Tutorial: How to Get into Orbit
How to Get into Orbit
Getting into orbit over Kerbin is rather simple, but it will require some knowledge and preparation. Space begins at 70,000m above the planet Kerbin. Stay above that for an entire flight around the planet and you're in orbit.
The process to get into orbit follows a simple progression:
- Launch straight up to 10km
- Change your Pitch to 45° east and keep the engines on until your projected Apoapsis is above 70km
- Change your pitch to horizontal just before you reach the Apoapsis
- Burn at Apoapsis until your Periapsis is above 70km
- Length: 15-20 minutes
- Difficulty: Harder than a suborbital flight, easier than an orbital intercept.
- Skills needed: Seat of the pants
- For version: Every version (tested on 0.20.2)
Step 0 - Rocket Design
A liquid fueled rocket with at least two stages preferably. Anything less will either only get you suborbital or an unwieldy expensive super large fuel tank thats only good for being an orbiting billboard.
The cheapest orbiter you can build with the current stock game (0.22) is:
- Unmanned: Probodobodyne OKTO2 or Manned: Command Pod Mk1 with Mk16 Parachute and TR-18A Stack Decoupler
- FL-T400 Fuel Tank
- LV-909 Liquid Fuel Engine
- TR-18A Stack Decoupler
- FL-T800 Fuel Tank
- LV-T30 Liquid Fuel Engine
For fun, use the LVT-30 engine for your first stage as it doesn't have thrust vectoring and thus will challenge you to actually fly the craft into orbit using your WASD keys keeping your navball on target. Your control module by default provides enough SAS control by itself to prevent you from going out of control for this mission.
Make sure your staging sequence is the way you want it, else you can add your flight to the countless list of catastrophic mission failures.
Step 1 - Launch Prep
Prepare your launch.
1. Set your map view with the m key to see your rocket at the launch site from space, tilted so you are looking north. You want to be able to see your apoapsis marker during your gravity turn so you can gauge when to cut your engines and coast up to it prior to burning your orbiting maneuver.
2. Set your thrust to maximum by holding Shift.
3. Toggle on SAS by hitting t.
Step 2 - The Launch
Say your countdown if you wish, and hit spacebar to launch into...well, space...without the bar (you'll make a space station with a bar at this end of the galaxy later).
Step 3 - Get up to 10,000 meters
Keep your rocket pointed straight up (use your navball to keep your dot on the top dot on the blue part of the navball) until you hit around 9,900 meters. Your first engine should cut out before this, just jettison it with the spacebar and burn your final engine. Throttle your second engine down to 2/3rds power since the atmosphere is weaker here and won't slow you down as much, and you will save precious fuel.
Step 4 - Gravity Turn 45 degrees East until 70km Apoapsis
Now for the fun part. Assuming you are pointing straight up, hit the d key to turn your ship using your navball until your dot is able to slide left and right on the 90 degree east line. Then tip on that line down toward the ground until you hit the 45 degree east mark. Hit your t key for SAS to help you keep it there, but don't rely on it. You will need to make course corrections until you get past 70km and enter space. At this point you should be going into space at a 45 degree angle from the ground, and in an easterly direction. Doing so will gain you speed and not waste the fuel you will need to get into orbit.
Step 5 - Get Your Apoapsis above 70km
While climbing up to 70km or 70,000 meters, it's now time to switch to your map view and control your ship from there entirely. Hopefully your navball is toggled on, else click on the collapsed tab at the bottom of the map view.
You will need to keep burning your fuel until you see your apoapsis marker reach 70km. You can see how high it is by hovering your mouse over it. Once it hits 70km (I usually shoot for 75km to buy me some head room) your craft will be able to coast up to it without any further fuel. Feel free to cut your engines with the x key and save some fuel for your orbital burn.
Step 6 - Orient for On-Orbit Burn
As you approach apoapsis (preferably before 30 seconds prior) orient your ship to the 0 degree latitudinal mark, heading east. Again, you should be in your map view when you start your burn. Hit tab to center your view on Kerbin and zoom out so you can see your orbit as it forms.
Step 7 - Burn into Orbit
Once you are 10-30 seconds away from your apoapsis, begin your on-orbit burn using the Shift key to throttle up. Full throttle is best at lower altitude apoapsises since you don't want to burn past apoapsis lest you waste precious return fuel if that's your intent. If you aren't concerned, go full throttle baby at any point near apoapsis and claim a stake with the stars. You only need to burn your fuel long enough until you see a periapsis marker appear on the other side of the orbit from the apoapsis, and you see a full orbit circle, then cut your engine with the x key. Congrats, you made it into orbit. It's usually a good idea to keep burning your fuel until your new periapsis marker is above 70km. If it's below, then your orbit will cause your craft to aerobrake, eventually returning to Kerbin. If your periapsis is ever above 70km, congrats, you will orbit Kerbin forever. If you have a manned flight, and fuel is low, then only burn until your periapsis is below 70km to ensure a safe return to Kerbin.
After orbiting for a while, depending on your fuel (with this design you won't have much if any at all) you can orient for a deorbit burn by burning backwards in the direction of your travel, once you are at your apoapsis point for maximum efficiency lest you be stuck in space with a manned crew forever.