immelman

I mostly agree, but on (more correctly getting off) Eve all bets are off...

You know I blame you for making me get out and push! Thank you for your Landing and takeoff Delta-V vs TWR graphs I've used them a lot Landing Weight 21.9 Tonnes, Take-off weight 18.7 Tonnes:

I've added another picture to the album to make this clearer.

To meet up with Jeb who is orbiting Vall, the ion taxi headed off with the Vall lander in tow. Once transferred to Vall, Jeb burned to a rendezvous with the lander, leaving the taxi in circular orbit. The lander's periapsis was set on about 2000m above the terrain, with such a high TWR the lander only has to burn for 30 seconds to reduce it's orbital velocity: And then landed on a fairly elevated spot: Back up to orbit was straightforward, I ditched the landing gear immediately after lift-off and then burned at a 90 degree heading and on the horizon to minimise the delta V required: I had more than a hundred delta V left after obtaining a circular orbit and so I pushed the lander back up to 60 km before docking back with the ion taxi: Next stop Tylo, that should be fun!

Hi there, can I enter my lander for this challenge? 24 tonnes landing 21.2 tonnes lift-off weight to a 97x97 orbit:

First a little rearranging, the ion powered taxi is going to tow the Vall lander to meet up with Jeb at Vall. Jeb will go there direct after landing on Laythe. First though the ion taxi docks with it's refuel supply, there is a little bit more than I planned. Jeb heads off to land on an area of Laythe that is pretty flat and as importantly mostly under 2000m, Laythe's air is thin enough that I don’t want the shock when the parachutes opening to break the dock with the lander can. Setting the periapsis at 25km was enough to land where I wanted to, although I did need to start up the jet to stop undershooting and hitting the ocean: The landing was on quite a slope and I was surprised the craft did not tip over: Take off and back to orbit was very easy, in fact with such a light craft you need to throttle down so you don’t just blast straight up without reaching orbital speed. Start your turn at about 4km. I ditched the jet at 133km And then did a transfer burn to Val, this was one of the places fuel was very tight, if I had needed more fuel to get into Laythe orbit with the lander I would have had to ditch some of my spare fuel for the ion taxi and use the taxi to tug the lander can to Vall as well. In the end I got a pretty eccentric orbit at Vall before running out of fuel:

This is a fairly small escape burn with a large inclination change later to get a Jool encounter, about 600 m/s in all: With a little messing about I have a Laythe intercept after the Jool encounter: Followed by several aero-braking manoeuvres: Finally we come into dock with the Laythe lander

So Jeb has landed on Eeloo and is still waiting for his transfer date, next off is Laythe. Meanwhile I've transferred landers and fuel stations for: Laythe Vall Tylo Dres Duna Eve Moho Why yes not so much a Grand Tour, but a Grand tour times two!

Looking back at this I should have planned to have the refuelling ship at Duna, Dres is a pain to get to cheaply, to check it out I used an Eve - Kerbin slingshot, which worked, but to really save fuel the Kerbin slingshot really has to be exactly right on Dres's inclination node. Even then the best you are looking at is about 150 m/s saved. If I ever do this again I'll look more at a big oberth burn at Eve to transfer more onto Dres's inclination with an intercept closer to apoapsis. Here is the Eve transfer: And one adjustment to get the Kerbin encounter afterwards: Eve encounter, how many times is it now?! Last fine tuning of the resulting Kerbin encounter I needed it to be as close as possible to maximise the boost: I still needed a 247 m/s oberth burn at 74 km to get the Dres encounter, not that great: Dres encounter and final orbit, I made it 3100 m/s, like I said not worth it...

Fuel is pretty tight for this stage, the taxi heads off to Moho without refueling, I did the burn in several stages. The idea is to use Eve to drop my periapsis down to Moho's and to adjust my inclination so my descending node is also placed on the periapsis. This reduces the size of the injection burn to get into Moho orbit. For this run to get enough of an orbital adjustment I needed to get very close to Eve here is the last burn before my Eve close encounter: 103km above Eve, this is as close as I want to go for a slingshot! Resulting Moho encounter, perhaps I should have spent more time looking for another Moho encounter after this and used this one to lower my Apoapsis and also my injection delta V, I might give this a try when Jeb finally gets here. I brought the Moho periapsis as low as possible to get the best oberth effect for my injection burn, it was on the dark side but with the battery I have enough charge to do the burn, not as efficiently however Injection burn, I make it 2863 m/s to Moho orbit from LKO, which is pretty low. It was a good thing too, the tug ran out of fuel during the following inclination burn! Not disastrous, it only needs about 50 m/s more.

A pretty frugal return: An inclination change and several aerobrakes later and the Moho Lander is picked up:

The Duna lander has to be moved into Duna orbit by the ion drive tug, which then returns to bring the Moho lander to it's target: Several Aero-braking steps: And an inclination change far out: And we drop the lander off in a close 50km orbit:

Small adjustment of the Eeloo periapsis: Followed by a 400 m/s burn to get a close orbit, I make that 1983m/s from LKO to LEO, not bad! Of course there is something I'd forgotten, the efficiency of solar cells reduce with distance from the sun. At Eeloo orbit they were working at less than 50% efficiency, something I discovered as I tried to set up my landing. The Mun and Eeloo have almost the same deltaV budgets to land and take-off and it had worked when I tested it on the Mun, what was going on??? The lander has 14 SP-L panels which equals 1680 charge/min (max expect 15% less depending on angle to the sun), Three ion drives use 1571 charge/min and it is about a 5 minute burn for 700 m/s (deltaV for Eeloo landing) = 7855 charge to land the panels should have provided 7000 charge, with the rest taken up by the battery. Instead I was running out of charge after two minutes... This was the hardest landing I've attempted, it's a good thing Eeloo is so flat. In the end to land I had to use only two drives (with a TWR of .85) while ensuring I kept enough charge in reserve for the final 200 m/s or so to actually land without pancaking into the terrain at 70 m/s which I did a LOT... In the end I made it, but since I had to have the panels open on landing, I lost three of them: So now I had to get to orbit with even less charge! This was a stressful takeoff, I made it first time but it was not fun, watch the charge plunge! Almost no charge, had to turn off one engine while maintaining altitude: Circularising burn, had to turn the craft to face the sun to get the charge I needed: Ditching the extra drive and panels once in orbit:

Next transfer is the Eve lander: With this insertion I want an inclined orbit which overflies the highest terrain on Eve, I need a small correction to do this: And a final burn to circularise and we are orbiting Eve! This stage ends up with about 329 m/s left, again a fl-t100 spare versus what I need to de-orbit! I will have a bit more fuel for corrections on the way down...

Moved the Tylo lander's Pe close and then circularised, the lander ends up with an extra fl-t100 of fuel since we did not need too many manoeuvres to get to Tylo orbit.

First off is the Tylo lander aero-braking into Jool's atmosphere. With completing the Jool 5 challenge a couple of times recently I had a very good idea of the height I needed to aim for, it worked first time too! I got a really good passing orbit here that with a tiny adjustment gave me a Tylo encounter next orbit. This was so lucky, I was expected to have to do more complicated manoeuvres to avoid Laythe sweeping me up: Meanwhile the Laythe lander was heading into it's Laythe encounter, several gentle aero-brakes later it's in a good close Laythe orbit:

The Jool stack consists of three landers. The Tylo lander will use the nuke transfer engine to land and the Laythe and Vall landers will aero-brake at Laythe. When Jeb arrives at Jool he will tug the Vall lander to Vall with him. Total mass for this portion of the mission is 17 Tonnes. Once it reached Jool it is time to break it down into the individual landers: The Vall lander also has attached fuel for the ion craft when is arrives I want to swap it around so I can use the more efficient 48s engine: And the complete craft is ready to go:

Upon Jool encounter the Eeloo lander we get this trajectory after Jool: This has to be "pulled in" by a 267 m/s retrograde burn, I may have been able to get this by putting my Jool periapsis further out, but Laythe and Vall were always in the way: And we have an intercept! Fantastic, this is very satisfying, following a tiny correction my Eeloo lander has the planet in it's sights:

There are a number of very small corrections in these flybys, here is one of the biggest to get the best boost for a Jool encounter: The final trajectory at the second Kerbin encounter: At Periapsis the flyby was 132km it's interesting to compare the orbital velocity versus the craft still orbiting Kerbin! And the resulting Jool encounter, I still need to adjust the inclination: Here is the Eeloo lander's inclination burn and preparing for it's Jool slingshot, 104 m/s: And the Jool stack's, I was lucky enough to get a Lythe encounter at the same time: So far so good! Both vessels successfully flown through the flyby sequence!

Depending on what you want to cook. The great thing about a big turkey is that you have a lot of KSP time while the bird is roasting...

If these slingshots don’t work then I might as well pack it in, so I'm going to concentrate on getting these right before launching the other parts of the mission. Both the Jool stack and Eeloo lander head off via a sling shot off Eve followed by further sling shots twice off Kerbin. After the latest update a 1.2km/s burn using ion drives does not need multiple boosts: I did not need to correct the Eve transfers very much at all to get the Kerbin encounter afterwards and could refine it: Up until the last Kerbin encounter both vessels followed pretty much the same trajectory, here are their Eve closeups: This is where it gets complicated... To hit Kerbin a second time close to the transfer window for Jool I need to make sure my first Kerbin slingshot bumps my apoapsis no more than about 40 billion meters. Other wise I'll have to spend a ridiculous amount of Delta V to slow down to get the encounter, in fact around 32 billion meters works best. You can get a Kerbin encounter much earlier, but that does not work for Jool: For the Eeloo lander, aiming for a 32 Billion Meter AP I only needed a 15 m/s burn to get my second encounter, 45 m/s for the jool transfer (whose AP was .5 billion Meters more):

Thank you! I've really enjoyed planning this out, but I can also see the attraction of the whackjob approach as well

Glad you liked it. For Tylo squeezing down the weight is very helpful, otherwise the mass of your lander gets out of control very quick...

Thats a good one! in addition to: http://imgur.com/a/iNqmQ#0 let me show you how I approached this. Here is a lander using three 47-8s and 8X50 tanks in asparagus which will (just) get down Tylo and back up: And here is the same set-up with the additional fuel to get down to LTO a mass of 9.8T: Now here is the same set-up with the Nuke 9.1T: BUT the nuke by Tylo orbit is "free" I've already paid the fuel to get it there, so if we look at the fuel needed to get down to LTO, land and back up again it is 6.9T. In other words using the nuke saves almost 3T plus the mass of fuel to get to Jool: It's the better choice (I think) even though in landing the lower TWR means it needs more Delta V to get down, it is so much more efficient that it still beats the 3 47-8S setup...

Next to assemble was the Jool and Eve stack. to do this I undocked the turbojet which will also serve as the Laythe lander: And the two nuke engines, which are now going to power the two stacks: Resulting in the two craft ready to go: I'm also going to keep track of the rocket fuel used, for the section to circularise and adjust inclination I had 22 units spare, which is about 1/4 of a ton, not bad...