Advise how to reduce rudder to roll coupling

[PPandelaers]

Hi folks,

 

Got a Cap 232 ARF of some unknown brand "Hype" in Europe. Many problems,
first of too heavy, wing profile weird but symmetric. High speed stalls at a
blink.

Size 80" wingspan.

 

Now the question. Can make it fly pretty good with a DA50, but there's this
enormous roll-coupling anytime you touch rudder. Also some pulling to the
gear, but nothing unusual.. Best way to test it is to fly knife edge, it
rolls on it's back in both directions, very quickly!  The wing has NO
dihedral. CG is definitely OK, falls nicely straight down on stall turns

 

Thought first it had to do with dihedral, but in knife edge, the wing
doesn't fly? What could it have do with it? Tried on simulator AFPD,
roll-effect by lack of dihedral is minor.

So, I thought it's the shape of the rudder, I have to increase the bottom
portion. So I did to a very significant amount, lowering the center (balance
of the surface if you cut it out in cardboard)  of the rudder-surface about
1 ", I noticed some real improvement, but still far from OK. I had hoped
that this much would have reversed the rolling direction. 

 

Any ideas on what I could do? Mixing my radio, 20%  rudder to roll, still
way insufficient.

 

Thx!


Patrick

 

 

 

 

 

 

 

 

 

 

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