18t (or less) Returnable Manned Mun Lander

[Aragosnat]

Here is mine that I'm going to test soon. Later today for me.

Also good at getting at no nav burn marker help. Been getting encounters with impacts more often then not. Also going to make one without a probe for the pilots to train with.

[Yemo]

@cantab:

With your info that placement order is relevant, I was able to build multiple versions of the 3x jet booster pack, each optimized for either part count, weight or aerodynamics (FAR).

@Greep:

I like your battery cluster with attached rocket vessel ;-). How do you seperate your lowest booster, I tried explosive decoupling in 0.90, but it took quite some time to overheat and I lost a lot of vertical speed until then.

@xcorps:

With cantab s tip in mind, I placed 1. a small fuel tank (54 liquid), 2. then the tricoupler, 3. a symmetric pair of intakes around the fuel tank, 4. one jet engine below tricoupler and then repeated 3 and 4 two times.

The 3 additional intakes compared to your design weigh nearly nothing, but massively increase efficiency for the jets. For 15.7t to 18t vessels, 54 liquid fuel and the right ascent path, they burn out before they suffocate. But fuel level is adjustable for weight and ascent path differences.

[sumrex]

I'll have to double check my rocket, but needless to say I did not burn one ounce on science modules and could not be at all picky about where I landed. If it indeed fits the bill I'll post a file for the rocket.

[katateochi]

Just uploaded a vid of my craft doing it's thang;

[ghpstage]

You didn't just beat the 18t limit you smashed it. Very impressive!

I've never tried the 48-7s before, looks like they are well worth using.

[lirg03]

You didn't just beat the 18t limit you smashed it. Very impressive!

I've never tried the 48-7s before, looks like they are well worth using.

48-7s is extremely capable on light rockets/landers. In the case of heavy (Eve) landers, a lot of 48-7s works pretty well.

[Greep]

Even thou its unmanned and non-return, it's still a nice solution to getting that contract done on the cheep though. Also, Welcome to the forums!

Thanks

@Greep:

I like your battery cluster with attached rocket vessel ;-). How do you seperate your lowest booster, I tried explosive decoupling in 0.90, but it took quite some time to overheat and I lost a lot of vertical speed until then.

You can still do it, you just can't thrust limit the boosters, that's all. I would've used a decoupler, but I'd never done a trip to the mun on batteries before so I was just saving every part I could :/ I'm really liking the new career mode and how it pushes you to the limit, my previous mun rockets were these giant skipper/s1-srb beasts, and this was quite small!

[NoPanShabuShabu]

Girders, while not massless in the VAB, are during flight. They're just there to protect the engine. It's all good though, new design, much better, less worrisome. Just trying to get the fuel load right to avoid flameout.

Those girders aren't massless, it's the small ones which are.

[KevinW42]

Silly old me forgot to take a screenshot and I already overwrote the craft file with a bigger lander, but I just barely managed to do a Mun landing with no upgraded buildings (aside from the astronaut complex). My ship was exactly 30 parts and 17.8 tons with a fairly basic asparagus stage design with the FL-T400 fuel tanks and 48-7S rockets. Only the core stage made it to Kerbin orbit, and I used my very last drop of fuel returning to Kerbin from the Mun.

I've certainly come a long way in terms of optimization since my first Mun lander.

[Slugy]

I have two manned ships to suggest here, both require Fuel Systems and Aerodynamics: a 7.35T lander (29 parts), and a 30 part 14T lander with legs, science jr and goo.

The two 48-7S get fired at around 16000m while the jet is still running.

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For this one it just stages normally.

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Edited December 23, 2014 by Slugy

[Yemo]

@Slugy: What was your ascent path with the 7.4t vessel? How high did you get before the jet flamed out with those 4 intakes? I remember another thread where a guy achieved something like 80km apo, 40km peri just with a jet and a massive number of intakes.

[Slugy]

The ascent path was normal rocket style, with a slow gravity turn, it gets a speed boost from the 48-7Ss so the engine runs out of fuel at around the same time as air ~30km.

I think getting a high apoapsis is hard with the basic jet because of it's poor thrust at high altitude - it's a champ for low level lifting though.

The science equipped one is slow to ascend, and I only had a slight turn before staging the lvt-30 and then made a very slow initial turn to allow vertical velocity to build.

[Yemo]

I just tried it, but I only had about 2900m/s dV left when in 80km LKO. It would be very interesting for me, what your 80km LKO number is. While 2900m/s is certainly enough for good pilots, I d probably need a bit more for a stress free Mun trip. I d really like to use this and/or the more forgiving Chimera from page 6.

Anyway, a great design!

[Slugy]

Heh - 2900m/s is about right - I made a rather sloppy ascent (shown in pic) and had 2835m/s left (pretty sure 2950m/s is doable) - which is plenty if you do a direct descent to the Mun (so no going into orbit): see the pics for larger one, aim to just skim the surface and brake full at a minute or less from impact! It's fairly tight, but does have some room for error (~300m/s) - I did have some tighter designs but they are too unforgiving to consider on a hard mode career without building upgrades ...

You could always add a little more fuel to the rocket stages.

Cheers.

[Kesa]

I just tried it, but I only had about 2900m/s dV left when in 80km LKO. It would be very interesting for me, what your 80km LKO number is. While 2900m/s is certainly enough for good pilots, I d probably need a bit more for a stress free Mun trip. I d really like to use this and/or the more forgiving Chimera from page 6.

Anyway, a great design!

Mun intercept requires at least 900 dv, and I find my self ease with 800 to 1000 m/s to land, depending where I come from (LMO/direct crash course), and a little fewer to ascent, so I would say 2900 is ok.

Landing is the difficult part. As said above, lower the PE to surface skim, and place node at it. You can use the manoeuver node to see how many time you have to burn, but I prefer use the formula : burn when time to impact = speed * acceleration / 2, with acceleration constant (precaculed and rounded down), so I don't have to constantly adjust manoeuver node. For the end of the landing, I know use the info of KER (either impact time or suicide burn info), but I guess KER is using a formula with altitude to terrain, quite simple to understand, but not to head compute (plus altitude to terrain requires IVA, which is very painful on landing)

@Katateochi you're definitely a master!

You learned me that 48-7s could actually be used in a non ugly way. Subscribed! And you're getting the most of the jet engines.

[Kesa]

6.6 t !!

Ok, it is easy to screw the ascent path, and it needs an hardocore EVA reeentry, but after three trials, Jeb it made it to the mun! And back. Here is one picture in the VAB, and here is a poor mission report. Also, depending on play style, tech requierement does not need grinding.

It is an Lite copy of Katateochi's one, without wings and only one jet engine on first stage, two rocko 48 7 s on snd stage and without any parachute on third. Oh, and there is a fourth stage called EVA suit.

Ascent Path is hard, designed to be a direct transfert (no LKO). I did not fly it enough to give a precise one, I start turning slowly at 5km. I'm still above 45° at 20km, and I know I'm ok if I am a bit above 30km and faster than 500m/s with more than 100 m/s verticaally when flame out. And I'm very good if third stage ignite above 36km, and I can burn prograde without falling.

On my very lucky try, I had 1643 m/s after the transfert burn, and 723 after landing.

The EVA part is tricky because no navball. I aim a direct crash course to one pole, because water mean sure and instant death.

A kerbal on EVA has a 60 m/s crash tolerance, but can bounce if it lands on feet or on helmet. Feet is easier as Kerbonaut tend to put feet down when rcs is activated (but can be rotated by left click and drag), but the head being considerably larger, it is more reliable, as the Kerbal can bounce high enough to be killed on the second impact.

Edited December 25, 2014 by Kesa
added content

[Torquemadus]

The best I could manage within the 18t limit was an orbit and return mission.

[Kesa]

The best I could manage within the 18t limit was an orbit and return mission.

That's quite hard without rockomax 48-7s nor jet engines. Congrat!

Also, solid fuel booster are very inefficient mass wise. Try replace you booster with one or two LV t 30. How to fit two lv t30 in an efficient non ugly way under your rocket? this is a question I haven't been able to solve. But a single LV T 30 can handle 18t. that will seem slow but it will be fine. If it's uncontrollable, add some winglets at the tail.

Oh! That reminds me, the Mk55 radial had a nice ISP buff - it's now 320-360 instead of 290-320. It's TWR is still kinda meh (same as T45), but it also had a gimbal range buff... I might actually use it for something now

Unfortunately the 24-77 is still the same as before..

24 77 is pretty useless, appart for aesthetic purpose. I would have love to see radial engines having a 10 to 30 ° gimbal, like the shuttle engines. That would make them very usefull to balanced assymetric craft. And maybe no gimbal for this tiny over powered 48 7 s. Also, It is far to cheap!

Yeah, you attach one, offset it, attach the next, offset that, and so on.

Maybe it's cheaty, since otherwise I'd need 12 cuboct struts, but it's not like I'm gravhacking or fuelhacking.

My point was that attachement nodes seems to have been thought as part of the difficulty of the game, and even then radial engines are under powered. The more I think, the less I feel it's cheaty. It should be doable without alt F 12 (though Katateochi has a very nice workaround with normal grider segments!), as this is a pointless restriction (it's just stupid that a small cube of struts requires as much science as a turbojet, and it increases part count). And crafts abusing of part clipping (yours is not) could be punished with aerodynamic and structural drawbacks.

Also, I really have a problem with the 48 7 s because it is even better than most bigger engines for most purposes. In a limited extend, part count discourage you to abuse of them in early game, but its irrelevant. I'd prefer there was some aerodynamics in KSP, and thrust to area ratio would matter, so 48 7 s will be a poor atmospheric engine.

Edited December 25, 2014 by Kesa

[Duban]

Has anyone had any luck creating a Mun Lander in 18t or less? I can get the fly-by. I can get an OKTO lander down. I can't get a manned mission down and back up again yet, not without EVA Thrusting.

I keep coming up ~700 m/s short in my calculations on how to get in and out again.

This is my kind of thread. I am a master when it comes to ultra-light designs. The trick is to create smaller, smarter, and more detailed landers. I could reduce their weight/cost even farther if I wanted to replace the capsules with rover chairs, but that's too cheaty for my tastes.

3.8 ton round trip to the Mun: http://imgur.com/a/AUAyj

4.61 ton round trip to Duna: http://imgur.com/a/5NSFg

15,500 credit round trip to Bop and Polhttp://imgur.com/a/BI4TO

19,300 credits round trip to Tylo (with help from reusable shuttle and lifter): http://imgur.com/a/M68qg

Edited December 26, 2014 by Duban

[Slugy]

This is my kind of thread. I am a master when it comes to ultra-light designs. The trick is to create smaller, smarter, and more detailed landers. I could reduce their weight/cost even farther if I wanted to replace the capsules with rover chairs, but that's too cheaty for my tastes.

They are very impressive, but the thread has rather drifted from the original point of it being a career mode craft with a lack of building upgrades.

[ghpstage]

You can still do it, you just can't thrust limit the boosters, that's all. I would've used a decoupler, but I'd never done a trip to the mun on batteries before so I was just saving every part I could :/ I'm really liking the new career mode and how it pushes you to the limit, my previous mun rockets were these giant skipper/s1-srb beasts, and this was quite small!

Woah.

I hadn't seen this even though I posted on that page.

After seeing people slagging the Stayputnik off, and being bored I tried playing around with it, eventually ending up with nearly the exact same solution to the same, very niche problem

The only differences are that I used 14 batteries after a first, 8 battery run failed but gave me a decent benchmark, I took 2 goos as they require less tech, and I did use a decoupler as I was thinking about a return mission and wanted to save even the tiniest specs of fuel.

I then slapped solar panels on it and sent it to Minmus (might even be able to make it back from there next time), and thought, why not elsewhere.

Turns out it has the dV to reach out and clear the Jool exploration contract if your careful with thrust and use aerobraking.

Edited December 27, 2014 by ghpstage

[Greep]

Woah.

I hadn't seen this even though I posted on that page.

After seeing people slagging the Stayputnik off, and being bored I tried playing around with it, eventually ending up with nearly the exact same solution to the same, very niche problem

The only differences are that I used 14 batteries after a first, 8 battery run failed but gave me a decent benchmark, I took 2 goos as they require less tech, and I did use a decoupler as I was thinking about a return mission and wanted to save even the tiniest specs of fuel.

I then slapped solar panels on it and sent it to Minmus (might even be able to make it back from there next time), and thought, why not elsewhere.

Turns out it has the dV to reach out and clear the Jool exploration contract if your careful with thrust and use aerobraking.

Well there's only so many ways of slapping together 18 tons when you have 120 science, so near duplicates are bound to happen. Like I think there is exactly one way to orbit at start.

And yeah, I used to go for launch upgrade first but now I do the tracking station first... it's surprising what 18 tons can get you

Now if only I can get to duna without patched conics :3

Edited December 28, 2014 by Greep