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Old 01-06-2018, 07:33 PM   #1
SUPA-FNX
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Question Howdy from Finland !

Hi everyone !

I am new here and eager to start commenting and discussing about space exploration.

I have a question for starters.

I would like to design an imaginary space ship, but I would like it to be pretty realistic in many aspects.

I read about space shuttle that it dropped the SRBs at 46 km and they weighed 69% of the entire mass of the craft...and it was also using the SSMs at full thrust to that point. So possibly we can assume that it had lost about 75% of the entire mass at that point.

My question is as follows:

Does the space rocket Tsiolkowsky equation act like this....so it is not linear ?

Is there any calculation how the fuel is being burned ( percentage WISE at certain altitudes and speeds ) if the LEO is the goal ( 28 000 km/h ) on a typical space ship...if shuttle was not typical ?

I have hard time understanding the Oberth Effect relating sentence where the rocket accelerates faster at higher speeds due to kinetic energy. Does this relate to this phenomena ?

Yours truly ,

SUPA-FNX aka Juke

Last edited by SUPA-FNX; 01-08-2018 at 06:28 AM.
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Old 01-07-2018, 08:49 AM   #2
Thorsten
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Quote:
Does the space rocket Tsiolkowsky equation act like this....so it is not linear ?
Sorry, but this kind of begs the question - do you know the equation, and do you know what a linear vs. a non-linear equation is?

So no, the question is not linear, and the stage concept of rockets during ascent also makes things more complicated because also the efficiency of the rocket engines changes quite a bit from stage to stage and also due to the ambient air pressure.

Quote:
Is there any calculation how the fuel is being burned ( percentage WISE at certain altitudes and speeds ) if the LEO is the goal ( 28 000 km/h ) on a typical space ship...if shuttle was not typical ?
I'm not sure what a typical Space Ship is supposed to be - surely the Shuttle is one of a kind, but also the Saturn-V is different from a Russian rocket.

Basically you have to compute the numbers during the design of the rocket based on what stage concept you intend to use and what kind of engines you'd like to have - and if you don't know how to do that, you're unlikely to come up with a 'pretty realistic' spacecraft.

Quote:
I have hard time understanding the Oberth Effect relating sentence where the rocket accelerates faster at higher speeds due to kinetic energy.
I suspect you may have misunderstood something because the Oberth effect is concerned with burning close to a gravitational source vs. far away. So no, iI don't think it's particularly relevant for the Shuttle.
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Old 01-07-2018, 08:27 PM   #3
Ripley
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Hi SUPA-FNX, welcome to OF!
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Old 01-08-2018, 06:08 AM   #4
SUPA-FNX
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Originally Posted by Ripley View Post
 Hi SUPA-FNX, welcome to OF!
Thank you Ripley !

Glad to be here !

---------- Post added at 06:08 AM ---------- Previous post was at 06:05 AM ----------

Quote:
Originally Posted by Thorsten View Post
 Sorry, but this kind of begs the question - do you know the equation, and do you know what a linear vs. a non-linear equation is?

So no, the question is not linear, and the stage concept of rockets during ascent also makes things more complicated because also the efficiency of the rocket engines changes quite a bit from stage to stage and also due to the ambient air pressure.



I'm not sure what a typical Space Ship is supposed to be - surely the Shuttle is one of a kind, but also the Saturn-V is different from a Russian rocket.

Basically you have to compute the numbers during the design of the rocket based on what stage concept you intend to use and what kind of engines you'd like to have - and if you don't know how to do that, you're unlikely to come up with a 'pretty realistic' spacecraft.



I suspect you may have misunderstood something because the Oberth effect is concerned with burning close to a gravitational source vs. far away. So no, iI don't think it's particularly relevant for the Shuttle.
It seems to have mathematical constant.....so it cannot be linear right ?

https://en.wikipedia.org/wiki/Natural_logarithm

I know what kinda rocket engines I'd like to have, but they don't exist yet.

Yes...and now I know what Oberth means...with his effect.
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Old 01-08-2018, 06:25 AM   #5
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Old 01-10-2018, 06:18 AM   #6
SUPA-FNX
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Originally Posted by IronRain View Post
 

Thank you IronRain !
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