Onward to Jool! - A Jool 5 challenge log.

[DerekL1963]

Note:  This isn't being played as part of a campaign, so there pretty much isn't any RP.  I'm coming at it as an engineering exercise, since that's pretty much my play style.  So there's going to be a lot of dry reporting on engineering, testing, and development.

Comments and questions are welcome!

A week or so back, I came across a mention of the Jool 5 Challenge.  I've played KSP since 0.19, so it's not like I haven't heard of it before - but for some reason, this time the bug bit.  I decided to take on the Challenge, even though I've never attempted anything nearly so big before.  Since the Challenge requires some form of log or report, I'm starting this thread to first keep track of my design decisions (in case someone is ever interested) and then to eventually serve as the required report.  My current plan is that even if I don't fly it as a Challenge, I'm going to fly it as flotilla mission.

I'm going to start with a series of posts detailing how I got to where I stand today, then I'll follow with updates daily or as warranted.

Next up:  The Tylo lander.

Edited October 11, 2016 by DerekL1963

[Mister Dilsby]

Anyone who makes a serious run at J5 is my friend: flotilla, mothership, or other-ship. Good luck!

[DerekL1963]

Once I decided to take on the Challenge, the natural first step is the most difficult landing and return in the Challenge - the mighty and obnoxious Tylo.  I've landed on Tylo in the past, but never taken off again.

Unsurprisingly, my first few attempts didn't work out so well.  Landing was easy once I got enough d/V, taking off and actually reaching orbit proved to be the real challenge.  After several iterations, much swearing and much pacing of my balcony while taking a smoke break this lander finally more-or-less succeeded.



It wasn't an ideal design...  mostly because those big radials ended up being jettisoned about 5 kilometers up during the descent, and my t/w ratio took a huge hit at a critical time.  But it did land, if a bit fast, and it did return to orbit, though it didn't have enough delta-V to rendezvous.  I tried adding more fuel to the radials, but the vehicle grew heavier faster than the altitude at which they were jettisoned decreased.  So finally, I trimmed it back to this point (less fuel in the radials and it couldn't return to orbit) and called it good.
  
I also made a note to add some kind of crew transfer vehicle, reasoning that it didn't make any dang sense to move the big heavy mothership around any more than necessary.

Next up: (After I take a break from taking a break and get some of my housework done.)  The Laythe lander.

[DerekL1963]

After tackling Tylo, the next task was the next big challenge - Laythe.  Easy to land on, because atmospheric braking can absorb a great of velocity, difficult to take off from because that same atmospheric drag eats a lot of delta-V.

Since Laythe's gravity is essentially the same as Tylo's, I simply Hyperedited a Tylo lander into orbit and attempted to land.  Entry was pretty spectacular, and though a number of temperature warnings popped up towards the end nothing actually blew up.  Trying to return to orbit...  did not work out so well.  Presumably because of the broad flat faces of the radials and the core, I ran out of fuel not much above the lower atmosphere and plummeted back into the ocean.

This was the next pass at the design:



Here too, I encountered a problem - it wasn't aerodynamically stable.  As I tried to pitch over to start my gravity turn it would flip head-over-heels and make a kamikaze dive into the ocean.  I tried several variant with ever increasing amounts of control authority (torque from reaction wheels, gimbaled engines, even RCS) but the best I could do was delay the onset of the tumble.

The final solution was something of a Hail Mary play - all but forgoing the gravity turn and flying an insanely lofted trajectory (more-or-less straight up until well into the upper atmosphere) which actually worked, though at a considerable cost in delta-V.  That didn't particularly bother me, since it actually had delta-V to spare and having a lander of almost the same weight as the Tylo lander meant I could hang one on each side of the mothership and they'd balance each other.

I also played with solar panels on the Laythe lander to save weight...  but they proved problematic because the radial tanks shaded them.  I tried cladding the exterior of the core with OX-STAT panels, but it took a ton of them to barely keep the batteries charged.  In the end, it was easier to save parts count and just accept the weight of a PB-NUK.  (Which wasn't actually all that much greater than the weight of all those panels - solar at Jool sucks.)

A few more design-build-fly iterations later, I reached what I think is my final configuration.



Next up: (after fixing dinner and being all domestic and stuff and catching up on our anime with my lovely wife)  The Vall lander and a change in architecture.

Edited September 29, 2016 by DerekL1963

[DerekL1963]

The next task was designing the Vall lander.  So once again, I started with an existing lander (the Tylo lander as it happened).   That lander could handily reach the surface and return.... and that's when the epiphany hit me.  I was already planning on adding a crew transfer vehicle or tug of some kind - what happened if I added refueling capacity?  I quickly Hyperedited the core of the Tylo lander into Tylo orbit - and found that it could easily reach Vall.  Thus the next elements of my architecture fell into place.

• The mothership's orbit would be between Vall and Tylo to minimize the delta-V required during the multiple trips back and forth.
• All landers would self ferry from the mothership to their destinations.
• The crew and landing fuel would then arrive via transfer vehicle.
• After the landing and return to orbit, the transfer vehicle would return the crew to the mothership.
• The Tylo lander would be refueled by the transfer vehicle when it picked up the crew, and self ferry to Vall.
• At Vall, the transfer vehicle would refuel the lander and transfer the landing crew.
• After the landing and return to orbit, the transfer vehicle would return the crew to the mothership.

About this point, I made the first engineering mockup of the mothership's configuration with the two landers sitting on top of radial tanks.



Surprisingly, this configuration flew quite well, the CoM was only mildly offset.  (And that offset will be even smaller in the final mothership which will be much larger than this.)

With the architecture beginning to fall into place, I returned to the Tylo lander (now the Tylo/Val lander) - since it needed to self ferry, a cruise stage seemed a natural addition.  After re-fueling, the cruise stage would serve as a crasher stage - which meant I'd be able to land with the radials still attached (though practically empty of fuel) and avoid the problematic drop in t/w ratio of the first version.

The original Tylo lander;


The revised version with a cruise/crash stage:


I was concerned about the weight of this version...  but set that aside for the moment.  Onward to designing the tug.

Edited September 29, 2016 by DerekL1963

[DerekL1963]

I've been calling it a tug - but now it has a formal name, the Tanker/Transfer Vehicle.  The design is a straightforward derivation of a vehicle I've built many times before.

There are two key elements of it's design.  First, the core  LF/O tanks are X200-16's to match the lander tanks, which bumps the parts count a little but provides a handy "fuel gauge" when loading it at the mothership.  The X200-8 will be loaded to give a little extra margin.  Second, the radials (and their attached LV-N's) were positioned to place the loaded and dry centers of mass practically on top of each other.  This made balancing the RCS a breeze, and even fully loaded the T/TV handles like a sports car.

Looking at delta-V, I had another epiphany...  If I used the LF capacity of the center tanks (and left the O tanks dry), then the T/TV has more than enough delta-V to return to Kerbin.  This simplifies the design of the mothership, I won't need drop tanks.  The current (untested) plan is for the T/TV to dock at the aft end of the mothership and provide a portion of the thrust.

[DerekL1963]

Update: 09/28/2016

All of which brings us to tonight's work, I was curious whether the Tylo/Vall lander could reach Bop or not.  After Hyperediting a fueled lander core to Vall, I was quite surprised to find that not only could it reach and land on Bop - it could then return to the mothership without being refueled.  On the actual mission, since the mothership is between Vall and Bop I'll probably make a pitstop there to top off the fuel tanks and give myself a little extra margin.

I'm actually quite pleased with myself - I've now made one lander do triple duty.

A beauty shot of the lander rendezvousing with a docking target in the planned mothership orbit.

Edited September 29, 2016 by DerekL1963

[DerekL1963]

Update: 09/29/2016

Just out of curiosity, I decided to see if my Tylo/Vall/Bop lander (last seen docked to the "mothership") could make it to Pol, land, and return.  To my great surprise, it did so - though it was a nail biter, as it docked back at the mothership with less than 200 m/s (less than 10%) delta-V remaining.  So, now it's the Tylo/Vall/Bop/Pol lander - and I can cover all of Jool's moons with just two landers.  (The second you will recall is for Laythe.)  That;s pretty cool if I do say so myself.  And I'm pretty pleased that I've now landed on all five of the Joolian moons, leaving Gilly and Eeloo as the only solid bodies I haven't landed on.  (Though I have lithobraked on Gilly.)  I think Eve and Dres are the only bodies I've landed on that I haven't also taken off from.  I've only ever returned (from outside Kerbin's SOI) from Duna and Moho though.

Both the Bop and Pol returns shaved it a bit close, so I'm pondering on adding a small LFO pod they can dock to and cart along.

The last task of the night was assembling this monstrosity, a mockup of the entire assembly.



256 tons in total (though 40 odd of that is the T/TV) will all the hardware needed to execute the mission.  The plan is to execute a complete (unkerbaled) dress rehearsal of the entire mission, mostly to validate my fuel requirements but also to work out my mission techniques.  (The radial orange tanks are LFO for refueling the landers, the core is LF only for refueling the T/TV.)  Hopefully I'm carting around too much fuel and can trim that weight back some.  Once the dress rehearsal is done, then I'm ready to figure out how to move the entire SOB from Kerbin to Jool.

But all that starts tomorrow...  I'm too tired tonight for the discipline required, and I need to double check my mission plan before starting.

[DerekL1963]

Update: 09/30/2016

I found an error in my design in the very first thing I did today...  When I undocked the Laythe lander, I found my RCS was 45 degrees off.  Not a huge problem as problems go, but when every kg costs so much to deliver, I don't want to waste any of it.  Since it was the first thing, I simply deleted the whole stack from the Tracking Station.  Then, in the VAB, rather than redesign both landers I just swapped the stock RCS for 45 degree RCS from RLA Stockalike.

I didn't get back to the dress rehearsal because Real Life intervened (stupid apartment won't clean itself) and I'm going to bed early tonight because I have an SCA event to go to tomorrow. I did get a couple of things done in the time I did have;

Concerns were raised about the off-center CG caused by the different weights of the landers.  I'd done some short burns to test, but never any real transit...  So I slapped some LV-N's onto my dress dummy, and flew it from LKO to the Mun and it performed like a champ - missing the target orbit by only 175 meters.



After reading @Aegolius13's Jool-5 Mission Report, I realized I'd never looked at MK3 parts..  I never fly planes, so it never occurred to me.  So, I went into the VAB and designed a MK3 based mothership just to explore the possibilities.

 

Edited October 1, 2016 by DerekL1963

[chicobaptista]

Nice report! I'm conducting a Jool5 mission myself and am planning to shamelessly ste-- erhm, "get inspired" by other fellow Jool fivers. I like the reusability of the landers. However, if anything gets wrong, wouldn't it be better to have some redundancy? Duplicates might make it easier to balance the loads also, just slap them in opposite sides.

[DerekL1963]

4 hours ago, chicobaptista said:

Nice report! I'm conducting a Jool5 mission myself and am planning to shamelessly ste-- erhm, "get inspired" by other fellow Jool fivers. I like the reusability of the landers. However, if anything gets wrong, wouldn't it be better to have some redundancy? Duplicates might make it easier to balance the loads also, just slap them in opposite sides.

Thanks!  (And isn't imitation the sincerest form of flattery?  )

The T/TV provides some redundancy as it can rescue a crew stranded in orbit.  Or I can go refuel the Laythe lander with the T/TV and use it for Val/Bop/Pol.  So basically, unless they're stuck on Laythe or Tylo I've got some options.  But really, nothing should go wrong (famous last words eh?) - that's the point of all the mission technique development and dress rehearsals.  Like NASA, I practice and practice - then the real mission runs smooth as glass.  It's a bit of an odd playstyle but I enjoy it.

The unbalance turns out to be a non-issue as yesterday's test showed, the error is well within MJ's normal performance level. (175 meter miss in a 50km orbit?  That's down in the noise)  Doubly so considering the test vehicle is missing the mass of a couple hundred tons of Kerbin->Jool transfer fuel, which will pull the CG even closer to normal (it's less than half a meter off axis now).

And duplicates of both landers would push my lander mass alone to 180 odd tons...

[DerekL1963]

Update: 10/02/2016 (Sunday's update Monday morning because I was tired and cranky as I was finishing up last night.)

Hurled a series of probes from Kerbin to Jool to gauge the delta-V required, and to learn to recognize a good window vice a bad window.  NASA has supercomputers, and I have the sand box.  (Plus, most delta-V maps are for 'ideal' circumstances.  They've never worked well for me.)



Seriously, one of the most important tools I have is my steno pad for keeping track of things like the performance of each probe...  I probably have have a dozen scattered about the apartment, each dedicated to one task or another.  It was a habit I learned at my mother's knee and that I've never been able to break...



That delta-V information then lead to the design of this beast...



Theoretically it can be assembled in orbit, and theoretically it has sufficient delta-V...  In reality, it failed miserably because the burn time was a large fraction of it's orbital period and it ended up in an oddball orbit as MJ doesn't handle that at all well.  So, I either need to use a node-splitter or raise the altitude of the assembly orbit so that the burn time is a more reasonable fraction of the orbital period.

But, most importantly, I've shown that the mission is at least theoretically possible with my current skills, and that gives me the confidence to proceed.  I really need to run that dress rehearsal and double check my fuel calculations.  If I can decrease the size of the mothership/fuel farm I'm golden.  If not..  well, I don't want to think about that much.

Now it's time to adult for the day, and then catch up on anime premieres.  (Hey, I do have a life and hobbies other than KSP!)

[DerekL1963]

Update: 10/03/16

- Just out of curiosity, I hyperedited the beast above into a 3000 kilometer Kerbin orbit, and it made it to Jool with a whole 200 m/s of d/v.  White knuckles indeed.

- The dress rehearsal is underway, and the Tylo phase of the mission is complete.  One moon down, four to go.  I did made a slight error and brought the quad lander back to the mothership rather than transferring directly from Tylo to Val, wasting a bit of fuel.

Edited October 4, 2016 by DerekL1963

[JacobJHC]

I myself have completed the Jool 5 challenge and think your idea of stowing the mothership in between Tylo and Vall is really smart, not only can the landers fairy there and save fuel but you could use Tylo for an assist out of Jool to save even more fuel.

Good luck with the rest of your challenge.

[DerekL1963]

4 hours ago, JacobJHC said:

I myself have completed the Jool 5 challenge and think your idea of stowing the mothership in between Tylo and Vall is really smart, not only can the landers fairy there and save fuel but you could use Tylo for an assist out of Jool to save even more fuel.

Once I started looking at the problem, it just made no sense to haul all that extra weight around from moon to moon.  The challenge is hard enough without putting one foot in a bucket of cement.
 

4 hours ago, JacobJHC said:

Good luck with the rest of your challenge.

Thanks!

[DerekL1963]

Update 10/04/2016

Sorry for no pictures at this stage, but I'm saving the "cool" shots for the actual run.

- Tackled the next difficult moon, dropping deep into Jool's gravity well to land on Laythe.  After several rounds of F9, found a set of ascent settings in MJ that reached orbit without tumbling head-over-heels, it may not be the most optimal profile but it is 8% better than my best handflown trajectory.  The T/TV sucked the Laythe lander dry of LFO and monoprop and after leaving the lander in orbit headed back to the mothership arriving with less than 150 m/s of d/V onboard.  May have to 'borrow' some of the capacity of the transfer tanks to add a little margin.

- Overall, the fuel situation is starting to look a little dicey, so I may have to increase the size of the mothership a bit.  But, that's why I'm running the dress rehearsal, to find these things out.  The rules allow one refuelling mission if you run out, but I'd like to save that for unexpected contingencies - planning on running out of fuel is against the spirit of the challenge.

- I also found a booster design with performance to spare, so enlarging the mothership *shouldn't* be a problem.  (Famous last words.)

[DerekL1963]

Update 10/05/2016

Quiet evening tonight, after a week of working on this a good part of each day and practically every evening it was time to take a light night and watch some anime.  Still, I got a few things done.

- Designed and tested a lifter for the part of the new mothership design I was most worried about launching, and tested it's ability to dock.

- Tested the full mothership+boosters+landers+tug assembly on Kerbin orbit, both dynamically (how much torque to change attitude in a reasonable time, ability to fly stably during burns, doesn't wobble all over creation) and thermally (a simulated trans Jool insertion burn to ensure it doesn't blow up).  After that, a quick jaunt to Minmus from LKO verified that it flew straight and normal.

I'm pretty pleased, on orbit ready to depart for Jool it's 200-odd parts.  No lag or framerate problems.  All but a dozen or so parts are stock or modified stock (I.E. using Modular Fuel Tanks to make LF tanks from stock LFO tanks).  The whole thing breaks down into six parts for on-orbit assembly.   (It's going to take a metric buttload of fueling trips though.)  At a hair over 4k m/s of d/V it's got performance to spare.

- My VAB directory and subassemblies list was full of old and obsolete designs, half built designs, experimental designs, test fixtures, etc...  So I cleaned both out of anything not pertinent to the current revision.

Edited October 6, 2016 by DerekL1963

[DerekL1963]

Update 10/072016

- Pondered my orbital assembly process, tested a booster for the core.

- Designed an orbital tug to support assembly and fueling in Kerbin orbit.  It's big enough to ferry the core and the landers.  The booster units and the T/TV will self ferry.  The plan is to launch the core and landers with only oxidizer on board to save weight, and that way I also only have to design my refueling system around lifting fuel.

- Continuing the dress rehearsal, started to set up for the landing on Val when I discovered I was running short of the LF for the T/TV.  Since I'd just designed an orbital tug, this was the perfect time to test it!  Hyperedited in into Jool orbit with a Jumbo-64 (orange tank) on it's nose and sent it to dock with the mothership...  Only to find it didn't have enough monoprop or torque, which was fixed with a quick trip to the VAB and then followed with a successful docking.  Still need to update the design of my core vehicle though.    LFO for the landers is looking good, mono a bit dicey.  

- Only two moons to go!

In some ways...  the dress rehearsal and this incremental design procedure is a massive PITA.  In others, it's lead to simpler and more straightforward designs.  Slow and steady wins the race.

The orbital tug in refueling mode.

Edited October 7, 2016 by DerekL1963

[DerekL1963]

*Whew*  At long last, the dress rehearsal is over.

- Successfully landed on Bop.  While the lander didn't have the d/v to return to the mothership, it could reach a stable circular orbit around Jool.  I sent the T/TV out to refuel it and both returned to the mothership.

- Successfully landed on Pol.  The lander docked to the mothership with less than 3% of it's fuel remaining...  If I'd decided to exercise the rescue option (as at Bop), there was enough LFO at the mothership and enough LF for the T/TV for a rescue mission.

- Successfully returned to Kerbin.  

While a rescue option at Pol would have cut into the margin, the T/TV still should have been able to return to Kerbin.  So while I've added the LF I boosted earlier in the dress rehersal to the mothership design, I don't think I need to add more.  Monoprop was a bit dicey,but the dress rehearsal didn't have the monoprop left over from orbital assembly that the full mission would.  LFO as designed should be sufficient.

Next up, finish revising the design and start working towards orbital assembly!

Edited October 11, 2016 by DerekL1963

[DerekL1963]

OK, took a couple of days off... real life and other hobbies and stuff.   So, a couple of posts to catch up and I'm ready to start the run.

First, a bit about the development of the mothership.

The first design for the mothership emerged out an engineering mockup to study the placement of the landers.  Basically a set of orange tanks with everything else mounted to them, simple and straightforward.




This shot shows an early configuration and two features that eventually changed.   Originally I had a large crew compartment, but the crew was eventually cut from six to two and the crew compartment slashed to save weight.  I'd also hoped to use the T/TV to help boost the vehicle...  but no matter how much I paced and swore there simply wasn't enough room under the base of the tank farm for the T/TV and the drive units.




My first overall design was this monstrosity.. (with 12 LV-N's!) it was marginal, but it worked.  And I had no idea how I was going to launch the huge drive unit, even unfueled it weighed a ton.




Eventually I hit on this scheme...  Very cool looking, the drives could be launched easily, but it was a bit marginal in terms of performance.



I found out during the dress rehearsal that I needed to carry more fuel, which meant the two drive unit design simply wasn't big enough...  But once the two new fuel tanks were mounted to the side of the existing core, it was easy enough to go from two drive units to four.   I was kinda sad I lost the cool 'dragon spine' look though.   But with a t/w of .16 instead of .1, and nearly a 1000 m/s more dV, practicality took precedence over cool.



It gets pretty hot when I'm boosting out of Kerbin orbit, but I don't get any alarms and it doesn't blow up - good enough.

1.2 comes out today...  but with all the work I've put in so far under 1.1.3, and the delay for mods to catch up (even though the ship is almost all stock),  I'm just going to soldier on with 1.1.3.

Edited October 11, 2016 by DerekL1963

[DerekL1963]

The the rest of the infrastructure to support orbital assembly...

I posted this tug last week, but the more I thought about it, the less happy with it I was...  I can't put my finger on why, I just was.



So I reached back for a design I've been using since .20 or so...   It's a nice compact design that is very maneuverable even when laden with fuel.  The ISP is impressive, but that's unloaded ISP.



Speaking of fuel, all of the components of the ship are launched with only oxidizer on board to save weight.  In the same way, the drive units are only partially fueled at launch...  So, I need a fuel depot.  Five orange tanks worth, about three flights should fill the ship to the brim.



And last, but not least, a humble vehicle to ferry the crew into orbit.

[DerekL1963]

And my modlist...

Parts mods:

• RLA Stockalike - 45 degree RCS thrusters.
• Surface Mounted Stock-Alike Lights - various lights.
• Module Manager - for running a small script that adds MechJeb functions to command pods and probe cores.  (To avoid having to put MJ cases all over the place.)
• Kerbal Joint Reinforcement - pretty much what it says on the label, it strengthens parts and joints so you don't need struts to avoid spaghettification.
• Modular Fuel Tanks - for changing the contents of tanks, mostly converting stock LFO tanks into LF only tanks.

The vehicle is actually mostly standard stock parts.

VAB mods:

• Editor Extensions Redux - various editor enhancements.
• RCS Build Aid - for balancing the RCS on the various craft, makes docking so much easier.

Operational mods:

• TAC Fuel Balancer - makes it easier to move fuel between all the various tanks on the ships.
• MechJeb - gives various informational readouts as well as autopilot functions.
• Docking Port Alignment Indicator - provides a HUD with various useful readouts for docking operations.

I know what you're thinking.... "You have MJ, why do you need a docking HUD?"  Sometimes I dock manually, sometimes semi-manually, sometimes automatically.  And even during automatic docking ops, it can be useful to keep an eye on what's going on.  MJ's docking autopilot is notoriously thirsty for monoprop, so using the HUD I can cycle to autopilot on and off and cut way down on the mono is consumes.

Misc mods:

• Blizzy's Toolbar - provides a handy one stop shop for all the mod icons.
• Ambient Light Adjustment - improves screen shots on the dark side of the planets.
• Kerbal Alarm Clock - Handy for setting alarms for transfer windows, to prevent me warping past burns or SOI changes.

Edited October 11, 2016 by DerekL1963

[DerekL1963]

10/12/2016

And so, assembly of the Jool 5 begins...

The first launch is of the massive tank farm that will refuel the OTV (Orbital Transfer Vehicle) and later the Jool 5 itself.

 

Then the OTV is launched and docks with the Orbiting Fuel Depot 300 kilometers above Kerbin.  This will be the OTV's perch in between missions.
 

Next, the mothership core (the fuel tanks and docking hub) bids farewell to Kerbin as it takes it's first steps on it's journey to Jool.  Even though it's only loaded with oxidizer (to save weight), it's still a very heavy load.
 

Though it takes over 80% of the OTV's fuel, the core is safely delivered to the 3000 kilometer assembly orbit.  (It's assembled so high so that the lengthy departure burn is only a small fraction of the orbital period.)



But when I separate the OTV from the core by jettisoning the core's docking assembly...  I find a mistake.  Can you spot it?

Yep - somehow I managed to put the decouple on upside down.  Not enough weight to a cause a performance problem, but still very annoying.

My first attempt at docking the Quad Lander was an abysmal failure, because it wobbled all over the place...  I haven't seen a ship wobble like that since back before I started using KJR back in .22!  Eventually I had to undock the OTV and return it the fuel depot and de-orbit the lander.  Unlike the mothership, the lander was launched fully fueled since the weight was well within the capability of the booster and tug.  Going back to the VAB and looking at my design I theorized three possible causes:  a) the weight of the fuel in the lander (specifically in the radial tanks), b) that I had failed to strut the connection between the docking assembly and the lander, and c) carrying the radial tanks so far forward (by docking to the base of the lander).

Fixing "C" meant completely redesigning the lander and/or the docking sequence...  "A" and "B" could be fixed far easier, and tested in a single flight, so I went with that option - defueling the lander (leaving only the oxidizer), and strutting the lander to the decoupler and the decoupler to the docking port.

The second flight was much more successful, it still wobbled but it was manageable.  Of the struts shown below, all but the ones connecting the lander to it's cruise/crasher stage are new.

I was just a bit nervous during this portion of the docking...



But in the end, it was successful *and* I got the decoupler the right way 'round this time.



Six more assembly flights to go, but it was getting late so I called it a night.

[DerekL1963]

Update 10/13/2016

The first task last night was getting the Laythe lander in place...  after my experience with the Quad lander, I went into the VAB, drained the fuel, and strutted it.
 

Though it still wobbled, it was tolerable.  Docking was nerve wracking though - not only did the lander have to clear the docking compartment, the nose cones had to clear the fuel tank.

 

Almost half the fuel in the OFD has been expended just ferrying various components from LKO up to the assembly orbit...  But all the ferrying is over, the remaining components all self-deliver.

Next up are the four drive modules...  And I had an idea that was almost too clever.  The drive modules are launched only partially fueled to save weight - what if I could refuel them on the way up?  That would save a lot of trips with the tanker later.

So the next launch is of a 'stretched' version of the OFD orbiting at 1500k rather than 300k.  This means I'll spend less fuel hauling fuel from the OFD up the mothership at 3000k.

 

 

Figuring out how to get the drives into orbit was "fun" because there's no place on the base to attach anything, and I couldn't do a 'normal' asparagus because of the cooling system.  In this design all six boosters are firing at launch, with the four 'corner' boosters feeding into the two 'side' boosters.  At launch, only the nose tank (holding 2500 units) is fueled to keep weight down and to control CG so it won't flip head over heels.  It reaches orbit with only a hundred or so m/s of DV left in the 'side' boosters.  Originally the LV-N's fired during ascent, but once I figured out that they weren't actually needed I decided it was better to save their fuel for use on orbit.

 

A beauty shot of the second drive unit ascending with the Mun and Minmus visible.

 

 

After launch, the nose fuel is transferred to the aft tank, the drive unit docks to the OFD and fills the two aft tanks.  (Only the two aft tanks to keep the t/w ratio in a range I am comfortable with.  This is mostly to keep the length of the velocity matching burn during rendezvous down.)



Parking the first drive unit was fun because of it's size and weight...

 

 

And attaching the second added 'clearance' to the 'size and weight' mixture, just upping the fun level.  I hate docking, and heaven alone knows why I designed a mission architecture that requires so many.

 

 

In the end, the drive modules arrive with 9400 unit of fuel instead of 2000 - saving me four tanker trips later on.  And the four modules will completely drain the OFD...  efficient!
 

 

As always, questions or comments are welcome!

Edited October 14, 2016 by DerekL1963

[DerekL1963]

Update 10/16/16

Didn't play much over the weekend because of storms...

Launched the third and fourth drive units, refueled them at ORF-2 and docked them to the mothership.  Except for the T/TV carrying the crew, the vehicle is now complete.



Since OPD-2 is now empty, It was de-orbited.  Just for amusement, I rode it down into the atmosphere...
 

At this point I was getting an awful headache and packed it in for evening.   Next up, the tedious process of fueling the beast.