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Well, I didn't think it would be possible to get anywhere without Nukes, but I guess I was proved wrong once more Added you to the OP!

Wouldn't airbrakes be more practical, if you are going that way?

Man, that's insane. Those landings were really scary too. To think that I originally posted that landing on the Mun and going back might not actually be possible...

That's awesome. The way you placed the Panther to avoid roasting the Terrier stack is also really cool. Did the side fairing really help? Do you want a score to go with that? Since you already landed a similar design on the Mun, if you give me the mass of the craft, I will put you in the OP. But if you want to land it twice, I will need pics

Not in doubt, but the terms of the challenge are what they are. I am ok with being lax on other things, but I have to draw the line somewhere... If you tell me what science instruments you had on it, we can figure out the science you would have gotten, and give a score to your craft Well, if you already have access to the parts required to fulfill this challenge, you've probably already gotten most easy science from Minmus. Don't overthink things too much, the challenge is loosely based on Career mode, but with extra "unrealistic" constraints to make it more difficult/fun, and maybe learn a thing or two about Spaceplanes, Panthers, and flight profiles. @ManEatingApe: That was absolutely awesome and I wish I had added a style points clause to the score. Adding you to the Hall of Champions OP.

PPE 1 @Wanderfound: Nice! I also really like the design of your craft Adding you to the OP @AeroGav: if you didn't use big S parts, that satisfies the conditions of the challenge. Can you tell me how heavy the craft was? Also, I assume a single landing on the Mun. Did you get any extra science, aside from the trifecta Crew Report / EVA report / surface sample? If you want some numbers, you might want to use this plot. It shows how much liquid fuel you need to carry into orbit if you want to have the delta v specified in the legend, depending on the dry mass of your craft. A few numbers to help out: Payload: Mk1 Inline cockpit: 1.0t Mk1 Command pod: 0.8t Science Junior: 0.2t Mystery Goo: 0.05t Service Bay (1.25m): 0.1t Engines: NERV: 3t Panther: 1.2t Terrier: 0.5t Spark: 0.1t Fuel: FL-T400: 2.25t full, with 2t of LF/O and 0.25t of container (other LF/O containers follow the same ratio) Mk1 Liquid Fuel Fuselage: 2.25t full, , with 2t of liquid fuel and 0.25t of container (Mk0 has a marginally better ratio, NCS Adapter considerably worse) Lift/control: 1 unit of lift area: 0.1t 1 unit of control area: 0.2t Advanced Inline Stabilizer: 0.1t If you land it on the Mun and get it back, I will add you to the OP Main question is whether you can actually land it on the Mun and then get it off there again, considering the low thrust of the NERV.

The way I see it, you want to maximize your delta-v once you are already in orbit, which means that, for the same amount of fuel, you want the parts that get you into orbit to be as light as possible. Sparks have nearly twice the TWR of Terriers (1/5 the weight but 1/3 the thrust), while having an ISP that is close to the Terrier (320 to 345 at vacuum, though it's 270 to 85 at atmospheric pressure, so maybe they are a bit closer at the altitudes you start them). Since the amount of fuel you need increases exponentially with the delta-v, it will depend on the exact weight of the craft which engine ends up with a lower dry weight (sparks will need more LF/O). It's clear that, if you want to land on the Mun this way, either you have a very good intuition about what works and what doesn't, or you need to run some numbers. The delta-v left once on orbit seems to be the key parameter to optimize.

I am aware that making it SSTO is putting extra constraints on the relatively low performance of the Panther at high speeds and altitude, that's why it's a challenge I came across the Kondor while looking for inspiration for this challenge, it's a beautiful craft. But hey, Cunjo Carl managed to land his spaceplane on the Mun, so it's possible! I have a feeling using Sparks (like ManEatingApe did) instead of Terriers to boost yourself to orbit might be more efficient. My version used 2 Terriers, and I have a feeling I wasted a lot of thrust due to having to go into a zoom climb (hence very little lift) because of the relatively short but powerful boost at a low altitude. Maybe only one Terrier works too, but then you run into symmetry problems.

Thanks for the indepth response! Very interesting considerations, I will definitely try to get more horizontal in my next attempt. I know about the sound barrier (usually my way to punch through it is just to add moar Panthers, probably not the best way), my problem is that once I reach ~750 m/s at 10km my thrust starts decreasing (even if I keep the plane level), and then so does my speed. So instead I just keep climbing rather than waste speed for no reason. Will see if adding wing area and angling it with respect to the fuselage helps. Note that, unless my math is wrong, the "freefall effect" increases with the square of the velocity, so at half the escape speed, it's only supporting one quarter of your weight. Don't think it changes anything to your post, but it emphasizes the importance of lift area to support you while you get to escape velocity (or of TWR if flying a rocket instead).

@AeroGav: Thanks for the extra details! Why do you fly nearly horizontal for a while with your NERVs on, is it just so that you don't lose the lift from the wings? Also curious about why your time to Apoapsis goes from 14 min to 0s around 11:30, any idea why that is? Also, everybody seems to be able to reach cruise speeds at altitudes above 10k with Panthers, but every time I try I see my thrust plummet, so I am just flying at 20 degrees all the time until the Panthers give up (around 14 or 15k). @Gordon Fecyk: That's a more sensible design than what I am asking for here, but even if it was single stage, FAR would invalidate the submission... I like it though! How did you dock the lander back inside the spaceplane without RCS? (unrelated: what mod is changing the way your exhausts behave? Your Swivels/Reliant behave funky).

Nice! Did you fly it in the current aerodynamic model? Can you say how much it weighted? Also, at what speed/altitude did you turn on the NERVs? ...that landing video was... interesting. I have to find the time to try a Mun landing...

@Cunjo Carl: That's really impressive, congratulations on your exploit! I have to say, the asymmetrical layout is very interesting. I assume the objective was to be able to put only one Panther on it to reduce the dry weight? Also, I would have never guessed that a single Panther could get 23t off the ground! I assume when you say that Panthers do well at 800m/s+, you really mean that's the maximum speed they can achieve, not the cruising speed? I find Panthers tend to start losing thrust when you hit 700m/s or so (depends on altitude). Any opinions about how to score Mun shots? I think I will just need to keep Mun and Minmus attempts separate, I don't know how to compare them otherwise. Multiple landings are a lot easier on Minmus.

@ManEatingApe Nice submission! You ended up with a similar design than what I had, though mine had a lot more wing area (couldn't lift off from Kerbin without it) and air intakes. The 30 km constraint was to avoid people just rolling from one biome to another and artificially inflate their score. I never thought about rolling through 5 different biomes that way though, I will definitely keep it in mind the next time I start a Career game.

Must be one piece, no splitting apart. Will update the OP accordingly. Besides, who likes to spend time docking?

Exactly what it says on the tin. The idea comes from the common (?) wisdom that Panthers can't really get anything worthwhile to orbit without extreme amounts of effort. So I took it upon myself to see how far I can push spaceplanes with only a level 2 R&D centre. My current best is to get onto a Mun orbit and come back, with about 200 m/s delta-v of spare fuel on landing, but it was with a fairly unoptimized design and trajectory, so a Minmus landing shouldn't be impossible. Let me see what you can do! Rules: Vehicle must be a SSTO spaceplane. No splitting the craft at any point during the mission. No refueling. No parts that require a level 3 R&D centre. Vehicle must be crewed. Only stock parts. No (or at least very minimal) clipping. No gameplay mods (aside from informational ones). Optional constraints: Make the vehicle as light as possible. Bring as much science from Minmus' surface as you can; if you take science from more than one biome, then each science spot has to be at the very least 30 km away from the previous one (do a suborbital hop, basically). No parachutes to land it back on Kerbin. Hard (impossible?) mode: Do the same, on the Mun. If you want a way to score your submission: Score = Science/Wet_Mass A screenshot of the vehicle landed on Minmus, with the amount of fuel (etc) leftover in your tanks, and another of it landed (or splashed) back on Kerbin, will be considered a valid submission. If you've landed more than once, then you need to show a picture for each landing. I encourage you to provide a description of your profile ascent too! Good luck! SUBMISSIONS: Minmus: ManEatingApe 71.2 Wanderfound 44.12 Aerospacer 30.5 Mun: ManEatingApe 23.5 Cunjo Carl 7.7