'============================================================================
' Basic rocket design program assuming no drag and constant thrust.
'============================================================================
'
'This is a public domain program which you are encouraged to copy and give
'to your friends. A more accurate program which takes into account
'real, commercially available engines and real aerodynamic drag is available
'from:
'
' Cambridge Group
' 1921 N Gaffey #D
' San Pedro
' CA 90731
' (310) 832 8836
'
' The program allows you to design your own engines and handles supersonic
' flight.
'
'Useful data:
' Specific thrust of black powder (Estes engines) = 80s
' Specific thrust of composite propellant (Aerotech) = 214s
' Total impulse of A engine = 2.5 Ns
' B engine 5.0 Ns
' C engine 10.0 Ns
' D engine 20.0 Ns
' .....
' K engine 2560 Ns
'
' Metric conversion:
' 1 meter = 3.28 feet
' 1 kilogram = 2.24 pounds
' 1 ounce = 0.0279 kilograms = 27.9 grams
'
'===========================================================================
'
' Print header page
CLS
PRINT "Another public domain shareware program by:-"
LOCATE 5, 32
PRINT "CAMBRIDGE GROUP"
LOCATE 7, 16
PRINT "AUTHOR OF CAMBRIDGE GROUP ROCKET DESIGN PROGRAM"
LOCATE 8, 10
PRINT "All you need to predict rocket performance - high altitude, low"
LOCATE 9, 10
PRINT "altitude, multi stage, supersonic - you name it."
LOCATE 11, 10
PRINT "We provide source code in Quick Basic - easily moved to another machine"
LOCATE 15, 10
PRINT "1921 N Gaffey #D"
LOCATE 16, 10
PRINT "San Pedro"
LOCATE 17, 10
PRINT "CA 90731"
LOCATE 25, 1
PRINT "Hit any key to continue";
DO
LOOP WHILE INKEY$ = ""

g = 9.8066
'
CLS
PRINT "Zero drag rocket design program"
Start:
DO
   INPUT "Launch Wt (kg), Total Impulse (Ns)"; m0, Impulse
   INPUT "Specific Impulse (s), Burn Time (s)"; Isp, tb
   'Calculate effective exhaust velocity
   c = Isp * g
   'Calculate propellant mass
   mp = Impulse / (Isp * g)
   IF mp >= m0 THEN
      PRINT USING "Calculated propellant mass, #.#### kg, is grater than launch mass"; mp
      GOTO Start
   END IF
   'Calculate mass ratio
   MR = m0 / (m0 - mp)
   'Calculate velocity at end of burn
   vp = -c * LOG(1 / MR) - g * tb
   'Calculate altitude gain from this velocity
   s = vp * vp / (2 * g)
   'Calculate time from burnout to apogee
   tdelay = vp / g
   'Calculate altitude at burnout
   s1 = vp * vp / (2 * (vp / tb))
   'Calculate total altitude at apogee
   alt = s + s1
   'Print results
   PRINT USING "Max Velocity = ##### m/s, Max Altitude = ###### m"; vp; alt
   PRINT USING "Delay Time = ###.## s, Propellant mass = #.#### kg"; tdelay; mp
   PRINT
LOOP