To the Orbit!

[Personne]

Hi everyone, new Kerbonaute with a lot of newbie questions here!

I've introduce myself here and I thought this forum was more appropriate to discuss gameplay (if I'm wrong, plz be kind).

I'm currently having some issues doing something as basics as going on orbit.

It looks like the method I was trying to use (turn at 90° est at 10km then horizontaly at 60km and full power) is not working anymore, and I don't know if I'm doing wrong either as a pilot and an engineer.

Here's the rocket I lovely called "Orbital 1" (Orbital is my sister firstname).

There's two BACC "Thumper" booster in order to reach ~12km then a LV T45 "Swivel" with a FL T200 to finally get to the orbit.

Then there's my boy, the other LVT45+FLT200 who's supposed to carry me to space, or at least to orbit.

On "extra" I added two antenna so I can keep on tchating with my bros while I'm going to space, and two barils of that goo stuff cause ya know, science.

 

Those this set up looks good enough for you to reach the orbit?

Is there anything wrong with my engineer design?

 

Thx for helping, I'm just new to this game and I really wana understand the way it works, but I'm a bit lost^^

[DarkHawkGames]

Didn't notice the link, one sec.

Edited May 12, 2016 by DarkHawkGames
Didn't see the link

[Personne]

2 minutes ago, DarkHawkGames said:

Could you show me a picture of it please?

 

Here's the direct link!

[Gaarst]

Ascent profiles have indeeed changed since the Aero update of 1.0 last year.

The method that you have is outdated and doesn't work anymore, you now have to do a gradual gravity turn, just like real rockets.

To get up-to-date tutorials, I suggest you take a look in the Tutorials section of the forums, and especially to this post, explaining how to make a proper ascent and gravity turn in 1.1:

(Even though basics are always the same, know that there are several different ways to make it to orbit, so you should search and try a few to see which one suits you the best)

[DarkHawkGames]

You're probably using too much solid fuel in your rocket. As light as your upper stage is, that would get you very, very high, but it'd be really uncontrollable, and you'd be taking a lot of drag from the atmosphere. If I may make a suggestion, take your antenna and put it on the top, on the parachute, as close to sticking straight up as you can. Don't worry, the antenna being there won't affect the parachute deploying or anything, that's how I set it up on all my manned craft. Another thing, if you're going atmospheric, you really want to put a heat shield on the bottom of your crew capsule. It'd also be advisable to mount your mystery goo canisters on the sides, close to the parachute, where they're not blocking the hatch.. I find that makes them take less heat in re-entry.

[Personne]

8 minutes ago, Gaarst said:

Ascent profiles have indeeed changed since the Aero update of 1.0 last year.

The method that you have is outdated and doesn't work anymore, you now have to do a gradual gravity turn, just like real rockets.

To get up-to-date tutorials, I suggest you take a look in the Tutorials section of the forums, and especially to this post, explaining how to make a proper ascent and gravity turn in 1.1:

(Even though basics are always the same, know that there are several different ways to make it to orbit, so you should search and try a few to see which one suits you the best)

Thanks a lot! Have to say, I searched for one but did'nt notice it, sorry!

[DarkHawkGames]

12 minutes ago, Gaarst said:

Ascent profiles have indeeed changed since the Aero update of 1.0 last year.

The method that you have is outdated and doesn't work anymore, you now have to do a gradual gravity turn, just like real rockets.

To get up-to-date tutorials, I suggest you take a look in the Tutorials section of the forums, and especially to this post, explaining how to make a proper ascent and gravity turn in 1.1:

(Even though basics are always the same, know that there are several different ways to make it to orbit, so you should search and try a few to see which one suits you the best)

I thought something had changed! Is the gravity turn more or less fuel efficient?

[Gaarst]

1 minute ago, DarkHawkGames said:

I thought something had changed! Is the gravity turn more or less fuel efficient?

What ? You mean is it more efficient than the old "turn 45° at 10km" thing ?

I don't know if it's that much more efficient, but it's definitely the best way to make it to orbit without flipping or without spamming fins at the bottom of your rocket.

[Superfluous J]

2 hours ago, DarkHawkGames said:

I thought something had changed! Is the gravity turn more or less fuel efficient?

 

Try it. Take a ship that can get to orbit by burning up to 10km and then turning 45 degrees, and using that ship get into orbit with a proper gravity turn. Use a mod or math (or just burn your engine until the fuel's gone and see how fast you're going) and check the difference.

[bewing]

Math won't exactly help to figure out the costs of a particular launch trajectory, because to do it properly you'd have to integrate the atmospheric drag function over your flight path -- and we don't know the function and it's complicated.

So the only answer is to try it and see. However, attempting to turn some rockets in the atmosphere makes them unstable -- so for many of them you have to launch straight up anyway, even though it is a less efficient launch profile.

 

[Reactordrone]

14 hours ago, Personne said:

Those this set up looks good enough for you to reach the orbit?

Is there anything wrong with my engineer design?

 

Thx for helping, I'm just new to this game and I really wana understand the way it works, but I'm a bit lost^^

I don't think it has enough delta-v to reach orbit no matter how you fly it. If you have them, some steerable fins on the boosters will help with control and getting rid of the extra LV-T45 and replacing its mass with fuel will get it into orbit.

[Streetwind]

15 hours ago, Personne said:

Those this set up looks good enough for you to reach the orbit?

Is there anything wrong with my engineer design?

I agree with what's said by the posters above me: the SRBs will make practicing the art of flying a real gravity turn very difficult on you, because of the way they dominate the rocket with their huge thrust and mass. That's not to say that all-SRB first stages are not viable - they absolutely are. But if you're not careful, they will make your rocket difficult to steer. Since you're still practising, you might want to use something that's easier to fly.

Also, the two liquid stages on this are actively counterproductive.

 

Explanation:

When you design a rocket, you want to be able to stage away empty tanks and oversized engines so you don't have to carry them all the way to orbit. In rocketry, everything that is not fuel is either dead weight or payload, and we call this the rocket's "dry mass". By staging, you keep the same amount of fuel, but reduce the amount of dry mass; therefore, your fuel efficiency goes up a whole lot.

The more often you stage, the more often you can get rid of unneeded dry mass, and thus, staging often is ostensibly better.

However! Staging equipment is not free. For starters, you need a decoupler. A decoupler costs money and has a mass. This mass makes your rocket slightly less efficient during the entire flight time before that decoupler is staged away. And what's even worse: you need another engine. And engines cost a lot of money, and have a lot of mass.

So there comes a point where adding yet more stages actually makes the rocket less efficient. First, you arrive at a point where the cost savings from being able to downsize the vehicle due to efficiency advantages from staging get gobbled up by the equipment costs for decouplers and extra engines. And if you push it even further, there comes a point where the extra mass from more and more decouplers and engines removes more efficiency than staging will give you back.

This is especially a problem when you only have very heavy engines available to you, like the LV-T45 in your rocket. Therefore, I have a hunch that your rocket has already crossed that "too much staging, too little fuel in each stage" threshold. As you advance in the tech tree, you will soon unlock a nice, lightweight upper stage engine; but until then - and honestly, even then - I would recommend you simply use one upper stage with two fuel tanks instead of two stages with one fuel tank each.

 

Now, knowing that, you're better equipped to make a new attempt at building yourself an orbit-capable rocket   But, if you want to practice flying your gravity turn some, I can recommend you a very simple practice rocket with which to do it.

Mk16 Parachute
Command Pod
Decoupler
FL-T200 fuel tank x8
LV-T45 engine

This, as you may notice, only has a single engine on it. It is a single-stage-to-orbit vehicle ("SSTO"), so you can fully focus on flying.

It is also not the most forgiving of rockets.
- It does not have guide fins. While it can fly straight just fine if you keep your heading near prograde, large deviations may cause a loss of control.
- It is capable of reaching a stable orbit, but only just. If you fly it well, you will be able to get up to something like 80x80 km, and have just enough left over to deorbit again and perform reentry. If you don't fly it well, you will come up short.
- It rides its launch engine all the way to orbit. Because of all the mass you shed along the way, the acceleration provided by this engine will be extremely high as you approach the end of your flight. This makes it tricky to keep precise control of your trajectory and destination near the end, requiring you to carefully manage your throttle.

All of these things are intentional, since this is a training vehicle. It is perfectly possible to build a rocket with larger tolerances with the parts you have, but if you can get this one into orbit (and your Kerbal back down afterwards), you can confidently say that you know how to fly reasonably well.

 

Edited May 13, 2016 by Streetwind

[Personne]

thanks a lot for your answers @streetwind and @reactordrone (and of course all the others)!

To be honest I did'nt thougt this thread will got so many (and detailed!) answers, I was more expecting something like "RTFM noob." X)

I'll try the SSTO training and learn the gravity turn (I tryed yesterday but I think I did'nt understand verywell cause I did'nt even reach 10km x) Something in the first 5-10 degrees east part I'm doing wrong I guess)!

 

I've also installed Kerbal Engineer, is there any others "must have" add on I should look for? I mean I saw there's a lot of add on but as a beginner I really wana learn the game step by step so I want to install as few adds I can.

[Streetwind]

58 minutes ago, Personne said:

(I tryed yesterday but I think I did'nt understand verywell cause I did'nt even reach 10km x)

You probably turned over too much too early.

The concept of a gravity turn is that a single pitch maneuver at the right time will cause the rocket to tilt over naturally ("turned by gravity") in just the right way that allows you to go to space without further steering input and without SAS. Obviously that is something only computers are precise enough to get right, and humans like us will always have to steer a little more. But it should illustrate the reason why your rocket may fail to gain altitude. Too large of a pitchover too early may mean that gravity pulls your nose down too early - and trying to fight that is difficult and dangerous (will definitely waste fuel, may even lead to losing control of the rocket).

There are many guidelines, like "pitch over 5 degrees after reaching 50 m/s of speed" or the like, but the uncomfortable truth is that the exact moment, altitude, speed and pitch magnitude are all completely vessel-specific. Every rocket will perform a little differently. And often, the only way to figure out how to fly a proper gravity turn with a new rocket you just built is to... well, launch and see how it goes. Good players can guesstimate how agressive they need to be based on the rocket's thrust-weight-ratio, and can generally (but not always) avoid failing the first time. But that takes a lot of practice. It's a skill only experience will teach you.

As a newcomer, you'll more or less be flying the turn manually - you keep SAS on, keep an eye on your altitude, and steer the rocket to be roughly at the correct angle for each altitude by hand. For typical rockets, you want to be just above 45 degrees** as you cross 10-11 kilometers altitude. If you're steeper than that, you can compensate by flattening out more agressively afterwards (either by steering, or by throttling down). If you're flatter than that, you may have a problem unless your engine can push hard and let you fight the turn a bit. As a result, try erring on the side of being too steep rather than being too flat.

 

(** keep in mind that that's your pitch angle, not your heading. The heading is what's displayed at the bottom of the navball, and should always be as close to 90° as possible for a typical launch. The pitch angle is the little numbers written on the blue/brown ball itself. 45 derees pitch is the halfway point, where there's a prominent white line. Can't miss it! )

Edited May 13, 2016 by Streetwind

[Plusck]

50 minutes ago, Personne said:

To be honest I did'nt thougt this thread will got so many (and detailed!) answers, I was more expecting something like "RTFM noob." X)

I'll try the SSTO training and learn the gravity turn (I tryed yesterday but I think I did'nt understand verywell cause I did'nt even reach 10km x) Something in the first 5-10 degrees east part I'm doing wrong I guess)!

 

I've also installed Kerbal Engineer, is there any others "must have" add on I should look for? I mean I saw there's a lot of add on but as a beginner I really wana learn the game step by step so I want to install as few adds I can.

You have to descend very, very far down the stupid noob ladder before people will stop answering questions in great detail in here. It generally also requires said stupid noob actively disregarding good advice and being mildly offensive at the same time to really cause help to dry up.

For a proper efficient gravity turn, you need to start straight away but you've got to be careful not to overdo it. When you start off, the top of your flight curve (Ap) is very very close to the nose of your rocket, and the time needed to reach it (i.e. fly horizontally, briefly) is very low, mere seconds. Time-to-Ap increases, and Ap moves further up and away, as you accelerate, so the trick is to keep that time-to-Ap rising until you get to about 30s at 10km, then 40s for most of your time in the upper atmosphere, and then it should shoot up on its own as you approach orbital velocity (ideally at around 60km).

Since you have KER, you have time-to-Ap nicely presented in the top left part of the HUD, so the later stages of your ascent should be easy to perfect.

From the launchpad, it is harder to get right. Some suggest waiting until you get near to 100 m/s before starting the turn. This ensures you are not too close to Ap and therefore that you have time to get yourself on the right bit of that curve that will, eventually, get you horizontal.

 

And I agree completely in minimal mods until you learn the game. Theoretically, KER is perhaps a mod too far ; )

Edited May 13, 2016 by Plusck

[Warzouz]

31 minutes ago, Streetwind said:

... Good players can guesstimate how agressive they need to be based on the rocket's thrust-weight-ratio, and can generally (but not always) avoid failing the first time...

I can't agree more. I can't remember the number of recent take off where I cross the 45° at 20km (will do a hard ans expensive orbital insertion burn) even when forcing it of find myself ceiling at 5km (basically failed launch)... The first 20s of flight are the most important and it's VERY easy to fail.

The things you can tweak

• Too hard to turn : reduce TWR of reduce static winglet, or increase control surfaces winglets or start turning sooner
• Turn too quickly : turn later, increase TWR
• Can't keep trajectory : use SAS (I don't recommend that) add static winglets
• Flips : stay on prograde vector, add static wings
• Wobble : add struts, reduce control surfaces, reduce engine gimbal, deactivate SAS, restructure your launcher,

 

[Personne]

Well I understand the part above 10km (45 degree angle, on the east 90 till 70km) but O think I don't go there smoothy enough...

But I'll finally do it, just need to keep on trying!

Thanks a lot for all of your advices!

[Warzouz]

3 minutes ago, Personne said:

Well I understand the part above 10km (45 degree angle, on the east 90 till 70km) but O think I don't go there smoothy enough...

The more you "force" it to turn, the more you risk flipping if your rocket is not "dart shaped"

Last thing : don't panic if you have a hard time with your first rockets. Lighter rockets are harder to fly. Heavier rocket are more stable, if they are flippy, they do it more slowly and you may have time to counter it.

[Personne]

I just went to the orbit! And I came back alive on Kerbin! Except for my first try who keep om spinning around the planet x)

I know it looks nothing for people who travel to other planets but it's my first big step^^

When I first reached the orbit I time warped and watched my vaissel spinning around the planet with a big smile for almost 5min that was so cool x)

 

TO THE MUN NOW!

[Streetwind]

Congratulations!

[Plusck]

Yes, congratulations.

I totally forgot about that, but I think I did something like that when I first got to orbit. It's one of those indescribable moments.

Don't get addicted ; )

[Superfluous J]

4 hours ago, Personne said:

When I first reached the orbit I time warped and watched my vaissel spinning around the planet with a big smile for almost 5min that was so cool x)

 

36 minutes ago, Plusck said:

I think I did something like that when I first got to orbit. It's one of those indescribable moments.

I still do that sometimes