Hi, there,

I'm seeking the coordinates of the center of gravity (center of mass, not aerodynamic center, or center of pressure !!) for the naca 0018 airfoil. I already spent some time checking the resources available from cfd-online, and nowhere was i able to find this info! If you do have such info, please let me know. Sincerely,

Frederic Felten.

From the generic definition of CG, knowing the coordiates of the airfoil, you can calculate it.

Hi! Frederic,

If you assume homogeneous mass distribution, the coords of the center of gravity is the average of the coords of the airfoil contour, isn't it?

If you don't have homogeneous mass distribution, then the center is caculcated as

r_cg = sum_over_i( m_i r_i) / sum_over_i(m_i)

where r_cg and r_i are vectors. Basically, homogeneous mass distribution means all m_i are equal, which reduces to the average of r_i.

Hope this helps Srinivasan

Dear Mr. Felten,

I used my WingAnalysis Plus Cross Section Tool to obtain a position of the CG for the NACA 0018 at about 42% chord from the leading edge (along the mean chord line).

Regards, Patrick Hanley, Ph.D. Aerodynamics Software http://www.hanleyinnovations.com

[louisgag]

For those looking for an answer to this simple but interesting question,
for all NACA symmetric airfoils, with the closed trailing edge, the center of mass is at roughly 0.3994*chord from the leading edge. If the trailing edge is "open" (last coefficient is -0.1015) then the center of mass is at roughly 0.4015*chord.

This results from the calculation shown here: http://louisgagnon.com/scBlog/airfoilCenter.html