Duna can wait: Project Jool gets Green Light

[JayKay]

Since our somewhat spacey Astronomy department discovered (noticed?) that a launch window for Jool was coming up before one for Duna, the Duna Explorer has been put on the back burner and Project Jool has been fast tracked. There have been lots of experiments with propulsion systems for the Jool Explorer (more on that some other time,) but the real concern has been with landers for Tylo and Laythe. I decided the ship would need one lander for each moon, and that they could probably also be used on the other moons as well before going to the bigger satellites.

These landers would need to be pretty big to land two crewmen and a rover and take off from these challenging destinations. My first thought was to upgrade my Duna Lander. It is still untried on Duna, but I reasoned that it would need a lot more power to take off from Tylo or Laythe anyway, so I would see if I could get it to work on Kerbin--if it works on Kerbin, those moons ought to be no problem.

Getting the design to work on both might be a problem, so I decided to concentrate on atmospheric landings and takeoffs. So, I had to get the thing into orbit on Kerbin first:

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OK, so this isn't such a good design. I needed something lighter. I designed a new ship from scratch with both Laythe and Tylo in mind. It would need over 3000 dV for both the landing and ascent stages for Tylo, and parachutes for Laythe. I reasoned that by using aerobraking to land on Laythe, I would have lots of fuel in the landing stage still, which could be used to assist the takeoff in Laythe's atmosphere. Here's what I came up with:

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That last successful landing seems to be a proof of concept, to me anyway. I had to move fuel back and forth between its various tanks to get it to stand upright, thanks to those mushy legs. Once it was vertical, I transfered fuel back into a balanced condition, raising and lowering individual legs to compensate for the shifting center of mass. I'm still quite concerned about the thing's ability to land on even a slight slope. We may have to use the F5-F9 compensator to correct problems in that area. I may add Infernal Robotics jacks to manually adjust the lean without using the legs.

In any event, since Laythe has less gravity and atmosphere, and I accomplished the landing and takeoff with less than a full load of fuel, I think it's pretty certain the ship will work on Laythe. According to the dV numbers, it should also be capable of landing and taking off from Tylo. There's no way to know until I get there, though.

Meanwhile, work continues on the Jool mothership. Once it gets closer to completion there will be an update.

JK

[JayKay]

OK, so to make a long story short, after a couple weeks of experimentation, testing, failure and back to the drawing board, Project Jool is in the final test flight stage. I present to you, the Joolian Endeavour:

Almost 1000 tonnes fully fueled, 915 parts, and a crippling nexus for lag beyond all reason. Five actual seconds pass for every in-game second logged. Surprisingly, however, the ship is very stable and maneuverable and MechJeb can lock the ship on course effortlessly. The ship uses 5 large ASAS units plus 9 more smaller units at the rear, which allows it to turn without using any RCS. There is no flex in the spaceframe at all while under acceleration, which had been a problem with earlier versions. I can't get a precise delta-V figure for the ship, but I think it's around 15,000.

Docked to Sr. ports on either side of the command/hab section are two identical heavy landers, one each for Tylo and Laythe. Each lander also carries two rovers for surface operations. Besides the two heavy landers, the Endeavour also carries two one-man landers for smaller bodies, two MechJeb landing probes for scouting landing locations, and a pair of mini orbital probes. I have also developed a tug which will be docked to the front of the ship which will assist the heavy landers in reaching their descent orbits without using their on-board fuel, and then help recover the ascent stages when they return from the surface.

I have 9 LV/N engines mounted at the rear of the fuel tanks, but only 8 want to fire. Fortunately, the one which is not working is the middle one, so there are no balance problems. I am flying it to the Mun and back as a test run. The burn was estimated at almost 20 minutes for 745 dV, and with the lag, that would take over an hour. I fired it up and went to watch a movie, expecting it to be done when I got back, but miscalculated in that I forgot to take into account that after 15 minutes it would be firing at 90 degrees to its orbit trying to stay on course. I shut it down after wasting a bunch of fuel and it's on its second approach to the node now. I will fire it up 10 minutes before the node and hope it can escape orbit this time. This means several orbits would be needed to get enough speed for Jool insertion, unless I mount more engines on the back. Just what my poor CPU needs, more parts on this beast.

Well, I'm running out of time before my Jool window opens (less than 5 in-game days,) so I will have to figure out what I will do quickly.

JK

[Scotius]

Oh my stars and garters...what a magnificent, beautiful monstrosity have you built Of course, building two, or even three smaller ships to get lag to be manageable is unthinkable for a truly devout KSP player:sticktongue:. As it is, i salute your patience and endurance good sir

[JayKay]

Oh my stars and garters...what a magnificent, beautiful monstrosity have you built Of course, building two, or even three smaller ships to get lag to be manageable is unthinkable for a truly devout KSP player:sticktongue:. As it is, i salute your patience and endurance good sir

Anything worth doing is worth overdoing... The way I look at it is that the ship is a complete success, it's my computer that's failing.

JK

[Duke23]

I found this thread while looking around for what others are flying to the Jool system (planning my first mission soon). That, sir, is impressive. I got a good laugh out of the lander testing too...

Man I thought my current interplanetary ship's 6.5 minute burn to get to the Mun was bad. But it was well above normal working weight during testing, dragging a bunch of crap out there for a permanent base.

Anyway I'm curious, did the beast ever make it? Or are you still burning

Edited January 11, 2014 by Duke23

[JayKay]

Anyway I'm curious, did the beast ever make it? Or are you still burning

Actually, version .23 came out and I decided to try a career mode save. I've made a lot of progress on the tech tree, but nothing as grand as the Jool beast has been built. I have found it's a different game altogether when you are concentrating on getting science out of specific spots rather than setting your own goals. I haven't tried importing the save into version .23 to see if there's any improvement in the lag situation.

I did get the Joolian Endeavour to the moon and it's on a free return trajectory back to Kerbin. I intended to see how it would deal with Aerobraking once it got back to Kerbin. I may dust this save off yet and see how it goes.

Thanks for the interest.

JK

[Duke23]

Oh I see. Yes that certainly does change things lol. Massive ships like that fascinate me for some reason.

If you try it good luck, I just had to aerobrake my largest ship at ~32km coming back from Dres to assist capture. That was the scariest thing I've done since my first Duna landing I think ("no seriously, deploy the chutes!")... I'll admit I retried it a few times. 38km did almost nothing and I flew right back into Kerbol orbit, 23km was way too much all the thrust in the world wouldn't save me from making a large fiery hole in the ground.

[Soda Popinski]

Great thread. Wish I read this earlier. I would have brought more delta-V.

Been busy for the better part of a month on my own Jool mission. As of this weekend, I've managed to get the thing to Jool, aerobraked about 7 times to conserve fuel. After getting into Vall orbit, and sending a kethane miner down with the last drops of all the fuel I brought, I keep running out of fuel about 3 meters from landing, and toppling over after hitting the regolith. I'll get it eventually (yes I use the F5/F9 "crutch").