#orbit

27 messages ¡ Page 1 of 1 (latest)

humble pelican
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pls help me build rocket to go to orbit

wild mountain
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Did you already tryed?

humble pelican
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yea i built a shuttle but srvbs fell off

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and lost stabiliyy

wild mountain
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Make a normal rocket. Shuttles are hard

humble pelican
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ok

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wair imma just show a pic fo the shuttle

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/i tried my best

wild mountain
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As i said, shuttles are hard, learn to fly normsl rockets first

humble pelican
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OK give example

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i made a rocket that went out of the atmospere

wild mountain
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Then use that as a base snd extend it. Like add booster or myke tge stage bigger

humble pelican
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it got to space but not in orbit

wild mountain
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Add booster, make the stages bigger, use more efficient engines

humble pelican
late light
honest lava
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Basically you want to get enough sideways velocity (about 2200 m/s) but also being above atmosphere. But, going through atmosphere creates drag, so you want to leave it as fast as you can to lower inefficiencies from drag losses.
But, it’s also efficient to accelerate closer to the planet, so you also want to accelerate as low altitude as you can.
So, you want to balance these two things in what’s called a “gravity turn” which is a trajectory which you accelerate along, starting vertically up from launchpad, gradually tilting eastward, and at 10 km you want to face 45 degrees over horizon, and get your apoapsis, your highest point in your orbit, over 70km, which is space in ksp. Then, you want to accelerate while being close to your apoapsis, angle rocket a bit up over horizon if you pass apoapsis, and lower thrust if it starts go too far ahead of you. Then, make sure your periapsis is above 70km too, so you don’t fall back into the atmosphere too early.

During initial launch, you want your thrust to weight ratio of around 1.3-1.5, but on your upper stage, it can be lower, like around 1 twr. It works well to have a two stage rocket, first stage with 1.3-1.5 twr, about 1700 m/s in delta v and have powerful sea level optimized engines, like the reliant, swivel, mainsail, vector or dart engines(not including all engines in this list) , and second stage of like 1-1.3 twr, 1700 m/s delta v, and use vacuum efficient engines, like the terrier, poodle, wolfhound(or other vacuum efficient engine)
In total, you should have about 3500 m/s to get into a low kerbin orbit.
Once you get good at making low kerbin orbit rockets, try making them larger, so you can add heavier payloads, like for example a command module and a third stage for on orbit use only, so you could go to mun, minmus or beyond

Also, as already mentioned, shuttles can be tricky to pilot into orbit precisely, so it’s better to learn how to fly simpler rockets first, but once you do, I would totally recommend

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Learning how to fly space shuttle, as it can be really fun to use

humble pelican
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i understand Thrust
The amount of thrust produced by the rocket depends on the mass flow rate through the engine, the exit velocity of the exhaust, and the pressure at the nozzle exit. All of these variables depend on the design of the nozzle. The smallest cross-sectional area of the nozzle is called the throat of the nozzle. The hot exhaust flow is choked at the throat, which means that the Mach number is equal to 1.0 in the throat and the mass flow rate m˙ is determined by the throat area. The area ratio from the throat to the exit Ae sets the exit velocity Ve and the exit pressure pe.

You can explore the design and operation of a rocket nozzle with our interactive thrust simulator program which runs on your browser.

Thrust Equation
The exit pressure is only equal to free stream pressure at some design conditions. We must, therefore, use the longer version of the generalized thrust equation to describe the thrust of the system. If the free stream pressure is given by p0, the thrust F equation becomes:

F=m˙Ve+Ae(pe−p0)

Notice that there is no free stream mass times free stream velocity term in the thrust equation because no external air is brought on board. Since the oxidizer is carried onboard the rocket, rockets can generate thrust in a vacuum where there is no other source of oxygen. That’s why a rocket will work in space, where there is no surrounding air, and a gas turbine or propeller will not work. Turbine engines and propellers rely on the atmosphere to provide air as the working fluid for propulsion and oxygen in the air as an oxidizer for combustion.

The thrust equation shown above works for both liquid rockets and solid rockets engines. There is also an efficiency parameter called the specific impulse which works for both types of rockets and greatly simplifies the performance analysis for rockets. tho

wild mountain
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In ksp you don't really need to understand how thrust works.
Its enough that a engine creates thrust.

When you orbiting a planet you still fall back to the surface, but in the same moment you are moving very fast to one side, so fast that the surfaces "sinks" at the same rate you are falling because of the curveture of the planet.

So the most important for in orbit is to move very fast to the side. At Kerbin its 2300m/s to the east.
But because of the atmosphere and hills you have to fly a bit up first

honest lava
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just in launch, you need to have just enough thrust so that the thrust force is greater than the experienced gravitational force, so you can go up

humble pelican