 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.
When the blue "Launch Rocket" is
pushed on the design screen, the
graphics change to display the location and orientation of your rocket during flight.
Initially the rocket is sitting on the ground on its launch rail. When the red "Begin Launch" button is
pushed, a countdown from T-3 sec. begins. At T= 0, the engine fires and
you will see some small "flames" at the base of
the rocket. The flames remain burning during the powered portion of the flight but are
extinguished during the coasting ascent. If you are flying a 2 or 3 stage rocket, you
will see the spent stage fall away from the stack following staging.
When the ejection charge is ignited, the
nose cone is discharged and a small parachute is deployed for slow descent.
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
appears telling you how high your rocket flew. Clicking on the blue "Design Rocket"
button will return you to the design graphics.
The input variables
are located on the 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, CP,
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.
If you are designing a multistage rocket, you will need to check the
stability of both the launch (upper stage plus booster) and the flight
(upper stage only) configurations by using the menu button at the bottom.
You can also display the the CG and CP locations relative to the bottom
of the rocket or the bottom of the stage by using the menu button.
Pushing the blue "Launch Rocket" button changes the input
variables which are displayed.
The default input
screen is the Design screen.
You can select a one, two, or three stage rocket for design by using the menu
button at the top of 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. You can use
the selection buttons to choose either three or four fins located at equal
intervals around the rocket. 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
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 RocketModeler
based on your design.)
Launch several buttons, text fields, and sliders appear in the input
screen. The blue "Design Rocket" button returns you to design mode and
resets the graphics and input screens. The red "Begin Launch" button starts
the countdown for a new flight.
At any time during the flight,
you can push the white "Reset" button to return the roc