Why don't rockets enter space horizontal ?

Discussion in 'The Cesspool' started by Jerimiah, Sep 28, 2021.

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  1. Jerimiah Registered Member

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    Rockets generally are launched vertically into space , why aren't they ever launched horizontal ?
     
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  3. Ultron Registered Senior Member

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    With rocket propulsion type a horizontal launch would take more fuel. There are some alternatives which are viable, for example a big airplane takes the rocket on the edge of atmosphere and then the rocket engines start and rocket takes off to space.
     
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  5. Jerimiah Registered Member

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    Yes , that is what I was thinking , something similar to the shuttle design ! We may be able to just accelerate and let the momentum take us into space using a horizontal launch . I am considering the trajectory would be a natural curvature allowing the craft to curve into orbit providing the acceleration produced enough momentum ?
     
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  7. Seattle Valued Senior Member

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    The horizontal velocity is what gets you to escape velocity and that's essentially what the Richard Branson flight did with an airplane taking them up to where the atmosphere is much thinner.

    Other launches start vertical to get though the thickest part of the atmossphere and then tilt to reach that horizontal velocity.
     
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  8. billvon Valued Senior Member

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    They generally are horizontal by the time they get above the atmosphere. But for the first 30 seconds or so they go straight up both because it's easier to launch them that way and because that gets you out the really thick atmosphere sooner.

    You may occasionally hear the term "pitchover" shortly after launch, which is the beginning of the transition to horizontal.
     
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  9. sculptor Valued Senior Member

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  10. Jerimiah Registered Member

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    Thank you , I never considered they tilt later on in the flight ! Do rockets presently use HPFS ? (high pressure fuel system)

    I have seen Richards space plane , it looks kinda ''flimsy'' though but I do like the concept of just flying into space rather than using rockets .
     
    Last edited: Sep 29, 2021
  11. billvon Valued Senior Member

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    Most modern rockets have three phases of pressurization.

    In the tanks themselves there is a pressurization system that does two things. One, it ensures that the fuel and oxidizer is under enough pressure to flow into the rocket's propellant pumps. However, this could be accomplished simply through the weight of the fuel itself and from the acceleration provided by the rocket. Two, it ensures that the walls of the tanks stay rigid. Most rockets require pressure in the tanks (generally 15-60 PSI) so they don't buckle under the stresses that come from acceleration. This either comes from an inert gas (like helium or nitrogen) or from the propellant itself (i.e. autogenous pressurization.) Some tanks (balloon tanks) require pressure at all times, or they will crumple even sitting on the launch pad.

    Once the propellants get to the rocket, they are usually pressurized to an intermediate pressure by a low pressure pump, then to a pressure to higher than the combustion chamber pressure by a high pressure pump. This pump has a lot of work to do since chamber pressures can be in excess of 3000 PSI. A significant fraction of the propellants are used in these pumps to generate the necessary power to run them.
    The Virgin Galactic ship uses a hybrid rocket.
     
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  12. Jerimiah Registered Member

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    Thank you , I am really appreciating and enjoying reading this information !

    I have made several GPR rockets and successfully launched them on a very small scale , designed to only travel a couple of meters by the limited size and fuel . I do believe in sharing free science to help the world and the mechanical stress levels in rocket science may be reduced by having an outer shell and an inner shell that has a vacuum or part vacuum between the shells .
     
  13. Seattle Valued Senior Member

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    I don't see anyway of just flying into orbital space that way however. I'm no expert of course.
     
  14. Jerimiah Registered Member

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    It isn't a difficult concept using momentum and what you may call kinetic energy (kE) .

    An accelerated object will continue in momentum even after the acceleration is discontinued , the momentum will take the craft over the ''line'' !

    Of course there is additional ways , such as stages and hybrids .
     
  15. billvon Valued Senior Member

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    Yep. But to get to orbit you have to reach 16,800 mph. You can't just "coast" up to that speed. You need to accelerate constantly for a long time. If you accelerate at 1G horizontally, for example, it would take 14 minutes of acceleration to reach orbit - and that's above and beyond the acceleration you need to get above the atmosphere.
     
  16. Jerimiah Registered Member

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    Why would such a great speed be required to get to orbit ? Gravity is a force so surely as long as escape force is equal to gravity , orbit should be reached ?
     
  17. James R Just this guy, you know? Staff Member

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    Jeremiah is no longer with us, but for those who are interested in billvon's informative posts and in this topic in general, I want to add something in response to this.

    The key word is "orbit". In principle, we could launch a rocket straight upwards into space. If we did that, then the rocket would fall staight back down again, landing somewhere to the west of where it was launched from (due to the rotation of the Earth's surface during the flight). To get the rocket to stay up there, we must give it enough horizontal velocity for it to "miss" the Earth when it falls back down. Anything in orbit (with engines off) is always falling towards the Earth, but as long as its speed is high enough the Earth's surface curves away below it at a sufficient rate that it never hits the ground. Instead, it keeps falling continuously round and round.
     
    Last edited: Oct 1, 2021
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