YawDyn Change Log
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For changes prior to version 12, see the AeroDyn change log.

v12.00 21-May-2001 D. Laino 
 Extensive rewrite of the code to convert to Fortran90.  Included elimination of
the INCLUDE files, and the introduction of new MODULES to replace them.  Nearly
all arrays have been converted to allocatable based on model parameters.  
Subroutines have been separated into 3 files now: Yawdyn.f90, AeroSubs.f90, and 
GenSubs.f90.  A forth file, AeroMods.f90, holds the modules.
 The Pitt & Peters dynamic inflow model has been replaced with a Generalized
Dynamic Wake model.
 Other features added:
 An error.log file is now generated to record any serious warnings or errors
during a simulation.  This file is cumulative, meaning it will add errors from
subsequent simulations until it is manually deleted.  This should prove useful
in running large batches of simulations.
 Other bugs addressed:
 Added rotor torque as an output in YawDyn.  Created variable Torque to replace
POWER in torque calculations which already existed in YawDyn.
 Reduced outputs to screen for program.  Reduced write statements in code.  
 Improved error outputs to be more precise.  Added error and warning tally.
 Separated yawdyn.ipt into two files: yawdyn.ipt and aerodyn.ipt.  Created
new variable T_Shad_Refpt for the tower shadow defecit, separating it from
the geometric hub sling variable (SL).
 Created new module AeroTime for the aerodynamic time variables.
 Replaced YAWRAT with YAWVEL (= YAWRAT * SL * CTILT)
 Put ElemOpen and ElemOut in Aerosubs for all AeroDyn program to use.  The filename 
(like element.plt) is now passed in the argument to ElemOpen.
 Changed pitch and edge moment outputs to reflect values from the undeflected blade
reference frame.  This is more realistic since the pitch axis should not flap.
 Added inertial terms to the thrust equation.  Added pitching moment contribution
to the rotor torque.

v12.01 14-Sep-2001 D. Laino
 Added calls to Conv2UC (of AeroDyn) in YDin to make text inputs case insensitive.

v12.02 20-Sep-2001 D. Laino
 Moved GRAV constant from AeroDyn to YawDyn in module Machine.  Put output of GRAV
in YDOut.

v12.03 03-Oct-2001 D. Laino
 Eliminated references to the rElement and CoverR arrays deleted from AeroDyn 12.34.

v12.04 11-Oct-2001 D. Laino
 Changes to USRMES include eliminating Switch module and changing output format for
ID from I2 to I3.

v12.05 12-Oct-2001 D. Laino
 Initialized each of the allocated arrays in FindTrim to zero to avoid any possible 
errors.

v12.06 08-Apr-2002 D. Laino
 Cleaned up unused AeroDyn modules in YawDyn.
 
v12.07 22-Apr-2002 D. Laino
 Fixed length of Int2LStr and Flt2LStr for consistency with AeroDyn 12.41 functions.
YawDyn must be updated if AeroDyn 12.41 or later is to be used with it.

v12.10 24-Jul-2002 D. Laino
 Added TeeSL to input file to offset the teeter axis upwind of the rotor apex.

v12.11 05-Aug-2002 D. Laino
 Fixed bug in output of YawAng and YawRate to yawdyn.opt file.

v12.12 01-Nov-2002 D. Laino
 Fixed bugs in teeter loads equations in subroutine AERO.  THRUST was not being 
summed over both blades, and blade out-of-plane moment had mixed terms for blades
one and two.

v12.13 13-Nov-2002 D. Laino
 Added hub loss constants to YawDyn.
 
v12.14 13-Jan-2003 M. Buhl
 When compiling on a Sun, I found that many literal strings spanned multiple
  lines, which is not normally allowed.  I fixed the strings that I found
  in yawdyn.f90\main() and ydin().

v12.15 15-Jul-2003 D. Laino
 Hugh Currin got warning messages comiling in Linux because the SNGL operator
was being applied to YawAng and YawRate in YDOut, but YawAng and YawOut are
already single precision.  I deleted the SNGL operator.

v12.16 7-Nov-2003 D. Laino
 Added AeroDyn module InducedVel() to subroutine FindTrim because of changes
to AeroDyn to accomodate Fast.  This makes no difference to how YawDyn works,
but is needed to accomodate those who compile YawDyn with AeroDyn.

 
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