Jool-5 Mission Questions

[HeronRocketry]

Hello. I have just joined the forums and am planning to begin my first major mission, a Jool-5 attempt. I have gone interplanetary a few times, but am having problems with designing the ship. My estimations include transfers between all moons for the mothership and 5 landers, one for each moon. Correct my numbers if I am wrong:

 

18,150 m/s for Energy Mothership (This is for all lunar transfers and interplanetary transfers)

3800 m/s for Gravity Laythe Lander

????? m/s for Gravity Laythe Plane (I am not sure whether to use an SSTO or lander, so if someone could help with the delta-v values, it would be awesome)

1900 m/s for Atom Vall Lander

5000 m/s for Delta Tylo Lander

500 m/s for Alpha Bop Lander

280 m/s for Photon Pol Lander

 

The problems that I have been having are:

1. How to get 18,150 m/s on a ship. I can learn to dock if necessary (still bad at rendezvous), but am clueless due to my inability to design something with more than 12,000.

2. How to design landers. I can easily design one to get down, but what are the best engines to get up?

3. How to transport the landers. I imagine that it will be difficult to fit a bulky lander on the craft (while still looking good, one of my priorities)

 

Hoping you get back to me, (And hope you like my ship names),

Signing off: Heron Rocketry

[Mike Mars]

I'm sure members way better qualified than me will address your questions, but I am just curious.

Why do you need 5 landers?  Why not just one which can refuel from mothership.

Taking a very simplistic approach, I would think that weight is your enemy.

MM

[MythicalHeFF]

Five landers? I recommend just using two, one for Laythe, and one for the rest of the moons, but with an extra stage attached for Tylo, but I’m sure it’s possible to use just one for the entire mission. 

(The lander can then re-dock with the mothership and refuel again to land on Vall, Bop and Pol, it’s easy to make a lander that has enough dV for all three)

You also don’t need that amount of delta-v anyway if you take advantage of gravity assists, and use the ISRU unit to refuel on a low-g moon like Pol. 

[Mako]

Once upon a time I attempted the Jool-5 mission. I took an interplanetary vessel with two landers -- one lander designed specifically for Laythe and one Tylo-land-and-return staged multipurpose lander for the rest of the planets.

The intended order of operations was to land first at Laythe and return to the ship. Then, the Laythe lander could be jettisoned to reduce dry mass. Next, we would go to Tylo and during landing and ascent from we'd stage away even more dry mass from the multipurpose lander. After rendezvous with the main ship we'd go to Vall where we'd refuel and reuse the multipurpose lander. Bop and Pol would be like Vall. Then we'd return home to Kerbin and be big darn heroes

We never made it home. We never even made it past Vall. My excitement of the success of the tested-only-on-Kerbin multipurpose lander after pulling off the landing and return at Tylo and then Vall got the better of me and I time accelerated too fast enroute to Bop. We got shot out of Jool's sphere of influence by an unexpected moon slingshot before I had any idea what was going on, and by the time I could stop it we were too far with the last quicksave being before the Tylo landing.

One day I will return to Jool and each of  its moons in one mission, and I will use this same profile. I think the engineering was proven on that first attempt.

I recommend launching your mothership with as little fuel in the tanks as possible to get into orbit. This will make it easier to get a very high delta-v capable mothership into orbit. Once in orbit, launch your lander(s) and dock with the mothership. Lastly, launch as many refueling vessels as needed to top up your mothership/landers.

I can't speak to the necessary delta-v requirements for any part of the mission as things have changed a lot since my attempt. It's likely none of my designs would work today. 

As for lander engines, for Laythe you can pretty much use whatever you'd use for Kerbin. For everything else you want engines with good vacuum ISP, and for Tylo you want to make sure you have plenty of thrust. Tylo is like landing on Kerbin without anything but engines to get you down safely, but harder.

I don't remember exactly what my main vessel looked like, but I'm pretty sure I used a puller style ship with engines in front to pull the fuel and landers as opposed to a more usual pusher design. It seemed to increase the stability of the vessel, especially when changing heading.

Good luck and welcome to the forums. It's a fun challenge and I'm really looking forward to attempting it again myself.

[HeronRocketry]

Thanks for all the great replies, everyone! Here are my updated plans:

 

Gravity Laythe Plane : ??? m/s

Photon Lander

Energy Mothership

 

Now, I do need to figure out how to make an SSTO. Sorry for the unrelated questions, but how do you use mechjeb to autopilot rendezvous, what is the simplest laythe SSTO, and what is the simplest LKO vehicle I can use to dock the landers?

 

Thanks for all the fish,

Heron Rocketry

Edited March 5, 2018 by HeronRocketry
Just a short while after I posted this, I completed a launch vehicle and mother ship. The questions I had on here are now void, so I just replaced them with my new questions.

[Mako]

SSTO planes can be a bit tough, but if I remember correctly they're easier to get into orbit on Laythe. Also, now that water is significantly less destructive, landing and taking off again should be easier. The biggest tip i can offer is to makke sure that Center of Lift is behind Center of Mass on your SSTO.

I can't offer any advice on Mechjeb since I've never really used it. But, it sounds like you're looking for a small orbital tug vessel to aid with docking. That's not a bad idea, and Mechjeb might be helpful with utilizing that for launch and for redocking after landing. I feel like I did something similar, but it's been a while.

Don't be afraid to test everything individually on Kerbin or in LKO. It'll give you a pretty good idea of how well everything will work. If your Laythe lander can land and take off to orbit there it should work on Laythe no problem. Be sure to test it's water landing and take off capability. Your Tylo lander will need to be capable of making a safe propulsive landing on Kerbin, but it needs to also be able of slowing itself down during desent without relying on atmospheric drag. If your Tylo lander can get into orbit on Kerbin, it should be able to do the same on Tylo. Tylo is harder to land on but easier to take off from compared to Kerbin.

It's a very fun mission to plan and execute. I'm sure other folks can be of even more help than me, but I'm happy to offer as much assistance as I am able.

[ElWanderer]

It's been a while since I did a Jool-5, but:

I kept the mothership in mid Jool orbit, rather than taking all that mass from moon to moon.

I had a nuclear powered tug for transfering Landers about.

As has been suggested a lot, I had a multi-stage lander that would leave the descent stage on Tylo, the upper stage had enough delta-v to do Vall descent and ascent, then (short-fueled to help the tug) both moons in one go. I had a Laythe spaceplane.

In your original post, I think some of your delta-v estimates are on the low side. I could've sworn it took me 1200m/s each way to land on and return from Vall, for example, and unless you have a very efficient autopilot, you'll want at least 3km/s to land on Tylo (the more the better if landing manually) and the same again to ascend (though that can be done more cheaply if you get a good gravity turn going).

[Kerbalstar]

For MechJeb hit rendezvous autopilot, select your target in map view and hit engage autopilot. If you want to dock use the docking autopilot, right click on the other vessels docking port and hit set as target. Right click on your vessels docking port and select control from here, hit engage autopilot and you're done! Make sure your craft has RCS though! As for the rest of it I can't comment as I've never been to Jool. Going to Laythe now though.