![]() ![]() If I want to go to Eve, is it more efficient to make orbit first and then execute an ejection burn, or to just keep launching up at sunset until my periapsis is low enough? If you launch straight up at sunrise, you will be heading Kerbol-prograde, and if you launch at sunset you will be heading Kerbol-retrograde. Will add more as i get them but overall its a defferance but not a large number. ZZ% = Turn Shape (less is more horozontal)īoth these are right on the edge, not being active they wont excape according to tracking center, Base Line test Gravity turn tests are layed out as follows and are auto flown to the target alt by mcjeb, XX / XY / YY / ZZ%. ![]() Testing was as follows, All probes are one solid burn, no pausing (save 2-4 secs switching for jeb help on auto accent). Well heres my plimary testing after 2 tests of a. I hope my pictures help you understand it better Edited Jby rodion_herrera This is why you need to have a good mental picture or data of the layers of atmosphere of the planet you're going to leave from (with data on the varying densities at different altitudes), so you can plan an efficient ascent. A more accurate depiction of that "gravity well" is like this.Īnd now it is clear, when you look at the above image, why you need staging, and why the first few stages need to have lots of thrust, because the "gravity slope" nearer the body is steeper, and thus you need more thrust, to get out of it.but the further and further you go away from the planet the "shallower" the "gravity slope" and this is why it takes only a few seconds of burn to change apoapsis or periapsis if you're in a higher altitude.ĮDIT: Furthermore, if the planet you are trying to launch from has a thick atmosphere, this means if you do the gravity turn earlier, then you would encounter atmospheric resistance (drag) that would slow down your vert and horizontal velocities that your effort to do the turn would be wasted. Well, this isn't exactly the shape of the "hole" that gravity creates around Kerbin, the earth or any other planet. NOW, an additional important note.remember our cross section diagram earlier? simple eh? That's why gravity turns make it easier for a rocket to get out of a planet. So instead of 30-35 degrees slope, you only encounter perhaps 20-25 degree slope, so now the climb is easier on your knees! ![]() but, there's an easier way.it's a bit longer, but at least, it requires lesser effort.you climb out the hole in a helix. Now if you were on the bottom, and you climbed straight out of the hole, it would require some effort, due to the steep slope (around 30-35 degrees in my drawings). this is the profile we get, after cutting across the green line: To make this clearer, let's imagine creating a cross-section of this hole, along the green broken line. Imagine there was a shallow, cone-shaped hole (or crater) in the ground, and you were in the bottom of that hole. Pardon for the simplicity of my drawings-I could make better ones, but I was just after a clearer and "pictoral" explanation of the situation. ![]() I hope the following diagrams I made help in understanding why the "gravity turn" is important, if only to save on fuel/energy (also, I'm not really an expert in Physics, so those who are into the physics and math of this, if I make any error, kindly please correct or clarify my points, thanks). And? Now what? That is not directed towards you specifically, just wondering what one might gain from it other than in a theoretical fashion. Ok, you went straight up and escaped SOI. Perhaps we do not always wish to escape it. Don't forget, gravity also has useful effects. I will do some testing tomorrow and report back. The loss of delta-v may not be enough to make an orbital escape more efficient. As rpayne said, you would be surrendering delta-v to gravity (which would decrease as one was further from the planet). Even though one would be fighting gravity on a straight-up accent, I believe the delta-v spent on velocity in the verticle direction is more efficent than the same velocity in the horizontal direction. However, I am interested in testing this to confirm it. This should have a gravity slingshot effect. I believe he was specifically asking about escape velocity.Īs for which is more efficent, I would imagine a gravity turn would be the best option. ![]()
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