I guess I'm a little late on this thread but thought I would let you know what I did to my mini sportster.
I've built about four of these planes this year and the first three followed the plans as provided. I had a lot of touble flying it at first but I was finally able to keep it in the air and bring it down most of the time without smashing it to pieces. All three of these had to be flown quite fast to keep it stable and it would buck all the way around a tight loop. In my last build I lengthened the wings by two inches leaving everything else the same and the plane flies much better. The max speed seems nearly the same and it has very little bucking when doing a tight loop now. The stall speed is greatly reduced and I can land it at a much slower speed. This little change has turned the mini sportster into my favorite plane to fly.
I'm using a 6x4.5 prop, 1806 Emax motor and either a 800 3s or 600 3s battery. The 600 works better because of the reduced weight.
I balance my plane slightly forward of the middle of the spar.
I've built about four of these planes this year and the first three followed the plans as provided. I had a lot of touble flying it at first but I was finally able to keep it in the air and bring it down most of the time without smashing it to pieces. All three of these had to be flown quite fast to keep it stable and it would buck all the way around a tight loop. In my last build I lengthened the wings by two inches leaving everything else the same and the plane flies much better. The max speed seems nearly the same and it has very little bucking when doing a tight loop now. The stall speed is greatly reduced and I can land it at a much slower speed. This little change has turned the mini sportster into my favorite plane to fly.
I'm using a 6x4.5 prop, 1806 Emax motor and either a 800 3s or 600 3s battery. The 600 works better because of the reduced weight.
I balance my plane slightly forward of the middle of the spar.
