Who Needs Command Seats? a minimalist Grand Tour. *IT IS FINISHED*

[immelman]

I like the layout there - I think I'll be reevaluating my landers.

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...

[immelman]

Wow, this is very cool. I can't imagine operating on such small fuel quantities.

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

Edited April 18, 2014 by immelman

[immelman]

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):

Edited April 18, 2014 by immelman

[immelman]

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!

[immelman]

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:

[immelman]

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:

Edited April 25, 2014 by immelman

[immelman]

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:

[immelman]

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.

Edited April 21, 2014 by immelman

[immelman]

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...

Edited April 30, 2014 by immelman

[immelman]

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:

Edited April 26, 2014 by immelman

[immelman]

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:

[immelman]

A pretty frugal return:

An inclination change and several aerobrakes later and the Moho Lander is picked up:

[immelman]

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.

Edited April 26, 2014 by immelman

[immelman]

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...

[immelman]

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!

Edited April 26, 2014 by immelman

[immelman]

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

[immelman]

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:

Edited April 28, 2014 by immelman

[immelman]

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!

Edited April 29, 2014 by immelman

[kenbobo]

more

damn 10 char limit

[immelman]

The Tylo transfer was pretty uneventful, I did get a pretty good intercept though. I have had intercepts in the Joolian system before which were already circularised, but the game changes them to less perfect intercepts after ejection:

As normal I placed my periapsis as close to Tylo's surface as I dared and reduced my apoapsis in several rounds after adjusting my alignment to the lander.

It's good to see the lander after more than 10 years orbiting Tylo!

The lander can was released and the ion tug docked with the Tylo lander and refuelled, it's looking very good on the xenon gas front.

One design mistake, the solar OX-STAT panels are weightless in the last patch, I should have put some on the lander can. The damn thing runs out of charge so quickly that docking it with the lander is tricky without knocking it so it spins uncontrollably...

Anyway once docked my lander is ready to go:

You might remember that the lander's transfer over to Tylo was super efficient and so I had an extra FTL-100 of fuel more than I planned. This made the landing a pretty relaxed affair.

I aimed for a region of Tylo that is pretty much at 2500m elevation so pretty flat. Then burned allowing a descent rate of 25 m/s, adjusting my angle of burn to ensure this, aiming to be at 3000 meters (or about 1000m above terrain when I had cancelled out my horizontal velocity).

This worked out really well and with the extra fuel I was able to descend at a nice easy 30 m/s until the fuel ran out on the nuke stage:

Then a quick burn after decoupling and I was down! you can see the generator from the destroyed first stage next to the lander:

Getting back to orbit went smoothly as well, ditched the lander legs, with the flat terrain I could burn horizontal immediately and circularised at 8000m.

There was enough fuel in the tank to increase my orbit to 129km before running out of fuel. This has been a strange tour so far, Eeloo caused me no end of problems, but I land and take off from Tylo first time in 15 minutes!

Edited April 30, 2014 by immelman

[Redshift OTF]

This is amazing! I love the dedication to efficiency you have. My favourite is the Eve lander. Mine is twice that weight for 8500 DeltaV.

[immelman]

Glad you are enjoying it! Regarding the Eve lander there is actually a bit more you can squeeze out with efficient designs. Check out http://forum.kerbalspaceprogram.com/threads/76153-Lightest-Eve-Lander

Tavert knocked it down by more than a tonne from my best!

[immelman]

Now in a low Tylo orbit, Jeb dumps the empty lander stage and docks his capsule back with the ion taxi ready to head off to Bop.

The burn out of Tylo is a fairly big one and also critical to correctly intercept Bop, doing this in several stages messed up the resulting encounter and so I had to throttle back and nurse electrical charge while doing it in one burn:

The injection at Bop was in the same manner as all the small moons will be, in that I don’t worry about inclination, just make sure the Pe is sunlit and aim to land on the equator to fix my inclination!

We aimed for the top of a mountain, I could get to like these gentle landings, after Tylo and Vall it's a pleasant change.

Landed, obligatory flag shot. maybe I should have taking a screenshot of how high you can jump on each body...

The only excitement was avoiding the kraken on the way back up, the first ascent I smacked into an invisible hill at 10000m. Best advice is to get a lot of altitude before you burn for orbit!

Edited May 1, 2014 by immelman

[immelman]

It's a straightforward transfer to Pol and insertion:

The spare fuel pod is finally exhausted and it is dropped before landing, trying to do this as efficiently as I can is really beginning to add up. This fuel was only supposed to last until exit from Tylo orbit.

Like me Jeb is looking delighted with these leisurely descents.

And we have arrived, six landings done!

To evade the Kraken just like on Bop, on ascent we were careful to climb before heading for orbit.

Next stop Dres, I'm looking at a cool Tylo slingshot for that!

[immelman]

Transferring to Dres would take more than 780 m/s, this includes escaping from Pol, inclination and circularising in Jool orbit.

I hope I can get better, first off Jeb needs to transfer to Tylo (286 m/s):

After this encounter our orbit is down to Tylo's, with our Pe down to Laythe's (to maximise the possibility of some sort of Jool moon encounter).

In the end using Laythe did not work, but I did get a Vall encounter which helped shift my AP closer to where it needs to be for a Dres intercept (7.4 m/s)

After this we need to look for a Tylo slingshot quick that can intercept Dres! The window is closing! Luckily with a 81 m/s burn we can get a Tylo encounter where we need it and we get an Dres close encounter!

To get a Dres intercept we need to shift the Tylo slingshot by less than a 100 m at periapsis, 5.26 m/s:

That gives us a Dres encounter for 379 m/s. Not bad, also very satisfying, playing around in the Jool system is a whole lot of fun!

Edited May 3, 2014 by immelman