Mission 1: Satellite to MEO (Medium Earth Orbit).
Lets get some fuel burnt then. First up, mission one, the satellite we built. This is going to get sent up to MEO (200km+) as a start point of a communications network.
As this is our first launch, i'm going to go through it from start to finish with you. Again, sorry if it is teaching the reader to suck eggs but that's the point of this.
Firstly, load the blueprint,
give it a final once over and press launch. It may say something about thrust or parachutes or whatever at the point, but because our build doesn't need parachutes we'll load it straight out.
On the right, there's a percentage bar and a button saying off with 'toggle engine on and off' next to it. As you may imagine, that turns on and off the engines (shock). Press it once to get rid of the annoying message, and again to keep the engines off. Notice the engines didn't light up? Thats because you need to select the engines you want to fire up.
But before that, I want to draw your attention to the bars on the left. These are your fuel gauges and correspond to all the fuel tanks on your build. So 3 gauges mean there are 3 tanks. Points to note, they aren't in stage order and they aren't labelled either, so figuring out which is which is only possible when they're moving. Also, it doesn't indicate the number of actual individual fuel tanks in the build, but the number of whole tanks.
So for example, this build has 3 sections and will register as 3 fuel tanks, despite each tank containing multiple building tanks. As long as a building tank overlap connects to another, it will be 'one' tank for the purpose of drawing fuel, regardless of how many or what configuration.
Now, we can turn on the engines required for that stage. In this case its just the one hawk, press on it and it should say 'engine on'. The throttle bar is sat at 50%, drag that up to 100% and then press the off button. There should be a slight roaring noise as fuel is turned into light, noise and heat, lifting your rocket into the sky.
As you pass 2m/s, a direction arrow will appear onscreen. This is the direction you are moving in relation to the body that is gravitationally influencing you, NOT the direction you are burning in. For the moment, this will point roughly straight up as you burn away from the ground.
Once your rocket is in motion, switch to map view and press on the moving triangle (which represents your rocket) and it should say FOLLOW. Press on that, and the map view will follow your rocket as it moves skywards.
At the top right will be 2 rapidly changing numbers.
- One is your rough altitude. I say rough altitude as it generally does work to average distance above the ground when in orbit, then your actual terrain distance to the hard stuff below you. There are a few instances this doesn't work. Like on Mars, it can read at 2,500m above the terrain but you've actually smashed yourself into Olympus Mons before you've been allowed to open your parachutes.
- The other is your velocity in the direction the arrow is pointing. Again, this is relative to the gravity you are being governed by.
Flight Path
This isn't a definitive flight path, or the best one. Its a good generic one but each build (and builder), depending on capability, ability and experience does it differently. Don't ask for the 'perfect' one, as we're trying to work that one out ourselves.
Like when I was a space dweeb, I used to burn almost straight up til the Karman line, do a 90 degree turn and then burn hard for escape velocity. And then wonder why almost everything crashed unless it had a ridiculously high TWR (6 or some damned thing) but I'd burn out of fuel and crash anyway.
The first 'checkpoint' as such, is roughly 2,500-3,000m. For the moment, we want to just be burning straight up and gaining altitude as quickly as possible. This is so we can clear the hardest part of the launch when you're fighting gravity and drag the most. But, we're going to have to come over at some point, and that is at roughly this altitude. Press the right (
no one goes left!) button until the rocket is tilted at roughly 15 degrees. It doesn't have to be exact, and you'll see the direction arrow slowly coming over as well until it points off the nose.
Switching to map view now and you'll see your triangle with a white line extending from the ground, through your rocket, up and then back down to the ground. This is your ballistic arc and is essentially the route you will take if you cut the engines and no forces other than gravity acted upon you. Obviously if you did that right now then drag would cut that arc massively but on an airless rock (the moon), you would fly that exact line until you impacted the ground.
The top of the arc is your apogee (its labelled Apoapsis, but that's just the game), or if you're a shooter, the culminating point of your ballistic path.
But we want to get that white line out of the atmosphere to above the Karman line, so we're going to keep burning for the sky.
When we hit the next checkpoint at roughly 5,000m, start bringing the nose over a bit more to roughly 30 degrees and making that arc even wider.
And again at:
- 10,000m to roughly 45 degrees.
- 15,000m to about 60 degrees.
You don't want to go any further over than 70 degrees until your apogee hits beyond the karman line. This allows you to gain height as well as speed in the upper atmosphere.
At some point (after 76.9 seconds actually), stage one will burn out. Its very unlikely you'll be in orbit at this point. In fact, you'll probably have the apogee just breaking 30km-ish.
Now, here comes the experience and dead reckoning part. Because you are still sub-orbital, unless you get this next bit right you'll still crash into the ground. You need to be attaining 1667m/s+ before your rocket re-enters the atmosphere.
Now, the most efficient way is to stage when appropriate and keep burning until your apogee is clear of the atmosphere. Then cut engines until you are at the culmination point of the arc and then burn prograde until your arc becomes a circle.
This is the best way and gives you a lovely first time circular orbit to show to your friends.
However.
There are several 'problems' with this and it all comes down to TWR and Dv. Because from the culmination point onwards you are
falling back to Earth and also, every second you are not burning in the atmosphere, drag is slowing you down, meaning you are spending more Dv getting back to speed.
So.
- If you have a high TWR and plenty of Dv, then go ahead.
- If your TWR is quite low though, you are going to have to either start your orbital burn earlier or allow yourself more height before cut off to give yourself the time required to accelerate to escape velocity.
Unfortunately, there's no hard and fast rules for this (cos air resistance is a turd in game) so it is very much a matter of trial and error.
Some people, especially if they're aiming for a set orbit height, will burn up until the apogee is that specific height and then go prograde. That gives them much more time to get into an orbit before they come back down.
Anyway, I mong it hard by burning too late and end up
slightly elliptical at apoapsis 64km / periapsis 39km.
But we're in LEO with fuel to burn and another 150km to climb. So we burn prograde at either end until one end (which will become your apoapsis and move to the opposite side of your orbit eventually because its your highest point, regardless of where you started your burn) is roughly around 200km.
Once you've achieved that, wait until your little triangle is at the apoapsis before you burn again. That may take a while, so use the arrows next to the map button to time warp until you are if you don't want to wait that long.
Once there, simply rotate to face prograde again (direction arrow...) and burn into the periaposis comes up. As it come closer, it'll start to slide off. You can ignore that and just have an ish 200km orbit, or if you're a perfectionist, keep chasing the apoapsis and gradually you'll get a lovely circular orbit all of your own.
I wasn't bothered, so here it is at apo202 / peri201.
Mission finished?
Not yet.
Firstly, you need to get rid of the second stage tank and engine. Now the purists will be like 'de-orbit it'.
No.
Separate and select 'clear debris' (or destroy it, whichever). We could de-orbit it. Hell, with the amount of juice left, I could powered land the damned thing.
But today is not that day.
Then, press on the solar panels to unfurl them.
Now, you're asking why it has an engine and RCS, if we never used it? Because now you have the option of moving it around the SOI into other orbits if you want to.
Right, give that a crack. Once you've nailed it, come back for mission two.
