Dec 262017
 
A VGA demonstration of gravity.
File ORBIT11.ZIP from The Programmer’s Corner in
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A VGA demonstration of gravity.
File Name File Size Zip Size Zip Type
ORBIT.001 181 106 deflated
ORBIT.004 311 186 deflated
ORBIT11.DOC 5728 1823 deflated
ORBIT11.EXE 124114 64054 deflated

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Contents of the ORBIT11.DOC file


ORBIT 1.1 - A Gravitation Demonstration - Special Version - 3/7/92

ORBIT provides a visual demonstration of the laws of Universal Gravitation.

This has been developed primarily as a home project.

The menus are organized into progressive demonstrations of gravitation.

This program may be copied and used by those interested in gravitation.

The QuickBASIC 4.5 source code may be available in the future.

Watch for an updated version soon.


ORBIT 1.1 - A Gravitation Demonstration - Special Version - 3/7/92

Description of the program menus.
---------------------------------

MENU ITEM - File

Load a configuration from disk

Allows the user to read the orbital parameters from a file
which was previously stored on disk.

If the program sees that there are ORBIT parameter files
on the disk, then a selection window appears allowing you
to select which file to read in.

Save a configuration to disk

Allows the user to save the current orbital parameters
being executed to a file on the disk.

A window is displayed showing the existing parameter files
which are on the disk. The user is prompted to enter a new
file number from 1 to 8. The user is then prompted to enter
up to a 30 character description to be attached to the file.

Run with current parameters

This menu item either continues normal execution of a demo
or a simulation after the user terminated it, or it will
begin executing the orbital parameters just read from a disk
file.

Check best video mode

ORBIT will tell you what the best video mode available on
your computer is. With this version of ORBIT, there is a
small chance that it will operate correctly on anything other
than VGA. The next version will be more video-mode aware.

Exit ORBIT

This will exit ORBIT and return to the operating system.

MENU ITEM - Edit

View the current ORBIT parameters

This displays a screen showing the current parameters of
all the planets, and the object. The Universal Gravitation
constant is included, as well as certain program system
constants.

The user may press the 'Print Screen' key for a printout
of these numbers.

Edit the Universal constants

The user may change the value of the Universal Gravitation
constant to see the effect. The user may also change the
program system constant of Velocity change for every fire
of the thrusters.

Good values for these are:

Gravity Constant: 6.668E-21
Velocity change per thrust: 0.50

Warning: if you just press ENTER here, the corresponding
value will be changed to zero.



MENU ITEM - Demos

Various demonstrations of mass bodies attracting objects by their
gravitational pull.

One planet attracting an object

One planet attracts one object. The object has no initial
velocity.

One planet and a moving object

One planet attracts one object. The object has been given
a small positive Y-velocity. See how the orbit traced out
differs from the previous demo.

Elliptical orbit around a planet

One planet attracts one object. The object has been given
a little larger positive Y-velocity. This time, the object
falls around the planet into an elliptical orbit.

Circular orbit around a planet

One planet attracts one object. The object has been given
enough positive Y-velocity to orbit in a circle. See the
result when thrust is applied.

To apply thrust, press the arrow key for the direction in
which you want the thrusters to fire.

Try to learn how to move the object into lower and higher
orbits using a minimum amount of thrust.

Orbit around two planets

Two planets attract the object. How does the orbit traced
differ from one planet?

Orbit around three planets

Three planets attract the object.

Black Hole

The planet attracting the object is not plotted on the
screen. Can you guess where it is by watching the orbit of
the object?

Random planets

Five planets of random mass, radius, and position are
generated.


MENU ITEM - Real Simulations

Here are a few simulations using real engineering units for planet
mass, radius, and position. I have tried to obtain accurate
numbers here, however they probably all need some fine tuning. For
example, the Geostationary orbit takes 23.06 hours, and should
actually take 24 hours.

MENU ITEM - More Info

Additional information about the program.

MENU ITEM - Help

Program help screens and other reference information.

MENU ITEM - Quit

End the program and return to the operating system.


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