# Coordinate System in FAST

**URL:** <https://forums.nlr.gov/t/coordinate-system-in-fast/632>\
**Category:** Computer-Aided Engineering Software Tools\
**Created:** [January 24, 2013, 4:41pm UTC](https://forums.nlr.gov/t/coordinate-system-in-fast/632 "2013-01-24T16:41:35Z")\
**Posts on this page:** 1\
**Showing post:** 1

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**Author:** ![Neelabh.Gupta](https://avatars.discourse-cdn.com/v4/letter/n/df788c/32.png) [@Neelabh.Gupta](https://forums.nlr.gov/u/Neelabh.Gupta)\
**Post date:** [January 24, 2013, 4:41pm UTC](https://forums.nlr.gov/t/coordinate-system-in-fast/632/1 "2013-01-24T16:41:35Z")

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Dear all,

I am using FAST local flapwise/edgewise/axial forces for different spans in NREL 3-bladed turbine. The ‘OutListParameter.xls’ from FAST archive folder mentions something like this, where I presume the axes of edgewise and flapwise forces are swapped? Additionally, I as a user, would, appreciate if the flap-wise and edgewise forces are mentioned as ‘shear’ forces?

 ![Local_forces.PNG](https://europe1.discourse-cdn.com/nrel/original/1X/c47dedd607b8e114c7608f9cebbf143890a2fd72.png)

Also, I just want to confirm, if the coordinate axes mentioned in FAST user guide for 2-bladed downwind turbine are same for 3-bladed upwind turbine (blade coordinate system)?

Secondly, I am using these three component forces to apply point loads at different location in my Finite Element Model (FEM). This is basically done in order to replicate the same bending moment and shear force nature along the blade as derived from FAST (for maximum conservative value of flapwise moment in time series). I am using different ‘shear centers’ (point about which twist moment is zero: an assumption considering its small compared to flapwise and edgewise moment) to apply these loads. Is it the correct way to go about it, considering am not considering aero centre and centre of mass?

Honestly, I am not an aerodynamics engineer and hence don’t know much about these terms. Sorry for flooding this topic with so many questions, but I am in the middle of it and its hard to comprehend. Any kind of insight to this, would be appreciated!

Thanks a lot,  
Neelabh

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