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I made this program to help me better understand gravity and orbits and such. I especially wanted to understand how you can pull off a "gravity slingshot" manoeuvre. I never really understood that. For those who don't know what "gravity slingshot" is, it's a way of using a planet's (or star's) gravity to greatly accelerate a spaceship so that it flys off at incredible speed. This technique is described frequently in science fiction and was actually used for missions like Voyager (they used jupiter's gravity).

I treid to make this program as accurate as possible. What's surprising is how simple the mathematics are. All I really needed was one formula, provided for me so kindly by THE Sir Issac Newton. It is the formula for the force of attraction between two objects.

Controls:
you control the spaceship (the little line in the corner of the screen). The dot in the center is a planet.
arrowkeys control thrust and angle of the spaceship.

Ctrl points the spaceship towards the planet.
Spacebar resets the position of the spaceship.


Enjoy!

Feedback please.

P.S: Of course, if you remove the 'cls' at the end of the loop, the screen will not be erased every frame. Try removing it. The trails left by the spaceship are interesting.

Interesting. You should try to make it so that you can set the planets gravity and therefore change how hard it is to escape the field.

You can alter the code to change the gravity.

in the lines:

vx#=newxvalue(vx#,atanfull((px#-rx#),(py#-ry#)),50*(1/((px#-rx#)*(px#-rx#)+(py#-ry#)*(py#-ry#))))
vy#=newzvalue(vy#,atanfull((px#-rx#),(py#-ry#)),50*(1/((px#-rx#)*(px#-rx#)+(py#-ry#)*(py#-ry#))))

Change the number '50' to whatever you want. It will change the strength of the gravitational field.

its clever are you planning on using it in a game or converting it to 3d???

When I started I had nothing in mind. I just wanted to make a program to accurately simulate orbits and slingshot effects. If I ever make a 3d space sim, I'll definately use accurate physics like in this program.

Thats nice.

I lowered the gravity, held down the control and up keys ... my very own spirograph!