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JackBush

How to get a mobile lab up there

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Please don't laugh (too hard) but I've been struggling to come up with a ship that will take a mobile processing lab along with a Science Jr and Mystery Goo up to either Minmus or Mun. Here is what I have at this point: http://imgur.com/BIioKL5

Without trying to explain myself, I'll just ask: what would you do?*

*After you've finished laughing, that is.

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1 hour ago, JackBush said:

Please don't laugh (too hard) but I've been struggling to come up with a ship that will take a mobile processing lab along with a Science Jr and Mystery Goo up to either Minmus or Mun. Here is what I have at this point: http://imgur.com/BIioKL5

Without trying to explain myself, I'll just ask: what would you do?*

*After you've finished laughing, that is.

Naw, not laughing.  Maybe chuckling a little.  But strictly reminiscently, since we've all been there, my friend.  :)

First, I'd say lose the paraphernalia poking out the sides of the rocket.  Keep things radially symmetric. You can set the Science Jr. on top of the command pod, you're not really giving up much by lugging it home (it's a tiny fraction of the pod mass).

When I want to land a lab on the Mun, my typical construction is to put four of the long skinny 4-ton LFO tanks radially attached around the lab, with a Terrier on each one, and a nosecone on top of each (for aero when launching).  That gives 16 tons of fuel, which is a nice stage amount, with enough thrust for landing on the Mun and a pretty good Isp.  It also gives a nice squat stance for landing (put the landing legs on the radial fuel tanks, so that when landed the science lab is only barely above the ground).  A Poodle would be lighter, more powerful, and slightly higher Isp than four Terriers, but I'd have to sling it under the lab which makes the ship taller, and I prefer the low squat stance with Terriers; they're good enough for this.  (Those radial stacks are also a convenient place to put things like reaction wheels, 1.25m batteries, etc.-- i.e. stuff that you want to avoid putting in-line on your main stack so you keep the central stack nice and rigid.)

Then put a Rockomax decoupler under the lab, with a 16-ton tank and a Skipper.  Then under the Skipper is another Rockomax decoupler, a Big Orange Tank with Mainsail, and a bunch of radial Kickbacks for liftoff.

You can play around with the details, but the core idea is, don't try to land a lab-on-top-of-fuel-tank-on-top-of-engine, it's just too topheavy for a lander.  Mount stuff radially to the lab.  If it's just four 1.25m stacks, the drag's not too bad on liftoff (especially with nosecones on them), and it vastily simplifies the design of the ship otherwise.

It's almost never a good idea to put one Big Orange on top of another Big Orange, or at least I've never found a good reason to do so.  If I need that much fuel I go up to the big 3.75m tanks.

A favorite somewhat-heavy booster stage that I tend to use a lot for 2.5m stacks consists of a Big Orange tank with Mainsail, and an even number of Kickbacks radially around it (quantity depending on ship mass).  If it's just 2 boosters, then they stage off together.  If it's more than two (i.e. 4, 6, or 8), then I don't make one symmetry group; instead, I make two symmetry groups, with one group at 100% thrust and the other group at whatever percentage is needed to give TWR 1.5 on the pad (typically around 60-70%).  That gives my SRBs some additional legs-- I take off on all SRBs at once, but the hundred-percenters run out of fuel and are jettisoned first, and I can continue flying for quite some time on the 2nd group before they run out and I activate the Mainsail.  Sort of a "poor man's asparagus."

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Will a science junior fit inside a 2.5m service bay?

Or fit two (or more) FLTx00 tanks on the side and stick a science junior plus a nose cone on top of each one. If you want to land, this gives you wider places to stick on legs.

 

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Depending on the TWR you want, you can keep the 2.5m tank under your lab and run fuel lines to the radial terriers. If your radial connections are on the lab itself, you can decouple the tank when it runs out, and still have your radial tanks full. It would be useful for a transfer burn to the Mun and Mun orbit insertion where TWR is not as important as takeoff/landing. 

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I initially didn't understand why you have the Mk1-2 pod + heatshield + stack separator on top there. Since there is no propulsion system attached to them, you're going to have to bring the mobile lab all the way back to Kerbin and then ditch it in the atmosphere if you want to bring anyone back.

If you really need to bring the pod home, it is possible to add the smallest 2.5m fuel tank + radially mounted twitches to the command pod and have it lift off the top of the lab on the surface of the Mun. Alternatively, bring the top part down to 1.25m scale and just have a single-occupant command pod lift off (much easier on weight and fuel). If your contract imposes a 5-kerbal capacity, you can always add lander cans or command pods. Just don't forget the docking ports (radially on the MPL works fine).

To land an MPL on the Mun, I always use four radial rockets (similar to Snark's suggestion, except I generally put an X-200-8 on the bottom of the MPL and radially attach four FL-T200 tanks to it, with terriers underneath and fuel lines to keep them supplied from the centre tank, although this gives you far more fuel than you need). If you need more kerbal capacity, you can attach these in pairs and put lander cans or command pods on top of one of the pairs, and leave it all behind when you go back home.

The other advantage of reducing the Kerbin-return section to the 1.25m form factor is that it completely solves the Science Jr. issue, since you have a 1.25m section to house it (and even bring it home safely if you want). The other options would be under the docking port or in a 2.5m service bay: it does fit.

And finally, to future-proof the lab if you leave it on the surface, add batteries, solar panels (the retractable ones) and antenna to it. Then you can leave a scientist on it to generate science points, and come back later in the game to pick him up. If you don't have a spare scientist, just dump the lab on the surface and then come back to it once you have more staff. Whatever you do, you will not regret having plenty of batteries.

You could also future-poof your lab to make it possible to complete a potential "expand your outpost" contract. On the Mun, that generally means leaving a docking port fairly low down at a pre-defined height (the centre-line of the biggest landing legs is a useful indicator) so you can drive a future rover up to it. Be prepared for pain and frustration in the process though...

 

For the Kerbin ascent part - I never build so tall, because that means I'm lifting a huge amount of fuel + unused rocket engine above a single engine. My centre stack tends to be X-32 + X-16 (or rarely a single orange) with Skipper underneath, then asparagused 1.25 stacks (generally two side stacks of 2x FL-T800s) with Reliants or Aerospikes. That gives a relatively cheap and reliable (and efficient) middle stage for a wide range of payloads. Then add asparagus 2.5 tanks (with bigger or smaller engines, depending on payload) and/or boosters to get out of the lower atmosphere.

Edited by Plusck

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Thanks for all the responses! I haven't had a chance to get to them yet, but I will. I've been tied up with Saturday's NFL playoffs and other things. And will be again today. 

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Plusck allready gave a nice answer, so I just add this:

Landing legs on the engine fairing are pretty pointless. As soon as you stage they stay with the part that you throw off so you end up without landing legs on your lander :)

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Build wide. (Yes, I launched it just like that, aerodynamics and all)

41A599E310A277358D13DA9ECCA5C01F6389DE4EF977B33A8BDDAC6299BF0D0CE4DBDD15DE837EB9

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1 hour ago, Alshain said:

Build wide. (Yes, I launched it just like that, aerodynamics and all)

41A599E310A277358D13DA9ECCA5C01F6389DE4EF977B33A8BDDAC6299BF0D0CE4DBDD15DE837EB9

Thanks, Alshain. I'm wondering what your launcher looks like under that lander. Got another pic? 

Thanks to everyone, especially for going into so much detail and putting up pictures. Great people. Great forum.

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Sure, it's my standard Tier 6 40 Ton lifter. (The outer fuel tanks are held by small hardpoints btw, it's hard to see).  Also I sent a separate fuel tank to refill it, just because it would have been hard to launch all in one go.  The lander makes the full transfer on it's own, gets topped off by a tank, and then lands.  Of course you don't have to do it that way.58A5AD50D732BDA582775E7F18B28D4F16725533

Edited by Alshain

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6 minutes ago, Alshain said:

Sure, it's my standard Tier 6 40 Ton lifter. (The outer fuel tanks are held by small hardpoints btw, it's hard to see)

Beautiful. Hope you don't mind if I copy; I'm getting so frustrated (as you can guess from my original design).

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Not at all. I could give you the craft file if you want, but you will learn more if you try to recreate it.

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8 hours ago, Alshain said:

Not at all. I could give you the craft file if you want, but you will learn more if you try to recreate it.

I agree. I'm looking forward to getting to it tomorrow. i want to work on some of Snark's advice, too.

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You could design something like this as a lander:

 

Stack it on top of the mobile laboratory. I made this back in the pre-1.0 days, but it still works fine. Some aspects of it are overdone and could be removed to save mass, but it has the nice wide stance for low-gravity landings and enough dV to get you down to the surface (from Mun/Minmus orbit) and back to Kerbin in one go.

As for your design, it's not horrible, just overbuilt. You don't need that much fuel to get where you're going with that lab because you're wasting a lot of energy hauling extra weight. The first stage of your center stack is the right size, but you don't need the second stage. What is currently your third stage can become the second stage (with a Skipper) under your lab/lander to push it the rest of the way to the Mun. Get rid of all that stuff sticking out on the sides. Take the legs off the lab and pack 3-4 radial chutes instead -- being sure to leave yourself just enough fuel to soften your landing with a power-assist from the engines. Get rid of the heavy pod on top and replace it with a lander like what I've made above. It's heavier than the pod, but if you lighten the whole launcher you can gain significantly more utility (and science for less total mass) by being able to land on the Mun while your mobile lab stays in orbit. EFFICIENCY!

Edited by arise257
Further explaining

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If what you want is a little science factory on the Mun then abandon your scientists there! Or plan to recover them some day in the future. 

This will let you reduce your payload significantly to just the MPL (with two scientists onboard), probe core, some power, an aerial, experiments and a couple of small tanks and engines (Sparks are good). You shouldn't even need landing struts at that mass if you make sure you hit a fairly level spot. Tweak it for whatever you have unlocked so far. 

Would probably halve the mass you will be shifting and make the lifter much simpler (and cheaper). 

This weighs about 8t and I only used about half the fuel landing it on the Mun so you could probably use less fuel for a ~6t craft...

3mPpILf.jpg

Some design considerations:

You want some decent sized solar panels, as running the MPL takes a bit of power. I have a couple of Gigantors on here but smaller deployable ones would easily do. 

Batteries are important. Otherwise you will run out of power when transmitting and at night. 

Position the experiments so that the data can be collected easily from them and brought back into the MPL. Don't forget an EVA report and surface sample. 

Any engine with some gimballing will be able to cope with a bit of offset mass like a Science Jnr and Goo (the other experiments are physicless). 

 

Edited by Foxster

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“And for your moon mission, Bob, this is what we came up with”

“Haha, it’s been a while since I read up on aerodynamics, but that doesn’t look like something that will handle well during re-entry”

...

“Re-entry?”

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4 minutes ago, Kerbart said:

“And for your moon mission, Bob, this is what we came up with”

“Haha, it’s been a while since I read up on aerodynamics, but that doesn’t look like something that will handle well during re-entry”

...

“Re-entry?”

Thart made I larf!

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I had a thought that the new Mk1 Crew Cabin would make a nice, light Munar return craft for a couple of crew on a mission like this...

I saved some weight by using the same pair of Spark engines to land the craft on the Mun and for the return to Kerbin with the Cabin. 

That Cabin does pose a little challenge though - no side doors! So I spent a while trying to figure out how to get the crew onboard from one end. Worked out pretty good in the end. Oh, and don't say "Use transfer to move the crew". That doesn't move the juicy science goodness, needs to be done via an EVA. 

Craft file: https://www.dropbox.com/s/lbib5tgfqbl9uba/Mun%20MPL%206.craft?dl=0

Edited by Foxster

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I love this, Foxster. i don't have some of those parts yet, namely the orange rubber-tire type fuel tanks. But I'll give it a shot. I've got a lot of build ideas now. Thanks to you and everyone else.

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Just one more slightly mad idea. (You might be able to tell that I'm a bit bored!). 

Mount a return-capable rover under the MPL that is also used as the landing engines. Have a bit of a drive around and then fly home....

rhCyBFK.jpg

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pKZSb5i.jpg

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Fun stuff! Out of curiosity, what do you have tucked away in the service bay? And what are the gold round fuel tanks feeding?

BTW, you may be bored but look like you're having fun!

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1 hour ago, JackBush said:

Fun stuff! Out of curiosity, what do you have tucked away in the service bay? And what are the gold round fuel tanks feeding?

BTW, you may be bored but look like you're having fun!

I'm guessing the gold fuel tanks were fuel for the descent, feeding the same engines on the rover. It makes sense to leave those empty tanks attached to the lab and just send the rover into orbit. Good little spacecraft design there!

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1 hour ago, FlyingPete said:

I'm guessing the gold fuel tanks were fuel for the descent, feeding the same engines on the rover. It makes sense to leave those empty tanks attached to the lab and just send the rover into orbit. Good little spacecraft design there!

Spot on. 

The service bay has the science stuff and batteries. 

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