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#1 2018-06-28 03:18:14

Quaoar
Member
Registered: 2013-12-13
Posts: 489

NASA rocket simulator: how to build a rocket

Would you like to build a rocket, trying many kind of fuel and oxidizer combinations?
Now you can do it on NASA online simulator: you have only to choose the chamber pressure, the fuel-oxidizer ratio and the nozzle/throat area ratio, then the simulator returns the chamber temperature, the characteristic velocity and the sea level and vacuum exhaust velocity of the rocket.

https://www.grc.nasa.gov/WWW/CEAWeb/ceaWhat.htm

https://cearun.grc.nasa.gov/

The output is for an ideal rocket. I also tried to simulate some real rocket like for example the glorious Saturn V F1, to test how reliable the simulator is: the Isp of the real F1 was almost 96% of the ideal F1.

Last edited by Quaoar (2018-06-28 03:21:40)

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#2 2018-06-29 10:00:43

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,103
Website

Re: NASA rocket simulator: how to build a rocket

Hi Quaoar:

I suspect the 96% thing is the effects of nozzle efficiency and chamber c* efficiency.  Most well-designed nozzles deliver about 98% of the theoretical exit stream kinetic energy,  due mostly to streamline divergence effects.  Most well-designed rocket combustion chambers lose a percent or so of combustion completeness,  which lowers chamber temperature and c* velocity a little bit. 

There is also the engine operating cycle.  In the old designs,  a certain amount of chamber gas got tapped off to run the turbopumps,  and then dumped.  This gas did not go through the nozzle.  The newest designs minimize or even eliminate that gas loss.  If you include dumped turbopump drive gas in the massflow that divides thrust,  it does lower Isp a little.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#3 2018-06-29 13:06:33

Quaoar
Member
Registered: 2013-12-13
Posts: 489

Re: NASA rocket simulator: how to build a rocket

Hi GW

It's ever a pleasure to hear you.

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