Originally Posted by
karolh
Posting this for a hobby friend of mine. He recently bought a Hangar 9 Carden 50cc Extra and fitted it with an EME 60 with the stock muffler and the model flew great. He opted to fit a tuned pipe so he modded the lower half of the fuse making a tunnel to accomodate the pipe and also relocated the tail mounted rudder servo forward using a pull pull arrangement.
The model was rebalanced to ensure that the CG was as it was before, but now the model flies in a slight nose high attitude when flying level and requires a touch of down elevator trim to do so. He is pretty much at his wits end trying to figure up what might be the cause of the change in the model's flying attitude as nothing else was changed
and we would certainly appreciate your thoughts on this. Thanks.
What did rebalancing require?
Are you positive the CG was corrected after the modifications to be where it had been before the mods?
Needing the trim you describe could come from a couple of different sources. The trim is needed because the horizontal tail is now carrying more weight due to a more aft CG. The tail's lifting ability has changed due to different airflow being encountered from the change in fuselage configuration and/or exhaust location.