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Saturday, December 28, 2013

CRRCsim: the Needle 115 is now available

Thuro, the designer of the Needle Serie (100, 124, 115) just released the CRRCsim version of the Needle 115, in 3 different color schemes.
You can download the Needle 115 here. Then, after unzipping the file, you just copy

  1. files with .ac extension  in the directory "Objects" of CRRCSim 
  2. files with .xml in the directory "Models" of CRRCSim
  3. files with .rgb in the directory "Textures" of CRRCSim
Then start CRRCsim, and use the configuration menu to change of plane and color scheme.

Many thanks to Thuro (thuro.at)for providing this new plane for this great slope simulator !


  1. You should give a better look at the parameters written in the xml file, which define glider's performance and handling. As I showed in the analysis "Are F3F gliders realistic enough in CRRCsim ?" which were posted on Planet Soaring on January last year, sometimes they are completely off.
    In the definition of the Needle again some parameters have been used which provide largely un-realistic flight performances. The biggest problem are:
    - CD_prof="0.00053", this is really much too low and results in incredibly high efficiencies (almost 100 at Cl=0.2, and about 50 at Cl = 0.6) even for a high performance model like the Needle; it should be around 0.01
    - CL_a="-0.000003", this is the lift curve slope and should be about 5.9; setting it to practically zero means that the wing will not create more lift with increasing angle of attack; as a result the lift coefficient of the wing is fixed and the model never stalls; additionally, it becomes totally insensitive to wind direction changes (e.g. turbulence, which is available in the latest CRRCsim version);
    - CL_de="-0.6", this is the lift or downforce produced by moving the elevator; note that it does NOT describes the increase of lift obtained pulling the elevator (which is in fact a consequence of the increased angle of attack) but rather the very small counter-effect due to the elevator itself (if you pull the elevator it will generate some downforce, but at the end this will be more than compensated by the increased wing lift due to the increased angle of attack which develops because of the nose-up pitching moment generated by the elevator); it should be about 0.2 (note change of sign); as it is set now this CRRCsim model is actually (mistakenly) using the change of lift produced by the elevator instead of the change of lift produced by the wing (which is zero because of the wrong CL_a noted above); as a result max/min total lift coefficients are 0.45 (positive lift) and -0.15 (negative lift), which is a much too narrow range although probaly enought to simulate an F3F run; other parameters in the xml file aimed at specifing a max/min CL of 0.6/-0.4, which would be a more realistic range, but they are actually useless because of the misuse of CL_a and CL_de.

    I believe these major flaws prevent a realistic flying experience using this model in CRRCsim and I suggest updating them in the xml file to enjoy the beauty of this new model.

    Happy flying,

    Luca Gasparini

    1. Thank you Luca for pointing this. I forwarded your comments to Thuro. I also felt the N115 too fast on CRRCsim compared to other plane.


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