Going to orbit...

[lugge]

Hi folks,

well, I just started playing KSP a week ago, after 1.0 release. I did all the tutorials and started a career mode game.

My first "milestone" was going to a stable orbit, for which I spent 3 evenings.

I couldn't build/control a rocket which can go high enough AND reach enough lateral velocity.

I tried lots of designs and spent all my science in rocketry, because I thought I need bigger engines.

I got better after each try, but I was still unable to get into orbit.

However, yesterday I noticed I can upgrade my launch pad so I can go for bigger rockets (140t instead of 18t).

Yeah, that was my problem. With 140t rockets unlocked, my task was easy.

I just added a bunch of engines to my craft (solid boosters). I missed orbit again, added another bunch of boosters and, finally, got to orbit.

However, somehow this feels like cheating. After I unlocked the 140t, it was merely a question of how many engines i added.

Before, with the 18t limit, I had to think of every detail of my rocket. Now, I can just add MORE ENGINES. Feels weird.

So, my questions are:

- What is the smallest rocket for reaching a stable orbit? Is it possible with 18t?

- Is this the way KSP is played? Just add engines? Funds have been no problem. Now, with the 140t unlocked, i feel like I can reach everything...

Somehow I have the feeling I have to improve my pilot skills, because at some point "more engines" will stop working...

That's it folks :-)

Greetings

[EricT43]

Welcome!

I am a relatively new player myself, but I can say that getting into orbit is definitely doable without upgrading the launch pad. More than likely your ascension profile is inefficient. If you go straight up, and then vector sideways when you get into space, which is how I tried to do it when I first started, it requires a lot of fuel. There are a lot of tutorials on this website and on YouTube for getting into orbit, I would suggest checking those out. Make sure you find tutorials for version 1.0 or later, as there were changes to the game that makes some of the older tutorials obsolete. I'd highly recommend the new Career Mode tutorial series from Scott Manley on YouTube - he is an expert at the game and I think he covers getting into orbit in the first or second video.

[seaces]

I have also just started the career mode and i got to orbit with not that big craft and the key to that was getting basic SAS module and better control fins so that I could get in better trajectory.

[Octa]

Try these historical missions from the wiki to get a feeling for flying in orbit:

Sputnik

Vostok

Gemini

The designs there should be able to fly in 1.0 with a few changes like fins at the button (for stability) and heat-shields for re-entry.

It's very likely that you just need a tweak in your launch profile. How dou you fly to space at the moment? Do you have stages on your central stack?

[Taki117]

Don't forget your gravity turn! At about 50m/s pitch east about 5 degrees then follow prograde, a good rule of thumb is 45 degrees by 10km. From there it's all about gaining horizontal velocity.

Check this video for more information.

[KerikBalm]

Pictures would help, but yes, its easy to get into orbit with less than 18 tons.

You'll want to use liquid fuel engines, as they have a higher Isp. You'll want to stage, and you'll want the LV-909 for an upper stage (lightweight, higher Isp).

LF engines are more expensive than SRBs... so sometimes a more massive design is cheaper.

If you find that 140 tons becomes too limiting, use more liquid fuel engines, and less SRBs

Its even easier if you've unlocked turbo-ramjets or rapiers... but those are so far down the tree, that I can't imagine you having them and a non-upgraded launchpad.

[Grunnt]

There's no mention in your post of using decouplers or staging. Possibly you are trying to get a single humongous rocket into orbit in one go? Staging and your ascent path are key.

First (bottom) stage: solid fuel boosters. Second stage: engine with high atmospheric ISP (efficiency). Third stage: rocket engine with high vacuum ISP. Then the final stage is your pod with a parachute and a heat shield.

Ascent: first go mainly up while the atmosphere is still thick (to avoid too much loss from drag) and when the atmosphere gets thinner slowly turn towards horizontal (to avoid too much loss from gravity). Doing a good gracity turn is quite hard and requires practice, but there's help for that on these forums.

[Streetwind]

Achieving orbit becomes a lot easier if you unlock the tech node with the LV-909 "Terrier" engine - or accept a part testing contract for it, so you have a limited number of them for use.

When I get home I can show you the rocket I used to get into orbit in my 1.0 career save, without upgrading VAB or launchpad. It was a very simple construction.

An important lesson in rocketry is to understand that larger =/= better. How far your rocket takes you depends on the fuel mass ratio, not on the absolute fuel mass. A rocket with 9 tons fuel and 1 ton dry mass will fly exactly as far as a rocket with 900 tons fuel and 100 tons dry mass. So whenever you have the chance - figure out how to downsize!

[DoToH]

What is the smallest rocket for reaching a stable orbit?

Is possible to answer this question by doing the math, taking into account part stats. But it's funnier to try and fail (or success).

Is it possible with 18t?

Yes

- Is this the way KSP is played? Just add engines? Funds have been no problem. Now, with the 140t unlocked, i feel like I can reach everything...

Somehow I have the feeling I have to improve my pilot skills, because at some point "more engines" will stop working...

KSP is a game. There is no "correct" way to play it, just have fun. If you find it too much easy, tweak your difficulty settings and start again. I'd recommend to take a trip (land and return) to Moho or Tylo before doing that. Orbit is, for experienced players, trivial. You'll find much more to do (and more difficult).

At some point, "more whatever" will stop working (not exactly true, but your PC will not be able to handle so many parts) and you'll have to begin with the "less everything" way.

Edited May 7, 2015 by DoToH

[Streetwind]

Achieving orbit becomes a lot easier if you unlock the tech node with the LV-909 "Terrier" engine - or accept a part testing contract for it, so you have a limited number of them for use.

When I get home I can show you the rocket I used to get into orbit in my 1.0 career save, without upgrading VAB or launchpad. It was a very simple construction.

An important lesson in rocketry is to understand that larger =/= better. How far your rocket takes you depends on the fuel mass ratio, not on the absolute fuel mass. A rocket with 9 tons fuel and 1 ton dry mass will fly exactly as far as a rocket with 900 tons fuel and 100 tons dry mass. So whenever you have the chance - figure out how to downsize!

Okay, as I promised, I am home. Here is the rocket I achieved orbit with: https://dl.dropboxusercontent.com/u/44754370/screenshot50.png

Parachute, capsule, heatshield, decoupler, tank, Terrier, decoupler, tank x5, Reliant.

Mind you that was in 1.00, I hear 1.02 added more atmospheric drag, so it probably needs more fuel now. Adding an extra tank to each stage will probably do it, the engine has enough thrust. And just look at the engineer's report window, how much part count and mass and size tolerance there is left! You can easily get away with using twice the number of the smallest tanks if you don't have these bigger ones unlocked yet. If you have radial decouplers on hand you can also strap a pair of Hammer boosters to the bottom sides and use those as a first stage, only igniting the Reliant engine when they burn out. (Don't forget nosecones for your side boosters!)

Edited May 7, 2015 by Streetwind

[lugge]

Ok guys, I started a new game and managed the stable orbit with a 17t rocket, easy going.

Thank you for your replies. I read all of them, however, i wont mention all of them now because this would take too long ;-)

My big mistakes were:

- in my previous attempts, I started gaining horizontal speed to late. Now I start at about 10km, that works fine for me.

- I used SRBs for gaining lots of speed in a short time (maybe too much speed?!). Now I have one loong rocket with only LF engines (3 stages). It takes forever to reach 10km and when i reached it I'm only about 300m/s. I wonder how it works, but it works :-)

So, why is it this important to get horizontal speed this early?

In my opinion, I have to gain altitude as fast as possible. Because low altitude means more gravity, more gravity means more trust necessary for not falling back to earth. Less trust for gaining vertical speed and altitue. Thus, I tried to get away from the evil gravity and atmosphere as fast as possible. I didn't bother gaining horizontal speed when still in atmosphere. Short: I didn't do a gravity turn.

Whats the mistake with my thoughts?

And, why is the LF-909 this good?

It reads poor. Nearly no trust...

Greetings and thanks!

[Streetwind]

Gravity is actually almost identical in low Kerbin orbit and on the surface. It doesn't drop very much at all.

The reason you're in freefall in orbit is not because gravity disappears. The word "freefall" actually describes pretty well what's happening: you are falling. Gravity is constantly pulling you down, hard, and you're fully affected. However... as Douglas Adams once wrote in "The Hitchhiker's Guide to the Galaxy", the trick to flying is simply missing the ground when you fall. And that's why you're going sideways when you're in orbit. You're going sideways so damn fast that even though you're constantly falling, you keep missing the entire planet. That's a pretty neat mental image, isn't it?

So yes: upwards speed gets you into space, but sideways speed makes you stay in space. And you need only a little bit of upwards speed but a lot of sideways speed, because a planet is a pretty big target to try and miss. The gravity turn maneuver is the most effective way to get your sideways speed up as quickly as possible while maintaining juuuust enough upward speed to make it above the atmosphere.

Why the LV-909 is so good: Thrust isn't everything to a rocket engine. Fuel efficiency is also very important. Two factors govern how fuel efficient an engine is:

1.) Engine weight. The engine is not fuel, so its weight is dead weight. The less of it it has, the better. The LV-909 happens to weigh very little.

2.) Specific impulse. This figure, appreviated Isp, is roughly comparable to a fuel consumption indicator. The higher this number, the more you get out of the same amount of fuel. The LV-909 happens to have a pretty good Isp in the vacuum of space, so it makes a great upper stage engine. But note: because it's optimized for space, it runs poorly inside the atmosphere - that's what the "ASL" entry for Isp signifies. It stands for "atmospheric/sea level". So try not to rely on it too much below 15km of height. The higher you go, the better it runs. Above 30km, it should be more or less maxed out. (This applies to any engine; you can see Isp increase as the rocket climbs if you rightclick a running engine during flight.)

Also, upper stages tend to be small. You can easily get away with a low thrust engine because you're only moving small masses.

[Ulzgoroth]

- I used SRBs for gaining lots of speed in a short time (maybe too much speed?!). Now I have one loong rocket with only LF engines (3 stages). It takes forever to reach 10km and when i reached it I'm only about 300m/s. I wonder how it works, but it works :-)

Going much above 300 m/s at low altitudes isn't worthwhile. You don't want to hit the sound barrier while the air is dense enough to matter, because transsonic drag is a lot worse than subsonic drag.

So, why is it this important to get horizontal speed this early?

In my opinion, I have to gain altitude as fast as possible. Because low altitude means more gravity, more gravity means more trust necessary for not falling back to earth. Less trust for gaining vertical speed and altitue. Thus, I tried to get away from the evil gravity and atmosphere as fast as possible. I didn't bother gaining horizontal speed when still in atmosphere. Short: I didn't do a gravity turn.

Whats the mistake with my thoughts?

Gravity doesn't decrease significantly between sea level and Low Kerbin Orbit. When you're in orbit, look at your trajectory on the map, zoomed out far enough that you can see it all the way around the planet. It's only a tiny bit above the ground, relatively speaking.

The thing that does drop off with altitude enough to matter is air resistance. But that drops off fast, by 30 km you are not going to experience very much decceleration due to drag.

And, why is the LF-909 this good?

It reads poor. Nearly no trust...

The 909 isn't good for thrust, but it is relatively light and has high ISP.

Being relatively light helps make your top stage have a good fuel fraction. (For thinking with rockets, you should basically ignore how much fuel you have in absolute terms: what matters is what fraction of the initial mass of the rocket is fuel.)

High ISP means that for a given fuel fraction, it can do more.

The low thrust doesn't matter so much when used for an upper stage because first of all the stage doesn't mass much, and secondly the stage is mainly accelerating horizontally, not fighting against gravity. Using 909s for a first stage would be a bad idea. (It's an even worse idea than the low thrust alone indicates, because the 909 also has bad ISP and thrust in dense air. It only gets its good performance in near vacuum. Near vacuum includes Kerbin's atmosphere once you're a bit past 10 km up, though.)

[SRV Ron]

It can be done with the pad and VAB limits. (Barely.) This design did orbit in 1.0

With a pad upgrade and the LV909, a Mun flyby can be done with this three stage.

[paolot]

So yes: upwards speed gets you into space, but sideways speed makes you stay in space. And you need only a little bit of upwards speed but a lot of sideways speed, because a planet is a pretty big target to try and miss. The gravity turn maneuver is the most effective way to get your sideways speed up as quickly as possible while maintaining juuuust enough upward speed to make it above the atmosphere.

Please, when do you perform the gravity turn in 1.0.2?

At which speed and altitude?

I play KSP from 2012 (maybe version 0.13), and up to 0.90 I started gravity turn at 50 m/s, placing the nose of the crafts at an angle so that the direction indicator is at 45°, and when the apoaxis is at 75-80 km I go horizontal to gain enough lateral velocity to go in a good orbit.

Now, in 1.0.2, if I do this way, the craft (every craft I try) starts to spin and rotate, and even adding more and more SAS modules is no use at all!

I have to go straight vertical up to 30 km or so, and then perform a very gentle turn!!!!

But it seems to me very unrealistic!!

Thank you!

[MarkusF]

It can be done with the pad and VAB limits. (Barely.) This design did orbit in 1.0

With a pad upgrade and the LV909, a Mun flyby can be done with this three stage.

Actually you can easily do a Mun flyby without upgrading any building. Check out my thread about my current "hard" career: http://forum.kerbalspaceprogram.com/threads/120031-Diary-of-a-hard-career?p=1916310&viewfull=1#post1916310

Here's a picture of my vessel, with which you can get into orbit and set your apoapsis above 250km (high orbit) with a materials lab and a goo container. It has a total mass of 12.28t

- - - Updated - - -

Please, when do you perform the gravity turn in 1.0.2?

At which speed and altitude?

I play KSP from 2012 (maybe version 0.13), and up to 0.90 I started gravity turn at 50 m/s, placing the nose of the crafts at an angle so that the direction indicator is at 45°, and when the apoaxis is at 75-80 km I go horizontal to gain enough lateral velocity to go in a good orbit.

Now, in 1.0.2, if I do this way, the craft (every craft I try) starts to spin and rotate, and even adding more and more SAS modules is no use at all!

I have to go straight vertical up to 30 km or so, and then perform a very gentle turn!!!!

But it seems to me very unrealistic!!

Thank you!

Just start very early and turn very slightly to the east. Try it with a rocket with fins at the bottom, launch without SAS, at 50m/s give it some control input until the prograde indicator moves slightly away from the center and just watch it turn by its own.

When to start is hard to say. The higher your TWR, the earlier you have to turn. But whatever you do, never point the nose outside of the prograde indicator's circle, or your vessel is in danger of flipping due to the sideway forces. You can press F12 (i mapped it to F8 for myself, in order to resolve the conflict with the STEAM screenshot key) to see the aerodynamic forces.

[Sacs]

- Is this the way KSP is played? Just add engines?

No, you must also add struts.

[ghpstage]

This is my early career orbiter, it needs only the first two 5 science techs and general rocketry (20 science). Its capable of lifting 2 goos and a material lab into space high over Kerbin for the extra science.

Please, when do you perform the gravity turn in 1.0.2?

At which speed and altitude?

I play KSP from 2012 (maybe version 0.13), and up to 0.90 I started gravity turn at 50 m/s, placing the nose of the crafts at an angle so that the direction indicator is at 45°, and when the apoaxis is at 75-80 km I go horizontal to gain enough lateral velocity to go in a good orbit.

Now, in 1.0.2, if I do this way, the craft (every craft I try) starts to spin and rotate, and even adding more and more SAS modules is no use at all!

I have to go straight vertical up to 30 km or so, and then perform a very gentle turn!!!!

But it seems to me very unrealistic!!

Thank you!

A low altitude 45 degree turn is neither a gravity turn, nor is it gentle. If you turn off your prograde marker you will spin out.

An ideal gravity turn will have you do a small, 5 degree(ish) (pretty much the edge of the starting prograde marker!) turn at 1-3km and not require much, if any input afterwards, the rocket will slowly lean over all by itself.

Edited May 8, 2015 by ghpstage

[paolot]

Thank you, ghpstage!

I said "unrealistic" because Space Shuttle at launch didn't seem very gentle during the turn.

In KSP versions before 1.0.0, I never had problems in keeping direction at 45° angle from rather low altitude (below 1000 m) and velocity, using SAS obviously.

[Superfluous J]

I play KSP from 2012 (maybe version 0.13), and up to 0.90 I started gravity turn at 50 m/s, placing the nose of the crafts at an angle so that the direction indicator is at 45°, and when the apoaxis is at 75-80 km I go horizontal to gain enough lateral velocity to go in a good orbit.

If you are used to building rockets powerful enough to do that kind of gravity turn in KSP 0.90 and before, my guess is that your rockets are going WAY too fast for 1.0.x

How quickly do you get to 100m/s? If you're going 100m/s before you hit 1km altitude, lose some boosters (in the VAB ) and try again.

Also, as some have said in this thread, fins and aerodynamic rockets will help lots.

EDIT:

The space shuttle did NOT turn 45 degrees less than a kilometer from the ground.

https://www.google.com/search?q=space+shuttle+ascent+trajectory

Edited May 8, 2015 by 5thHorseman

[paolot]

Thank you all for the answers and the suggestions.

I tried to use tail fins/wings with an otherwise very unstable craft, and things went a bit better: I started the turn at 70 m/s at some hundreds meters of altitude (desired orbit was polar).

But I couldn't use SAS, because it causes strong (destructive!) spin and roll in every directions, so I had to use manual piloting.

The craft (a probe) is here, if someone wants to try it.

5thHorseman, at this link from your link, it is said that Shuttle starts the roll at about 255 m (767 feet), after 10 seconds of flight, and ends it at about 1055 m.

Did you mean this?

How quickly do you get to 100m/s?

It varied for the different crafts, as I used throttle from 50% to 100%.

But yes, sometimes I got 100 m/s before 1 km altitude.

Edited May 8, 2015 by paolot