Stab profiles

[Adam C]

Okay this is purely a theoretical enquiry.

As I begin to consider building a scale design, I note that some designs use slab flat stabiliser profiles and some symmetrical.

What in terms of performance is the difference?

Im using the hq3.5/12 profile for my wings.

I guess the profiled stab gives better performance over a range of airspeed??

[sp250]

A flat plate tailplane will give the most drag due to earlier separation and laminar flow over less of the chord. A symmetrical aerofoil will give the least drag and also a more crisp elevator handling. An inverted semi-symmetrical aerofoil (lifting downwards) will also give the least trim drag as well. As it will require less decalage because as it is working harder at countering the forward pitch of the main wing. Might have been better at explaining this, but you can get the drift OK.

John M

[RobbieB]

Symmetrical definitely.

Eight to ten percent thickness with the maximum thickness at 40% chord.

[chris williams]

NACA 009 is my usual choice, although I suspect the difference between that and a flat section would be very difficult to quantify...

[Adam C]

Chris,

You means in terms of performance?

Adam

[chris williams]

Yup, all my 6th scale models have flat stabs and fly very well...

[AdamChambers]

The only major difference I can find online is to do with trim changes across different airspeeds.

Flat bottom slab stabs tend to require more trim adjustment than symmetrical .

Given Im talking about slow moving scale designs, can there be much difference in flight characheristics?

[Tom Pack]

S8020 is the go to profile for me…..never has let me down.