Better efficiency to get to orbit and then elsewhere

[redpiz]

Hi. I've been playing for some time now and I am trying to get bigger stations in orbit and also build lunar colonies. My problem is thought that I always burn to much fuel getting to orbit and then I don't have enough to do what I want. I try building bigger rockets but the added weight doesnt seems to just cause the same problem. Bsically I want to know how to get into orbit the most efficiently.

[Pecan]

Welcome to the forums.

Efficient launches depend on four things:

1. Use multiple stages to jettison excess mass

2. Don't carry anything you don't need on any stage

3. Use the most efficient engines (highest Isp) that give you a thrust to weight ratio (TWR) of 1.4 - 1.6 (there's more to this but those figures will do for now ^^)

4. Perform a 'gravity turn' during ascent rather than going to space then turning sideways.

Generally, less is more.

[Randazzo]

Hi. I've been playing for some time now and I am trying to get bigger stations in orbit and also build lunar colonies. My problem is thought that I always burn to much fuel getting to orbit and then I don't have enough to do what I want. I try building bigger rockets but the added weight doesnt seems to just cause the same problem. Bsically I want to know how to get into orbit the most efficiently.

If you're talking about flight path into orbit, if you're using stock, you'll want to keep your speed under terminal velocity and start your gravity turn to the east at around 7000-8000 meters and gradually nose over towards a 90 degree eastward heading (0 degree planetary). IF you pull it off well, you can get into low orbit for less than the oft quoted 4500 m/s.

Although I haven't seen your designs, I'm going to assume you're trying to make your vehicles appear at least within the realm of possibility. If you build a bigger rocket, you need bigger engines or more engines. You will eventually come to the limit of what you can lift without building some bonkers asparagus staged monstrosity. Being more efficient can help, to a degree, but that too has limits. Alternatively you can start looking at multiple launches and assembling your stations/ships in space.

You can also come up with some pretty powerful lifting stages utilizing clipping as well, but there's always the risk of sudden disintegration. An example, using three Skipper stacks clipped into a fourth fuel tank stack with no engine, connected by fuel lines:

This particular one is a single stage to orbit.

Edited April 2, 2015 by Randazzo

[Thraeorn]

The best thing anyone can do is play around. Fail and Fail often is key to learning and depending on your situation you might need to play around a bit to see what works.

But here are the things that have worked for me.

You don't always need to build super massive rockets. Small does just fine too! Shooting of entire stations at once is asking for disaster. Not even the great Mir or ISS was put into orbit in one go and if you look at them, they are all modular. Which means smaller parts build the larger. Just like everything in kerbal. So with a bit of planning you can plan smaller rockets for your smaller parts and larger rockets for your heavier parts.

TWR is important, too much weight means a slow rocket and more fuel being burnt up. So keep an eye on the size of your rocket and the weight. I have a rocket I build an named it the LunaV (after saturn V) I studied the stages of the Saturn V and build loosly based. Command pod and the cargo of a lander. Each with it's own stage and weight. This then became key to when I decided to take my moon rocket and switch out the stages with other cargo. (back up a save by default to not over ride) So by play around with different cargo I got an idea of maximum weights for the intended heights and weights. Heights as in how much fuel do I need to go into orbit as opposed to the mun.

So just like nasa does, test flights are important to do to make sure your rocket is up to the task. Reverting also helps XD.

Sometimes though you might want additional boosters, like SRB's In this case I break them off a little before or after the turn but never during. Things in motion remain in motion unless acted upon by another force. So if you don't want your booster to end up in the side of your rocket in a fireball of doom. Don't seperate at that time. having the seperatron fire at the same time the stage drops the srb if aimed right can pull it away but they only have so much power so again just be smart.

Other than that, Rocket science is easy, it's the engineering that gets you.

[celem]

Colonies and stations in particular are quite tricky to get to orbit using stock parts without any kind of assistance. (pure stock) This is because you are dealing with very heavy payloads, and in general 1 ton on the top equates to some 10 or more tons of lifter. Big payloads therefore very quickly lead to truly massive lifters that test your desgn skills and your pc's performance. The biggest single help (to me at least) is the KER mod which gives you the data on your design without you reaching for pen/paper and calculator.

If these two things are particular goals of yours (stations and colonies) then you will likely need to learn how to assemble things in orbit efficiently, which means learning to rendezvous and dock. Launching any worthwhile station as a single piece is an exercise in massive rocketry, break it down into logical modules and "plug'n'play". Same principle applies to surface bases, massive grand tour interplanetarys... I tend to stop around 100 tons. Once the payload weighs more than that it gets split so that I dont have to design a custom lifter (since i have some 100t designs saved).

You can of course launch anything, you can stack together 10 thousand tons of hardware and blast it into the sky. But not only will your pc cringe, its just not efficient when you look at the cost/payload introduced with career mode.

[Claw]

Hiya,

It's not a big deal, but for future reference you will probably get faster and more responses posting in the Questions forum. It's not a big deal though, since it looks like plenty of people are helping here too.

Welcome to the forums!

Cheers,

~Claw

[Wolf Baginski]

Some Mods can help. Kerbal Engineer Redux doesn't replace the pilot, but gives you the deltaV for each stage as you build it. which is useful. Once you build a stack with two stages you can see what changing the relative stage sizes can do with the same fuel. Or you can do the calculations by hand. It's easy to make the first stage a little too big and lose total deltaV

One thing to consider is having a slightly too-big stage and don't quite fill the tanks. It gives you a margin for a heavier payload. But you don't want to lift fuel you don't need.

[Nothalogh]

As others have stated, Kerbal Engineer is indispensable.

As for the gravity turn, I have found it is best to execute it so that I am fully horizontal at about 45km, at that point my first stage will have burnt out and I will accelerate up to orbital velocity and partially circularize on the second stage, payload stage separates and finishes circularization burn of under 60m/s.

Bear in mind that this was all with FAR and DRE, but with the new stock aero the general plan should hold.

[EtherDragon]

Welcome! Yea lots of great help in this community. If you want a video tutorial, I just updated my signature with a video link to just that sort of thing!