This file explains the power and propulsion system of CRRCSim to enable you to create your own configurations.
Most things here are taken from the developers documentation, which is extracted from the source code using a tool called doxygen. It may happen that this document is out of date, but the documentation in the source code is not.
23.09.2005 | Jens Wilhelm Wulf | The system has just been implemented into CVS. Took most texts from source code to put this document together. |
This system manages everything related to battery, engine, propeller. Throughout it the SI unit system is used (with a small number of exceptions).
Values used are:
H
and D
in momega
in rad/sn
in 1/sV
in m/sM
in NmF
in NJ
in kg m^2R
in OhmI
in AU
in VC
in AhOne airplane needs exactly one Power system, even if the latter is empty. The Power system for one airplane can contain the following items:
The system is configured using a description in xml. Currently we use .air-files to describe airplanes, so you have to create an additional file containing this description. For example for biplane2.air there has to be a file called biplane2.xml. Please take a look at the examples you'll find in the subdirectory ./model/.
Here's an example of a system with one battery; there is a gearbox with two engines driving one prop.
<power> <battery filename="nicd12_30" throttle_min="0"> <shaft J="2E-6" brake="0"> <engine filename="astro_cobalt_10"> <gearing eta="0.95" J="0" i="2.5" /> </engine> <engine filename="astro_cobalt_10"> <gearing eta="0.95" J="0" i="2.5" /> </engine> <propeller D="0.3" H="0.2" J="3E-6" n_fold="-1" downthrust="2" /> </shaft> </battery> </power>
Take a look at the individual items for details of their description.
If you don't want to define every single item of the system, you can take the easy way. Use a description like this:
<automagic F="12" V="15.8"> <battery throttle_min="0"> <automagic T="420" /> <shaft J="0" brake="1"> <propeller D="0.243" H="0.17" J="0" n_fold="5" downthrust="2" /> <engine> <automagic omega_p="2827" eta_opt="0.78" eta="0.7" /> </engine> </shaft> </battery> </automagic>
This will create a power system which delivers a thrust of F=12 N
at a velocity of V=15.8 m/s
. The battery will be designed to last T=420 s
. You also need to fill in the dimensions of the propeller. It is best to take everything else as shown in the example.
If you use this automagic way of creating the system, the program will output the configuration it calculated from your values to give you a starting point for fine grained tunings.
As long as you only have the old .air-file, CRRCSim will print descriptions of the power systems it uses to the console to give you a starting point.