I have sort of accepted that the cause of the crash was the crystal vibrating out, that seems to be the most logical explanation as I found it in the grass at the crash site. I feel better for believing it was my fault for having an airhead moment when I installed the receiver, instead of thinking it was caused by an unknown event. I have learnt a lesson by this and I will have to be more thoughtful in the future. I have always wrapped radio gear in foam on my other planes so I don’t know why I thought it was acceptable not to do it on this one.

As for the flight behaviour, I am sure it was caused by the increased rudder.

From the info you guys have provided, It has brought up an interesting point as to why my Somethin’ Extra also has ideas of its own whilst in the air. I have found that it is not a good idea to use the ailerons when using the rudder because it snaps. If I am prop hanging and try to use the ailerons it flicks out quick and the nose nearly always ends up pointing south. I searched RCU prior to buying the SE and most of the guys said they extended the rudder to help with Knife edge so this is what I did with mine at the building stage.
It looks like I over enlarged it, as the turns do tend to tighten in to spiral if I’m not careful and it weather veins quite bad in a breeze. If I fly a down wind leg slowly it will do a flat turn and line itself up into the wind virtually hands off. Interesting to watch but annoying when trying to do other stuff.

When I think about it, because the SE was my first aerobatic plane and I just thought I had to get use to the constant wing tipping when flying in a breeze and assumed this type of plane flew like this. It can be a constant battle to keep the wings from tucking under when breezy. On a calm day it is an amazing aeroplane, and you wonder how it stays up at such a slow speed and it lands like a heli most of the time.
I am going to cut down the rudder to a more acceptable size as it was never any good at real knife edge anyway.

Can anyone shed some light on the characteristics of the rudder ? Is the height of the rudder more of a problem than the length? Should the rudder be short in height if it is long out the back and tall if short out the back?

Any info appreciated.