How to get an orbit with little fuel

[nicktdg]

I've recently started a science save on my game, however I feel like I never have enough fuel to get into orbit. I fear if I add more layers the weight will be too much to return

 

[monstah]

Do you have any decouplers already? Remember that staging is a major aspect of reducing the mass of a rocket, you put the heavy-lifting stuff on the bottom and then eject it when its job is done. You only have to return the science, not the heavy engines and fuel tanks.

[OhioBob]

What I find works pretty well is to give the second stage (the upper stage) a mass of propellant approximately equal to the mass of the payload.  And the first stage (the lower stage) a mass of propellant equal to two times the mass of the payload.  In this case the "payload" is everything that sits on top of the second stage, thus it includes the mass of decouplers, fairings, etc.  You might have to tweak it a little bit, but generally those ratios result in a rocket that performs quite well.

[adsii1970]

I have an easy solution:

<ALT> <F12> and drop your craft into orbit!

Seriously, here's what I do when I am starting over again, either in career or science mode:

1. Define the mission to the contract. In the early stages, do not attempt to squeeze more out of a mission than you can afford to.
2. Once you've defined the mission, think of what you need to include in your plans - is a return trip necessary? What needs to be brought back?
3. Build your lander. Do some research. Find out how much fuel you'll need to take off from the surface, then double it. This gives you enough to land.
   1. Are you going to abandon your lander and reenter in a command module?
   2. Lander + heat shield + chutes?
4. Then build your "trajectory stage" around your lander. How much do you need to get from Kerbin orbit to the Mun or Minmus? How much fuel and RCS do you need for orbital insertion? Oh, and don't forget to include docking ports and fuel to get you pointed back to Kerbin.
5. Build your booster stage to lift everything into Kerbin orbit. Include monopropellant to help get you pointed in the right direction during ascent (using gravitational turns) and achieving orbit around Kerbin. This is all your booster stage is for. Get rid of it as soon as you achieve orbit to reduce your vehicle weight.

Edited January 4, 2018 by adsii1970

[Geonovast]

Do you have some screenshots with what you've go so far?  Hard to help ya out without knowing where you're at beyond "can't get to orbit."

Are you doing a gravity turn, or shooting straight up and cranking it 90 degrees?

 

[Jas0n]

And remember that if you don't have the tech/skill to get into orbit, there is a lot of science to be collected around the KSC which can get you to around third tier on the tech tree.

[wumpus]

As far as I can tell, it is literally impossible to get into orbit one the first launch (without decouplers).  The theoretical power of all the engines you can spam on the rocket (thanks to mass limits) + the power of the Kerbals RCS thrusters (assuming they are willing to wait for a rescue) isn't enough to get to orbital velocity (this might include accent delta-v). [edit: I don't think you have mass limits in science mode, but I still can't recommend trying to get to orbit without decouplers].

"Weight too much to return": you want to return just the capsule (and possibly a heatshield) + parachute.  Nothing else.  You need a decoupler just below the capsule and just take that.

I've never tried a "science  career" (other than way back when that was just "career mode", probably before beta) but shouldn't that have all the buildings  fully upgraded?  As far as I know, you should be able to spacewalk and retrieve "the science" from any science parts added to the rocket [save game before leaving the capsule, it is a good way for kerbals to be lost in space].  Once you have retrieved "the science" you can leave the rest behind you.  Hint: try to build any "science parts" near the capsule so you can simply reach them, but make sure the rocket is still as symmetric as possible.

Returning with a science jr is possible, but it takes some trickiness to keep the rocket from trying to land capsule side down and burning up.  Start with just returning the capsule.

Edited January 5, 2018 by wumpus
oops. Forgot science vs. career mode definitions.

[Fearless Son]

To start with, do not try to reach orbit with only the starting tech nodes.  Focus on a making a few milestones first, things like getting to a new high altitude or a new speed record.  You will get a modest amount of science for this.  You should have a Mystery Goo^TM Containment Unit unlocked at the beginning, and this will be your best friend at the start of the game.  Take a reading with it while on the launch pad, then recover the rocket.  Take a reading on it while the rocket is shooting toward the sky, then recover the rocket.  Take a reading while the rocket is splashed down east of the Kerbal Space Center, then recover the rocket.  Take a reading while the rocket is landed at Kerbal Space Center, then recover the rocket.  Take a reading while the rocket is landed in the grasslands west of Kerbal Space Center, then recover the rocket.  Etc.  

Just keep doing that until you have enough science to unlock a few more nodes in the tech tree.  That should give you a few more options which should make getting into orbit (and anywhere beyond) much easier.  

[Nich]

I have not played stock in years but I remember getting Mun flybys with starting parts. Orbit shouldn't be too hard hard.  But yes I always go for milestones anyways they pay better in career mode.

 

My first three flights

1. flying and upper

2. Suborbital

3. Orbit

[Leafbaron]

The rocket equation is going to be your friend here. In stock, a perfect and i mean perfect launch trajectory with perfect thrust to weight ratios to avoid drag loss while minimizing gravity losses simultaneously, orbit can be achieved with 3300 m/s to 3400 m/s of delta v (change in velocity) 3600 m/s is a good number to shoot for with excess just in case. The rocket equation is what you use to determine how much your ship has.

Change in Veloctiy= ln(mass_start/mass_end)*Velocity_exhaust

Where mass_start is equal to the mass of your fully fueled rocket and mass_end is equal to your rocket completely dry or having used all fuel. 

Velocity_exhaust is equal to I_sp*9.81 m/s ISP can be found under the info tab on all rocket engines.

 

For example, my ship weighs 20 tonnes, and dry my ship weighs 6 tonnes and I'm using the LV-T30 "Reliant" engine which has an isp of 310 in vacuum. Since this will be a single stage to orbit we will assume average isp of 300( (265 isp @ 1atm and 310 @ vacuum most of the flight will occur at near vacuum pressures)

ln(20/6)*300*9.81=3543.29 m/s. This rocket will make it to space (read orbit) assuming good piloting. 

This is an example of how you can use the rocket equation to get to space. just remember to keep your TWR @ 1.2 minimum on the launch pad and remember TWR= thrust/mass, this number will be in m/s so around 11.772 m/s is the number you want to see. 11.772/9.81=1.2 GEEEEEEEEEES baby!

 

Hope this helps, sorry its so mathy....

 

[Ty Tan Tu]

I have not noticed anyone saying this, so to state the obvious - reduce drag. Pointy shaped = good.  Blunt shaped = bad.  Narrow = good.  Wide = bad. Keep things from hanging off the sides, even fins are going to add drag. If you do not need fins, don't add them. If you do need them, try three not four

[Starman4308]

4 hours ago, Nich said:

I have not played stock in years but I remember getting Mun flybys with starting parts. Orbit shouldn't be too hard hard.  But yes I always go for milestones anyways they pay better in career mode.

 

My first three flights

1. flying and upper

2. Suborbital

3. Orbit

There have been some significant changes. You don't get the RT-10 at the start node anymore, and I'm not sure if explosive decoupling works anymore in stock, so it's vastly harder, if not impossible, to hit a Mun flyby on your first flight now.

[magnemoe]

My standard is always to do pad and runway science. 
Then an short jump, just an trashcan and an pod, followed by suborbital and orbit. 
This unlock lots of science and all the achivements awards pays well so you can unlock eva who give lots of science, Mun orbit is next, followed by Mun landing. 
Do an second, this time with scientist and send another scientist to Minmus Minmus is nice as you can jump around a lot and this tend to solve the science issues. 

[Blaarkies]

On 1/4/2018 at 10:20 PM, adsii1970 said:

1. Build your lander. Do some research. Find out how much fuel you'll need to take off from the surface, then double it. This gives you enough to land.

Be careful with that wording. Doubling the fuel will never double the range, even if you are using ION drives. So if you meant that it will give you enough dv to land AND take off, it won't

 

Edited February 2, 2018 by Blaarkies

[Nich]

13 hours ago, Starman4308 said:

There have been some significant changes. You don't get the RT-10 at the start node anymore, and I'm not sure if explosive decoupling works anymore in stock, so it's vastly harder, if not impossible, to hit a Mun flyby on your first flight now.

I believe it was a 2 stage reliant with no fins.  But it my have been a single stage.  Required a perfect gravity turn and reaction wheels to prevent flipping.  It was also a 1 way trip

[TranceaddicT]

All that grimy, grubby science cluttering up the KSC.  Ugh, it's everywhere.

I'm done with running around KSC gathering science. 

Now, I use KEI.

 

[GoSlash27]

On 1/5/2018 at 8:53 AM, wumpus said:

As far as I can tell, it is literally impossible to get into orbit one the first launch (without decouplers).

wumpus,

It is possible to make orbit in an SSTO powered by the Reliant or Swivel and a big stack of FL-T100 tanks without exceeding the pad limits. Bringing it home is a pain, but it can be done.

Best,
-Slashy

[wumpus]

My copy (1.3.1) only allows flea engines for the first launch in career.  If you are in sandbox, all bets are off and you can build an SSTO spaceplane if you want.  Between the mass limit limiting the number of flea engines, the need for explosive staging, and "only' 400 m/s available by bailing out and using the jet pack in a last ditch circularization effort there simply isn't enough delta-v to orbit (actually the various inefficiencies are irrelevant, you can't even get the theoretical delta-v with the mass limits).

I've had upgrading issues before, so my copy might not be fully functional.

[Superfluous J]

34 minutes ago, wumpus said:

My copy (1.3.1) only allows flea engines for the first launch in career.

Mine too, but imo if I don't hit the spacebar I didn't launch.

There's enough science on the runway and launchpad to unlock the first propulsion node. Then it's just a stack of tanks and the engine (reliant or swivel, I forget which it is) to a pretty simple orbit.

[GoSlash27]

^ What @5thHorseman said. You're never going to make orbit on Fleas, at least not within the starting pad limit. It is possible to do as an SSTO using the Swivel or Reliant (either will work but the Swivel is easier). The tech required to make orbit can be easily unlocked by doing science from the pad and runway without going anywhere, so the first actual "launch" can indeed make orbit.

Best,
-Slashy

[Vanamonde]

This question about how to play the game has been moved to Gameplay Questions. 

[Mr. Peabody]

On 2/3/2018 at 3:38 PM, GoSlash27 said:

wumpus,

It is possible to make orbit in an SSTO powered by the Reliant or Swivel and a big stack of FL-T100 tanks without exceeding the pad limits. Bringing it home is a pain, but it can be done.

Best,
-Slashy

Case and point. This rocket was only my second in the career game and I even managed to collect high orbital science with it.

[Brainlord Mesomorph]

If you want advice on how to make money in early career:

DO NOT GO ORBITAL! 

Get up to suborbit and wait. Do some science. You'll start getting a lot of very profitable suborbital tourism contracts. Worm your way through the tech tree to the size 1 crew cabin. And then you can just spam suborbital tourism. My "Zed5 Passenger Missile", is a cash cow! I do so much suborbital tourism I want to set up a concession stand!

Then when you get bored with that, THEN go orbital, and start spamming orbital tourism for a good long time before you do lunar orbit, etc, etc, etc,

(eventually tourism dries up)

 

(Brainlord Aerospace actually starts out as an amusement park company)

Edited February 6, 2018 by Brainlord Mesomorph

[Spricigo]

19 minutes ago, Brainlord Mesomorph said:

If you want advice on how to make money in early career:

DO NOT GO ORBITAL! 

Get up to suborbit and wait. Do some science. You'll start getting a lot of very profitable suborbital tourism contracts. Worm your way through the tech tree to the size 1 crew cabin. And then you can just spam suborbital tourism. My "Zed5 Passenger Missile", is a cash cow! I do so much suborbital tourism I want to set up a concession stand!

Then when you get bored with that, THEN go orbital, and start spamming orbital tourism for a good long time before you do lunar orbit, etc, etc, etc,

(eventually tourism dries up)

 

(Brainlord Aerospace actually starts out as an amusement park company)

Flawed logic...if you will move to orbital tourism better sooner than later.

Also, with just a bit extra science,  satellites and stations  are excellent alternatives for tourism mission.

[Brainlord Mesomorph]

11 minutes ago, Spricigo said:

Flawed logic...if you will move to orbital tourism better sooner than later.

Also, with just a bit extra science,  satellites and stations  are excellent alternatives for tourism mission.

Perhaps you misunderstand. Suborbital tourism is dirt cheap and has a much higher profit margin than orbital or lunar.

One Reliant and a fuel tank can lob 6 or 8 tourist at once up out of the atmosphere and back in 2 minutes.

Suborbital tours are fast easy money that goes on and on  ..  UNTIL you hit orbit. (then tourists insist on orbit and your costs (and the amount of effort it takes) go way up!) 

Where's the flaw in that logic?

Edited February 6, 2018 by Brainlord Mesomorph