Re: CG placing

Jon Berndt wrote:

>>I am modeling an R/C UAV, 2.2m span and 6.5 kg
>>the METRICS file looks like this:
>>    AC_CGLOC     28.3 0.0 0.0
>>    AC_AERORP    28.3 0.0 0.0
>>    AC_EYEPTLOC  17.0 0.0 15.0
>>    AC_VRP       28.3 0.0 0.0
>>and the undercarriage is:
>>AC_GEAR NOSE_LG     10.0   0.0  -10.0
>>AC_GEAR LEFT_MLG   37.5 -17.8  -10.0
>>AC_GEAR RIGHT_MLG 37.5  17.8  -10.0
>>
>>the model.xml file links directly to the .ac model
>>and the .ac model in AC3D has the origin (0,0,0) at the center of gravity.
>>
>>When I launch FG with the aircraft on the runway, it spins around like a
>>bouncy ball and ends-up about 3m below ground....
>>    
>>
>
>It looks like you are doing the correct thing. There is a problem when modeling landing
>gear forces when at rest. Careful selection of spring and damping coefficients is needed
>to prevent the aircraft from turning into a bouncy ball. But, it does require some work to
>get the right values. Also, even with the best values, there will still be some (maybe a
>lot) of jittering. This is one area where we have known for some time that we need to do
>some work on the FDM.
>
>Jon
>
>  
>

I am trying to implement an RC aircraft landing gear.... basically just 
poles (no suspension).
Is it ok to choose a damping coeff and spring constant equal to 0?

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