Alternate tail airfoil
 

On an airplane project am now working upon, the Hoz-stab section is shown on the plan. It is symetrical an a chord varying from 5 to 8 inches.

What I have found is an RAF30 airfoil which matches about the first 60% of the length. The area between 70 to 80 percent is too thin. Looks the region is too thin, and will not permit adequate spar height here for good enough rigidity and strength.


I need recomendation as to another airfoil about same up front, but thicker in this 70 to 80 percent zone.


Wm.

RE: Alternate tail airfoil
 

Use an NACA symmetrical of the proper thickness.
It's not of primary importance what the horizontal section is.

RE: Alternate tail airfoil
 

I have a feeling that you are not reading of the importance to what has been mentioned.

It is just too thin in the 70-80% vicinity,

Wm.

RE: Alternate tail airfoil
 

You give the impression that this stab is very highly loaded and, thus, having sufficient spar height is critical. So, take the RAF30 and thicken up the 70-80% region to meet your requirements. Then, if you're really concerned, do it in Profili/xfoil so you can tweak the section to minimize drag.

RE: Alternate tail airfoil
 

Unless the span is very long, the sizes you mentioned are in the size range of a .60-size airplane. You could easily make a horizontal stabilizer out of 1/4" sheet stock, so the thickness may not be as critical as you think. Even so, the exact airfoil usually isn't that critical on a model...almost any airfoil that has the thickness you desire will work.

If you're building a model from a plan, and it's already a proven model, why is the section shown not adequate?

RE: Alternate tail airfoil
 

Paul's right Coos. If you want it a bit thicker back where the hinge line goes then just fudge it up a little with a french curve or your shoe sole. Tail airfoils for stuff with fans on the front are not that big a deal. As long as it doesn't make you flinch in pain to look at the thing it'll all be fine.