.LAUNCHER Launcher Version 1.0 August 25, 1987 A single stage to orbit launch vehicle simulator. Written by Robert Castle, CIS 70330,605. The source code for launcher (written in Quickbasic) is available for a $20 charge from Robert Castle 306 Lost Rock Dr. Webster Tx. 77598 This software is for the enjoyment and hopefully the enlightenment of the user. No warranty of any kind is expressed or implied. Getting Started Quickly ----------------------- The launcher program is written for the IBM PC or compatible. A CGA card or equivalent is required. Initial Startup --------------- The program is started by simply typing "launcher" at the DOS prompt. You will be prompted for your name and the name of your next of kin. Any answer here will do. You will then be asked if you have EGA capability. If you do hit the "Y" key. If you don't hit any other key. Vehicle Selection ----------------- You will be presented with a vehicle selection menu. Since no single stage to orbit vehicle currently exists I made up some reasonable numbers. There are 2 already defined launchers and a third "make up your own". I suggest you start with the "advanced" launcher for your first several tries. Use the arrow keys to position the arrow on the screen to the vehicle of your choice and hit enter. Running ------- You will get a brief page of explanation. After reading it press enter and you will start the simulator. You have control over only 2 (but critically important) flight control parameters: the pitch angle of the vehicle and the throttle. PITCH ANGLE ----------- This is the angle of the vehicle relative to the surface of the earth. An angle of 0 is "level" and an angle of 90 is straight up. The up and down arrows change this angle by 5 degrees. The page up and Page down keys change the angle by 1 degree. THROTTLE -------- The throttle has only limited control. The HOME key gives you full throttle, the left arrow key gives you 65% of Full and the End key shuts down the engines. You can go from 65% to Full and back as many times as you like but after a SHUTDOWN you can only go to the ORBIT throttle setting (by pressing HOME). This throttle setting is designed for Orbit adjust maneuvers. ie do not shut down until you are in orbit or very close to it. The throttle will automatically limit itself to keep the "G" level on the vehicle below limits (usually 3 Gs). OBJECT ------ The object (other than learning a "feel" for orbital mechanics) is to get into a 250 nmile circular orbit to rendezvous with a space station. The program will display how well you did if: 1. you run out of fuel 2. you press escape HAVE FUN!!!! DESCRIPTION OF DISPLAY AND MORE DETAIL -------------------------------------- Number Display -------------- The number display looks like this Alt= xxxxx Vel= xxxxx Throt= xxxxx Gs= xxxxxx Ang= xxxxx Vh= xxxxx FPA= xxxxx Qbar= xxxx Ha= xxxxx Hp= xxxx Alt= Current altitude, in feet if altitude less than 1 nautical mile, in nautical miles otherwise. Vel= Current velocity in feet per second. This is the inertial velocity (in this model the earths rotation is NOT modelled). Throt= The throttle setting in percent. Gs= The G level or acceleration level being felt by the occupants of the vehicle (that is YOU). Ang= The pitch angle of the vehicle in degrees. This is relative to the surface of the earth and not inertial. Vh = The horizontal component of velocity. This is the same as plotted. In feet per second. FPA = This is the Flight Path angle of the vehicle in degrees. This is the angle of your travel relative to horizontal. If the angle is positive you are climbing toward apogee (your highest point). If it is negative you are falling toward perigee. Note this is NOT the same as the pitch angle. That indicates the direction at which you are THRUSTING. FPA indicates the direction you are actually going in. Qbar= This is the aerodynamic pressure on your vehicle. You may have heard of MAX Q or Maximun aerodynamic pressure mentioned with regard to space launches. The Qbar is one half the velocity squared times the atmospheris density. As you velocity goes up the Qbar will go up but as you climb the atmospheric density goes down so the Qbar goes down. Qbar is thus only a problem at low altitudes and high speeds. Keeping the Qbar down is the only reason to throttle down to 65%. Ha and Hp. The apogee and perigee altitudes in nautical miles. These will constantly change as you are thrusting. While you are climbing into orbit you should think of these as the apogee and perigee altitudes that would result if you stoped thrusting NOW. These are the primary things your are trying to target. To be perfect you should get them both to 250 (the target orbit). PLOT ---- The Apogee is plotted against the horizontal velocity. The apogee is the main thing you are trying to target. ANGLE to APOGEE --------------- A "clock face" is drawn that shows the angle to apogee. This is required so you can tell where you are in the orbit. You are at the "tic mark" at the 12 o'clock point and the hand points to the apogee or highest point of your orbit. Note that during the climb into orbit the apogee may move quickly. This does not mean you have moved around you orbit that quickly but that you have changed the shape of the orbit by applying thrust. HINTS ----- 1. Slowly decrease the pitch angle at first. WATCH YOUR QBAR. Go to 65% throttle only to keep from violating the Qbar limit. Go back to Full as soon as you can. 2. Watch the plot. You want to hit a 250 nmile apogee at orbital velocity (about 25000 fps). 3. Watch the angle to apogee and the FPA. You want to keep apogee in front of you. Bring the pitch angle down to almost zero after a couple of minutes. 4. Shut down with both apogee and perigee low and use orbit thrust to tweak them up. F9 will run the simulation at 10 times normal speed. 5. Remember orbit burns at perigee affect the apogee altitude and vice versa. To increase altitude burn posigrade (pitch of 0), to decrease altitude burn retrograde (pitch of 180). 6. Don't be afraid to use negative pitch angles late in the climb into orbit. This can "push the apogee" around ahead of you and keep from it getting too high.