The secret of this tailless AND finless aircraft, is very simple, and lies in the particular shape of the ailerons :
This induced a strange evolution of the airfoil at the tip, but anyway, it works well !! The wing flies right, and gets under control without much trouble.
Root : 310 (mm)
"Paoli Special" 12%
| Swept back
(at the leading edge)
19° (about 450 mm)
My scanned paoli plan !
The paoli blueprint of my paoli, in autocad, by Fred Vander Hoek (Springville, California).
Here are the data for locating the CG of you Paoli wing...
|CG location on mean chord||Distance from the leading edge|
mesured at the root
I must add that the "paoli solution" was displayed in the french magazine RCM, in an
article written by B Rigoulot.
Indeed, Mr Paoli was a pilot during the WWII, and was concerned with pure flying wing. He comes to this wholy simple and efficient solution.
My wing was bigger and with a greater aspect ratio than the one display in the magazine. And it still works well...
General handling :
The first flights were not uneventful, for the winch was a bit too strong, and the center spar in kite carbone broke once... Two pieces of flying wing were recovered without much problem...
This is quite surprising for me, the wing can easily be winched by bungee.
It goes up fairly right, and you can easily adjust the position during the winching.
The most perillous is the start : you need to hang to something (there is no fuselage ...)
and then you have to succeed in freeing the wing at the horizontal.
If not you will crash your wing as I have done twice, that means that the wing make a quick U-turn down to the earth, and maybe into the earth... You cannot correct the pattern, for there is no fin, and it is quite frigthening to see his work explosing without the possibility of doing anything. The first time, its was not too much "injured", but the second the center was properly written off... By now, the two external panel, almost intact with the ailerons, are awaiting further repair and a new center panel.
The paoli flying wing has a really discret adverse yaw. I cheat a bit, for I programmed on my radio a function that is to be used with the "rudder stick" : when pulling it right, only the right aileron goes up. It prevents from too much skiding turns. It creates a virtual "yaw axis", but it interfers with the control on the lateral axis. This impose a way of turning and moving all the stick quite unusual when compared to other gliders.
The flying wing has a quite odd behaviour when it faces strong cross wind gusts. I live in Le Havre, France, and it is a windy place, and I experienced yaw oscillation due to those cross wind gusts. They have variable amplitude, and it takes 2-3 period to be damped. The duration of the whole phenomenon is from 2 to 10 seconds, which appears to be very long when up in the air.
I did not try to cause strong behaviour, by putting the wing in strange position.
I only tried the symetric stall, and stall in a curve. It was very gentle anyway, it took a height about 15-20 meters to recover and
carry on the flight normally, without moving the trims. The wing was really not willing to spin !
There was a strange penomenon, that can be describe like a roughness in the air : from time to time, it seemed as if the wing was glued in the air, sinking quickly without reason, as if it was reluctant to glide. You then needed to push the elevator stick, and then it was as if you put soap on it, it was gliding well again. This probleme was partly curred by moving the CG further back, and this was without consequences on the stalling skills, so I did it !
Concerning handling hability, in order to find the lift, it needs to be more attentive than with a conventionnal plane. Without any fuselage, it is quite difficult to see the angle of attack, and it needs all your attention not to get "nose high". I can't tell you whether it climbs well, for it did not live long enough to meet thermals. But it is not heavy at all, I am quite confident
Adjustements and modifications :
It appeared that the further back the CG is, the better the wing glided. I was quite afraid at the beginning of that point and I put it quite far forward (about 17%), but too much is to much, and the flying skills were not optimised. By moving it back, the flying wing became lesss "heavy" to handle, and the period of the oscillation was shorter in the turbulences, for it was less stable.
I tried turbulators in the region of the aileron, in order to cured
the "gliding problem" described before. Indeed, the effects were wholy similar to those described in
an article on boundary layer separation and turbulators in a french magazine.
The "hysteresys" aspect of the phenomenom seemed to be typical.
When I removed it, in order to see whether it was effective, I noticed that the behaviour was different. So they were not totally ineffective. Without them, the wing was more "extrem", I mean that it glided better, but it was less stable in yaw, too. The dag provided behind the CG acted as a fin... But the "hysteresys" problems were helped by the turbulator.
So I put others, but cut with "Zig-Zag" scissors this time. But I may be biaised about them, for I only achieved 2 or 3 winching with them, before I crashed the wing. In my memory, I seemed to have both gliding skils and yaw stability, but I can't tell you more until now.
I will conclude by saying that doing such a flying wing took not
a lot of time, and then it was really an enjoyment to fly an unusual glider.
I am quite angry against myself for having not be carefull enough on winching start, but
I can tell you this first prototype will be rebuilt and enhanced.