career rocket woes

[grumphie]

so, ive been playing career mode. fun and all, but now im hitting a wall: im barely getting any science from my experiments because i've done them too often(fair enough). so, i need to go to deeper space: the mun. so, i borrowed my normal payload from my orbital rockets. its an rather basic thing, with room for one brave kerbonaut, 4 parachutes, 12 batteries, 4 mystery goo, and an science junior.

while my other rockets were decently capable of shooting the thing into low(80-100km) orbit, i'd always end up with like 4-36 feul and the like left, allowing me to do an few experiments, transmit everything back to the space center, and lower my orbit enough for rentry. so, i set out to design an new rocket. big deal, i thought, i made it to the moon and back like an dozen times already. designing an rocket to get there should be easy enough.

o god, i was wrong. im not even trying to get to the mun anymore, im just trying to shoot an rocket into space that has enough fuel to make an larger orbit. right now, im just failing miserably. my average atempt ends either with an wobbely rocket that explodes at 3000M or an rocket that falls back to kerbin just shy of space or an orbit because of lack of fuel and/or thrust. thile my attempts get better and better, an highly eppeliptical orbit(80km -> 300-ish km) is still the best i can manage - not even close to even getting in the gravity well of the mun, let alone get into orbit, do some experiments, maybe land, and get back again.

so, now im asking here: what should i do? i cant upload screens of my botched attempts until later, but are there any general tips anyone can give me or any examples might be showed of an simple career rocket that can reach the mun? im still fairly new to the game(dune is the furthest i've savely reached, landed and came back from again, not counting my probes) so im fairly certain im missing some things.

thanks in advance

grumphie

[capi3101]

First, listen to the Hitchhiker's Guide: don't panic. Second, how far along the tech tree are you? Third, what would you like to take with you to the Mun and back?

[grumphie]

im not really panicking(im well beyond that point:P), just mad at myself to suddenly forget about everything i know about spacecraft design. in my head, things should work, while in reality they dont.

i've gotting every third tier(the 45 science levels) research, everything under that, and heavier rockets.

i'd like to take:

jeb kerman

an goo container

an science junior

to lunar orbit, and back to kerbin without everything falling apart once i land. im very certain that once i get an lightbulb moment once i get an rocket capable of doing that i can shoot heavier things and devise an way to land there and get back again. however, im rather terrible at making very effiecient takeoffs or orbital teansfers, so i always take an overkill of electriccharge with me to make sure i dont run out of it halfway through and get an uncontrollable ship, can transmit anything i need and also make surei have PLENTY of fuel, as im unable to get into orbit and the like with an small margin.

[SRV Ron]

If you have batteries already, you should be able to build this and orbit Mun or Minmus. This assumes that you have the radical decouplers and the LV-909 for the upper stage.

Your intercepts and return maneuvers should look something like this;

Build no more then needed . Without bracing, you will have control issues in larger designs. Orbital Jeb has minor control issues on the SRBs that bracing would eliminate.

[SRV Ron]

Note that both maneuvers are set up for fail safe reentry.

[capi3101]

Batts come in at Tier 4 (with Science Tech). SRV Ron's designs will work for a Munar flyby, though the name of the game is going to be power conservation. No SAS and disabled reaction wheels when the engines are off or you won't have enough juice to fire the chutes at the end of the trip. Do your science while you're in the Mun's SOI and don't circularize; just take the free-return home.

Next one after Sci-Tech you want is Flight Control, and then Electrics on Tier 5; at that point, you finally have access to OX-STAT solar panels.

[Dave Kerbin]

Can you upload a screenshot of your rocket (side view), we might be able to identify what is going wrong.

You can read my posts on building a Mun mission with basic but practical tech (no need for engine nozzle landings or jerry-rigged decouplers). Since you have the Science Jr. you already have Survivability which is the key technology. You also have batteries which are useful but not essential (though you wouldn't be able to transmit any crew reports en-route without them). If you don't have Stability researched you might want that, the radial decouplers make staging a Mun capable rocket much easier. I also had General Rocketry which improved the booster stage design and made it much more stable thanks to thrust vectoring.

http://forum.kerbalspaceprogram.com/threads/53661-Return-soil-samples-from-Mun?p=709242&viewfull=1#post709242

http://forum.kerbalspaceprogram.com/threads/53159-Science-leads-to-wonderful-things?p=707046&viewfull=1#post707046

[Seret]

Do your science while you're in the Mun's SOI and don't circularize; just take the free-return home.

This. Transfer out to a Mun encounter, then a wee burn to drop your Pe into the atmosphere and aerobrake in to collect your fat science payoff.

[grumphie]

not at my home pc atm so no screenshots, but this morning i was able to shoot my science into an 10 second SOI of the moon, allowing me to do some science. however, my rockets are still quite bad - i dont see how im ever gonna shoot something to the mun with these parts. same with this rocket. onoy just hit orbit with my final stage, leaving only an tiny bit of fuel just enough to launch myself to the mun and lower my periapsis to earobreak at 50km, even though i designed it with the idea to reach orbit with my first 2 stages, and only use my upper stage fornreaching the mun and maybe visiting minmus.

[grumphie]

these are not relaly all my tries, i think ive had about a dozen other tries before i changed the name on about each munar(and about half a dozen times i reverted flight or changed it until it fixed some eroors liek wobbling and the like)

so far, only the munar VII(or better, VI with me changing this now for the VII model) actually made it to the mun. at one try i just put an bunch of rockomax 16 tanks and the poodle under it with some boostes next to it, and while it made it to 68km, it couldnt push itself into orbit, with my initial plan to dump those tanks once i reached the mun. the sepratons on one of them was meant to give me an boost to leave the mun.

every time i think i will make it, things look good in the initial stages, i reach a few hundred m/s while trying to reach orbit(heck, my rockomax try reached 576m/s), but falls just short of fuel or thrust at the end. and when i DO reach space, i either lack the thrust to push my ship into stable orbit, or end up with so little fuel left that im lucky if i can make it back to the planet

edit:

my bit more succesfull munar VII that almost made stable orbit using only the first stage, allowing me too have an shot at reaching minmus or stable mun orbit.

Edited October 19, 2013 by grumphie

[RSF77]

Do you have fuel lines? Asparagus staging? I can't tell but it looks like the last big rocket with all the poodle engines doesn't have it. Also structural connectors, tie everything together.

This seems like basic stuff so sorry if I missed something here, I haven't played career mode so for all I know these parts aren't available.

Edited October 19, 2013 by RSF77

[Dave Kerbin]

Those rockets all look like they have just 2 stages for getting to the Mun, or a total of 3 powered stages when you include the Mun lander itself.

While it is possible to make a 2+1 stage Mun lander I personally think it is easier to develop a rocket with 3 to 4 stages plus lander so you can shed as much weight as early as possible, which greatly increases the amount of fuel you'll have left over. Carrying the weight of most of your launch vehicle into space is going to use up most of your fuel.

The first stage needs to get you off the ground and moving. Because it has to lift everything else it's going to need a lot of power and so it will weigh a lot by itself. You'll want to get rid of this stage pretty quickly to lighten things up.

My suggestion is that this 'launch' stage should get you to between 3000-5000m altitude and moving at 150-200m/s. Solid boosters are a good choice unless you are experienced with fuel lines and drop tanks. Your third screenshot, Munar I, looks like it has a good solid booster stage (probably more power then you need, but if it's the first thing you get rid of that's not a problem unless your ship goes out of control).

The second stage and third stage are two parts of the same thing. I suggest 5 strong liquid engines (LV-T45 are very good for keeping stability) to maintain the thrust/weight ratio needed to keep gaining speed in the low atmosphere. I would set it up so that you can drop the 4 outer engines as you reach higher altitudes (the center engine becomes the third stage), make sure the middle engine has more then twice the fuel if you are running without fuel lines. If you have access to fuel lines I would run a line from each of the outer engine tanks to the center engine's tank, and instead give the outer engines about 25-50% more fuel then the center, since the center engine will be able to draw from those outer tanks first. With fuel lines used you might setup the center engine with a T800 fuel tank, and each of the outer engines with a T800 and a T400. Drop the outer engines when their fuel supply is used up, which reduces the weight you need to carry substantially.

After the 3rd stage single engine has burned all its fuel you should be close to the edge of the atmosphere (with an AP above it) and within reach of a stable orbit. The 4th stage should be a high efficiency orbital engine (LV-909) with a fuel tank like the T800, maybe a bit more if you didn't have fuel lines used in the previous stage. This orbital stage should stabilize your Kerbin orbit and then be enough to send you to the Mun and circulize your orbit there. Use any fuel left to assist your descent burn with the final stage, your lander.

Overall my suggestion is that if you feel you are running out of fuel, add more fuel to the earlier stages, not the later ones. If you are not gaining speed in the atmosphere you need more engines (watch your m/s speed, if it starts to go down for part of the burn instead of up it means you don't have enough thrust and are wasting fuel), but try to shed as many engines as soon as you can, they weigh a lot and need extra fuel just to keep them along.

[Oddible]

The above thread has good advice about multiple staging but careful staging vertical or you'll get wobbly fast, go horizontal. Dump your tanks in pairs. You have some pretty good tech already. One thing that helps a LOT is Fuel Systems tech so you get the fuel lines and can run asparagus staging - so your can run all your rockets and they pull fuel from the tanks you'll dump in your early stages. Here is my Mun lander (no Science Jr) with battery power only, and my Duna lander (no return trip so I only took a probe core, 1 lander for Duna, 1 satellite for Ike) with solar, but you get the idea from the ship design.

A few tips: Don't take the Science Jr to the Mun your first trip, take the smallest lightest (and shortest lander) rocket. Remember weight matters, and everything you put on your ship has a huge impact on the weight. Get rid of all those Sepratrons. You don't need that many legs. Those radial chutes are weighty too so only bring as many as you need.

Keep it simple.

Edited October 19, 2013 by Oddible

[Seret]

careful staging vertical or you'll get wobbly fast, go horizontal.

Horizontal can get pretty wobbly pretty fast too, if you've got more than one layer of radially-mounted boosters.

Keep it simple.

Best advice. Keeping the ship as small and simple as possible will make it easier to fly. You should be able to get an easy Mun flyby with a 3 or 4 stage ship. Something like 4 large SRBs firing simultaneously with a LV-T45 to get you into the upper atmosphere, obviously dump the SRBs when they burn out, and drop the next stage in the upper atmosphere, another LV-T45 to get into orbit and maybe start the munar insertion burn, then a LV909 on your final Mun flyby stage to do/finish insertion and to set you up for aerobraking back into Kerbin. You shouldn't need any tech above Tier 3. Those radial chutes are handy for coming back and recovering Goo Pods or the science pod if you've got it.

Edited October 19, 2013 by Seret

[Dave Kerbin]

Horizontal can get pretty wobbly pretty fast too, if you've got more than one layer of radially-mounted boosters.

Best advice. Keeping the ship as small and simple as possible will make it easier to fly. You should be able to get an easy Mun flyby with a 3 or 4 stage ship. Something like 4 large SRBs firing simultaneously with a LV-T45 to get you into the upper atmosphere, obviously dump the SRBs when they burn out, and drop the next stage in the upper atmosphere, another LV-T45 to get into orbit and maybe start the munar insertion burn, then a LV909 on your final Mun flyby stage. You should need any tech above Tier 3. Those radial chutes are handy for coming back and recovering Goo Pods or the science pod if you've got it.

I agree, simple is the way to go. That's why I don't go heavy on the asparagus staging for untested manned rockets, it's a bit of advanced technique and if you build it wrong your ship will lose control and either spin or flip over. Onion staging, with or without fuel lines, works well enough and requires almost no previous experience to build and fly correctly.

Oh, and since no one explained it for grumphie here is what we are talking about with 'asparagus' and 'onion' staging. Let's assume we have a rocket composed of 5 engines and 5 fuel tanks - one engine+tank is in the center, the 4 others are attached to the sides.

In 'flat' staging (I don't know if there is a proper term for this) you would burn all 5 engines and then they would all be released at once, letting the whatever stage is above them start. This kind of staging means you need to carry new engines for each stage, and until that stage is reached the engine is dead weight.

In 'Onion' staging the 4 outer engines are dropped first. To accomplish this there are fuel lines leading from the outer fuel tanks to the inner ones. This means that the 5 rockets are initially using fuel from the 4 outer tanks only. The inner tank remains full. When the outer tanks are empty they and the outer engines are dropped and the inner engines continues on with the full center fuel tank. You can also make a poor man's version of onion staging by just giving the center rocket a bigger fuel tank if you don't have fuel lines yet. In this type of staging we effectively reuse the center engine for 2 stages, saving weight.

In 'Asparagus' staging the fuel lines are more complex. Assume that the 4 outer tanks are labeled 'left' and 'right', 'forward' and 'rear'. The left tank has a fuel line leading to the forward tank, and the right tank has a fuel line leading to the rear tank. The forward and rear tanks then have fuel lines leading to the center tank. When it takes off all 5 engines will be drawing fuel from the left and right tanks. When those tanks are empty they and the left/right engine are dropped and the ship begins using the fuel in the forward/rear tanks. When those are empty they are dropped too and we have with the center engine and the full center tank. This kind of staging is obviously more complex - bigger asparagus rockets can have dozens of seperately released tanks and a maze of fuel lines to contend with. The complex draining and dropping of tanks also leads to potential balance issues - if the tanks are not all placed at the same height, or don't drain uniformly the rocket's center of mass can shift, which means the rockets are now pushing it up and into a turn at the same time, causing it to spin rapidly or flip over.

[capi3101]

OP, I misread your post that indicated your current tech level - sorry about that.

There's one more option: try to get your payload up in one go, without staging. This is a kind of booster I specialize in for light payloads like what you have here.

Okay, so two goo containers, a science junior and a Command Pod for a munar flyby. 4550 to orbit and 860 for an intercept with a free return. I'll give a little extra in case you need to maneuver - say another 25%, so 1075. 5,625 m/s of delta-V is all you need. 1.15 tonnes just for the stuff you want to bring. Let's then go with twelve batteries (.06) and two radial chutes (.3). So that's 1.51 tonnes of payload.

First, the transfer stage - you're light enough that a 909 will do the trick easy (.5), and you need a stack decoupler of course (.05). 2.06 tonnes deadweight, and a 909 has an Isp of 390 in space, so all you need is an FL-T200; that will give you 1,441 m/s of delta-V, more than what you need to get to the Mun and back. Hell...that 1075 figure already included a buffer; this gives you almost twice what you need. So consider trying it with an FL-T100 if you think you can get away with it; you'll save some weight.

Actually, scratch that - half a tonne isn't that big of a deal with such a small rocket.

That leaves the booster, which is doable with the parts you have available. Your payload and transfer stages are 3.185 tonnes combined - so you'll want a centerstack with four outboard stacks; LV-T30s outboard and an LV-T45 in the center (the -45 gives you steering authority). That's 1060 kN of thrust total, sufficient for your needs. 6.5 tonnes of engines plus another stack decoupler (.05) and your deadweight is up to 9.735 tonnes. Ground Isp of your engines is 320. So you need a little over twelve tonnes of fuel in each stack. Two FL-T800s, one FL-T400 and one FL-T200 in each stack should do the trick. Your total mass is 71.61 tonnes; launch TWR is 1.51.

(I'm glossing over all the math here; I apologize and can elaborate more on the process if anyone is curious).

You've got struts, so use them. String the centerpoints of each of the outboard fuel tanks to the next adjacent stack, and then add one going to the center stack. Attach an additional strut from the top of the outboard stacks to the FL-T200 in the transfer stage. That should be all the strutting you need.

This is an SSTO booster, so you have to follow some guidelines for the flight - first, you start at full throttle but you cannot leave it there; watch the gee meter as you go and throttle back a little if you climb out of the green zone; towards the end of the ascent, you may only be burning at 1/3 throttle or so, which is totally normal. Straight up to 10,000 m, 090 at 45 degrees to about 25,000, then follow the navball. Burn along the horizon after 50,000 until you've got your apoapsis where you want it (usually at 100,000 m). Stop burning, plan an orbital insertion burn once your ship's altitude is over 70,000, and burn at about 1/3 thrust (it'll take three times as long to complete as the node will indicate). Once your periapsis is over 70,000, you're in orbit. After you've circularized, cut loose the booster and activate the transfer stage engine. Burn for the Mun when ready.

Hopefully I've given you enough juice to make it there and back without problems; follow the type of flight path that SRV Ron was kind enough to provide a screenshot for earlier in this thread - in particular you want to watch the altitude of your Kerbin periapsis on the return - you want that to be 30,000 or so. Make the burn and shut off your reaction wheels in the pod, no SAS either. You should have enough juice then to make the flight. Do your science in Mun's SOI, drop the transfer stage before opening the chutes when you get back, and you should be golden. I've designed this with more delta-V than it needs, so if it turns out there isn't enough electrical power, add another quad of batteries. The extra mass won't shave that much off your stage delta-Vs, and 1600 should be more than enough for just a Munar flyby.

When you get OX-STATs, ditch all but four of the batteries and add four OX-STAT panels; this design will still work and you could even consider sticking around in orbit for a while.

Edited October 21, 2013 by capi3101

[SRV Ron]

As mentioned, my Orbiter Jeb not only makes it easily to Mun and back, it was placed into 25K Mun orbit and returned to an aerobraking landing with fuel to spare. Note how much resources were left for that return maneuver especially in the capsule battery. That is due to slow maneuvering to position and shutting off the SAS as soon as maneuvers were complete.

[Stealth2668]

Here's what I used. I was able to orbit the mun while staying in Kerbin SOI (basically I didn't circularize around Mun.)

[Jerjare]

The key to staging is to remember that each stage has to carry everything above it. Your first stage should have the most engines and fuel. Once you get into orbit, you need a fraction of fuel to get to the Mun and back.

[grumphie]

my munar VII is now adrift in the solar system, goodbye halfal kerman. i was just an bit of fuel short of getting back into kerbin orbit. in better news, due to having some solar panels from my VI mission halfal kerman has greatly contributed to science, sending in tons of research. as an reuslt, i was able to research an bunch of new techs, most importantly, somewhat proper solar panels you dont have to manouvre your ship too much for, and fuel lines and the like. im now planning my munar mission to land jeb on the moon(no return guaranteed, sorry jeb), and im gonna take the advice on multiple stages and launch an monster rocket(made possible by the skipper engine) with basic onion staging, with 3 main stages:

1. the lander, having the 909(i think, its the small engine) for making an soft landing and taking off again, hopefully with enough fuel to get jeb out alive.

2. the orbital stage having the t45 and 2 t30's, with fuel lines from the t30's and a decoupler in between so the t30's can be dumped once depleted

3. the launch stage, consisting of an skipper engine and 8 t30's, with the t30 tanks also feeding the skipper tank and being dropped off once depleted.

so far, the first test flights have gone decent(the skipper broke my ship becausei accidently hitted spacebar while it still ahd some fuel left with my other engines not starting yet=crash), with the launch stage alone being able to propel my craft into semi-orbit, and i actually think it might be better to remove the t30's fromt he orbital stage and maybe add in an lighter booster for it, and add an little help for the lander stage considering i already ran out of fuel trying to return from orbit(i think im doing something horribly wrong there). still in heavy test phase though.

[kookoo_gr]

My advice on your creer space program. Watch Scott Manley's tutorial on how to land on other planets (he's using Minmus). Try to copy the tutorial, if you add at Manley's rocket two more liquid fuel tanks for liftoff, ie make them four then you'll be able to land on the Mun and return with fuel to spare. From there on for heavier payloads you'll have to adapt the rocket. Also your payload is too heavy, i use a comand pod, 1 battery, 4 solar panels, 4 landing legs, 1 science bay, 2 mystery goo canisters, 1 ladder, 1 antenna, 1 parachute, 2 radial parachutes, 1 LV-909 and 1 FLT-fuel tank.

Edited October 20, 2013 by kookoo_gr

[KSK]

Here are my Munar exploration and science vessels. They're not quite the all-in-one machines that you were asking for but they've got me a decent haul of data anyway and they're both pretty low tech. First up - the Explorer.

Orbital science pod. Only really works with some kind of solar panel on board, so you can do plenty of transmissions as the science modules aren't intended to be recovered. The fuel lines are only there so I could do a split fuel tank arrangement. That's more or less purely for aesthetics though.

Next - the Pioneer.

LV-T30s in the first stage, LV-T45s in the second stage with an LV909 in the third stage. Flies quite nicely, although you don't want to pitch over too far before jettisoning the first stage as it's a little top heavy once the first stage empties out.

Will land on Minmus and get back with around 50 fuel to spare. I havn't tested this yet but you could probably add a couple of goo pods to the capsule for extra science. Otherwise (without solar panels) you can get a single crew report from the surface, as many EVA reports as you care to stack up, plus a sample return.

It will (barely) land on the Mun and get back but unless you're using Mechjeb or are better at manually flying ascent profiles than I am, you probably wouldnt want to put anything else on it. I got back to Kerbin with about 1.5 units of fuel in the tank. Still you can get a lot of science with this by orbiting the Mun and getting lots of EVA reports from low orbit before going for the landing.

Edited October 20, 2013 by KSK

[capi3101]

Just now getting up to the point myself where I can recreate my Apocalypse 7 craft - not the first Munar lander I ever designed, but one of the most successful ones I had in the early going with 1.25 m parts. It was originally designed in 0.19 so it's in need of an update at this point, but I bet the same design principles apply. Your design philosophy is essentially the same as that of the Apocalypse - a direct ascent lander that also serves as the transfer stage back to Kerbin, a transfer stage and a booster.

Here's how I'd do it: Set your sci stuff with the CM. Put a stack decoupler on the bottom, then add four FL-T200 tanks, one centerline and three outboard. Run fuel lines (if you have them) from the outboard tanks to the center, and slap a single LV-909 engine on the bottom of the center tank. Put six lander legs on the outboard tanks, two on each leg. Struts for stability. If you want to add a reaction wheel or RCS if you have it, go ahead. You also want to add your power generation here.

Then the booster is two FL-T800 tanks with an LV-45 in the center and six FL-T800 tanks outboard with LV-T30s (use TT-70 radial decouplers to attach these). Set the engines to fire together and run fuel lines from the bottom of the outboard tanks to the centerline tank. On the bottom of each engine, add a stack decoupler and add an RT-10 SRB; these seven SRBs are what you use at launch. The fuel lines make the difference; the center engine stack should have enough juice to complete the ascent, circularize around Kerbin, transfer to Mun, orbit Mun, and de-orbit the lander. From there it's a matter of watching your fuel when you land. By using small tanks radially, you shorten and widen the lander, which means it will be less prone to tipping over when you get to the Mun's surface.

[cerberusti]

My first Mun lander was simple enough to describe in text (43 parts total, I had only Basic Rocketry, General Rocketry, and Survivability.) I am playing with no mods of any kind in career mode, this was my second flight.

If your technology level is higher there are better designs (especially once you have structs and fuel lines.)

From top to bottom:

Lander:

1) Mk16 Parachute

2) Command Pod Mk 1

3) Two Goo Pods attached in dual symmetry to the command pod (not blocking the door)

4) TR-18A stack decoupler

5) 2x FL-T400 Fuel tanks stacked

6) 4x LT-1 landing struts attached in quad symmetry to the lower part of the bottom fuel tank

7) LV909 engine

Orbital insertion:

8) TR-18A stack decoupler

9) 3 center stacked FL-T400 Fuel tanks, with 4 more stacks of 3 radially attached in quad symmetry (15 total tanks)

10) LV-T45 on center stack, LV-T30s on the other 4. Place the radially attached tank stacks slightly higher so that the engines are aligned at the bottom.

Launch:

11) TR-18A stack decoupler on each engine above (5 total)

12) BACC Solid Fuel Booster attached to each decoupler (5 total)

The lander is also your transit and return vehicle, although you may be able to use the insertion stage for transit if you make orbit with some efficiency. I had quite a bit of fuel remaining when I reentered kerbins atmosphere, and I burned a lot due to a poor choice of the landing site and the resulting panic burn (the site I chose looked flat from orbit... but was actually a steep slope.) It could probably carry a Science Jr, but I did not have it unlocked at the time (just got it with the payout from that mission.)

If you cannot make it to the Mun with the above it is probably an issue with how you are launching.

A basic and easy to follow launch:

1) Wait for the rocket to settle on the launchpad, turn on SAS, set throttle to full, then launch. Stage a second or so after the boosters run out of fuel.

2) At 10km turn towards 90, pointing your rocket up at a 45 degree angle (diagonal.) Switch to the map and wait for your apoapsis to hit 75km or so, then cut your engines (x)

3) Open the Navball, make a nav node at apoapsis burning prograde to circularize, point your ship at the target marker.

4) When half the time it lists for the burn remains until you reach the node, throttle your engines to max. Cut them when your periapsis is over 70km.