If I understand correctly, air-foiled surfaces (horizontal and vertical stab) are shaped symmetrically. What is the benefit of this and how can it be felt during flight? I am guessing that this will reduce the amount of turbulence coming off of the back of the control surface. Thanks for any input. Ed

they say they fly better.but i have no exspirents with this.i will watch this thread couse i would like to know allso

i think that the idea of the airfoiled tail surfaces is to add to the control of the tail. The idea is that when the surface deflects, it makes for a higher lift airfoil. That is why the surfaces are symetrical, so that it works both ways. The basic explanation is that they work better.

There are three reasons airfoiled tails are used on real planes. 1)airfoils produce less drag. 2)airfoils produce a greater pressure differential {lift}. 3) the additional thickness allows room for a main spar thick enough to eliminate the need for flying wires. The larger the plane the more effect they have on performance, IMHO it's not likely you will notice any difference in planes under 35%, the reynolds numbers are just too low.

Here is a good link for an answer to the question. I have seen AF Tail surfaces make a dramatic change in conrol and handling in several sizes of models. Always to the positive!


http://www.djaerotech.com/dj_askjd/d...mpairfoil.html


Regards
bill

Bill, we had a heated discussion about this at the field last year. I built airfoiled tails for both my 60 size stick and my 72" laser. The size of the surfaces were exactly the same and the control throws were not changed. None of the four pilots there could tell the difference on either plane.

OUTCAST,

It's not clear from your post what you compared to what. Did you have two planes which were identical except for the tail feathers and fly them back to back? If not, I don't know how much difference in performance you could expect to notice. Beyond that, you wouldn't really expect a night & day difference anyway, unless the flat surfaces were on the verge of stalling or something. Generally, that won't be the case. It's a pretty good bet that the tail surfaces with symmetric airfoil sections are more efficient at generating the lift they are expected to generate, and it is almost certain that they are lower in drag. Whether you notice it, or whether the benefit is worth the extra building time, is a different story.

banktoturn

I built the stabs to be removable at the field [with the STICK, the fin and rudder were also changed]. I used the same control horns adjusted to the same length. If you read my first post I didn't say there is NO difference, I said it's not likely you will notice it. I think as the planes get larger/heavier there may be a larger difference, but from a RC pilot's point of view you still may not notice. :^)

OUTCAST,

Cool experiment. That's what I call back-to-back comparison!

banktoturn

The "dramatic" improvement is subjective I will admit. I ran the same experiment with a 33% laser and a Kaos. The difference was mainly at the ends of the envelope. Slow flight got better and fast forward flight felt more locked in. The 33% laser with the Flat tail just was a flat pig in a TR. If you strayed a few degrees out of verticle it was flopping over like a fish. The design with AF tail had almost to much bite you could kick it from 45 deg off heading in a hover and all the way to 45 deg the other way at will. The slow flight was incredible- solid as a rock. I felt it gave a large improvement to the overall performance. The Kaos felt less jumpy and locked in as well. It had a little more power in control response like in slow rolls and snaps. It helps to give more power but also more even response from the surfaceor more lienear (sp) input.

I think it has to do with the airframe and what kind of flying you do as to its worth. An Ugly Stick would not be helped much but say a more precise aerobatic design would be helped quite a percentage. It gives that little bit of an edge in control IMHO

Regards
Bill

camel65 thats what i wanted to hear.....i will try it on a 40 size 3d plane.the hover is what im looking for thanks