would this method work in KSP2 as well?

Yes, I tried it myself before posting. You can use ore as ballast, as ore is denser than water. You need quite a bit of it, as rover wheels (at least the large rubbery black ones that I tried) provide quite a bit of buoyancy. Mine was slow as hell, though, and it had serious problems going uphill because it was so heavy.

Build a rover that is able to drive on the sea floor?

Grinding the biggest Crack of them all... Unfortunately it appears to be very hard to approach the bottom of the Dres canyon in a stable orbit, so the minimum altitude of about 60 meters above ground level is reached quite a bit before entering the canyon.

It turns out no steering of any kind is necessary. I launched straight up at dawn during a Duna transfer window and when Kerbin passed through the descending node with respect to Duna to land a capsule on the Duna surface without the need for a separate trans Duna Injection burn or any mid-course corrections. Launching straight up at dawn means you're launching into Kerbin's prograde direction around the Sun, which is what is needed for a Hohmann transfer orbit to Duna Launching when Kerbin passes the descending (or ascending node) means you won't miss Duna half an orbit later by flying over or under it. It did take some fine-tuning of the exact launch time to get this to work, but after half a dozen attempts I found that for my rocket, Year 5, Day 366, 4 hours 08 (which is just before dawn at the KSC) works fine. Full mission report here: https://imgur.com/a/Y9QpQsg

Decouplers exert a force on your craft during decoupling. So you could conceivably mount some decouplers around your craft and steer with them.

What, exactly, is your definition of ISRU? Would it be allowed to fill some ore tanks in the VAB and convert that ore into propellant on the fly, as long as you don't mine any ore?

I think one could pretty much fly endlessly in the upper atmosphere, by making a craft that has a fairing as its root component, and fully occluding the forward and backward nodes - that way it will not generate any drag when flying prograde. As to how to get it into a 49.9 x 49.9 km orbit: from an orbit just above the atmosphere (I started with a 50.001 km circular orbit) lower PE into the atmosphere. While in the atmosphere, fly with the nose pointing in the normal direction (i.e., sideways on, so that the craft does induce drag) until drag lowers AP to 49.9 km and then turn prograde to cancel all drag. I tried it (although I cheated my craft into Duna orbit) and completed a full orbit in this way without AP or PE degrading noticeably.

Another suggestion: include the pods as external payload attached to the external tank. Designs for this existed for the actual Space Shuttle, see, e.g., https://www.aiaa.org/docs/default-source/uploadedfiles/about-aiaa/history-and-heritage/shuttlevariationsfinalaiaa.pdf?sfvrsn=b8875e90_0

Yup. I've been working on an Eve SSTO for a couple of years and finally succeeded earlier this year: https://imgur.com/a/1AD3u40 . I did need a support package though. My Eve SSTO is barely able to make Eve orbit and has to be topped up from a tanker before returning to Kerbin.

@OJT Awesome Eve STS-2 mission. Landing on Eve and getting back into orbit isn't easy at the best of times, but doing it with a lander that fits inside a Shuttle bay is really quite hard. Congrats on pulling it off successfully, and from Eve sea level no less! Next challenge: Eve STS-3: land a Shuttle on Eve and return it safely to Kerbin ;). For the commander level: land at less than 1000 meters above sea level on Eve, and land the Shuttle on a runway.

Ok, I did look it up. According to the KSP wiki it is not possible to land on Jool: Source: https://wiki.kerbalspaceprogram.com/wiki/Jool. This matches my own experience in trying to land on Jool. My own experiments went as described: the craft will explode once you reach -250 meters, although I haven't experienced glitches or corrupt saves as a result. As to the note on "prior to version 0.23": Version 0.23 was released back in 2013. I don't think many people will be willing to play such an old version of the game, just to be able to complete this challenge. That said, by all means prove us wrong. Fly your own mission where you land on Jool, take a surface sample, plant a flag and get back to Jool orbit, and present video evidence of your mission here.

At 1:47 in your video, at about 10k or 11k altitude you give a series of yaw inputs to the right, as is indicated by the gizmo in the lower left corner. This dips the nose of your craft below the vertical, initiating flight with an angle of attack on the wing. Which in turn initiates an uncontrolled roll, which ends when your craft is flying with its wing vertically and towards an azimuth of about 160 degrees, at about 1:51 in the video. Please don't presume to know what I did or did not do. You have exactly zero evidence so your opinion on the matter is entirely baseless. That does not make any sense. Of course I try to keep my vehicle under control. You can use the airbrake part to lift your rover off the ground as @miklkit describes in their post. You can also use an airbrake to right a rover that has turned over. We are well aware what you are talking about. What you are apparently unaware of, is that it is possible to land a Kerbal on their own from low Kerbin orbit. Or build a small craft based around a command chair and re-enter the atmosphere with that. In cases such as these, a personal chute comes in handy to land your Kerbal safely. As to "but even in a returning craft from space there is no use as it either lands or too fast to bail": Yuri Gagarin, Gherman Titov, Andriyan Nikolayev, Pavel Popovich, Valery Bykovsky and Valentina Tereshkova would like to have a word with you. In case you don't recognize at least some of those names: those are the Vostok cosmonauts, Vostok being the first Soviet crewed spaceflight program, somewhat akin to the US Mercury. They ejected from their capsules after re-entry and landed under their own personal parachutes. This can be done in KSP as well.