Orbiting

[bradwiggo]

I am new to the game and don't understand things like delta-v. 

 

I am having trouble getting into orbit, most of the rockets I build either flip over halfway to the edge of the atmosphere, or run out of fuel after they have left the atmosphere, what am I doing wrong?

[Tex_NL]

Check Scott Manleys tutorials.

You can learn a lot from him.

[bradwiggo]

20 minutes ago, Tex_NL said:

Check Scott Manleys tutorials.

You can learn a lot from him.

Thanks, yes, I probably should watch them, I tend to jump in to things without first researching them. 

[Tex_NL]

Just now, bradwiggo said:

Thanks, yes, I probably should watch them, I tend to jump in to things without first researching them. 

Just keep in mind some of his tutorials may be pre-1.X and use the old aerodynamics model. Going straight up to 10km and then turning to 45degrees does NOT work any more. If you do that you will flip out.

[Clockwork13]

56 minutes ago, bradwiggo said:

I am new to the game and don't understand things like delta-v. 

 

I am having trouble getting into orbit, most of the rockets I build either flip over halfway to the edge of the atmosphere, or run out of fuel after they have left the atmosphere, what am I doing wrong?

You can watch tutorials, but in my opinion the best way to learn to orbit is to figure out how to do it yourself, to me that is also the most fun way of learning how to do things. Start by building a rocket that can go straight up without tipping over. Wings are a big help. Once you can do that, you can build a rocket that goes to about 100k altitude (70k minimum), then just burn in the direction you want to orbit.

[SurrealShock]

I think that you will need larger crafts with more fuel. Try using engines that have gimbal like the main sail. This will help you to control your aircraft. As far as getting into orbit you need to make sure you have a good amount of fuel. When you try and get into orbit raise your apoapsis to at least 100km this will keep you clear of the atmosphere. Then you are going to want to point your ship toward the pro-grade maker. This will raise your peripasis. Prograde until your peripasis is at least above 70km. Then, you will be in orbit. (Yay!!!)

Edited February 13, 2016 by SurrealShock
Mistake in sentence

[Vanamonde]

I wrote a guide, though I have been lazy about fixing the example craft download. 

[Sir_Robert]

1 hour ago, SurrealShock said:

I think that you will need larger crafts with more fuel. Try using engines that have gimbal like the main sail. This will help you to control your aircraft. As far as getting into orbit you need to make sure you have a good amount of fuel. When you try and get into orbit raise your apoapsis to at least 100km this will keep you clear of the atmosphere. Then you are going to want to point your ship toward the pro-grade maker. This will raise your peripasis. Prograde until your peripasis is at least above 70km. Then, you will be in orbit. (Yay!!!)

That's actually a fairly common mistake. Bigger is not actually better. If your rocket is bigger, it means more mass. More mass means less deltaV, and thus you'll need a bigger rocket to get where you want to go. You only need a tiny rocket to get to orbit. Only reason to go with big 2,5 meter parts (or bigger), is if you need to lift something big itself.

 

@bradwiggo: think of deltaV as mileage. It's how much bang you can get out of your rocket. Delta means difference, and V stands for velocity (speed). DeltaV is literally the amount of speed difference you could get if you burned all of the fuel. So if you had a rocket with 100m/s deltaV, and you burn all your fuel (while in frictionless space. Air drag will slow you down and cost extra), you would be going 100m/s faster than before you started.

To get to Kerbin orbit, you need about 3500m/s deltaV (with a final orbital velocity of 2200m/s. So losing over a kilometer/s speed to air drag). This number is ofcourse when you know which way to turn and when. As a safe number, try 4000 to 4500m/s deltaV. Remember, smaller is better. As upper stage, a FL-T 200 fuel tank with a Terrier engine. As bottom stage(s), FL-T 400 and a Swivel engine. See how much that gives you, and if not enough, add fuel (or another Swivel stage).

Note that it's possible to be going TO fast with such a small rocket. If you go to fast in the atmosphere, you run a bigger risk of flipping. A quick and easy way to test this is to check your time to Apoapsis. Try to aim for 40seconds to 1 minute. If you reach that, try throttling down a little to keep it near that number

Edited February 14, 2016 by Sir_Robert

[SurrealShock]

1 hour ago, Sir_Robert said:

That's actually a fairly common mistake. Bigger is not actually better. If your rocket is bigger, it means more mass. More mass means less deltaV, and thus you'll need a bigger rocket to get where you want to go. You only need a tiny rocket to get to orbit. Only reason to go with big 2,5 meter parts (or bigger), is if you need to lift something big itself.

I meant bigger as he needed a larger fuel tank to get into orbit.

[Waxing_Kibbous]

You should post a pic of your rocket so we can help out a bit better- also what tech do you have unlocked?

[bradwiggo]

5 hours ago, Waxing_Kibbous said:

You should post a pic of your rocket so we can help out a bit better- also what tech do you have unlocked?

This one gets into orbit: https://onedrive.live.com/redir?resid=6F294D80B5D8B123!6726&authkey=!AGlqSGueIJPBx0o&v=3&ithint=photo%2cPNG 

This one doesn't: https://onedrive.live.com/redir?resid=6F294D80B5D8B123!6725&authkey=!AGip8Nf06s-O9Ic&v=3&ithint=photo%2cPNG

The one that does can't get to the mun though. 

Also a question about refuelling: is the only way to get fuel to a refuelling station to bring it from kerbin?

Edited February 14, 2016 by bradwiggo

[Sir_Robert]

1 hour ago, bradwiggo said:

This one gets into orbit: https://onedrive.live.com/redir?resid=6F294D80B5D8B123!6726&authkey=!AGlqSGueIJPBx0o&v=3&ithint=photo%2cPNG 

This one doesn't: https://onedrive.live.com/redir?resid=6F294D80B5D8B123!6725&authkey=!AGip8Nf06s-O9Ic&v=3&ithint=photo%2cPNG

The one that does can't get to the mun though. 

Also a question about refuelling: is the only way to get fuel to a refuelling station to bring it from kerbin?

Yes, currently the only way for you to get fuel is to bring it from Kerbin. Eventually you will be able to mine it on the Mun and ship from there, but that's late game stuff.

As for the pictures: Both are massively overbuild. Get rid of the Solid boosters, they aren't needed (especially the upper stage ones. A good rule of thumb is to only use SRBs in the first stage), and only make it harder to steer. That is probably the reason you are flipping, to much thrust while you can't steer

For your early attempts at getting to orbit: Do NOT bring heavy science. It adds weight that makes it harder to get to orbit. Try getting comfortable with a small rocket before you add payload. Cut the upper stage fuel tank in half, and add that fuel to the lower stage. This alone will improve your deltaV, since you don't have to carry the mass from that extra fueltank with you (ditching useless mass as early as possible is a good tip for optimizing your rockets. Each kg you add costs you deltaV). I see your upper stage engine is a Swivel or a Reliant. Ditch it and replace it with the lighter Terrier. It is powerfull enough for such an upper stage, and again, less mass (thus more deltaV).

So in short, a few easy tips: Keep your upper stage small, add the fuel to the lower stages instead. Try to minimize weight: Use the smallest engine that is still powerful enough

[Ketatrypt]

1 hour ago, bradwiggo said:

This one gets into orbit: https://onedrive.live.com/redir?resid=6F294D80B5D8B123!6726&authkey=!AGlqSGueIJPBx0o&v=3&ithint=photo%2cPNG 

This one doesn't: https://onedrive.live.com/redir?resid=6F294D80B5D8B123!6725&authkey=!AGip8Nf06s-O9Ic&v=3&ithint=photo%2cPNG

The one that does can't get to the mun though. 

Also a question about refuelling: is the only way to get fuel to a refuelling station to bring it from kerbin?

Hello, according to your second pic, you are stacking SRB's.. That is a common mistake. (I made it too heheh) Liquid fuel is much more efficient then solid fuel. Your first pic there actually looks pretty nice - you use the Solid rocket boosters to help the rocket thru the lower atmosphere, and ditch them for more efficient liquid engine. but I would get rid of the SRB under the liquid engine for another fuel tank.. basically extend it, so you have 3 liquid tanks with a swivel engine (it has gimbling, helps with control) and then add your 4 SRB's radially...

 

Here is a rocket that I whipped up, basically followed your design, and it has enough fuel to almost go to the mun if flown right. (it should at least get to orbit)

A couple notable differences - You don't need as much power at take-off. 4 SRB's is just way too much power. Even 2 SRB's is quite a lot, but it works, just power back on the liquid engine at ~300m/s until you are over 10km altitude. Then you can power back up. The reason to do this is aerodynamic drag. If you go faster then 300m/s at those low altitudes you are just wasting fuel to aerodynamic drag. I also added in the second fuel tank for the main liquid engine, which will be burning from takeoff to orbit. And if you wanted, this has enough fuel/power you could even add another small engine/fuel tank on top of this for going to the mun/minmus.

 

Also, if you don't have a trained pilot, probe cores help a lot, as you can use stability assist. smaller rockets in general are harder to control as they can whip around pretty fast, but, with stability assist on (press T) it shouldn't be an issue.

Hope this helps and happy flying

Edited February 14, 2016 by Ketatrypt

[Waxing_Kibbous]

5 hours ago, bradwiggo said:

The one that does can't get to the mun though. 

Also a question about refuelling: is the only way to get fuel to a refuelling station to bring it from kerbin?

The terrier engine will solve these problems, at least for the first part of your game. Having a terrier at the last stage will open up the Kerbin system to your craft quite nicely, its a very efficient vacuum engine.

[bradwiggo]

2 hours ago, Waxing_Kibbous said:

The terrier engine will solve these problems, at least for the first part of your game. Having a terrier at the last stage will open up the Kerbin system to your craft quite nicely, its a very efficient vacuum engine.

The terrier doesn't have much vacuum thrust. 

[Sir_Robert]

23 minutes ago, bradwiggo said:

The terrier doesn't have much vacuum thrust. 

It's a small engine. Your upper stage is small. It doesn't NEED that much thrust.

And he never said anything about it being a high thrust engine. He said it's a very efficient engine. Which it is. Which is way more important

[bradwiggo]

15 minutes ago, Sir_Robert said:

It's a small engine. Your upper stage is small. It doesn't NEED that much thrust.

And he never said anything about it being a high thrust engine. He said it's a very efficient engine. Which it is. Which is way more important

I used it and ended up passing the highest point in the orbit before I had a stable orbit 

[Sir_Robert]

Just now, bradwiggo said:

I used it and ended up passing the highest point in the orbit before I had a stable orbit 

Please describe your process of getting to orbit, and we will tell you what to improve, because if that is a thing that's happening, something is VERY wrong with what you are doing

[bradwiggo]

7 minutes ago, Sir_Robert said:

Please describe your process of getting to orbit, and we will tell you what to improve, because if that is a thing that's happening, something is VERY wrong with what you are doing

I go straight up turning a little to the east, and then when I get to just before the apoaosis I burn prograde. 

[Sir_Robert]

Just now, bradwiggo said:

I go straight up turning a little to the east, and then when I get to just before the apoaosis I burn prograde. 

Well there's your problem. Turning like that not only means you can't get to orbit because you can't finalize your orbit fast enough, but turning to sharply like that is a guaranteed way to flip your rocket. You need a sideways speed of 2 kilometres per second to be in orbit. If you don't get started on that early on, you'll never get it

A gravity turn starts turning very early, and turns very slowly.

Go watch Scott Manley's tutorial (from the very first reply to your question) to explain how to do it

[Vegetal]

You are flying it wrong.

Basic rules of thumb for a beginner:

At launch, slowly begin turning east. At 8 to 10 km altitude you should be 45 degrees to the horizon. At 30km you should be close to horizontal. Keep burning until your apoapsis is above the atmosphere. When you get there, burn prograde until you circularize.

There. Do that and you will see the difference.

[Snark]

9 hours ago, Waxing_Kibbous said:

The terrier engine will solve these problems, at least for the first part of your game. Having a terrier at the last stage will open up the Kerbin system to your craft quite nicely, its a very efficient vacuum engine.

This.  The Terrier is a great upper-stage engine.  For example, if you have an upper stage that's basically just a Mk1 command pod, 2-ton fuel tank, and a Terrier, with a few small odds & ends (battery, parachute, etc.), then that combo has a dV of something like 2500 m/s, which is over 2/3 of the total dV you need to get to Kerbin orbit!  If you can build a 1st stage that can lift that and throw it by 1000 m/s or so, you're good to go.

6 hours ago, bradwiggo said:

The terrier doesn't have much vacuum thrust.

It has crappy atmospheric thrust.  It has good vacuum thrust.  Not really high, but plenty high enough for small craft.  Sir_Robert said it best:

6 hours ago, Sir_Robert said:

It's a small engine. Your upper stage is small. It doesn't NEED that much thrust.

And he never said anything about it being a high thrust engine. He said it's a very efficient engine. Which it is. Which is way more important

...You don't need upper stages to have a lot of thrust.  You need them to be fuel-efficient.

You need to have lots of thrust on the launchpad, because you're taking off straight up and you're directly fighting against gravity, so what you need is to muscle your way out of that.  It's about brute force.  That's why SRBs are great on the launchpad; brute force is what they're all about.

However, by the time your first stage is spent, you're not going straight up anymore-- you're going mostly horizontally, and you're not fighting gravity (much), you're accelerating sideways.  And you can take plenty of time to do that.  So fuel efficiency is more important than thrust, at that stage.

[Tex_NL]

15 hours ago, Vegetal said:

You are flying it wrong.

Basic rules of thumb for a beginner:

At launch, slowly begin turning east. At 8 to 10 km altitude you should be 45 degrees to the horizon. At 30km you should be close to horizontal. Keep burning until your apoapsis is above the atmosphere. When you get there, burn prograde until you circularize.

There. Do that and you will see the difference.

There is a much easier and more accurate rule of thumb:

The atmosphere gauge at the top centre of your screen has four colours: black, dark blue, blue and light blue. Don't make sudden angle changes but move slowly and gradually. When the needle passes from light blue to blue you should be at roughly 60 degrees. From blue to dark blue at 30 degrees. And from dark blue to black at 0 degrees.