Aerodynamic Normal Coefficient in FWMAVs geometric control

[juanmed]

Hello,

While reading the papers on FWMAVs control and design optimization, I found in your paper [1] references to "..C_L, C_D and C_N are the aerodynamic lift, drag and normal coefficient given by [19]... ". However, after checking [19] I could only find the definition and values for C_L and C_D, but not for C_N, the aerodynamic normal coefficient.

I verified as well other references but yet could not find references to the C_N. Would you please be kind to let me know where can I find more information on the aerodynamic normal coefficient, its values and mathematical derivation?

I would like to test out my control ideas, and need the C_N value.

Thanks for your time.

Juan Medrano

[1]Zhang, J., Tu, Z., Fei, F., & Deng, X. (2017). Geometric flight control of a hovering robotic hummingbird. Proceedings - IEEE International Conference on Robotics and Automation, 5415–5421. https://doi.org/10.1109/ICRA.2017.7989638

[19] Dickinson, M. H., Lehmann, F., Sane, S. P., Dickinson, M. H., Lehmann, F., & Sane, S. P. (2016). Wing Rotation and the Aerodynamic Basis of Insect Flight Published by : American Association for the Advancement of Science Stable URL : http://www.jstor.org/stable/2898158 Linked references are available on JSTOR for this article : Wing Rotation and the , 284(5422), 1954–1960.

[ffnc1020]

Hi,

C_N is simply C_N(α) = cos(α)C_L + sin(α)C_D, and you can write it as a function of the angle of attack α.
If you need a source you can cite these papers below. Let me know if this answers your question.

Cheng, B., & Deng, X. (2011). Translational and rotational damping of flapping flight and its dynamics and stability at hovering. IEEE Transactions on Robotics, 27(5), 849-864.

Whitney, J. P., & Wood, R. J. (2010). Aeromechanics of passive rotation in flapping flight. Journal of fluid mechanics, 660, 197-220.

[juanmed]

Thanks for your answer! This is clear now.