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I.  Purpose of program:  Program PROPEP finds the
                         performance of solid (or liquid) rocket
                         propellents.

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    Highlights:  1.  This program is basically the PEP program written
                     D. R. Cruise at NWC described in NWC TP 6037
                     titled "Theoretical Computations of Equilibrium
                     Compositions, Thermodynamic Properties, and
                     Performance Characteristics of Propellent Systems"

                 2.  The theory behind the program is described in
                     NWC TP 6037.  That document should not be used
                     as a user's guide.  This document supersedes the
                     operational part of NWC TP 6037.

                 3.  This version has been run on IBM PC 8088, 8086, 80286
                     and 80386 machines and several close compatibles.

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II.  Options:

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1.  Up to 10 ingredients may be input by the user to be evaluated.
    These ingredients may be either coded ingredients from the
    PEPCODED.DAF data file or user defined ingredients or both.

2.  There are also eight other options:
    1)  Delete exit calculations
    2)  Include ionic species in calculations
    3)  Include boost velocities and nozzle design data
    4)  Input pressures in atmospheres instead of PSI
    5)  Increase numerical precision of species list
    6)  Output a list of all combustion species considered
    7)  Fix temperature
    8)  Debug options


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III.  Use:

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A.  PROPEP operation:

    Four data files are required to operate PROPEP:

1)    JANNAF.DAT is a binary file containing reaction product
      specie heat of formation data.  It cannot easily be changed.

2)    PEPCODED.DAF is an ascii file containing propellant ingredient
      data.  Additional ingredients can be added TO THE END of this
      file with any text editor.  The input format must be identical to
      that used in the rest of the file AND, all lines MUST be EXACTLY the
      same length.  If you mess up the line lengths, PROPEP will not be
      able to read the file!

3)    SETUP.PEP is an ascii file that tells PROPEP where on your disk
      system to look for files it needs:

      Line 1 - Either HD or FD for hard disk or floppy disk.  If you
               run using one disk (a high density floppy or actual
               hard disk), use HD.

      Line 2 - Full DOS path to PEPCODED.DAF

      Line 3 - Not used by PROPEP, must be something, but does not matter
               what.

      Line 4 - Full DOS path to JANNAF.DAF

      Line 5 - Default output file name.

4)    INPUT.DAT is an ascii file containing user's input data described
      below.

Note: SETUP.PEP and INPUT.DAT must be in the current DOS default directory.


B.  Program Hints and Problems:

1.  Propellant weights must be greater than zero.  Sometimes even small
    amounts of an ingredient ( less than 0.5 ) can cause PROPEP to falter.

2.  The output with the various DEBUG options contains no labels.

3.  PROPEP will print out certain error messages if something is wrong
    such as the exhaust pressure input greater than the chamber
    pressure.

4.  The initial weight need not equal to 100.

5.  Occasionally, a set of ingredients will not converge on the steady
    state solution.  A message indicated the reliability of the results
    is printed, usually the results are wrong.

C.  User input data

    The 11 data lines required to run PROPEP are listed below.

   VARIABLE    FORMAT       DESCRIPTION

Data line #1

   FILNAM      A12          File name for PROPEP output

Data line #2

   USER        A17          Title to be printed as identification
                            on each page of output

Data line #3

   NIC,        3I5          Number of coded ingredients to read from
                             PEPCODED.DAF
   NIU,                     Number of user defined ingredients
                              1)  The combined number of ingredients
                                  may not exceed 10
   IRUN                     Number of runs

Data line #4

   DENEXP      F12.0        Density exponent used in calculating
                            D-ISP (density ISP) (defaults to 1.0)

Data line #5

   PROPTEMP    F12.0        Temperature of Ingredients (defaults to
                            298 K).  Used for temperature conditioning
                            effects.

Data Line #6

   CPA,CPB,CPC 3F12.0       Quadratic coefficients for solid specific
                            heat.  Used with temperature difference to
                            adjust the system enthalpy for heating or
                            cooling.  (defaults to 0.3 cal/gm K)

Data line #7

   KR(1),      8I1          Delete exit calculations, 1-yes, 0-no
   KR(2),                   Include ionic species in calculations
   KR(3),                   Include boost velocities and nozzle design
                              data
   KR(4),                   Input pressures in atmospheres instead of
                              PSIs
   KR(5),                   "N" orders of magnitude species precision
                              increase, 1-1 more sig. digit, 2-2 more
                              sig. digit, etc.
   KR(8),                   Output a list of all combustion species
                              considered
   KR(7),                   Fix chamber temperature, temperature is
                              input in place of exit pressure
   IDEBUG                   Debug options, 1-yes, 0-no

Data line #8 (used only if IDEBUG on line #7 not equal zero)

   KR(11)     5I1 (note 1)  Thermo data at every guess
   KR(12),                  Values of J,M,VF,VB,PR,VA in subroutine
                              TWITCH
   KR(13),                  Species composition every iteration
   KR(14),                  Log of equilibrium constant every guess
   KR(15)                   Classification of species each iteration,
                              from TWITCH

Data line #9 (used only if NIC on line #3 not equal zero)

   ITAG(I)    10I5 (Note 2) Ingredient code number from PEPCODED.DAF
                            ingredient code list.  This is the LINE
                            NUMBER of the selected ingredient in the
                            PEPCODED.DAF file.  Currently, it is also
                            the number printed in the file, but if you
                            add ingredients in the middle of the file, then
                            it will be left to the interested reader to
                            keep track of the line numbers!

Data line(s) #10 (repeat NUC times)

10 BLOK(I),   A30, (Note 3) Ingredient name
   JIE(I,L),  6(I3,A2),     Number of atoms of element
   JE(I,L),                 Symbol of element (must be upper case letter(s))
                              1)  Up to 6 elements
   DH(I),     F5.0,         Heat of formation, cal/gram
   RHO(I)     F6.0          Density of ingredient, lb/cu-in

Date line(s) #11 (repeat IRUN times)

   W1(5),     10E12.0       Chamber pressure, PSI or ATM
   W1(6),     (Note 4)      Exhaust pressure, PSI or ATM
   WING(I)                  Ingredient weights


NOTES:

1)  If IDEBUG in data line 7 is 0 then data line 8 is not needed.

2)  If NIC in data line 3 is 0 then data line 9 is not needed.

3)  If NIU is data line 3 is 0 then data line 10 is not needed.
    If NIU in data line 3 is not 0 then data line 10 is actually NIU
    data lines, one for each user defined ingredient.  These
    data lines must be formatted exactly as specified,
    ie.  A30, 6(I3,A2), F5.0, F6.0.

4)  The WING(I) variable contains the ingredient weights in the order
    they were input.  Example:  If NIC=2 and NIU=1 there are 3 weights,
    the first two corresponding to NIC=2 and the last one corresponding
    to NIU=1.  In addition, data line 11 is actually IRUN data lines,
    one corresponding to each run.

5)  Data lines 1, 2, 3, 4, 5, 6, 7, and at least 9 or 10 and line 11
    are always input.

6)  When the fix temperature is used the exit pressure is .01 ATM


D.  Notes on output:

1.  The gram-atom amounts for each chemical element are based on
    the given system weight.

2.  The enthalpy has units of kilocalories per system weight and the
    entropy has units of calories/K per system weight.

3.  GAS identifies the number of moles of gas produced per system
    weight.  Effective molecular weight is obtained by dividing GAS
    into system weight.  Note that although non-gases are not included
    in this computation this is the proper molecular weight to use in
    gas dynamic equations.

4.  RT/V = [ R(0.08205 l-atm/mole/K) * T(K) ]/V (system vol. in liters)

5.  The damped and undamped speed of sound is calculated assuming
    frozen chemical equilibrium conditions.  These numbers are equal
    if no solids or liquids are present.

6.  The chamber and exhaust composition follow in units of moles per
    system weight.  If one prefers to obtain partial pressures in
    atmospheres, multiply each composition by RT/V.  Species are
    solid if & follows the specie name and liquid if * follows the
    specie name.

7.  The first line of the performance results refers to frozen flow,
    no chemical reactions, through the nozzle; and the second line
    refers to shifting flow, reactions in equilibrium, through the
    nozzle.  The theoretical exhaust velocity can be found by
    multiplying ISP by 9.806 m/sec**2.

8.  IS EX is the isentropic exponent such that PV**IS EX = constant
    for isentropic flow near the nozzle throat.  The values of IS EX
    and CP/CV do not agree, because the gas in not perfect.

9.  The variables T* and P* are throat temperature (in K) and pressure
    (in atmospheres).

10. C* is the characteristic velocity in ft/sec, the nozzle thrust
    coefficient, CF = 32.17 * ISP / C*.

11. ISP* is the vacuum impulse to be obtained from a sonic nozzle.
    That term is used in air-breathing propulsion work.

12. OPT EX is the ratio of the nozzle exit area to nozzle throat area
    at which exit pressure equals ambient pressure.

13. D-ISP is the density ISP.

14. A*M. is the ratio of nozzle throat area to mass flow rate expressed
    as in**2-sec/lb.

15. EX T is the exit plane temperature in degrees K.

16. Optional output includes boost velocities.  These are shown in
    number pairs:  the first is the switch density and the second is
    the velocity in ft/sec.  Inputted densities follow in psi.  The
    next output shows the performance of the propellant through
    nozzles with expansion ratios of 1 to 100.  These include three
    kinds of impulses:  optimum (ambient pressure = exit pressure),
    vacuum (zero exit pressure), and sea level (exit pressure = 1 atm).
    Units are given in SI units as well as the older English units.
    Note that all impulses need to be corrected for nozzle half angle.
