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Trajectory Program Java Applet Version

Instructions:

The program already gives some instructions along with some sample inputs for simulations.

Portions of the program have windows with more information viewable by using the scroll bars.

However, it is still a work in progress.

Some browsers are incompatible for using the program with full screen view and can cause an operating system to crash. Otherwise, don't be intimidated by warning messages since you should be able to use the browser back button to get back to a normal state.

Use your mouse and keyboard to enter input values for the rectangular prism object as follows:

• The span is the length of the object in units of feet.
• The chord is the width of the object in units of feet.
• The thickness is the thickness of the object in units of feet.
• The mass is the mass of the object in units of slugs. For an object near sea level divide the weight in pound units by 32.17 to obtain the slug unit value.
• The start altitude is the altitude of the object at the start of the trajectory in units of feet.
• The end altitude  is the altitude of the object at the end of the trajectory in units of feet.
• The velocity is the start velocity of the object at the start of the trajectory in units of mach number. The mach number is the velocity of the object divided by the velocity of sound at the current location of the object.
• The trajectory angle is the angle representing the direction the object is traveling relative to a horizontal path parallel to the Earth's surface expressed in units of degrees. A trajectory angle of zero means the object is moving level. Positive trajectory angles reflect an object moving toward Earth to a certain degree while negative trajectory angle values reflect an object moving away from the Earth to a certain degree.
• The time increment is the time interval between a change in trajectory conditions in units of seconds. The smaller the time increment, the greater the precision. A time increment of 0.001 should work in most cases.
• The rotation factor determines how much the object tumbles. A rotation factor of 1 tumbles at the maximum rate. A very large rotation factor, eg. 999999, can simulate gliding rather than tumbling, at a fixed orientation.

To begin the program after entering input values use the mouse to click the START button.

A summary of calculation results will be displayed in the bottom window.

Then use the mouse to click the 2D Simulation button to begin the two-dimensional simulation of the trajectory.

A graph will appear showing a plot of the trajectory of altitude versus distance.

Use the mouse to click the START button on this graph to display the trajectory condition as time progresses.

Consider trying this example.

Assume the OEX recorder is a rectangular prism object with dimensions 17" x 22" x 7.5" weighing 58 pounds at sea level. Assume a start altitude of 100000 feet, end altitude of 200 feet, start velocity of mach 10 with trajectory angle of 10 degrees, rotation factor of 1 and time increment of 0.001. The following inputs can be used after performing the necessary unit conversions:

span = 1.833

chord = 1.417

thickness = 0.625

mass = 1.803

start altitude = 100000

end altitude = 200

velocity = 10

trajectory angle = 10

time increment = 0.001

rotation factor = 1

Technical Background:

The primary purpose of this applet was to simulate the C++ version of Trajectory program as a 2-dimensional trajectory path. Secondary goals included experimentation with exception handling. The current state of this project reflects technical complications in robustness by attempting some design incompatible with java programming alone. Otherwise, the exception handling involved some overkill with messages. Five java classes were designed as follows:

Trajectory.class :

This class represents design for the GUI and the scientific/mathematical computation of trajectory values.

SimulationPanel.class :

This class represents the 2-dimensional plotted trajectory. The scale is adjusted automatically depending on altitude and distance parameters. It is capable of showing the entire trajectory path in green, a real-time moving object as a red symbol and other dynamic data associated with the moving object.

Are.class :

Exception handling implementing message

Nve.class:

Exception handling implementing message

Tare.class:

Exception handling implementing message

There is also a javascript file (Trajectory) used to bypass a Microsoft restriction on java applet implementation.