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Here is my attempt to make a craft with 90 sepratrons. Well, 56 of them, in three rings around a very lightweight core. There is no room for luxuries such as attitude control, gimballing or RCS, so going in a straight line is not a guaranteed outcome. [IMGUR]BLxT6[/IMGUR] I claim 900 m/s. I might improve this a bit later. Edit: well, there's an improvement. Eight more engines, wheels locked and on all sides. [IMGUR]yaiD3[/IMGUR] New best: 980 m/s.

After many, many hours in Kerbal Space Program I finally feel ready to take on one of the most beautiful challenges. The new parts in 1.0.5 give me the possibility to create something that was not possible before: a small refueling explorer! I present you the Fuzzy Lama, flown by star engineer kerbonaut Bill Kerman. I really like flying it, just 69 tons fully fueled, very easy to fly in the atmosphere and phenomenal range in space. Part 1: Kerbal Space Center to Minmus: Next parts will follow when I have time, probably in the weekend.

Build a craft that can go to Minmus surface without staging and includes an ISRU converter and drills. Once you're there, the rest of the Kerbol system is open for you.

I wonder if you could save mass on the Jool trip by not taking a command pod with you. If it's only needed for Kerbin reentry, then maybe you could leave it behind in LKO and rendezvous later.

Slightly lower price, one part less, slightly heavier, but altogether a significant improvement on the combined ranking. LordCorwin, your hard work and tight margins have showed result, congratulations. Anyone want to try a solid rocket booster approach again?

OpenWorldAddict and LordCorwin, very nice entries, you have been added to the rankings! LordCorwin, I'm surprised you almost beat my weight record with a full capsule to escape velocity. I feel that Rid_14 or Rid_15 will take the overall title, unless NikkyD is working on something better too. By the way, NikkyD, there's nothing stopping you from taking another person's design and improving it, as long as your changes are significant for the end result, you will be ranked.

Translated: This challenge is about piloting skills: land a craft (stock or mod parts, doesn't matter) from Minmus orbit to the surface and take off again. You may not use SAS during any point. All reaction wheels must be switched off. All rcs thrusters must be switched off. Your only attitude control can come from the gimballing of your main engines (all of which must be pointed in the same direction). Piloting aids such as Mechjeb are also obviously not allowed. Entrants should preferably show their skills through an uploaded video, but an image album with plenty of pictures can also work. If there are multiple entries and people feel the need to be ranked and outdo each other, I suggest using fewer engines, more complicated craft, or a lower TWR. Maybe someone can even show us a landing without any gimballed engines!

No, simply lower is better. And actually there's no need to divide by the best result, since then we're dividing all by the same factor. Leaderboard updated, including the following entry: The Mini-bus! Not so cheap, quite some parts, but the lowest mass by a margin. I probably can't win my own challenge, but I'll give it a try in the rank I'm best at. Pad mass is 4,0905t, 13 parts and it costs 11826. The first stage tank is partially empty to save some weight. After Jeb climbing in the Rapier is started and released when it reaches 40 kN. Mini-bus goes diagonal, and just after mach 1 the engine is throttled back by half. Throttling back up at 11 km, flame-out speed is a very respectable 1620 m/s due to its high TWR. A parking orbit is entered. Not a very precise one, because the centre of mass is not exactly in the middle, and there are no reaction wheels. I aimed for the moon, but because of the lack of precision I missed. But there was enough delta-v to send Jebediah on a long trip. So 4,0905 tons, 13 parts, 11826 funds.

RoeddipusHex, I have no doubt that your craft can make it, but I would like to see some stats and one screenshot of it achieving Kerbin escape velocity. Thank you for all the nice entries! NikkyD and th3Jimmer, your entries have been added to the leaderboard and top the charts. Foxster and NikkyD, your entries have been disqualified for using a mod that is against the spirit of this challenge. Rule 1 "1. One launch only, no help from any spacecraft not part of the launch." implies that if you want to use a chair, you still have to include a capsule on the launch pad. But I'll start a separate "Take Command" leaderboard for you, since this is Jebediah we are talking about. LordCorwin, rule 6: "No abuse of physics glitches and bugs. No use of EVA rocketpack." Jebediah is not that stupid. A new ranking has been added! The Kerbals are very happy with all your suggestions, and they will decide by combining the three rankings in the following way: each result is divided by the current leader's result, and the three are multiplied to achieve a combined score. NikkyD is currently leading with 1, 7/2 and 1 giving 3,5.

Very nice entries! NikkyD, an innovative way to use a seat while keeping to the single launch. I just wonder if it isn't difficult to fly a rocket with a seat as a nose. Also, you used 9 parts, did I count correctly?

Nice one, ihtoit. When another modded entry appears, I will open a leaderboard for mod entries. Which mods did you use?

I have a similar problem, while still on the launch pad the radial decouplers start heating up rapidly without any reason, and reach 2000K in half a minute and explode. I removed the side boosters and put them on again at the exact same spot, and all was fine. Then in a next iteration of the rocket the radial decouplers heat up and explode again. This was in 1.0.3. I have just upgraded to 1.0.4 but I haven't checked yet if the problem is gone. It seems like some sort of weird feedback loop in the thermal system.

Aw man, I worked so hard on my assisted launch technique, and turns out it can be beaten with wings that easily... congratulations Nao, I will try to beat your record next!

Finally! The Assisted Launch Primarily Airbreathing Cargo Ascender (abbreviated A.L.P.A.C.A.) has made it to orbit! And the magic number is... 44,56%! Click the spoiler tag to see how it is done. The A.L.P.A.C.A. is a descendant of the Alpacalypse 2, with slightly more fuel but 55% more payload. It's takeoff mass is 41,185, and the payload mass is 18,35. I took extra care to add an extra reaction wheel and battery on the core stage, since the Aerospike doesn't have gimballing, and we're not allowed to use the payload's torque or battery. Rapiers seem the way to go for highest efficiency, flaming out at higher speed and altitude than Whiplashes. But the limiting factor is always their static TWR. For example the Rapiers on the A.L.P.A.C.A. give it a TWR of 1,04 when completely spooled up. So how does this take off? By assisted launch! When the Rapiers reach 70% thrust, the Aerospike is switched on and drains fuel from the two FLT-100's in the booster stages. This burn only lasts 18 seconds, but that is enough to bring the Rapiers to 140 m/s, after which their thrust only increases. The sound barrier is broken in 47 seconds. Jeb tries to keep a 20 degree pitch. The cockpit is getting a little warm at max Q, but nothing that Jebediah can't handle. On this launch air runs out slightly before fuel, 47 fuel units left over in the side boosters. After staging the core stage takes over, also recharging the battery (Rapiers don't have alternators). Jeb looks quite happy. With its low TWR of 0,69 raising apogee takes a while, but staging velocity was high enough that the thrust doesn't have to be pointed away from prograde. When the Aerospike is shut down, the A.L.P.A.C.A.'s orbit actually has a perigee! A 59 m/s burn was enough to circularise the orbit. 6 fuel units are left. Content with a mission accomplished, Jeb undocks the 18,35 tons of payload. So can this be improved upon? Seeing as I had tiny amounts of fuel left in both stages, 45% should be possible, maybe 45,5% with a larger rocket profiting from scale efficiencies. But I don't see 1.0.2's 55% as possible in any way. Here is what such a larger rocket would look like: 4 full ore tanks, large reaction wheel instead of small, X-200 32 and X-200 16 instead of C7 adapter and FLT-400, Skipper instead of Aerospike, and 8 boosters instead of 2. Delta-v and TWR numbers all look the same, and payload fraction is 45,28%. But I'm not going to launch it, because it has 84 parts and it would take hours to reach orbit.

I have made a rocket with about 46,5% efficiency, but I just came short 20m/s at circularisation. A few more tries and I can show you.

All right then, here it is. 37,06 tons on the pad, 15,28 tons of payload. 41,23%. This has become quite a tall rocket. The difference in ISP between airbreathing and rocket mode is very visible here: the two side tanks provide 3589,1 m/s for five engines, the tall core tank provides just 854,2 m/s. Takeoff is a bit slow with the 1,44 TWR and spooling up of the Rapiers. Pitching down towards 20 degrees. At max Q, between 10 and 12 km, SAS has to be switched off because the tall rocket is wobbling like crazy. Also Valentina is almost fried in her cockpit. At 28 km there are still 74 units of fuel left, but air has run out. So it's time to thank the boosters for their service and condemn them to a splash of death. One and a half minute of burn later apogee is at 70 km. Small correction burns are necessary to compensate drag losses at this altitude. After a swift apogee kick the orbit is circularised, with 10% fuel and oxidiser left. The payload: four 0,5t ore tanks with 3 tons of ore each, and a cockpit with monopropellant (1,28t), for a total of 15,28t. Clearly there is some room left, but my next attempt will probably be a simpler model, with less graphics, because this took a long time on my old laptop. 45% should be possible with a similar rocket. Rune: I concede to you the one-stage title. My Longsword design was reaching its limits, and may never have reached 33%. So I switched to a different idea. Red Iron Crown: Is this documented enough?

Rune, I broke your record again. By more than 4%. During a test flight that I wasn't planning to take to orbit. With lots of fuel left on both stages. Take off mass 31,66 tons, payload mass 11,78 tons, 37,21% efficiency. The secret to this improved efficiency is not building useless parts such as cargo bays, wheels or wings. My first stage flamed out with almost half the fuel in the tanks left, and the core stage made it to orbit easily. Here you see Jeb and his three loads of ore just before decoupling. I am working on a design that will reach over 40% payload mass, and when it's working you will get some more pictures.

I already posted this in a different thread, this was done in 1.0.3 which I believe is the same as long as you don't use heat shields (which I never do anyway). By chance I picked the same name as Rune, I did so because a Rapier is a sword and it's a long rocket. 7,1675t mass, 2,2475t payload, for 31,36% payload fraction. Imgur seems to be a bit broken at the moment, so here are the images one by one: Same as before, except that the FLT-200 has been split into two FLT-100's, one in the payload, one in the rocket. Burnout as high as possible, more than 1,6 km/s. Orbit is achieved (on the 10th try)! The untouched payload is separated.

Hm, right, I miscalculated the delta-v, making a spreadsheet for an airbreathing rocket is a difficult thing. Anyway, half the oxidiser in the FLT-400 is removed, so I have 40+90 liquidfuel units, or 650kg, for the jets, and 45+55+90+110 = 300 rocket fuel units, or 1,5 tons. This gives me 2987,4 m/s airbreathing and 783,4 m/s rocket delta-v, so 3770,8 total, so delta-v to orbit is 3706,6. The way to fly it is to go diagonal pretty much right from the start. TWR at zero speed is barely over 1, so build up sideways velocity to increase engine thrust. Then aim for a 20 degree angle at 6000 m and keep it. Throttle slightly back at max Q to avoid blowing up parts. Over 15km go as horizontal as possible without flipping, and a flame-out speed over 1,6 km/s should be achievable. Burn full throttle in rocket mode to 65 km apogee, and then burn lowest throttle to 70,5 km (without throttle the rocket tends to flip in the atmosphere that's left at 30 km). And most important: try and retry a lot.

My new try, now in 1.0.3! 7 parts, 5,1025 tons, "Try again, Jeb". As imgur is still not working for me, here are some old-fashioned pictures: Here's the ship. More than enough liquid fuel, but oxidiser was quite tight, so a little Oscar is added. Starting TWR is a comfortable 2,1. The gravity turn is started right away. When approaching 1000 m/s while below 10 km, the RAPIER is throttled down by half. Above 12 km throttle goes back to full. The engine flames out at 27 km with a nice horizontal speed. A 70x71km orbit is achieved with a little bit of oxidiser to spare. And then right away it is used to bring the orbit back to the ground. After a warm reentry Try again, Jeb comes down on parachute with jet assist. No Jebediahs were hurt during this flight.

I think you've won this category, Foxster. Any chance you could show a few more pics between start and finish? Also some stats would be nice. Since it's only two parts, I could look it up myself, but I won't do that for every entry.

Very hard to see indeed!

A slightly improved version, with an FLT-100 moved to the payload. Still the same 7,1675t mass, but 2,2475t in payload now, for 31,36% payload fraction. Imgur seems to be a bit broken at the moment, so here are the images one by one: Same as before, except that the FLT-200 has been split into two FLT-100's, one in the payload, one in the rocket. Burnout as high as possible, more than 1,6 km/s. Orbit is achieved (on the 10th try)! The untouched payload is separated. As an interesting side note, this rocket has a delta-v capacity of 2911,5 m/s, and I had 64,2 m/s left at the end, so that means minimum delta-v to orbit in 1.0.3 is less than 2850 m/s.

My first try in 1.0.3: the Longsword 2, powered by 1 RAPIER. 7,1675t takeoff mass, 1,685t payload mass, 23,51% payload fraction. As I had quite some fuel left at the end, this can and will be improved. Requia, which part of your rocket is the payload? I don't see anything that can separate, and in the original challenge the payload has to be a separable, inactive part.

Ouch, missed that! I'll try again tomorrow.