(05-06-2013, 11:55 AM)wingtipper Wrote: Mate im no designer but i think the 1st pic without the flares might be ok . As smuzz pointed out previously it is a short rudder . Try it 1st then add the balsa flare and try it again . My bet is it will fly better without . And if it drags reduce the rudder length
Too late for testing with out fairings now,
The fairing are in place the plane has been balanced and it's ready for a test flight.
Adding the fairings won't decrease the effectiveness of the verticle fin, Which is what I think you mean to say, as this plane doesn't have a rudder.
The verticle fin is no bigger than it was before but it has been moved back this will facilitate the desired change, which is, moving the center of lateral area further aft. You've got to remember that it's not just the size of the fin that matters, it's the area on the side of the fuse too, and it matters how far back that area is in relation to the C of G.
When there is too much lateral area too far forward then then forces are generated that want to make the plane fly sideways, So it Yaws. If the geometry is bad enough the act of yawing generates even more yawing force and things get really out of hand.
Putting the fairing on doesn't change the lateral area. It will reduce drag tho' and it should cause the air to flow around the fuse/fin junction rather than up the ramp that Kizza pointed out.
The sugestion was that the ramp might cause a pitching moment and that was to my mind a greater concern than the extra drag. Although the fairing should in some way improve both.
Of course it's all academic untill it's tested and even then it's sketchy because you have to repeat things many times to prove something for certain. I don't want a repeat of the first flight ever again let alone many times
I might get in that test flight this arvo if things go well
After watching the video quite a few more times. I can see that the plane leaves my had pretty straight and with the wings level. Just after it leaves my hand it Yaws hard to the right and then begins to roll to the right. Jag corrects the roll with ailerons and then it Yaws the other way, this time much harder, it also has the torque working with it on this side, it goes spinning off totally out of controll.
If you watch it closely you can see the tail go out as tho it was given a heap of right rudder just after it was launched, then it swings the other way initiating the spin.