My stearman is fitted with a MVVS 1.6 with a 18x6 carbon prop and this combo flights great.
This morning however I was lucky not to lose the plane, basically everytime i tried to take off as soon as i aproached take off speed she would skew violently to the left, eventually i managed to yark her off the ground but she continued pulling to the left i trimmed her out and continued without a second thought.
Next flight she did the same thing ( so it wasn't the rudder as i originally thought) and this time broke the control horn on the rudder, ah so that was it a cracked control horn.
Well no not quite, when stripping her down i found that one of the screws holding the cabanes to the body had completely worked loose hence when the top wing lifted (at takeoff speed) the whole thing would twist, I think i was lucky not to lose he plane.
found a sort of cure for the splitting of the undercarriage, i have applied heatshrink this keeps it together and has enough give so as not to crack again.