totm january 2020 Community Caveman Jool 5 mission

[ManEatingApe]

Four down...one to go!
Couldn't wait for the weekend...Vall landing is done! Update is tagged as "v24", please pull the latest version.

There was a slight accident during landing...

Jeb takes a quick break on the surface...

By sheer chance, I managed to get a perfect transfer orbit to Laythe on the 1st attempt.

Orbiting serenely over the endless ocean.

Notes:

• More images in my CCJ5 album
• Jeb and VICTOR are in a 60km x 60km equatorial orbit of Laythe
• VICTOR has over 1,500 m/s dV remaining, so could function as a shuttle to transfer Jeb to KILO after Laythe ascent
• Jeb can survive Laythe re-entry at orbital velocity
• Cleaned up debris and de-orbited TANGO and BRAVO landers.
• MIKE is still in Jool orbit, as I'm curious to see where it ends up getting flung via random gravity assists.

@dvader The mutex is yours, have fun!

Edited November 20, 2019 by ManEatingApe

[Muetdhiver]

Neatly done ! 

It seems we are getting to the pièce de résistance with the crazy spaceplane part on Laythe 

 

[dvader]

Sorry for the delay. I haven't been getting the email notifications lately but @ManEatingApe was kind enough to remind me.

LIMA is officially done! It worked well the first time so there was no reason to redo it. The ascent was poor, I would have liked a much steeper ascent profile to get out of the atmosphere quicker but it didn't cost too much. I still have about 150 dV in orbit (compared to 300 m/s during practice).

The trick is to use the aerodynamic forces overlay and keep the red drag arrow from the Kerbal centred on the craft. Whenever Jeb goes sideways, you just tilt the craft in the airstream so he goes the other way instead. That way you can keep him centred without switching back and forth between Jeb and the craft. I decided to do a powered landing with VICTOR just for fun and almost managed to land intact. I blew the fuel tanks but Jeb is much tougher than fuel tank!

There are screenshots here https://imgur.com/a/uZsrkKi  here and a video below.

 

I'll submit a PR in a few minutes. Who is next?

[ManEatingApe]

11 hours ago, dvader said:

The trick is to use the aerodynamic forces overlay and keep the red drag arrow from the Kerbal centred on the craft. Whenever Jeb goes sideways, you just tilt the craft in the airstream so he goes the other way instead. That way you can keep him centred without switching back and forth between Jeb and the craft.

Nice job! Congrats on being the first Caveman to successfully land a Kerbal on Laythe.
Really enjoyed the video, especially where you balanced Jeb on the ladder during the ascent.

Changes are merged and tagged as "v25", everybody please pull the latest version.

We have now landed on ALL FIVE moons and the remaining final mission is to return Jeb back to Kerbin safe and sound.
@Pds314 Would you like to fly your KILO design and bring Jeb home?

Edited November 26, 2019 by ManEatingApe

[ManEatingApe]

Ok, the final mission to bring Jeb back to Kerbin is up for grabs!

Jeb is currently in low Laythe orbit, hanging onto the ladder of the LIMA craft.

Rendezvous Jeb with the KILO craft in high elliptical Laythe orbit.

The KILO craft has 4,300 m/s dV remaining in 3 stages to bring Jeb back to Kerbin

The fairing of the final KILO stage can protect Jeb at interplanetary re-entry velocity.

 

@Mr. Peabody @Jacke @JAFO @IncongruousGoat @dvader @Muetdhiver

Who would like to have a go? Anyone at all is welcome to throw their hat into the ring.
You don't have to have contributed to this thread before, in fact if someone who has not flown a mission yet would like to volunteer that's fantastic.

Edited November 29, 2019 by ManEatingApe

[Jacke]

1 hour ago, ManEatingApe said:

Rendezvous Jeb with the KILO craft in high elliptical Kerbin orbit.

 

Shouldn't that be "...high elliptical Laythe orbit."

Interplanetary, especially the Caveman kind, is a bit beyond me.

[ManEatingApe]

2 hours ago, Jacke said:

Shouldn't that be "...high elliptical Laythe orbit."

Oops...yes it should, good catch Edited post to prevent further confusion.

2 hours ago, Jacke said:

Interplanetary, especially the Caveman kind, is a bit beyond me.

There's a first time for everything...

[Jacke]

3 hours ago, ManEatingApe said:

There's a first time for everything...

Yes, but I'd like to tackle interplanetary at a later date without worrying that I returned the craft but not the pilot.  Leaving Jeb in a Kerbol orbit with no way of getting him home would be a poor way to fail our Caveman Jool-5.

[dvader]

13 hours ago, Jacke said:

Yes, but I'd like to tackle interplanetary at a later date without worrying that I returned the craft but not the pilot.  Leaving Jeb in a Kerbol orbit with no way of getting him home would be a poor way to fail our Caveman Jool-5.

Quicksave/reload will fix that Jeb also has plenty of RCS fuel left so the catch and release maneuvers won't be too annoying. Since there's 4200 m/s left you also have a lot of options for hitting Kerbin and could perhaps even eyeball it. If not, I'd recommend the miss-and-hit method, where you don't even try to hit the first time, measure the time diff between when Kerbin passes Pe and when you pass Pe, then adjust your orbit to match Kerbins +- the time difference. It only requires a calcuation of the orbital period so it is doable in a spreadsheet.

If no one else wants to, I don't mind but it is the last chance to take an active part in this once-in-a-lifetime opportunity.

[IncongruousGoat]

14 hours ago, dvader said:

If no one else wants to, I don't mind but it is the last chance to take an active part in this once-in-a-lifetime opportunity.

I'd volunteer, but A: I've already contributed enough to this whole thing, and B: I have less than zero percent confidence in my ability to fly the transfer.

[Jacke]

2 hours ago, IncongruousGoat said:

I'd volunteer, but A: I've already contributed enough to this whole thing, and B: I have less than zero percent confidence in my ability to fly the transfer.

Really the same with me.   Is there anyone who's previously done Caveman interplanetary who hasn't contributed yet?

[ManEatingApe]

Why don't we break the return journey into smaller chunks. I'll get this party started...

KILO and Jeb are now in high Kerbol orbit intersecting Kerbin's orbit at PE.

Approximately 3,200 m/s dV remaining (Jeb is tucked inside the fairing).

More detailed screenshots in the spoiler and my Jool 5 album.

Spoiler

LIMA did not have enough dV left to reach KILO, so instead KILO aero-braked for free into low Laythe orbit then rendezvoused with Jeb.

The time to eject directly from Laythe is when Laythe is at the 3 o' clock position (using Kerbol as the reference 12 o' clock position).

Balancing Jeb on the tank during the ejection burn - not even a ladder to hang onto!

From memory and some trial and error Kerbin intercept takes 500 m/s over and above Laythe's 500 m/s escape velocity. I burned to 3,000 m/s (1,800 orbit + 500 escape + 500 intercept + 200 wiggle room).

Almost perfectly retrograde with no maneuver nodes.

The craft ran out of battery before we could achieve the correct velocity, so a second burn after recharging was needed.

Ejection angle a little more crooked but still very acceptable after 2nd burn.

 

General notes:

• We have enough dV to simply brute force a Kerbin intercept by braking in interplanetary space at PE until our orbit almost matches Kerbin then patiently warping until an intercept occurs.
• Optionally we can optimize this procedure by measuring Kerbin's angular offset at PE then use Kepler's 3rd law to calculate an intermediate orbit that will bring us to Kerbin next time around at PE (intercept if lucky, more probably near miss)
• We don't need any scripts or spreadsheets, just a little luck, optimism and some F5/F9.

KILO notes:

• There is only 10 units of EC on the craft - make sure to keep a solar panel pointed at the sun. You can easily run out of charge during maneuvers on the dark side of planets.
• The aperture between the fairing and solar panels is very narrow making it tricky to get Jeb in.
• Poor Jeb didn't even get a ladder! We've unintentionally created a K-drive with the ladder and fairing interaction. If Jeb grabs the ladder then the craft spins uncontrollably.
• To workaround this I re-branded the craft as KerbalScoop™ and kept Jeb carefully balanced on the tank during burns. Tricky but workable.

 

I've updated the repo. Who would like to take over?
A good next step would be to get a Kerbin intercept.

 

Edited December 1, 2019 by ManEatingApe

[joshudson]

I could eyeball that Kerbin itnercept as a Homlann but I will lose Jeb. With 4200 delta v available, I only have to graze Kerbin's SOI.

[ManEatingApe]

28 minutes ago, joshudson said:

I could eyeball that Kerbin itnercept as a Homlann but I will lose Jeb. With 4200 delta v available, I only have to graze Kerbin's SOI.

If you promise not to lose Jeb then you're welcome to volunteer!

[IncongruousGoat]

@ManEatingApe I'll step up. Knowing that we've got enough dV to take the brute-force approach makes me feel a lot better about taking it on - and might be what I end up doing, because it's a lot easier to plan than actually trying to set up a proper transfer.

Edited December 1, 2019 by IncongruousGoat

[ManEatingApe]

Just now, IncongruousGoat said:

@ManEatingApe I'll step up. Knowing that we've got enough dV to take the brute-force approach makes me feel a lot better about taking it on - and might be what I end up doing, because it's a lot easier to plan than actually trying to set up a proper transfer.

Great, you have the mission mutex!

[dvader]

On 12/1/2019 at 7:36 PM, ManEatingApe said:

• Poor Jeb didn't even get a ladder! We've unintentionally created a K-drive with the ladder and fairing interaction. If Jeb grabs the ladder then the craft spins uncontrollably.
• To workaround this I re-branded the craft as KerbalScoop™ and kept Jeb carefully balanced on the tank during burns. Tricky but workable.

I tried to deploy the fairing but it didn't help. It seems it is the decoupler that is too close to the ladder.  I have no idea what will happen once this enters the atmosphere but maybe Jeb can grab the ladder for those few hot seconds during reentry.

I guess the good news is that this is another worlds first. I very much doubt anyone has ever tried to push a Kerbal from Jool to Kerbin...

 

[joshudson]

If you can get into Kerbin orbit at all, it's within the rules to launch something else to pick Jeb up.

[Muetdhiver]

11 hours ago, dvader said:

I tried to deploy the fairing but it didn't help. It seems it is the decoupler that is too close to the ladder.  I have no idea what will happen once this enters the atmosphere but maybe Jeb can grab the ladder for those few hot seconds during reentry.

I guess the good news is that this is another worlds first. I very much doubt anyone has ever tried to push a Kerbal from Jool to Kerbin...

 

Maybe once in the atmosphere the drag will counteract the spin ? Also, a spinning craft might actually be beneficial as far as moderating the heat goes.

I thought we tested the return vehicle and that it did indeed work. Oh well

 

In the worst case scenario, we would have to redo the return transfer in an optimal manner, then get into kerbin orbit on engine power/mun assist/mild aerobraking. Then send a rescue vessel. Sounds like typical Kerbal stuff to me XD

Edited December 3, 2019 by Muetdhiver

[dvader]

51 minutes ago, Muetdhiver said:

I thought we tested the return vehicle and that it did indeed work. Oh well

Yes, but the fairing was longer back then. I don't know when it changed but it is much shorter now. Jeb had plenty of space back then.

Spoiler

 

47 minutes ago, Muetdhiver said:

In the worst case scenario, we would have to redo the return transfer in an optimal manner, then get into kerbin orbit on engine power/mun assist/mild aerobraking. Then send a rescue vessel. Sounds like typical Kerbal stuff to me XD

Worst worst case we send a rescue craft to Jool. With a bit of rule bending it might not be completely illegal since Jool 5 allows for one refuelling mission. There is/was an extra docking port on KILO so all we need is a tiny little ladder somewhere on the refuelling craft... Ladders are of course fuel since they "fuel" the ladder drives. Let's hope it doesn't get to that though.

[ManEatingApe]

22 hours ago, dvader said:

I guess the good news is that this is another worlds first. I very much doubt anyone has ever tried to push a Kerbal from Jool to Kerbin...

I'm thoroughly enjoying this mission becoming more and more Kerbal as it progresses...
Never thought that I'd see the day when clinging to a ladder seemed like a luxury

11 hours ago, Muetdhiver said:

Maybe once in the atmosphere the drag will counteract the spin ? Also, a spinning craft might actually be beneficial as far as moderating the heat goes.

I like your idea of lightly toasting Jeb evenly. As a plan "A' we should definitely chance our arm with the brute force approach using a final high speed aero-brake.

11 hours ago, Muetdhiver said:

In the worst case scenario, we would have to redo the return transfer in an optimal manner...

The optimal Kerbin encounter idea is a solid plan "B". We have enough dV for a powered braking into low Kerbin orbit (generous estimate is ~2,200 m/s) plus another 1,000 m/s to slow Jeb down to 1,300 m/s and use his EVA suit to re-enter.

With so many potential options I don't feel we need to consider a rescue mission just yet.

EDIT: Been doing some experimenting to reduce Jeb's drift relative to KILO when time warping. I found that if you orient KILO normal/anti-normal with Jeb inside the fairing, then wait a few seconds for things to settle before warping, it reduces drift nicely. Here Jeb is only 14.7 km away from KILO after warping all the way from Jool to Kerbin orbit.

Edited December 3, 2019 by ManEatingApe

[IncongruousGoat]

 We've made it to Kerbin! A PR has been submitted, and the album is here: https://imgur.com/a/Gv76004

Flying KILO is somewhat aggravating. Getting Jeb into the fairing after a warp is quite finicky (I ended up burning ~0.5 units of EVA fuel after losing patience with the process a couple of times), and the pusher plate arrangement is not super stable. I had Jeb fall out of the fairing during a burn once, and on several occasions I got him between the pusher plate and the fairing only for him to fall right back out as I tried to maneuver him into the fairing.

That said, I decided to not brute-force the transfer, and KILO still has ~3.5 km/s of delta-V to work with. My proposal for the next step is burn ~1.5 km/s capturing at Kerbin, aerobrake down to LKO, and then use the remaining dV to slow down enough for Jeb to do an EVA re-entry. There might be enough dV to just burn all the way down to LKO with enough left to slow down for re-entry, but the dV numbers I'm using don't account for the weight of Jeb, so I'm treating them as highly optimistic over-estimates.

[ManEatingApe]

4 hours ago, IncongruousGoat said:

 We've made it to Kerbin! A PR has been submitted, and the album is here: https://imgur.com/a/Gv76004

Nice work! The inclination on our new orbit is almost perfect and looks great.
I'm impressed that you got an encounter using so little fuel.

4 hours ago, IncongruousGoat said:

That said, I decided to not brute-force the transfer, and KILO still has ~3.5 km/s of delta-V to work with.

An important correction: KILO has ~1,850 m/s dV remaining (the staging sequence has been re-arranged so the dV indicator is showing you a figure for a stage comprised of just the Ant and the OscarB) meaning that we are about 250 m/s short of capture. We are so close!

There are 2 fixes:

• Revert to a previous save and tweak the intercept so that it is closer to Kerbin. A lower AP (e.g. within Mun's orbit) will allow better use of Oberth effect and allow us to capture. For example an anti-radial burn a few days before the Kerbin encounter will lower the intercept PE nicely.
• Keep going! We are (almost) in a perfect 3:1 synchronous orbit with Kerbin. Using Kepler's 3rd law plus some trial and error, boosting our orbit to 42,755,000,000m at Kerbol PE will give a nice subsequent Kerbin encounter with a PE of 6,000km. We can then burn anti-radial at the edge of Kerbin's SOI to bring this down to ~70km and capture propulsively.
   

Amusingly, somehow we've also acquired an extra 10 units of EC, as the decoupler now has 10 units of charge!
(this is not important, as the 10 extra units are not really needed and don't affect things in any way that matters)
 

Edited December 5, 2019 by ManEatingApe

[IncongruousGoat]

9 minutes ago, ManEatingApe said:

Nice work! The inclination on our new orbit is almost perfect and looks great.
I'm impressed that you got an encounter using so little fuel.

Thanks! 

9 minutes ago, ManEatingApe said:

There are 2 fixes:

• Revert to a previous save and tweak the intercept so that it is closer to Kerbin. A lower AP (e.g. within Mun's orbit) will allow better use of Oberth effect and allow us to capture. For example an anti-radial burn a few days before the Kerbin encounter will lower the intercept PE nicely.

I've still got all the named quicksaves I made when flying the transfer, so I think I'm going to go with this option. I'll see if I can get it done tonight after work - it shouldn't take too long, given that it's already mostly set up.

11 minutes ago, ManEatingApe said:

Amusingly, somehow we've also acquired an extra 10 units of EC, as the decoupler now has 10 units of charge!

(this is not important, as the 10 extra units are not really needed and don't affect things in any way that matters)

That's interesting. I'm going to blame Git on this one - it must have messed up latest.sfs a bit during a merge. I'll poke around the save file and see if I can work out what happened.

[IncongruousGoat]

We've made it to Kerbin, but better this time! The PR has been updated, and the updated album is in the same place it was last time.

I used up about 100 m/s in the correction burn, but I went ahead and tested the capture burn, and we have more than enough dV to capture, coast to Ap, and then lower the Pe for aerobraking down to LKO. So everything should be fine.

I decided not to rendezvous with Jeb at the end (he's ~12 km away from KILO) because KILO is still way out at the edge of Kerbin's SOI, and there's no point rendezvousing before it's time for the capture burn.

Oh, and I took the electric charge out of the decoupler. Still not sure how the heck that ended up happening...