Thanks, I mentioned it especially to show that we DID some reserch and analyses after first flight of Nobler :-))

And yet, I will mention another great analyze in SN article - about tails by David F. - there he wrote he had good results with thin tail. So that is why.

  I would note (since I was very close to that investigation) that there were two real kickers on that on - he was comparing a 1/2" or so flat plate and turbulators wires all over it with a airfoiled stab of similar thickness. We both thought that the consequential issue there was the flat plate and the rather wild pressure gradient's around the LE (and no normal pressure at all on the flat part), and that the airfoil maintained a positive normal pressure over a much larger space. The other key takeaway was that the alignment - which is the best reason to use a flat stab, since it's very easy - generally has a preferred rigging bias (1/4 degree on the Infinity and up to 0.6 on the Trivial Pursuit/Star Gazer and now, apparently, the Thundergazer) which obviates the need to get it exactly 0-0 as previously suggested. BTW, the flat stab and the rigging seems to be FAR, vastly, more critical than the airfoiled stab, probably because of separation on the "bottom" right where the nose radius ends (which is why the turbulators help - it bends the air around that corner).

   Also note the variant he *didn't* try - a really thick airfoiled stab like on the Imitation. I think if you want it to be thick (and I don't know) you probably do want it to be a stabilator vice conventional, just because the "top" ends up with a MASSIVE gap in the surface when it is deflected since the hinge line is so thick. Even rounding off the corners on the 1/2 thick stab (flat or airfoiled) seems to make a big difference, but when you have a 1" wide gap in the surface, that has to do something, probably bad. It had absolutely catastrophic effects on the wing when I build several airplanes with "integral flaps".  So I am not sure you are comparing apples to oranges when it comes to thick tails.

     On the other hand, I agree completely with the observation about the thicker stab Cl - yes, it's *some* better but not tremendously so, and you still have the same separation issue, even if it's slightly reduced. Again, the same thing has been found on wings, with very thin airfoils (like Howard's Jive Combat teammate Phil Granderson) performing better, or much better, than extremely thick airfoils with faulty LE shapes, like the Strega ARF and the Patternmaster.

    I had at one point convinced myself that it didn't matter at all, now it is clear that at least the proper LE shape and fairing in the rest of it smoothly makes a huge difference, so again, I agree with you, making it much thicker doesn't necessarily help from an aerodynamic standpoint. I think the 3/4" I suggested above is a good compromise between the aerodynamics and the axle size, but I am still not compelled to make a really thick stabililator system.

      Brett

If you fit the stoopid TUBE SPAR to the AIRFRAME , itll be light & ridgid , and you can use V tails . 

Have the darn flying surfaces pivot on the fixed tube .

A few circlips and washers might be needed , along with some way to eliminate horrible exposed horns & pushrod ends . 

Of course, who says that the axle has to have round cross-section? Round is a silly shape, you have least material where you need most, and especially with tubes, the shear and compression forces between top and bottom are not handled in good way.
Make the joiner square and only use round section where the bushings are. Not a big deal to build something MUCH stiffer & lighter from some ud-carbon and cross grain balsa. L

If you fit the stoopid TUBE SPAR to the AIRFRAME , itll be light & ridgid , and you can use V tails . 

Have the darn flying surfaces pivot on the fixed tube .

A few circlips and washers might be needed , along with some way to eliminate horrible exposed horns & pushrod ends . 

This is a cool discussion.

It is funny anyway, while wing aerodynamics is clear and I am sure I have it OK, elevator looks like black magic to me :-P

That is the main reason I am interested in stabilators. I want something I can understand.

It’s the best I can hope for.

Without the evil spirits being invoked Howard there is a easy way to demonstrate that. A little camera and a yarn thread taped on the wing somewhere.
Here is an idea with a longer thread or in another position you could possibly investigate this.

Those cameras are dangerous. We put one on Mark Scarborough’s really pretty airplane. When he saw how much the fuselage bent he added some ugly stiffeners.

I built a Profile model using the wing and parts from a SIG Chipmunk kit.  I do not know the proper term, but the elevator ends extend forward of the hinge-line into what would typically be the ends of the horizontal stabilizer.

I believe this is done on full scale planes to lighten the control forces (like spades).  I have never noticed any difference in how this model flies compared to a regular stabilizer/elevator setup (but I don't claim to have the experience to tell the difference).

It would seem this type is a compromise that falls in between a stabilator and regular tail.  As more of the horizontal stabilizer is attached to the elevator, it becomes a stabilator.

It also seems that having at least some stabilizer would allow for a stronger "beam" along the hinge-line to attach the elevator than just a pivot on a full stabilator.

I think I have heard that these balanced control surfaces are to be avoided in stunters.  If so, why?

I built a Profile model using the wing and parts from a SIG Chipmunk kit.  I do not know the proper term, but the elevator ends extend forward of the hinge-line into what would typically be the ends of the horizontal stabilizer.

I believe this is done on full scale planes to lighten the control forces (like spades). 

Aerodynamic balance, it’s called. Yep, that’s why it’s done. If you overdo it, especially on an airplane with a wimpy pushrod as I once did, it will flutter. That and the possibility of the elevator getting stuck at full deflection are probably why people caution about doing it. Full scale airplanes also have mass balance in front of the hinge line to prevent flutter.

     Everyone seems to want to underestimate how difficult stunt can be, and how demanding the requirements are.

      Brett

If you don't think that is true try sitting out for 30 years.  The first couple of patterns you fly wlll quickly remind you!

As for the stabilator, you are dead on.  I built 2 a long time ago.  Both could fly the pattern but you needed a hunting license in most states to fly them.  I flew sailplanes with the best of them in the 90's and the exact reason they are so effective on a sailplane is the reason they suck for stunt.

Ken

Well, I know one guy that tried it. I notice he no longer uses it.

Looks like he tried hair, too.

What we need is real data on relative wind direction. We need at minimum cameras on board filming and getting real data. All we say here is at best speculation of what hapens during flight. I think a few threads hooked to some wires should show enough information.

Did anyone do that on a control line model. If not we are just guessing. And frankly I am not buying the 20-30 degrees relative wind direction on the horizontal. I will believe it when I see it. Maybe someone wants to make a test flight and explore this subject. Has anyone see the control line flight where some one did a frame by frame analysis placed a dot on the model to see the actual trajectory of the model plotted on the screen? The fuselage was mostly in lime with the trajectory. It was here on the forum somewhere but I cant find it.

Yes there where attempts in the past to use this but If i was a betting man I would bet on bad pivot point applications contributed to the lack of success. For example all combat models work well with full flying elevators they track nicely but the pivot point is in the front of the elevator. I am not saying that you should put it there and also i am not saying you should put it in the center of pressure (neutral). This could be tested with a poor men wind tunnel (car).

I will do that as soon as I get this bird built up to get some real time data.

That being said full flying is used very successfully in RC but keep in mind they are actuated by servos, usually god quality servos with nice centering, a thing we lack in CL. When you release the stick ressure on the radio they go to neutral and you are in trim condition. We need a more forward pivot point position to help with that centering issue and or reduce the tail surface to help with the increased effectiveness of the tail. 

I thought you were looking for the video that Howard took by hanging a cam on Mark's "Pro-vile Impact". It was fairly windy that afternoon, and the profile fuselage's flexing caused the elevator to deviate from desired input due to the pushrod being off centerline.  Steve