I have a F9F -8 Cougar from Hobby King. 880mm wing, 1000mm length. I install a 4000mah 4s battery and check the CG which is 80mm back from the leadinf edge. Turns out very nose heavy, any where it should be?. Once in the air it can only br flown with full up elevator, making it difficult to land.

Thanks M Cannata

Sounds like they didn't get it right at the factory. Your description is of a very nose heavy condition, I have been flying an F9F Panther for a few years now with out any CG issues or any other for that matter. I nwould start moving the CG back in an increment of 3/8" inch since the problem seems so sever. If it starts to improve but you still have a lot of up elev in your trim start going back in 1/4" increments untill the bird straightens up and flies right. I am assuming the wing and stabilizer incidences are set in stone at the factory. I used this method on a scatch built PT-19 and it was safe and the result was a model that behaves itself. It is good that you have enough confidence in your skill to know it is the bird and not you that has the problem. Maybe some one else has figured it out as you can not be the only one to experience these issues. That is very similiar to a micro sized sukoi that was sold by great planes a few years ago. It was so nose heavy it was uncontrillable so they really got that one wrong. Best of luck and I am shure yyou will get this ironed out in short order.

Jackson