CRRCSIM how to
some additional info to "instructions" file of crrcsim


Compiled from crrcsim newsgroup (http://groups.yahoo.com/group/crrcsim)

Installation of CRRCSIM:
read carefully!!! "instructions" file distributed with crrcsim.
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How to change CG (#221)
The strictly-correct way to do this is to recompute the aero
coefficients in *.air with AVL and COEF.  However, for modest CG
changes you can estimate the new coefficients quite accurately by
hand.

Let's say you shift the CG by a distance "dx", a positive dx being a
rearward shift.  The new pitching-moment coefficients are then:

 (Cm_0 )_new  =  Cm_0  + (dx/C_ref)* CL_0
 (Cm_a )_new  =  Cm_a  + (dx/C_ref)* CL_a
 (Cm_de)_new  =  Cm_de + (dx/C_ref)* CL_de
 (Cm_q )_new  =  Cm_q  + (dx/C_ref)*(CL_q - 2.0*Cm_a)

Use the current coefficient values along with with your dx on the
righthand sides.  C_ref is reference chord, defined near the top of
the *.air file.  Your dx must be in the same length units as C_ref
(inches presumably).  Then just substitute these new values for the
current ones in the *.air file.  I suggest that you save your baseline
*.air file before mucking with it like this.

For a typical configuration you will find that only the first two
coefficients will be significantly modified:
 Cm_0 (pitch moment trim)
 Cm_a (pitch stability)

The other two will hardly change at all:
 Cm_de (elevator pitch power)
 Cm_q  (pitch damping)
and you really don't have to bother recomputing them.

But for a close-coupled configuration like a Zagi you should change
all four since they all may change significantly.  I can't say for
sure.

When moving the CG back you must keep an eye on your new Cm_a value.
Once this becomes positive you will become unstable in pitch and the
Zagi will become a real handful.  Just like the real thing.
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How to launch planes (#190)
all planes, gliders included, have an invisible engine to climb. 
Throttle control sets controls thrust up to max_thrust value configured in *.air
for max_thrust = 0 (e.g. Apogee) a hand launch is assumed and the plane starts with an initial speed.

throttle up/down with cursor up/down keys if input_method is configured to MOUSE or JOYSTICK_2.

throttle contol with 3rd channel if input_method is configured to JOYSTICK_3 or PARALLEL1 in crrcsim.cfg
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Batch file to start crrcsim with different configurationss (#155): 
You may create various copys of crrcsim.cfg with different names. The batch file copies one of these configurations to the crrcsim.cfg and starts the program.
If you make a shortcut to it on your desktop in Windows, add a "?" after the
program-name in the properties, and when double-clicking, it will ask for
any paramters.
You can then type in something like :  S zagi.air and it will start with the
slope-scenery and a Zagi. Of course, you'll have to prepare the different
.cfg-files first.

The "source"-"code" (it's hardly worth those names) for this batch-file is:

REM crrc.bat
if "%1" == "S" goto slope
if "%1" == "T" goto thermal
:slope
        copy crrcslop.cfg crrcsim.cfg
        goto start
:thermal
        copy crrcther.cfg crrcsim.cfg
        goto start
:start
crrcsim %2
REM crrc.bat

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How to change plane parameters mass, throw, tail area (#145): 

Increase Mass to simulate adding ballast, and vice versa.

Increase CD_prof to simulate adding "aerodynamic crud" and thus
degrade the energy retention.  For a glider, CD_prof should be roughly
equal to the wing profile CD multiplied by about 1.2 - 1.4 to account
for tail and fuselage.  Add more for a wrinkly EPP job and other
eyesores like exposed horns, bolts, towhooks, dings, seagull feathers,
etc.  

Changing elevator throw by some factor is simulated by multiplying all
the *_de parameters by that same factor.

Changing rudder throw by some factor is simulated by multiplying all
the *_dr parameters by that same factor.  Note that these are not used
on a r/e plane.

Changing aileron throw by some factor is simulated by multiplying all
the *_da parameters by that same factor.  Note that these really
control rudder throw on a r/e plane.

If the airplane has a significant dihedral angle (or EDA), like on a
typical r/e plane, then multiplying the dihedral angle by some factor
is approximated by multiplying these parameters by that same factor:
Cl_b
CY_p
Warning: this is not reliable if the dihedral angle is very small to
begin with.  One must regenerate everything with AVL in this case.

Changing total vertical tail area by some factor is approximately
simulated by multiplying these parameters by that same factor:
CY_b
Cn_b
CY_r
Cn_r
CY_dr
Cl_dr
Cn_dr

Alas, there's no simple reliable way to account for changing the size
of the horizontal tail.  It is necessary to regenerate all the numbers
with AVL in this case.
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Dynamic soaring: 
set the location to CAPE_COD, and the wind_direction to 180 in crrcsim.cfg file 
                           set wind direction 0 is for slope soaring
                           set location to DAVIS for thermal flying
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Modify stall behavior (#51):  
Modify the eta_loc, CG_arm, CL_drop, and CD_stall
parameters in the .air files for each airplane.  The eta_loc controls
the yawing due to asymmetric drag during a tip stall, the CG_arm
handles the pitching moment, the CL_drop controls the sudden loss of
lift, and the CD_stall controls the overall amount of drag due to a
stalled wing. 
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Use Windows WORDPAD or any Text Editor to change settings in the CRRCSIM 
Configuration file crrcsim.cfg or one of the plane description files *.air.
In these files you will find comments that give a short description of the values.
_____________________________________________________________________________
Find crrcsim sources at 
http://sourceforge.net/project/showfiles.php?group_id=8823
crrc_aero.c ... data definitions for *.air files
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Joystick: Set "input_method" in crrcsim.cfg to
          JOYSTICK_2 (elevator & aileron/rudder) or JOYSTICK_3(additional throttle)
_____________________________________________________________________________          
V1.0 written on 4.Oct.2001

Write me an e-mail if you have any input for that file:
WI@topcall.co.at

Have fun!
Walter