My YS63 14x4zinger YS bryon20/20 fuel hover my 5 1/4 topcap arf real easy. I was flying mine at set at 10,000RPM. If your not getting enough pull on uplines go down to a 13x4W APC that will help.

Swinging a 14x4W APC at 10,800 should pull at 4.5lb plane out of sight.

MY Saito91 turning 10,800 a 14x4w APC will pull my 7lb + U-Can-DO real good. NOt unlimited vertical but good.