Difference between revisions of "Rocket"
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[[File:Kerbal x launchpad.png|thumb|upright|The [[Kerbal X]] can achieve an orbit around Kerbin]] | [[File:Kerbal x launchpad.png|thumb|upright|The [[Kerbal X]] can achieve an orbit around Kerbin]] | ||
[[File:Kerbal 2.png|thumb|upright|The [[Kerbal 2]] is only capable of a sub-orbital flight]] | [[File:Kerbal 2.png|thumb|upright|The [[Kerbal 2]] is only capable of a sub-orbital flight]] | ||
| − | A '''rocket''' is a | + | A '''rocket''' is a vertically launched [[craft]]. Usually it uses [[rocket engine]]s to propel it forward and doesn't utilise the lift of [[wing]]s or [[winglet]]s. It only uses [[control surface]]s to help steering in an [[atmosphere]]. The main purpose of a rocket is to reach space and an [[orbit]], or at least a sub-orbital flight. |
| − | With various [[stage]]s rockets can dump dry mass and get more efficient, while a [[ | + | With various [[stage]]s, rockets can dump dry mass and get more efficient, while a [[spaceplane]] usually doesn't have stages. As they don't use lift to maintain altitude, the rocket engines need to counteract the gravity. To determine if the rocket can lift off, the [[thrust-to-weight ratio]] can be determined. If the ratio is above one, the thrust generated by the engines is higher than the gravitational force and thus the rocket will lift off. Because the engines drain fuel, the craft gets lighter so the ratio also increases with the flight. |
| − | Because rockets don't need lift surface, they work in every environment and don't need an atmosphere. But on the other hand rocket engines with sufficient thrust are far more inefficient than [[jet engine]]s with similar thrust. | + | Because rockets don't need lift surface, they work in every environment and don't need an atmosphere. But on the other hand, rocket engines with sufficient thrust are far more inefficient than [[jet engine]]s with similar thrust. |
| − | Rockets are | + | Rockets are built in the [[Vehicle Assembly Building]] and then launched on the [[launch pad]]. |
== Start == | == Start == | ||
| − | The usual flight profile starts on the launch pad on [[Kerbin]]. Prior to | + | The usual flight profile starts on the launch pad on [[Kerbin]]. Prior to liftoff, the jet engines, if any, need to be started to run at full throttle on liftoff. When the jet engines are running at full power, the liftoff can be initiated by activating the rocket engines and releasing any [[TT18-A Launch Stability Enhancer]]s. |
| − | The rocket then starts to rise and continues so until reaching about 10 km. At this point | + | The rocket then starts to rise and continues so until reaching about 10 km. At this point a [[gravity turn]] is initiated by tilting in the desired direction. Depending on the targeted inclination, the direction of tilting might be different. For example, retrograde orbits, where the crafts rotates in the other direction than the body beneath it, the tilt would be to the West. With the gravity turn the craft starts to pick up horizontal velocity, which is crucial for a stable [[orbit]]. The engines continuing to accelerate the vessel to raise the apoapsis and periapsis out of the atmosphere. |
| − | As soon as the apoapsis and periapsis are outside the atmosphere, the craft won't fall back and reached a so-called parking orbit. From this orbit it is possible | + | As soon as the apoapsis and periapsis are outside the atmosphere, the craft won't fall back and has reached a so-called parking orbit. From this orbit it is possible to initiate orbital maneuvers like the Hohmann transfer, to change the orbital shape. |
[[Category:Craft]] | [[Category:Craft]] | ||
Revision as of 15:59, 6 May 2014
A rocket is a vertically launched craft. Usually it uses rocket engines to propel it forward and doesn't utilise the lift of wings or winglets. It only uses control surfaces to help steering in an atmosphere. The main purpose of a rocket is to reach space and an orbit, or at least a sub-orbital flight.
With various stages, rockets can dump dry mass and get more efficient, while a spaceplane usually doesn't have stages. As they don't use lift to maintain altitude, the rocket engines need to counteract the gravity. To determine if the rocket can lift off, the thrust-to-weight ratio can be determined. If the ratio is above one, the thrust generated by the engines is higher than the gravitational force and thus the rocket will lift off. Because the engines drain fuel, the craft gets lighter so the ratio also increases with the flight.
Because rockets don't need lift surface, they work in every environment and don't need an atmosphere. But on the other hand, rocket engines with sufficient thrust are far more inefficient than jet engines with similar thrust.
Rockets are built in the Vehicle Assembly Building and then launched on the launch pad.
Start
The usual flight profile starts on the launch pad on Kerbin. Prior to liftoff, the jet engines, if any, need to be started to run at full throttle on liftoff. When the jet engines are running at full power, the liftoff can be initiated by activating the rocket engines and releasing any TT18-A Launch Stability Enhancers.
The rocket then starts to rise and continues so until reaching about 10 km. At this point a gravity turn is initiated by tilting in the desired direction. Depending on the targeted inclination, the direction of tilting might be different. For example, retrograde orbits, where the crafts rotates in the other direction than the body beneath it, the tilt would be to the West. With the gravity turn the craft starts to pick up horizontal velocity, which is crucial for a stable orbit. The engines continuing to accelerate the vessel to raise the apoapsis and periapsis out of the atmosphere.
As soon as the apoapsis and periapsis are outside the atmosphere, the craft won't fall back and has reached a so-called parking orbit. From this orbit it is possible to initiate orbital maneuvers like the Hohmann transfer, to change the orbital shape.
