This is a beta 1.0 version of the ModelRocketSim program written by Eric Bishop from the Ohio State University. You are invited to participate in the beta testing. If you find errors in the program or would like to suggest improvements, please send an e-mail to email@example.com.
With this software you can investigate how a model rocket flys by changing the values of different design variables. If you experience difficulties when using the sliders to change variables, simply click away from the slider and then back to it. If the arrows on the end of the sliders disappear, click in the areas where the left and right arrow images should appear, and they should reappear.
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The program screen is divided into two main parts:
There are two main graphics displays. During the design of a model rocket you will see a drawing of the current design. As you change tube length, or fin geometry the graphic will change. On the rocket you will see two circles. The circle with the black diamonds is the location of the center of gravity (CG). The circle with the black dot is the location of the center of pressure (CP). The location of the CG and CP will change during design. For a stable rocket, keep the CP below the CG.
During flight the graphics will display the location and orientation of your rocket. When the engine is firing, you will see some small "flames" at the base of the rocket. On the left and bottom of the graphics are some numbers which indicate the location of your rocket relative to the launch rail. The scales are in meters. When your rocket return to earth, a message will appear telling you how high your rocket flew.
The input variables are located on right side of the screen. During rocket design, you have two choices of input screens; Design and Materials. You can select the input screen using the buttons at the top. At the bottom of the input screen you will see numerical values of the CG and CP relative to the base of the rocket, and the rocket weight. By convention, input boxes have a white background and black numerals, while output boxes have a black background and green numerals. However, if your rocket is unstable, the color of the output numerals will change from green to red. During Rocket Launch, a different set of input variables will be displayed.
The default input screen is the Design screen. You can use the sliders and input boxes to change the length and diameter of the body tube, the length of the nose cone, and the length, width and height of the fins. Most of the variables on this screen will influence the location of the CP. The "Zoom" input controls the size of the graphics. To change the value of an input variable, simply move the slider. Or click on the input box, select and replace the old value, and hit Enter to send the new value to the program.
The Materials screen is used to provide information which affects the weight and CG location of the rocket. You can select from a variety of materials for the nose and fin using the pull down menus. If you choose "Custom" materials, you must provide the density of that material in the input boxes in units of grams per cubic centimeter. On this screen, you also specify the engine to be used during your flight, and the weight of the recovery system. You can select from three parachute sizes, which will affect the terminal velocity of your descent. The drag coefficient is based on the cross sectional area of the rocket and has a default value of .7. You can enter a different value for your own rocket design. (In future versions, this number will be computed by ModelRocketSim based on your design.)
During Rocket Launch you are able to set the angle of the launch rail, and to set the wind speed. Positive velocity is from the right of the graphic. You can return to the design mode by pushing the blue button, or you can launch your rocket by pushing the red button. At any time during the flight, you can push the white "Reset" button to return the rocket to the pad. At that time you can again change launch angle and wind speed. Elapsed time shows the progression of your flight
The Learning Technologies Project will continue to improve and update ModelRocketSim based on user input. The history of changes is included here: