Jebediah 5: Second Generation Jool 5 Mission

[OJT]

Ah ****, here we go again

Hello lads

A couple of months ago I started a Jool 5 mission thread on this forum. It took a lot of time and a lot of prep work, a lot of stuff was unknown to me prior to doing it. Last week, I completed the challenge on Jeb's level and my submission was verified by the thread admin JacobJHC. However, with newfound experience and knowledge, I can improve on my first design and complete Jool 5 for the second time, hence the name of this thread. Without further we do, let's get started

Mission targets:

• This mission will be done on Level 1. It will make the planning easier and I won't need to frantically check whether I did all the experiments, I will only need to focus on flying
• Vessels must be downsized from my first attempt, both in terms of weight and length
• Journey must be better optimized: there's decent amount of dV that could be saved with transfer maneuvers and reduce the mission time
• Self-imposed rule: the whole mission must be fully reusable. Everything, from boosters to Jool 5 vessels themselves, will be recovered on Kerbin

Since I am already familiar with Joolian system and already have the satellite network established, we're gonna go straight into action

Part 1: Kerbin

First of all, we need to build the stack in Kerbin orbit. First up is the mothership launch. Jebediah Kerman, the captain, is behind the wheel

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After reaching sufficient altitude, Main ship separates itself from the booster and finishes circularization. After that, I quickly switched to booster and splashed it down in the ocean

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Mothership in orbit. Now it's lander's turn. Valentina Kerman is piloting this rocket

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Lander separates and reaches orbit. Booster descends and splashes down

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Last, but not least, plane launch. No runway takeoffs this time: plane will be launched in a rocket with a very thick fairing. Vasya Kerman is in the cockpit

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You know the drill by now

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Booster was actually past the ocean by this point. But it had extra fuel packed, so I temporarily accelerated prograde and then burned retrograde to splash down in the ocean

KSC is far ahead

Island runway is below us

With all the vessels in LKO, it is time to assemble the stack. First we hook up the lander

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Then we hook up the Plane

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Now let's take a look at the whole stack

 

First let me give you some numbers: the whole stack assembled in LKO weighs just a touch over 200 tons, compared to 304 tons of the previous stack. The whole stack is also noticeably shorter, at around 34.5 meters: the Main Ship alone in the previous mission was 50 meters.

Main Ship is now made up of wide assortiment of tanks, from 2.5m to 0.625m diameters, totaling around 7.6k m/s dV with both landers attached. It has 6 NERVAs instead of 8, but thanks to downsizing it has the same TWR as the previous gen mothership. There are two docking ports, one behind for the stack and one on the side for refueling. Ship has lots of parachutes and can survive reentry from LKO and splash down in the ocean

Lander is downsized aswell, made up from 1.25m tanks instead of one 2.5m tank. Roughly same dV as in previous lander, enough TWR to land on Tylo and, subsequently, on other airless moons. This one also has ISRU equipment, although it is still the inefficient kind due to weight savings: I will have to pick my landing spots carefully. Lander has two docking ports aswell, one in front for the Main Ship, and one in the back for the Plane

Plane is also smaller, has different wing setup, inline air intake and is now powered by single RAPIER engine, compared to tri-engine config of previous plane (2 RAPIERs and 1 NERVA). As such, it also packs some oxidizer for in-orbit maneuvering, but it still packs enough fuel for Laythe phase.

This concludes the Part 1 of this Jool 5 thread. In next part, we will be departing towards the green gas giant. Stay tuned 

Edited February 4, 2022 by OJT

[Vanamonde]

This is an ambitious mission.

[Maria Sirona]

Hemlo, am back! Will Val be on Vall this time? Is the crew the same as on the previous mission?

[OJT]

Well well well

The progress on my mission goes slower than I initially planned: IRL stuff doesn't really leave me much time to play the game.  Today I finally found some time

Part 2: Jool Arrival

We're picking off from where we left it last time: Jebediah 5 assembled and ready to depart. Due to low TWR of the ship, the transfer burn have been split up into smaller burns to reach the edge of Kerbin's SOI and, after transfer window comes up, one big burn to get to Jool (this burn occured on the nightside of Kerbin)

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After two small corrections on the way, we arrive to Jool

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Luck was not on my side on this one: none of the large moons were in good positions for gravity assists. Therefore, I had to do initial circularization purely through engine burns. I circularized into highly elliptic orbit, then with couple of small adjustments and two Laythe fly-bys to lower my orbit I managed to get a Laythe encounter at sensible speeds

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My situation was somewhat critical: I used up more fuel for Jool circularization than I initially planned, Laythe encounter was still at quite high velocity and to enter even highly elliptical orbit would use up too much fuel to proceed further, let alone getting into low orbit. The mission was on the verge of failure, I thought about trying it again from Kerbin orbit (I did have a quicksave), but I did not want to back down and decided to go all in or nothing...

That's right, ladies and gentlemen: I aerobraked with the whole stack

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It got toasty. VERY toasty. Naturally so, considering I reentered at 3100 m/s. The main ship's command pod reached 93.5% heat level according to KER readouts. But the stack actually survived! (thanks to the revolutionary technique of spinning like a rotisserie to cook kerbals evenly spread the reentry heating)

Knowing that Jebediah 5 can take the beating, I did couple more aerobrakes and succesfully brought the ship into low Laythe orbit while using 75m/s dV worth of fuel for inclination correction and to raise the periapsis after finishing the aerobrakes

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And there we have it: J5 in Laythe orbit. In next part, we will start with the landings

 

On 2/16/2022 at 5:39 PM, Maria Sirona said:

Hemlo, am back! Will Val be on Vall this time? Is the crew the same as on the previous mission?

Eh, might aswell. I definitely won't torture her with Pol landings, that's for sure

Edited March 1, 2022 by OJT

[Maria Sirona]

11 hours ago, OJT said:

. I circularized into a highly elliptical orbit

Doesn't circularizing mean going into a roughly circular* (hence the name) orbit?

*Round

[OJT]

Time for the next part (or rather parts  )

Part 3: Laythe

Vasya Kerman is in the cockpit. He decouples, burns retrograde and descends down to the surface. The whole reentry section was quite calm and went without issues (as you can see from Vasya's face expressions)

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After sufficiently slowing down, I glide towards the island. After flying through the cloud layer, I suddenly noticed that the terrain was going uphill and because of that I had to activate the RAPIER engine to not crash into the cliff. Afterwards, I land on the top of the cliff and Vasya plants the first flag of the mission

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Weird graphical glitch on this screenshot

Soon after landing, I fly back to orbit, since I don't need to scout different biomes for science anymore. Still, I saw interesting geological formations on my way up like a canyon and a lake inside a crater

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Canyon

Lake

After couple of in-orbit maneuvers, I encounter the main ship and dock back to it

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Laythe done, next up will be Vall

 

On 2/23/2022 at 2:34 PM, Maria Sirona said:

Doesn't circularizing mean going into a roughly circular* (hence the name) orbit?

*Round

Yea, fair enough. I think writing "entering orbit" instead of "circularizing" would make more sense in that situation

Edited March 1, 2022 by OJT

[OJT]

Part 4: Vall

After departing from Laythe (I annoyingly forgot to take snaps), next up was Vall. Reaching it and entering orbit was fairly easy

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At this point, my mothership had around 2700 m/s dV left. In theory it should've been sufficient to reach Tylo and Pol while having fuel onboard to fill up the lander, but the margins would be too thin for my own comfort. Which means that I needed to refuel the main ship at least partially until I reached Pol. However, I absolutely did not fancy doing gazillion refuel runs like I did in my first Jool 5 mission, so I had to experiment on the fly

Ingame stat readouts were absolutely buggered due to multiple ships attached to each other, however KER readouts said that I had enough TWR to land with my main ship. The lander had LT2 landing legs, which, despite their flimsy looks, have surprisingly good weight/impact tolerance. And since the lander was at the bottom of the stack, I could mine the ore with the drills and make fuel. I was a bit scared that docking port might not handle the weight of the ship, but since the stack survived reentry, I decided to give it a try.

First I undocked the plane and left it in orbit. Then I descended towards Vall surface

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Good news! The Dacia Sandero is on sale in the UK The docking port stayed intact. These ports are much stronger than I gave them credit for. Valentina will do the honors (even tho the main ship itself is piloted by Jebediah)

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I only managed to refill the mothership to about half: any more fuel and I wouldn't be able to lift off. Even then the take off was really slow (launch TWR of 1.11), but I reached orbit in the end

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In orbit, the plane docked back to the stack

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Two down, three to go: Tylo is next

[Maria Sirona]

That mothership-on-Vall landing was epic! Also, Val on Vall

[OJT]

Part 5: Tylo

Main ship landing was worth it: it now had around 3300 m/s dV, 600 more than before, and the lander was also fully fueled, which meant that I didn't need to transfer the fuel from main ship into the lander. Plus, since the stack faired fine in Vall's gravity, I could easily land it on Pol in the future to refuel the main ship on the ground instead of doing lots of trips up and down

But first, we need to cross Tylo off our list of destinations. Which is where we're going right now

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Several retrograde burns, and I put the stack into low orbit. All burns were on the nightside of the moon, so the visibility might not be great  

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This time lander with Valentina goes down alone. First the plane undocks from the lander and docks to the side port of the main ship. Then the lander undocks and proceeds to land

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Landing was closer than I expected (and it might've taken several attempts). I touched down exactly as my fuel ran out. But we survived in the end

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Valentina plants the flag and climbs back into the cockpit for refueling. Climb back happened to be very stressful because Valentina refused to climb all the way towards cockpit for some reason (and I did test the ladders before commencing the mission), but eventually she did climb in, thank God

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Refueled and rested, Valentina flies back to orbit

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Some small maneuvers, and ship rendezvous with main ship and the whole stack reassembles back

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Inner moons are done! Only outer moons remain

[OJT]

Part 6: Pol and Bop

I decided to make one part for both moons this time. First is Pol. Reaching there took multiple burns: couple at Tylo periapsis, one burn to eject from Tylo's SOI and one burn for mid-course correction. Circularization didn't take much dV either

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We are again going to land the main ship with the lander on the surface. We know it can take it, and even fully fueled main ship will have more than enough TWR to lift off. You know the procedure by now: leave the plane in orbit, descend down

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Landing was easy, but I did need to briefly lift off and adjust my landing spot to land on a flatter surface

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Jebediah is planting the flag on Pol and posing for the picture

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Now all I needed to do is to refuel the main ship and return to orbit. Good thing? I could refuel the main ship in one go instead of doing refuel runs with the lander, saving myself the effort.

Bad thing? Refueling took a LOT of time. Combination of small drills, single inefficient ISRU converter, almost empty main ship and the amount of fuel tanks in the said ship meant that the refueling took over 9 ingame years. I was fast-forwarding on max speed and it still took about 20 minutes to fill up the ship. Can't imagine what Vasya in the cramped plane cockpit must've felt

Eventually, the ship did indeed refuel and I did indeed return to orbit

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Encountered with the plane and docked it to the stack

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Pol done, Bop is left. Burning towards it right now

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One mid course correction later I reach Bop, and circularization burn was on the night side again. One more burn to correct the phase angle and we're in low orbit!

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We're not landing the whole stack this time, since main ship is fully fueled, so Jeb will go in a lander. I docked the plane to the side and descended in the lander

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Jeb plants the flag and flies back to orbit

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Both ships meet up and redock

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And with this, all of the moons are done! It's time to go home

[OJT]

Part 7: Return

By the time I finished with all moons, I happened to be quite close to Jool-Kerbin transfer window. And I also had way more fuel than I would've needed, so return to Kerbin was very comfortable. I first ejected from Bop, did a gravity assist around Tylo to lower the phase angle and then did one big burn to leave Joolian system all together

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I did one more mid course correction and after 2.5 ingame years we return to Kerbin

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I had enough fuel, so I opted for retrograde burns instead of aerobrakes. I also did a normal burn to make the orbit equatorial to make recoveries easier

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With stack in low orbit, it is time to recover all three vessels, one by one. First up is the plane: it decouples, brakes in the atmosphere, glides towards KSC and lands. I overshot the space center a little bit, so I had to turn around and fly briefly under engine power. Runway landing was smooth

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Next up is the main ship. It doesn't have landing legs of its own, so it will be splashed down into the ocean. I was actually reentering a bit too fast for parachutes to trigger by themselves, so I had to burn retrograde at the same time to slow down. We splashed down in the end, not far from Island Runway

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Only lander left to be recovered. It doesn't have parachutes and its engines don't produce enough thrust in Kerbin sea level, so I'm gonna send another craft to recover it. I intially wanted to put a Mk.3 Cargo Bay on said vessel, but VAB checks showed that lander doesn't fit into it, so I changed the concept of the recovery craft: it now has docking port on the bottom similar to main ship (since we know by now that docked ships are rigid enough to survive reentries) and lot's of parachutes to safely splash down. It is autonomous and it is also single stage, so I won't need to switch away from it to recover boosters

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After rendezvous with the lander, both ships dock and return to Kerbin

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Parachutes deploy after reentry and both crafts safely splash down in the ocean east from KSC

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This concludes my second Jool 5 mission! All mission targets have been achieved: vessels were noticeably downsized, delta V used was quite lower than in my first attempt and every single craft used, from boosters to landers, were recovered on Kerbin, making this mission fully reusable! Probably my finest KSP achievement so far. Next set of pictures shows the flags I planted

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See you next time lads!

[king of nowhere]

On 2/23/2022 at 3:17 AM, OJT said:

After two small corrections on the way, we arrive to Jool

Luck was not on my side on this one: none of the large moons were in good positions for gravity assists. Therefore, I had to do initial circularization purely through engine burns. I circularized into highly elliptic orbit, then with couple of small adjustments and two Laythe fly-bys to lower my orbit I managed to get a Laythe encounter at sensible speeds

 

You have to plan the gravity brake with a large advance, as much as one or two years earlier. This way, if none of the moons are in a goo position, you can just add a couple m/s prograde/retrograde burn, which will change your time for arrival at Jool by many hours.

Once you are close to Jool, that would be far too expensive.