(You might still be throttling your engines at this point, so there's more than one thing going on here.) This adjustment is called "the gravity turn, or "gravity roll." Turn until your rocket is pointed about 40-45 degrees above the horizon. ![]() At 10,000 meters, take a relatively sharp turn to the East (right). We need to step back a little to the 10,000 m altitude point. ![]() For any reasonable rocket, you should go to full throttle by about 15,000 m or so, if not before. You would have to go out of your way to design a silly rocket with ultra high TWR and horrible drag such that you couldn't be at full throttle by 20,000. After about 12,000 meters allow your rocket to increase speed fairly quickly. Increasing speed isn't necessarily a matter of increasing throttle, but often a matter of decreasing the throttle less frequently. Note that the craft's speed will naturally increase as its mass decreases from less fuel. Here are some general guidlines that should apply to most (nearly all) rockets:īelow 1000 m, don't travel faster than around 100 m/sīelow 3000 m, don't travel faster than around 130 m/sīelow 7000 m, don't travel faster than around 200 m/sīelow 10,000 m, don't travel faster than around 300 m/sīelow 12,000 m, don't travel faster than around 400 m/s Rockets with very low TWR might not need to throttle back much if at all. Rockets with very high thrust to weight ratio (TWR) will need to throttle back more. I can't tell you how much "% throttle" you should adjust to, because it depends on the rocket. At the initial lauch, start off at full throttle, but be prepared to quickly lower the throttle. ![]() The velocity limit changes with height (altitude). If you go too fast you'll be wasting much or most of your thrust (and thus fuel) to drag forces. During this time, adjust your throttle to limit your speed. Go straight up for the first 10,000 meters."Optimal" (or at least quite efficient) method for achieving orbit (on Kerbin specifically) I do agree however with the author of the video that going too far straight "up" is wasteful. So in conclusion, there are losses associated with this "upwards velocity" but it's not a total loss. The optimal transition tradeoff between course correction losses and drag losses happens almost invariably at around 10,000 m altitude (specifically with Kerbin). By that, the gravity turn should be done earlier rather than later. It is most efficient to perform course corrections at the point of lowest, orbital kinetic energy. And similarly, since the initial orbit is so terribly elliptical, it will invariably involve the following: b) later when the orbit needs to be circularized, it must involve course corrections (perpendicular to the velocity vector) that are done at higher orbital kinetic energies. ![]() Also, orbital energy is only increased by the component of the thrust vector (your heading when you apply thrust) that is parallel with the velocity vector, i.e., parallel to your orbital prograde vector. There is a loss associated with the component of thrust being parallel to the gravity vector, which is why prograde and retrograde maneuvers are most efficient at apoapsis and periapsis. The true losses come from a) performing a maneuver such that a component of the thrust vector is parallel to the gravitational acceleration vector (gravity losses), in other words, increasing the apoapsis at a location other than the periapsis. The "upwards velocity" (as it was called) eventually gets converted to potential energy, which gets stored in the orbit (albeit initially, an extremely eliptical orbit). Orbital energy has two components, kinetic energy and potential energy. (btw, the terms "upwards velocity" and "sideways velocity" are not my terms they were from the video.) It's true that it's wasteful to go straight up for too long when achieving orbit.
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