>In yours experience how many holes I can make in my belly air brake and which diameter.
>I've tested my KR2 with a passenger on board at take off weight of 483 kgs ( about 1063 lbs.) and C.G. at 26,9 % wing chord. >Ewerythig OK but now the pitch is VERY sensitive. >I've landed with some difficulties with 15 kts of wind not exactly in axis ( cross??) but i can use again my plane :-)) >Ciao >Franco Negri ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ I've never read anything scientific about holes in airbrakes so all I have is my experience. You can see my speed brake at: http://home.hiwaay.net/~langford/flesner/19.jpg (speed brake) The holes are 3/4" as that is one of the hole cutter saws I had. I seem to recall the holes are to help create extra drag. One of the U.S. Navy WWII torpedo planes had a speed brake with lots of large holes. Your C.G. location is approx where mine is with just me (200 lbs) and full fuel (25 gal). My KR is standard but has a 24" stretch on the fuselage. At that C.G. my KR still handles well. Even with an additional 150 lbs in the passenger seat it does not seem to be overly sensitive. The controls are light at all C.G. locations for me but it has yet to feel over sensitive. Larry Flesner
