SSTO to laythe and beyond

[Nich]

So i have built an MK2 2 rappier 1 nuke design with 5 km dV in LKO. Even better it has full science and room for 6 kerbals. Now I just need to figure out the route

[PLAD]

Val, that's an impressive packing job, a rover and a jet in the cargo bay of a really good SSTL. If I see it right you have about 3100m/s left in the tank after unloading the cargo? Excellent data taking too. It looks like the low TWR made the Mun flyby route cost about 60-70m/s more than a high (~>2)TWR ship could have done it in, due to less Oberth effect and the larger correction burn required. Low TWR makes the whole mission possible so it's certainly worth it.

I'm looking forward to the rest of the mission, especially seeing that tiny jet fly around.

[Nefrums]

I'm impressed that you got that to Laythe in less than 1.3kdV. Well done!

What's the plan after Laythe?

[Val]

Thank you, All, for the praise.

The low dV route is all credit to PLAD. I'd never have the patience to discover such a route for myself. Though, it's a really slow path in real-time, at least for me. Around 3-4 hours it has taken to reach Jool, each of the 3 times I've used it. Maybe I lack the right tools or skill to do it faster. Most of the time is spent in the MJ Node Editor, trying to find those encounters, and then trying to find them again, when the first burn was too inaccurate.

I'm not sure how much dV will be left after ascent from Laythe. In my previous attempt with the smaller M-5 Space Hustler, it cost 1.2 km/s of the 2.6 km/s I landed with. If it costs the same for this one, I'll have ~1.9 km/s dV left. Not sure if I can do anything with that other than heading back to Kerbin.

I'll be sure to take pics when I go flying in the Nano Jet. I did circumnavigate Kerbin to test it's range before departing for Laythe.

Not sure when I'll have time to continue the journey, though. Will be busy with RL stuff next few days.

Edit: Added craft files to the Mission post.

Edited July 21, 2015 by Val
Craft files

[Foxster]

Well I made it there. Somehow. I know I wasted a load of dV, including nearly landing on Vall by mistake! Oh well, as the pilots say, "Any landing you walk away from is a good one".

Not sure what to do with poor Madre Kerman though. Her craft has 1056 dV left. Should she be able to make orbit with that? If so, it will make the recovery mission easier, which will definitely not be via an SSTO!

Edited July 21, 2015 by Foxster

[Val]

Well I made it there. Somehow. I know I wasted a load of dV, including nearly landing on Vall by mistake! Oh well, as the pilots say, "Any landing you walk away from is a good one".

Not sure what to do with poor Madre Kerman though. Her craft has 1056 dV left. Should she be able to make orbit with that? If so, it will make the recovery mission easier, which will definitely not be via an SSTO!

http://i.imgur.com/ACBS0Gb.png

How much dV did you start with in LKO and what route did you take?

[Mister Dilsby]

Well I made it there. Somehow. I know I wasted a load of dV, including nearly landing on Vall by mistake! Oh well, as the pilots say, "Any landing you walk away from is a good one".

Very nice! Are you using the RAPIERS in airbreathing/LF only mode, or are you also running them closed cycle (and carrying some oxidant) for the push out of atmosphere before the nuke takes over? I am just starting to play with the 2-RAPIER 1-LVN config but so far have been running the RAPIERS as jet only (and getting to LKO with 1700 m/s on the first try )

[Nich]

All my designs have a ton of OX in them because there are no LF only options for adapter parts. In addition my craft is to big to leave the atm on nukes alone. My current plan is to bring 50-100 OX to laythe just to make sure I can pop out of the atm.

My craft is at 5km dV at 71x71. I want to get it up to 6.7km dv so I can attempt to match Val

[Nich]

It seems this challenge has been pretty much maxed (after VALs impressive feat) And all of my designs are looking like craft that have already been created. I was wondering about the IRSU rule. Is it acceptable to use an IRSU if you only process ore from Kerbin i.e. don't bring a drill? I have seen else where someone mention at a certain point IRSU + ore tanks beat LFO tanks. I would probably have to bring TONS of payload to compare to VAL point wise but it would at least give me a fresh start.

[Val]

It seems this challenge has been pretty much maxed (after VALs impressive feat) And all of my designs are looking like craft that have already been created. I was wondering about the IRSU rule. Is it acceptable to use an IRSU if you only process ore from Kerbin i.e. don't bring a drill? I have seen else where someone mention at a certain point IRSU + ore tanks beat LFO tanks. I would probably have to bring TONS of payload to compare to VAL point wise but it would at least give me a fresh start.

Thanks for making my day, by calling my feat impressive (especially because my cousin was read it over my shoulder).

In my opinion, there are even more impressive feats done in this challenge. Nefrum visititing multiple moons of Jool, PLAD using the smallest ship and least dV and Red Iron Crown showing us 5+ km/s dV is possible (which is what made me interested in trying this challenge and to learn to build SSTLs/SSTOs).

So there's definitely many ways to impress in this challenge.

Don't be discouraged. Let it be an inspiration

Edited July 23, 2015 by Val
Inspiration

[Batz_10K]

I've been experimenting with flying-wing type designs. They seem to have improved with the new aerodynamics, This one has sufficient reserves for a one-way trip to Laythe, although I think I need to get some more experience with gravity slingshots in the Jool system...

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[Val]

I've been experimenting with flying-wing type designs. They seem to have improved with the new aerodynamics, This one has sufficient reserves for a one-way trip to Laythe, although I think I need to get some more experience with gravity slingshots in the Jool system...

http://imgur.com/a/J4UQM

That is a very nice looking and capable design. I like flying wings. And you're slingshotting in Jool system looked pretty good to me.

I've been wanting to use the low-temperature wings for variation in my designs, but was worried about re-entry, so I didn't. You've shown that it is possible to use them. Very good.

[Batz_10K]

That is a very nice looking and capable design. I like flying wings. And you're slingshotting in Jool system looked pretty good to me.

I've been wanting to use the low-temperature wings for variation in my designs, but was worried about re-entry, so I didn't. You've shown that it is possible to use them. Very good.

Thanks! Yeah I haven't had too many issues with the wings overheating, although they are usually the first things to show temperature indicators. (well apart from my first attempt at aerocapture at Laythe doing 3700m/sec... it was a very short attempt ). I did make sure they had fuel in them to help soak up some of the heat, though..

The only thing to watch for is that as the wings are mounted close to the CoM some of the control surfaces are reversed on the pitch axis. (on that design the innermost control surfaces work ok, but all of the outermost ones are reversed (and of course, "invert" only works on deployment, not the pitch axis...)). Also as the control surfaces are close to the pitch axis, they don't have much effect anyway.

I worked around the issue by disabling and inverting 2 of the control surfaces, and dedicating the other 2 to roll control, and binding the 2 disabled control surfaces to an action group. That way I could "trim" the aircraft for takeoff and low-speed flight with heavy fuel loads. - you can see them active on image number 3. It also comes in handy if you want to pitch the nose up for re-entry) - The inner most control surfaces were used for pitch control only. The only other way of dealing with the issue is to move the wings back further behind the CoM and use canards - but then it isn't a flying wing anymore...

Hmmm. I wonder if it will fly on Duna

[Val]

I'm back from vacation and had some time to explore Laythe with the Rover and Nano Jet, well mostly Nano Jet.

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Still considering my options for a return journey.

Should I:

1. Try a direct route and hope I can survive aerocapture at Kerbin
   
2. Use one or more gravity assists, to slow down before aerocapture.
   

1 seems the simplest, if I can survive. For 2 I'd need to figure out a route or just try and wing it.

[Red Iron Crown]

Val, I did a direct aerocapture at Kerbin from a straight Jool-Kerbin Hohmann transfer without burning up (barely) during my mission. It's definitely doable, but don't set your Pe below 45km or so. It works better if you point radial or antiradial for the aerobraking itself, more drag. For some reason Kerbin's atmosphere is far friendlier to aerobrakers than any other.

[Val]

Val, I did a direct aerocapture at Kerbin from a straight Jool-Kerbin Hohmann transfer without burning up (barely) during my mission. It's definitely doable, but don't set your Pe below 45km or so. It works better if you point radial or antiradial for the aerobraking itself, more drag. For some reason Kerbin's atmosphere is far friendlier to aerobrakers than any other.

Thanks. I'll give it a try.

[PLAD]

Val, nice exploration mission there. Being able to explore multiple islands during your stay is superb.

What UT year and day is it in your mission right now? We could search for routes that flyby Eve on the way back to Kerbin, though that will add complexity and it sounds like you can safely aerobrake from a direct flight. The problem is that a Jool-Eve-Kerbin route will have you hit Kerbin's atmosphere faster than you would with just a direct Jool-Kerbin flight. However if you are willing to go Jool-Kerbin-Eve-Kerbin then there is a route that will allow you to arrive at Kerbin at less than the Jool-Kerbin value (about 2000m/s at 70km) about half the time.

[Val]

Val, nice exploration mission there. Being able to explore multiple islands during your stay is superb.

What UT year and day is it in your mission right now? We could search for routes that flyby Eve on the way back to Kerbin, though that will add complexity and it sounds like you can safely aerobrake from a direct flight. The problem is that a Jool-Eve-Kerbin route will have you hit Kerbin's atmosphere faster than you would with just a direct Jool-Kerbin flight. However if you are willing to go Jool-Kerbin-Eve-Kerbin then there is a route that will allow you to arrive at Kerbin at less than the Jool-Kerbin value (about 2000m/s at 70km) about half the time.

Thanks, PLAD.

I haven't had time to try the return yet, so the UT date is still Year 9, Day 229, 2h, 54m according to the load screen.

[PLAD]

Doh! I see you're in a good direct return window right now, AlexMun's porkchop plotter tells me that you can leave in the next few weeks and arrive at Kerbin in 968 Kerbin days or so and hit the atmosphere at about 2050-2100m/s (above circular v at that altitude). FF tells me you can leave Jool on Y9 D285, go K-E-K and arrive on Y14 D155 at about 1910m/s. Not much gain for doubling the travel time and adding two flybys. The arrival speed drops to around 1410m/s if you are willing to wait until Y11 D405 to depart. (Jool Y11 D405-Kerbin Y14 D123 -Eve Y16 D141 -Kerbin Y16 D318).

Red Iron Crown's advice was more useful, I think.

[Val]

I finished my return journey. It became a lot longer than expected. Longer than the trip to Jool took.

I couldn't get a direct return to work, always ended up hitting Kerbin at 5.5 km/s. Way faster than was survivable while doing capture.

So I ended up pretty much doing PLADs route in reverse. Mostly by accident, though. I had hoped to be able to do it with less.

• Kerbin flyby
  
• Kerbin flyby
  
• Eve flyby
  
• 3 idle orbits
  
• Kerbin capture
  

(Image links to album)

Edit: Images from Kerbin landing are uploaded and captioned.

Edited July 31, 2015 by Val

[Red Iron Crown]

Awesome, Val, congrats on your successful return! That's the first time I've seen so many assists used for the return, very impressive.

[Val]

Awesome, Val, congrats on your successful return! That's the first time I've seen so many assists used for the return, very impressive.

Thanks

But it's not like I planned to make it that way. It just happened. After trying 4 hours to get a survivable direct capture, I gave up and figured I'd try to use a random Encounter to set up a 2:1 resonance with Kerbin, like PLAD did on the out going journey, and then try capture on the next Encounter. That wasn't survivable either.

So then I started looking to get an Eve encounter, to lower AP to Kerbin level. Wasn't that well timed. Even with adjustments, it took 3 idle orbits before I could get another Kerbin Encounter.

All in all, I think the whole return journey took 7-8 hours.

[PLAD]

Wow, you did it backwards. And you figured the whole thing out on the fly. Superb. You should get 'Master Astrodynamacist' now. I can't quite read the remaining dV number at landing, it looks astoundingly low (22m/s?!?). That must have been dramatic!

That low Tylo pass must have been impressive to watch live.

I wonder what the fastest speed your ship can aerocapture at Kerbin is?

[Val]

Wow, you did it backwards. And you figured the whole thing out on the fly. Superb. You should get 'Master Astrodynamacist' now. I can't quite read the remaining dV number at landing, it looks astoundingly low (22m/s?!?). That must have been dramatic!

That low Tylo pass must have been impressive to watch live.

I wonder what the fastest speed your ship can aerocapture at Kerbin is?

Thank you

I had 91 m/s dV left (22 m/s is in Atmosphere on the nukes) or about 15 minutes of atmospheric flight on the Rapiers (according to MechJeb), so not that dramatic.

Tylo did indeed look very nice. My PE was a few 100 meters below the highest point on Tylo, so I was a little nervous. For a few seconds I actually thought, I was so low that my landing lights lit up the surface, but it was just the sun coming up over the horizon.

3.8 km/s didn't heat it that much so could probably survive a little more, maybe 4 or 4.2 km/s. But heating is proportional to the speed cubed, I think, so it's hard to guess.

[herbal space program]

Well I've been out of action for quite a while due to the pesky demands of meat life, but I'm going to finish this thing now. Congrats to everyone who's made it already. I've managed to get a fleet of 4 SSTO12s to Jool encounter trajectories using the famous PLAD K-E-K-K-J route. I went to school on Val and others' designs for the SSTO12, using all Mk1 fuselages, adding shock cones at both ends, and employing wet wings:

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The design uses 2 Nervas and 3 RAPIERs and weighs 56.1t fully fuelled, 20.1t dry. So far the best I've gotten it to LKO with is 4.8km/s dV, which is obviously not record territory but nonetheless respectable. The best I've done so far for the Jool multi-assist route is 1,231 dV all told, with all flying done manually. It's so hard to set up all the other parts that I never managed to work in a Munar assist, so my Eve ejection burns were around 1060 dV. Getting the orbital inclination at launch just right to avoid a plane correction later was also too much of a bother for me, so I ended up losing another 70m/s or so doing that right after leaving Kerbin orbit. The rest was just tiny little corrections this way and that to get each approach just right. It's hard for me to imagine how one could actually do a perfect launch into this route manually, as the stock interface just doesn't have the resolution. I did so many burns that were under 1m/s. anyway, I will post the whole story once I get finished. Hopefully the ~3.7km/s I have left on my initial Jool trajectory will be enough...

Edited August 19, 2015 by herbal space program