camacju

Yes, that's correct Landing gear stability doesn't matter since I take off completely flat on the runway and land on the water

Well, I'm usually able to balance both even with engines at the aft. I place the fairing and engines first, then balance fuel tanks around that, put wings at COM, then put the payload at COM. The result is a stable plane at all points in the flight. The problem here was that my initial plane had too much fuel in orbit, so I took off some fuel tanks and added them to the payload, which shifted dry COM too far backward. It was surprisingly easy to fly it backward. The one problem was that it had no yaw stability because the vertical tailplane was now in the "front" of the craft. I sidestepped this problem entirely by flying upside down and backward, and splashing down in the ocean. That way I can still benefit from wing incidence.

For the landing gear, they're autostrutted by default so I just imagine some struts connecting them to the hull. I could just use bigger landing gear with a negligible penalty to fuel usage - I don't really think that matters. Or I could move the landing gear a bit upward and inward, to the same effect. Essentially this is just an aesthetic thing. The payload deployment could easily be done by deploying the fairing and detaching the payload, and the craft would still be just as reusable, but I thought it looked better to do it this way. In my opinion it's no different from a cargo bay.

After realizing that it's possible to fit two Rapiers and two Nervs into a 1.25m fairing without clipping anything, I decided to give the Purist Single Stage category a shot. 60.684 tons launch mass, 37.240 tons payload mass. Payload fraction is 0.614

Pretty clever deployment method

I think 4 degrees is the best for hypersonic lift/drag ratios. I stuck with 5 degrees however, and simply increased the wing loading. Leaves a bit of room to squeeze out further range from the craft if desired. Is 30 laps possible? Well, the craft went a good deal further than 25 laps. Initial ascent Laps 1-10 After 10 laps, the estimated range of the craft is 22 laps, but I know that it can probably do 25. At the very least it'll easily beat the previous record. Laps 11-20 Estimated range is 6 laps, but a seventh is possible because this craft has quite good glide performance. Laps 21-27 27 laps around Kerbin * 600 km Kerbin radius * 2pi = 102,000 kilometers range. Link to craft file: https://drive.google.com/file/d/13kK7BonPxk5ay5fCuNEACpR32ukdDTrr/view?usp=sharing Link to loadmeta file: https://drive.google.com/file/d/1Sk6wfQgtkaqEWVd1poHkQxfiMA4lAqW9/view?usp=sharing

Impressive for such a small rocket! Also, welcome to the forums.

First lap is complete. I have 84.4% of my initial fuel as compared to 83.6% in my previous run, but I believe I was less efficient on the ascent this time. Assuming equal ascents, I am using fuel 19% more efficiently but I have 12% less fuel, for a 5% increase in overall range. That translates to a range of about 24.7 laps, and I believe that this craft can glide to a 25th lap. I guess we'll see tomorrow.

That's fine - I have some ideas to get even more range anyway, and this is the perfect opportunity to try them out.

They're attached to a 0.625m tank and slightly offset outward. While they're not as densely packed, I don't need as long of a fairing, which makes the plane easier to maneuver while climbing. I didn't know that worked with service bays also! However that doesn't really produce any beneficial effects, as the service bays will always have a free front and back node to occlude.

Not that I could link to - I learned that trick on Bradley Whistance's discord server. I wouldn't be surprised - it's pretty obscure because it's hard to discover by accident. The fairing has to be the root part of the vessel and the parts attached to the fairing have to be the right physical size - the size of the attachment node doesn't actually matter.

Putting things on a fairing's interstage nodes reduces the drag of the fairing in some cases

On the other hand, the aerodynamics have changed significantly, so it's a lot harder now to get to an orbit efficiently. My best payload fraction for a rocket SSTO (granted, it wasn't really very optimized) is about 20% with a Vector and two Nervs. I suspect 25% will be quite difficult to achieve in the purist category, but I could see a 40% design using some creative aerodynamics.

I actually don't have the craft file with me - it was only ever an auto-saved ship and then my next mission overwrote the craft file. If it's helpful at all, the fairing is the root part, and the Rapier, cockpit, and air intake are attached to the interstage nodes. I also attached a couple nose cones to the other interstage nodes,

I don't remember the specific heating level but in the past I have gotten a kerbal down with no heatshield with 120% atmo heat. All you need to do is take a gentle aerobrake trajectory and spin the craft as fast as possible

Yeah, that's what I was thinking as a replacement. Bit more annoying to get all the node occlusion right however, plus it's still got some parasitic drag.

It's not an exploit - if a part is occluded, it can't produce lift. Consequently, if a part produces lift, it also must produce drag. (With the exception of certain magic wings, and those have been fixed in the newest version of KSP anyway.) Additionally, it's possible for a part attached in a fairing and offset outward to have less drag, but this requires it to be node attached, not radial attached. So in my design, this would really only serve to reduce the drag of the nose cone, but that's just on the front of the fairing anyway, so its drag is already at a minimum. Wings can't be node attached. Even if it were an exploit, the wings are attached to the fairing base, so I wouldn't be taking advantage of anything. Inside the fairing would be a big ball of very lightweight and draggy parts - struts, sepratrons, empty fuel tanks, etc. Blowing the fairing would make that ball of parts serve as a giant airbrake, letting me dive down to the ground way faster.

RAPIERs don't flame out at a set speed - instead, they flame out at a set Mach number, which is around Mach 6. The speed of sound is different depending on the time of day, latitude, and altitude. Therefore a RAPIER can go a lot faster if it's near sea level on the equator at noon. I launched at nighttime because the earliest part of the flight is the fastest, so I would spend more time on the other side of the planet and get greater benefit from the speed of sound bonus during the daytime. In my screenshots, you can see that the 1900 m/s screenshot is at Mach 5.7 at low altitude, while my third-to-last screenshot is at Mach 5.7 at a higher altitude. This is over a 200 m/s difference. You can see from AeroGUI that the speed of sound is different. I've gotten a RAPIER to 2110 m/s surface speed before, and I know someone else on Discord who's gone even faster. It's all a matter of Mach number. By the way, are we allowed to deploy fairings for speed runs? If so, I think I can easily beat 37 minutes.

Just to be clear, the limit is only one Mite booster, correct?

New submission - circumnavigation is 37 minutes 3 seconds No clipping On runway Speed! Halfway This was a Mechjeb-less flight so I'm a bit off target from KSC Death dive down to sea level, deploy gear and flare at the last possible moment. This took a lot of quicksaves Landed

Wow I completely misread the rules. I guess I’ll swap the cockpit out for a lander can and shave off a lot of mass. For the speed run, none of the fuel tanks are clipped into each other or any solid part but they do stick out of the fairing. However I left some empty space in the fairing so the total volume is still realistic. If this is a problem then I’ll just rearrange the fuel tanks and fly the mission again The stripes are probably due to intersections of the polygonal meshes with the cockpit, rapier and fairing. I could make the fairing narrower or wider and the stripes would disappear.

Well, there is the restriction that I have to use an aircraft cockpit rather than a command pod. If I remember correctly the lightest cockpit is about 300kg heavier than the mk1 command pod. So that more than makes up for the difference. Also you can see the effects of the aero optimization in that I only used 66 liquid fuel while you used 85. edit: the mk1 command pod is 840kg and the mk1 in-line cockpit is 1030kg. So if I were to switch the cockpit I would have a lighter craft.

@zolotiyeruki Here are two more submissions for this challenge. The first is a new record for fastest circumnavigation, in 37min 57sec. Could be faster with more optimized wings but I'll take it for now. The second is the lightest craft that I could get to circumnavigate, at 2.01 tons. I saw that in the previous incarnation of this challenge people were trying low-mass submissions.

This was pretty fun to do! I'm not very experienced with mass optimization - I focus more on cheap crafts or high payload fractions - so this mission still has room for improvement. 1.47 tons Mun flyby mission. Adding a landing shouldn't be much harder if I use the EVA jetpack also, I might try that this afternoon. In SPH Vertical takeoff Accelerating at sea level Spark engine ignition Spark cuts out Circularizing Mun transfer Mun encounters Flyby Reentry Descent Landed

Okay - this isn't an official entry since the "payload" cannot be separated but at the very least it should serve as a good proof of concept for future entries. (Or I can just send up a kerbal to pull all the parts off using EVA Construction) Category would be Single Stage Technical. The main improvement comes from my recent attempts to make a maximally efficient orange tank lifter, and discovering that 1 nuke for a just under 55 ton craft was more efficient than 2. Additionally, I found that for the same craft, 2 rapiers is a bit too much for efficiency, and 1 rapier is a bit too little for comfort. So I doubled the mass of the craft to just over 109 tons and included two nukes and three rapiers. Craft in VAB - 109.323 tons In orbit. 13494 liquid fuel remaining is 269.88 Mk0 fuel tanks which is 74.217 tons. Add the 0.1 tons of probe core, reaction wheel, and batteries for 74.317 tons, for 0.680 payload fraction.