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I'm currently working on reaching a 0.1 release of my first space simulator program. One of the trickier problems that Im trying to solve is the modelling of atmospheric drag on any given object (usually a rocket of some sort), but Im unsure of how exactly to do so.
I did check the wikipedia pages on the subject and found that the drag force is equal to 1/2*density*velocity squared*Drag Coefficient*cross sectional area.
[ame="http://en.wikipedia.org/wiki/Drag_equation"]http://en.wikipedia.org/wiki/Drag_equation[/ame]
This introduces several problems, as well as:
-where does the drag force act? I would guess that this might be at a "center of pressure", similar to lift, but how exactly can I figure out where that is?
-How to find cross sectional area? This sounds really easy, until you realize that the profile of the spacecraft is going to be a combination of several rectangles & circles in 2d, rotated at any given angle. I have no idea how to begin determining the Area as a function of angle to the airstream velocity
-What exactly is the drag coefficient? I know from the article above that Cd should be a function of the reynolds number, which itself will depend on velocity, Area, and fluid viscosity. But given this, will viscosity depend on altitude, and if so how do I model it accurately?
Any help is appreciated.
I did check the wikipedia pages on the subject and found that the drag force is equal to 1/2*density*velocity squared*Drag Coefficient*cross sectional area.
[ame="http://en.wikipedia.org/wiki/Drag_equation"]http://en.wikipedia.org/wiki/Drag_equation[/ame]
This introduces several problems, as well as:
-where does the drag force act? I would guess that this might be at a "center of pressure", similar to lift, but how exactly can I figure out where that is?
-How to find cross sectional area? This sounds really easy, until you realize that the profile of the spacecraft is going to be a combination of several rectangles & circles in 2d, rotated at any given angle. I have no idea how to begin determining the Area as a function of angle to the airstream velocity
-What exactly is the drag coefficient? I know from the article above that Cd should be a function of the reynolds number, which itself will depend on velocity, Area, and fluid viscosity. But given this, will viscosity depend on altitude, and if so how do I model it accurately?
Any help is appreciated.