THREE MODEL ROCKET PROGRAMS: ALTITUDE, STABILITY, TRACKING By Burton L. Craddock TRACKING The program Tracking calculates the altitude in meters of a model rocket using either a single elevation-angle-only tracking device or two-station elevation and azimuth angles tracking device. The single elevation-only tracking device method assumes that the rocket flight is perfectly vertical with no change in the horizontal distance between the rocket and tracking device. Most model rocket flights will not have a perfectly vertical flight, however. The baseline for this method is the horizontal distance in meters between the launch pad and the tracker. The two-station theodolite system (elevation and azimuth tracking) can accurately track a rocket altitude with a horizontal component in its motion. An azimuth is an angular measurement in the horizontal plane. The baseline for this method is the distance in meters between both theodolites. This method is used worldwide for contests and record-setting peak altitude measurements. This method will not work when the rocket is directly above the line through the baseline and both azimuth angle readings are either 0 or 360 degree. The two theodolites are calibrated when both theodolites are directly aimed at each other along the baseline and the azimuth and elevation pointers on both theodolites read 0. ONE STATION Tracking starts with a menu selection. You press the f1 key for the single elevation-only tracking devise or press the f2 key for the two-station theodolite system. After the tracking method has been selected, you are prompted to accept the current baseline by pressing the f5 key or to enter a new baseline by pressing f7. The next steps for the single elevation-only tracking are the following steps. For the single-elevation method, you are then prompted to enter the elevation angle. The elevation is an angle between 0 and 90 degrees, measured at the rocket's peak altitude. After this figure has been entered, the computer calculates the rocket altitude. You then have the option of running the program again or quitting. TWO STATIONS If you have two-station theodolite tracking, you are prompted to enter the azimuth and the elevation angles of both stations. The azimuth angles are between 0 and 360 degree. The elevation angles are between 0 and 90 degrees. The output provides altitudes calculated from each station, the average of both altitude values, the percentage error from the average altitude, and the printout TRACK LOST for absolute percent errors greater than 10 percent or TRACK OK for absolute percent errors less than 10 percent. Burton Craddock has a Bachelor of Science degree in computer science with a minor in physics from the Illinois Institute of Technology. He has been programming on the 64 since 1987. He lives in Chicago, Illinois. Gazette, June 1994