Need information on aerodynamic parameters of lift-drag plugin

asked 2017-01-27 14:48:53 -0500

Ajith kumar
31 ●3 ●5 ●6

Hi all,

I recently created a aircraft model and applied liftdrag plug into its control surfaces. I followed cessna aerodynamic parameters. But, I couldn't get the required flight. I think It would be useful if I fix these parameters according to my model. So, please give the source(or citation of research paper) from where the aerodynamic parameters such as cla,cda, etc are taken

<a0>0.4</a0>
<cla>4.752798721</cla>
<cda>0.6417112299</cda>
<cma>0</cma>
<alpha_stall>1.5</alpha_stall>
<cla_stall>-3.85</cla_stall>
<cda_stall>-0.9233984055</cda_stall>
<cma_stall>0</cma_stall>.

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answered 2017-11-13 12:00:40 -0500

Duckfrost
209 ●2 ●13 ●9

updated 2017-12-04 05:14:11 -0500

Here I give a simple tutorial on how to get started with this plugin creating a simple example of movement with drag and lift in a robot with buoancy ( in water basicaly). This should serve as an extra of the previous answer. Here you have the video of this example:Video

I created a two link model, with a fin that will move and generate a drag that will move a sphere floating in water. You need to spawn the robot using the main_sphere_with_fin.launch. Inside it you have a world launch and a robot spawn. In this robot spawn among other things you spawn the urdf of the model where the plugin is set up. The urdf of floating_sphere_with_fin.urdf.

Inside it I set up the plugin in this fashion:

<gazebo>
        <plugin name="sphere_caudal_fin" filename="libLiftDragPlugin.so">
          <air_density>1000</air_density>
          <cla>0</cla>
        <cla_stall>0</cla_stall>
        <cda>1.2535816618911175</cda>
        <cda_stall>1.4326647564469914</cda_stall>
       <alpha_stall>0</alpha_stall>
       <a0>0</a0>
          <area>0.0334265458342</area>
          <upward>0 0 1.0</upward>
          <forward>-1.0 0 0</forward>
          <link_name>sphere_caudal_fin_link</link_name>
          <cp>0 0.19 0</cp>
        </plugin>
    </gazebo>

As you can see here I only set the drag because I want it to move through the friction with the water, and no lift because the fin would generate one significantly. The Center of pressure ( cp) is places on the fin ( that is the distance from the center of the sphere to the tip of the fin where I want it to generate the force). Of course all this depends on your application.

Here I leave you the code of all the files used:

main.launch

main_sphere_with_fin.launch

ocean.world

sphere_with_fin_complete.launch

floating_sphere_with_fin.urdf.sdf

Hope this was usefull. If you state a more precise case scenario we could try to apply all this to your case in particular. This is just an example of how to use it in a basic way.

Edit:

This is an extra example for a more complex robot fish to move it through drag also: VIDEO PART 2