Best launch profile?

[Fergi182]

I have only recently started playing KSP and i am really enjoying it. I was wondering, having watched many youtube videos with differences, is there a better launch profile that is very fuel efficient. I guess it probably changes depending on your destination but generally what is most fuel efficient way to launch a rocket if say you are heading to the mun. (At what altitude do you begin a slight gravity turn? When do you turn completely parallel to kerbin and other such things.

[Nicholas4132]

If you want to learn how to launch a rocket into orbit, download the mechjeb mod, and use the ascent autopilot to get to orbit. I usually orbit around 100km. Watch mechjeb carefully, and just mimic it the next time you launch a rocket without mechjeb. That's how I learned.

[Boex]

My 'parking orbit' is generally as low as possible, normally 70-80km. Launch profiles also depend on the power of your rocket. A powerful rocket I normally start my gravity turn at 10km, to about 45 degrees pitch. When my Apoapsis hits 50km I normally head completely horizontally. I've been meaning to try more a few different approaches, but mine seems to be pretty efficient.

[Jimbow]

At 10km I tilt over to about 45degrees. Keep burning to I get apoapsis to 100km then cut power go horizontal until 30-20secs from Ap. Then burn to I get to orbital velocity. Probably not the most efficient.

I think the most efficient way is to keep pro-grade(orbital) but thats not always the most effective to get the orbit you want.

[Nibb31]

For Munar/Minmus transfers, I usually make a parking orbit of 160km, because you can warp faster above 150km. If I want to do geosynchronous orbit, I use a parking orbit of 475km, because you have a nice convenient 90° angle to launch to GEO altitude. If I want to practice docking, I usually go to 475 or higher, because you are moving slower than in low orbit and the relative speed between the two ships is easier to manage with RCS.

The best moment to start the gravity turn depends a lot on your ship, but it's usually between 15 and 30km. You want to be pretty much horizontal when you reach 70km.

[pebble_garden]

When to make the gravity turn depends a lot on your launch vehicle. I like to wait until it's climbing at 300m/s before I think of making the turn. But that generally happens between 10-20km. You don't want to turn too early or you spend too much time slicing diagonally through atmosphere. Yet you don't want to wait too long either, as it can waste fuel.

I've found that if you make the gravity turn to 45 degrees pitch and your velocity vector drops below that, you've turned too early. On the other hand if you adopt the 45 degree angle and the velocity vector doesn't follow, you've turned too late. Ideally they should move in synch.

Once you're above 45-50km you can feel free to rotate to any pitch angle you like; the atmosphere is too thin to cause significant drag issues. So at that point I start pitching over to horizontal (or even a bit below that!) to start thrusting sideways and putting energy into my orbital velocity.

One trick I've learned is to mouseover your apoapsis and watch whether it's rising or falling as you start to burn sideways. If it's rising above your target orbit height you can burn a few degrees groundward to stop that. How many degrees you burn down depends on how far around your orbit you are from apoapsis. I don't recommend cheating down across that angle by burning more than 5-10 degrees before the phase angle of your apoapsis.

Edited September 3, 2012 by pebble_garden

[Serratus]

I make first gravity turn as soon as I clear the tower. It's just a 5-10deg. It's mostly because at some point we will have to worry about where do the jettisoned parts land. That way they always land in the ocean. Then a gravity turn to 45deg at 15Km, and with speed over 300m/s. Then as I go through exosphere, I start the horizontal burn.

I use 100Km as parking orbit, because below that is for space planes, and above there are all the satellites...