This Java applet simulates 800 seconds of flight of a simple one-stage rocket. The rocket is launched from the surface of Earth, straight up (i.e. along a radius line), and fires its engines until its fuel is exhausted. Air drag is taken into account via the standard Newtonian drag formula.
The default parameters implement a simple model of a SpaceCub, but you can change them as needed to model other rockets (though the frontal cross-sectional area is fixed at 3.6 m^2).
| Mass | total mass of ship plus fuel (kg) | Fuel | mass of fuel (kg) | CD | coefficient of drag (0-100%) |
|---|---|---|---|---|---|
| Exh. Rate | mass expelled per sec (kg) | Exh. Velocity | exhaust velocity (m/s) |
I believe that the simulation itself is accurate as far as it goes, but it could go farther. First, I am not certain the drag formula is correct for supersonic speeds; I am probably underestimating the drag under these conditions. More importantly, one can never achieve orbit by thrusting straight up. I need to angle the rocket and allow a circularizing burn, so that a proper orbit can be attained.
Finally, the output is as crude as the input. The rocket modeler wants to know not just position, but velocity, acceleration, etc. I will need to expand my GraphPane class to handle multiple sets of data.
If you have any comments, questions, or suggestions, please write to me at joe@strout.net.