Fliegenmong

Hi All

I have a vexing question about aerodynamics, it should be noted that I have been involved in aero modelling for many a year and my Father before me AND his father, I have also held private pilots licence, and yet I cannot figure out this problem

My Son flies an ELECTRAFUN, simple pod and boom type a/c three channels elev. Rudder and on or off motor. He / we have flown it many many many times, and after so much wear and tear it was time to purchase a new wing, and new tail feathers, (Vertical & Horizontal stab).

Out to the flying field for test flight – sharp dive to the left. Bend some right trim into the vert stab, still a sharp dive to the left but controllable with full right rudder after even more trim was bent in – however as soon as the motor is cut the application of full right rudder still produces a diving left hand turn!!!

Now this should not happen naturally, Radio has been range checked no glitches or anything of the sort.
To date I have moved the wing toward the (left) down going wing. No result, I have jacked up the leading edge of the down going wing with balsa shims, no result. As a last resort I made a helluva big ‘Barn Door” fixed aileron (down) on the wing that drops (left), and STILL it keeps diving into a left hand spiral, even though now there is slight tendancy to roll right under power as the aileron is so big. Full trim is to the right , maximum right deflection, left is more really just centre – still spiral dive left. CG is within range, nothing has changed except the aircraft – as mentioned – now has a brand new wing, brand new vert & horizontal stab, everything is needless to say all square tail to main plane angles of incidence are correct or at leaqst unchanged and I can still not figure out why this airplane still dives to the left!!

We are of a collective 65 odd years of experience and I cannot figure this out! Please what am I missing!?!?!?!