any possible obstructions in the flight path.When to begin and the amount of tilt in a gravity turn are based mainly on three things: The trajectory of a rocket started from Kerbin reaching the altitude of 70km On bodies with atmospheres, atmospheric pressure and drag also comes into determining the most efficient gravity turn. The altitude to start a gravity turn with a pitchover maneuver at depends on several factors. If the craft has gained enough lateral speed at an altitude above any mountains or atmosphere, it then begins a stable orbit. By the end of the gravity turn, no fuel is wasted fighting gravity. Since the majority of this vector change is done by gravity and not by the flight controls, another tiny amount of fuel is saved. The farther the vector tilts to the side, the percentage of thrust spent fighting gravity becomes smaller and the percentage of thrust spent gaining speed becomes larger. As this happens, the craft will gain more speed sooner since it is traveling in a vector that is not directly opposed to gravity - the centrifugal force starts to decrease the effect the gravity, effectively saving fuel and time. The torque generated by the winglets placed on the bottom will tilt the rocket to the right direction in the atmosphere, but out of atmosphere or without these winglets the operator of the craft has to control the tilt. By turning away from vertical slightly, gravity will pull the velocity vector of the craft down towards that direction and the craft has to tilt to follow it. Then once a certain altitude is reached, a slight turn is made, called the pitchover maneuver. Assuming a perfectly flat launch site, the maneuver begins as a vertical launch, and follows with the vertical climb. The gravity turn maneuver is accomplished as follows. In other words, a straight vertical launch is the least efficient launch. If a launched craft followed a purely vertical flight path, then it would spend all of its thrust accelerating in the slowest direction, effectively spending the most Delta-V to gain the least speed without gaining any lateral speed necessary to orbit. Since the gravity of the local celestial body is always pulling on the craft, it will always accelerate most slowly when pointing directly away from that body and would accelerate faster in any other direction than straight vertical. Gravity turns work by fighting gravity the least amount possible to gain enough altitude and horizontal speed for the desired maneuver. The forces on a rocket after tilting the rocket by 30° Instead of killing all horizontal speed and then beginning a slow descent to the surface, it's actually more efficient to slow both your horizontal and vertical speed at the same time. This efficiency also applies to landing from orbit. It's a shorter path, so it saves more fuel. Think of a gravity turn as "cutting the corner", so to speak. As a craft starts ascending vertically, it slowly turns to the side until by the end of the turn it points sideways.įor an analogy, imagine getting to orbit without a gravity turn: it would be a straight up flight, then a 90 degree turn once high enough to orbit. A gravity turn combines these two steps into one maneuver, saving fuel in the process. In order to maintain a stable orbit, the craft must have enough sideways momentum at a high enough altitude to avoid colliding with any surface features or getting slowed down by the atmosphere, if any. In order to escape the surface, a craft must rise faster than gravity pulls it down. A gravity turn is a maneuver used to launch a craft into, or descend from, orbit around a celestial body while using minimal fuel.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |