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The trip to Jool Because of the Minmus assist I had more Kerbin relative velocity than normal so I can go straight into an Eve encounter from the Kerbin assist Kerbin flyby Mun flyby for plane change Eve assist Kerbin and Eve assists Second Eve assist Jool encounter Final Kerbin assist Tylo and Laythe assists to slow down for aerobraking Necessary because otherwise aerobrake speed would be far too high After the assists, aerobrake is a much more manageable speed Laythe aerobrake Lander detaches Aerobraking Chute deployed Descending

The Pollux booster is the 1.875m SRB. If you've got 1.8m structural tubes then you probably have the DLC so you should have the Pollux also.

I had some ideas to reduce costs even further. Second ultra low cost submission: 12960 funds Craft is very similar to the other one I submitted, but stripped down further. It consists of four parts: -Laythe ascent vehicle: cheaper, lighter, more delta-v, and more TWR than the previous mission. Could probably be even lighter/cheaper but that's a lot of effort for what's probably minimal gain. -Descent module: fuel tanks for ballast, parachutes, goo canister -Station: Mk1 crew cabin and probe core (lighter and cheaper than two Mk1 command pods), fuel, Terrier engine. Like the previous mission, Terrier is used for orbital insertion, the trip to Laythe, and the return -Two stage SRB launcher: No Kickback boosters this time; Thumpers are enough On pad Gravity turn Second stage ignition Coast to 60km Orbital insertion Kerbin orbit For this mission I'm trying something new for gravity assists. Sometimes my Mun assists won't give me enough energy for a good orbital resonance, or the angle won't be right - like this time. Mun transfer I use Mun assists to get to Minmus, where I fly by Minmus and then fly by Mun one last time. Now I can get a good resonance Minmus flyby Final Mun assist Next: Gravity assists to Jool

Here's my entry: 3445 funds Launch Gravity assists Final orbit setup Final orbit:

Do you have differential throttle enabled? If so then Mechjeb will try to do exactly that - use the engines as large RCS. It's really only useful as a substitute for engine gimbal, like if you are using Nervs. The Thuds should have enough gimbal that you can safely turn off differential throttle.

The Three Thousand Body Problem

For missions where you have an atmosphere, delta-v becomes a bit unwieldy of a metric, due to the changing specific impulses of engines, plus the fact that in a single stage launch you usually switch engines at some point. My preferred metric is mass fraction, i.e. how much payload you can put in orbit with this much mass of launcher.

If clipping and aero glitches are allowed then this challenge becomes pretty easy, just make a dragless craft and dive it down to Jool's surface and back up without slowing down at all

Both have been done. Lt Duckweed and Stratzenblitz both accomplished the Jool ssto using props, Nervs, and ions. Bradley Whistance took a SSTO to both Tylo and Laythe with no ISRU. He used a Rapier+Nerv+Wolfhound+ion craft

Some other things that were thought impossible: -Sea level Eve SSTO -SSTO to Tylo and back, no ISRU -SSTO to Jool surface and back

Are we allowed to leave Kerbin's SOI and re-enter it later?

Here's my Jool dive going below 0 meters on Jool and returning to space safely. It doesn't get the rest of the way home, but it's certainly possible to do so.

Ooh I want to do that challenge now

I usually go outward to 6:5, then either pass in front of Kerbin to get an Eve transfer, or go into 4:5 then get an Eve transfer after one more Mun assist. Depends on the position of Mun and initial Kerbin eject velocity It does, but Kerbin-Eve-Kerbin-Eve-Moho is pretty easy, so I would do that instead. Kerbin-Eve-Eve-Moho is possible also

Getting to Jool for about 850 m/s is fairly routine now using multiple Mun gravity assists, and I've done that many times. My best Jool system encounter used just over 840 m/s and theoretically the minimum is 830 m/s but I've never seen anyone do that. But 1050 m/s is old news. Additionally, even if you don't use multiple Mun assists, it's better to do Kerbin-Eve-Kerbin-Eve-Kerbin-Kerbin-Jool since you get more control over your orbital period, so you don't need to wait for a K-E-K-K-J transfer window. Plus, it requires a smaller initial burn (you don't need to encounter Eve with as high of a speed since you can get more energy from a Kerbin assist then come back) That's why it's better to eject into a resonant orbit with Kerbin using the Mun assist, instead of trying to time the Eve transfer. Then you can swing by Kerbin again to fine tune your transfer. Just leave Kerbin 11 years before the Eve transfer window and the Mun assists will take care of the rest (including plane changes). If you set up the orbits just right, you could go Kerbin-Mun-Mun-Minmus-Mun-Eve, but that would require a lot of planning for no additional delta-v savings.

I think this would be the most efficient way to flyby every body although I could be wrong: Start in Kerbin orbit Mun transfer Use Mun and Kerbin assists to get to Eve Time your Eve encounter so you fly by Gilly also. If that's not reasonable then just skim by Eve while touching Gilly's orbit and then get another encounter later Use Eve assists to get to Moho. Again just skim by to not alter your trajectory too much so you still intersect Eve's orbit Use Eve and Kerbin assists to get to Jool In Jool's sphere of influence, fly by Laythe and set up a good Eeloo encounter Fly by Eeloo and return to Jool Use Tylo and Vall to capture and get encounters with Bop and Pol, then escape Jool on a trajectory to Dres Get a weak Dres encounter so you don't mess up your Jool intersecting orbit, then encounter Jool again In Jool's sphere of influence get a Laythe or Tylo assist to lower your transfer orbit down to Duna, aerobrake there and fly by Ike Then you're home free - get a Kerbin encounter with Ike assists, Mun assist to a Minmus encounter, and get a free return trajectory Properly planned, this should take <900 m/s of delta-v although I would budget 1000 m/s just in case things go wrong.

Do you have to land at the destination or is a flyby okay?

Will I get extra points if I use 3333 vacuum delta-v instead of sea level delta-v?

How about 75 LF? The main reason I think Rapiers are viable is that they have a more favorable mach and pressure vs thrust curve than other jet engines, which means that even though they're less efficient they can be competitive at a higher speed. Very similar plane but less fuel initially loaded. Only 70 fuel Steep climb to cruise altitude. Could have done this significantly better - I had the throttle open too long and went up to 50 km before pulling out of the dive at 14 km. Way inefficient + slow At 24 km and 1700 m/s the rapier flames out a lot so I throttle back to maintain even thrust. I should have started my dive earlier. Approaching airfield Landed at 10:07. i bet I could shave a full minute off this time

@Pds314 I redid the craft to not be clipped and also to target the runway. Shaved off a few seconds also In SPH, 200 fuel load Takeoff The craft can cruise at 2 km/s but it guzzles fuel. It uses way less fuel at a cruise speed of 1750 and altitude of 10 km, so I go at 2 km/s for a while and then climb to 10 km. This is what happens if I try to go at 2 km/s the whole way - I run out of fuel over the desert Meanwhile at 1750 m/s and 10 km, I have a lot of fuel remaining while I line up for the Dessert Runway Landed at 8:26

Oh, I missed that ): I'll do another entry soon

Duplicate of submission for Pds314's challenge (: Here's my submission for featherweight class at 8:36. Single rapier powered plane, 4.7 tons. Launch Cruise at 12 km. The ideal efficiency regime of the Rapier is such that it's at full throttle and still at the edge of flameout. That means that there's usually an optimal altitude to fly the Rapier at - the lower the drag the lower the altitude. Death dive toward dessert airfield, trying to scrub off velocity Approach Landed

Here's my submission for full throttle mode at 8:36. Single rapier powered plane that uses the full 200 liters of allowed fuel. Launch. 4705 kg mass, single rapier powered Cruise at 12 km. The ideal efficiency regime of the Rapier is such that it's at full throttle and still at the edge of flameout. That means that there's usually an optimal altitude to fly the Rapier at - the lower the drag the lower the altitude. Death dive toward dessert airfield, trying to scrub off velocity Approach Landed - I overshot the runway a bit but it never said I had to land there, just reach it, and I definitely reached that far

Will my earlier 2.1 liquid fuel run still count then? It used a Mk1 lander can

This is what you said. There wasn't any specification that it needed to be a command pod, just not a command chair. Airlock is not a command chair Oh, is this what you meant? The pilot remained in the command module from takeoff to touchdown. Surface operations before takeoff were never mentioned either, nor did the pilot bail out of anything. Edit: I mean, I could just launch with a command pod bolted on, transfer the pilot, and detach the command pod. That would satisfy the spirit of the "no bailing out" rule while adding absolutely no change to the mission at all