StanK

Congratulations to @michal.don. Even though it is a quick build, your concept looks promising to me and satisfies this challenge's requirements. Rocket assisted landing on a short runway, or VTOL on a vacuum world could be benefits of this design. At the acceptable cost of looking a bit silly when pancaking through the last bit of atmosphere. @Physics Student, you'll need to land in one piece to be added to the Advanced Aviator list. Without returning safely and bragging about your mission at the Kerbal bar a badge would be useless anyway, right? I love the design though, so will mention that landing on parachutes is very much allowed - only the take off has to be horizontal. And thanks for the cockpit screenshot, just imagine sitting in that seat

That's a beauty @Physics Student. Did you also manage to land it in one piece? And now I'm asking for stuff, I would love to see a cockpit view after the flip if you've got one :-) This will be a nice design challenge, and I think possible. Perhaps using fuel pumping to initiate the flip. Just using jet fuel consumption will probably be too slow to get the effect fast enough. And Physycs Student's reverse probe core solution will help a lot too.

@Rosvall joins the list of Advanced Aviators with yet another creative design. Good work! Rolling to counter a small CoM/CoT misalignment is great plan too, and it evidently works. If it can be done in stock I don't know about it. It would be a great addition. I have not personally looked for a mod here so perhaps that is out there. I have two workarounds here if this is important for fuel distribution. First, the CoM is implicitly available, because it is the center of your screen. Zoom in as far as you can and you'll have a reasonable estimate. The CoL does not change for SSTOs (ignoring airbrakes). So if you put an object - like a radial battery - on the CoL, you can compare this to the zoomed in CoM and ensure aerodynamic stability before reentry. Second, lower trust so that SAS keeps the craft steady. Then you can see on the bottom left how much SAS needs to be steering. Pumping fuel around can change the CoM and the amount of steering required by SAS. When the dials indicate minimal steering, stop pumping fuel and increase trust. Repeat for the desired trust level

Well done @tsgaerospace! And that is a bold design to omit trust vectoring! I like how the aerospike seems to push the craft up, rather than forwards, into space when it's turned on. And indeed, landing anywhere on Kerbin is allowed, so this one counts.

That is an awesome entry @foobar. Congratulations on completing the challenge, and adding a new style for single jet+rocket development.

That is a good looking one @Wanderfound. Well done! And good to see there's room for passengers to enjoy the ride as well. Thanks @goduranus for showing it can land. And having reversed normal trust to break is a bonus. To show you my gratitude, you and previous Advanced Aviators can now wear a badge:

Good to hear the turbofan can survive re-entry, that would be the hard one to fix. My own attempt required some quick saving/loading as well to get the landing in-one-piece.

Nice one @Martian Emigrant, it's always good to see a practical use of the "thud" engine. And it can drive along too, you say? Mission complete! Thanks for the second entry @Scarecrow, that is exactly showing off the spaceplane design skills to keep that working that we are looking for. I didn't check before, but did you manage to land it safely in one piece as well? Frontal reverse turbofan. I did not believe it until I saw it @goduranus. Getting anything into space using a turbofans and atomic engines shows craftsmanship on it's own right. Did it also manage to come back to Kerbin's surface?

Congratulations @Scarecrow! You are the first to successfully finish the challenge. Coincidentally, I also grant you the honour to be the last do do so with a merged-rocket-and-jet or DIY-rapier solution. I will update the rules, and no longer allow this in the future - my apologies for this (also feel free to suggest how to clearly put this in a rule if my rule isn't). That's a great idea @goduranus, I did not think of that. Will you have enough trust and high altitude/velocity to create a viable SSTO though? Would be nice to see. As above, I'll update the rules for this as it is too similar to using a switching rapier.

Nice proof of concept @Sivonen, too bad fuel ran out just before orbit. I love the unusual shape, I have not seen an outline like that before.

Flipping at high velocity, from my archives: Album: http://imgur.com/a/PzIyi This could definitely work, but it will mess with the aerodynamics too. So I'll believe it when I see it.

That's a valid way to engage in this challenge. Although from my experience, "simply" is not. I'll have a dig in my archives and see if I can find the images for it.

To follow up on the famous K Prize, this challenge asks you to show off your master spaceplane design and flying skills. Build a spaceplane capable of reaching orbit, and returning safely using a single jet, and a single rocket engine. I have found this an interesting limitation that makes spaceplane design a lot harder. Mostly because the trust vectors are no longer trivially aligned with the CoM. Enjoy! Rules: The spaceplane must follow the rules as defined by the K Prize. In short: a horizontal take-off stock SSTO that can reach orbit(pe>70km) and land again in one piece. The provisions of the K Prize do apply to this challenge too. Use exactly 1 jet engine - defined as an engine that requires intake air and liquid fuel to run. Use exactly 1 rocket engine - defined as an engine that runs entirely on on-board fuel. An ion engine is also allowed. Rapier engines are allowed, but cannot switch mode during the flight and as such operate entirely as a jet, or entirely as a rocket engine. Merging/clipping/offsetting the two engines together into one is also not allowed (this is not much different from a mode switching rapier). Please remember to take pictures or a video as proof and for our enjoyment. Advanced Aviators: @Scarecrow - Rotate the engines, why not? @Martian Emigrant - The perfect case for a Thud @goduranus - Reverse trust in reverse @StanK - Me @Wanderfound - With spare seats @foobar - You can see through it @tsgaerospace - Pushed up into space @Rosvall - Rolling into space @michal.don - Pancake to accelerate! ...can proudly wear their badge: I have done a few times in past versions. To show it is still possible in 1.3 below is my own new entry: Album: http://imgur.com/a/dDIOT

Yes! +1

It just so happens I've got one laying around for this one The FlipFlop has been designed to do exactly this, with all the inconvenience that goes with it. And it is a fully functional SSTO - although with barely enough space to pack a toothbrush. No mods. If I have time I can go back and check what the "flip" time was. It should be around the 3 second mark at super-sonic speed. The design: The Flip: Full album at: http://imgur.com/a/PzIyi