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Dear my fellow aircraft builders! I am in the early stages of a Learjet 45 (XR) project, currently working on the flight model and basic 2D cockpit. The fuselage, wing sizes, positions, stabilizers are all build from a 3-view-image that I imported and measured within a CAD software. So all positions and sizes set in Plane Maker should be "quite good". Area of interest is the horizontal stabilizer that is a moving surface to control the pitch trim and of course the magic center of gravity (cg). Facts: The Learjet 45 (LJ45) has a moving horizontal stabiizer to control the pitch trimI modeled that through the use of the appropriate settings in the control surfaces and made the hor. stab. a moving surfaceAccording to the FAA certificate the LJ45 has some "strange" hor. stab. max. deflections http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/880d41da2731227386257d5d006b9505/$FILE/T00008WI_Rev20.pdfi.e.: leading edge up trim = -0.3° and leading edge down trim = -9.5° -> that means NO positive incidence of the hor. stab. at all? I modeled that in Plane Maker the following way:set the incidence of the hor. stab. to -4.9° (middle position between -9.5° and -0.3°)set the control surface defllection up and down to 4.6° (so i can reach -0.3° and -9.5° with max. trim in both directions)set airfoil to symetric NACA009 (I have NO information about the hor. stab. airfoil of that bird)cg of gravity is set in the middle according the FAA cert. and AFM (middle of 1% MAC and 28% MAC)Problem (or maybe this is not a problem, but just "normal"?):: when I go the a very fast speed (within the envelope!) e.g. 330 KIAS at 3.000 feet (.. and loose my licence ;-) the max pitch trim brings the hor. stab to -0.3% (nearly straight level, but no pos. incidence allowed) the hor. stab still produces too much DOWNFORCE that the nose of the aircraft goes UP and I can not trim the plane and must use elevator to hold it straight leveled.I can test more situation and bring the aircraft to exxtreme weight/balance situations WITHIN the flight envelope and weight / balance specs. that I can not trim the aircraft Ideas / Questions: Is this a problem? Or is it "normal" that a aircarft is NOT trimmable within the flight envelope and weight / balance specs?Did I read the FAA spec. correctly? i.e. the incidence is always negative betwenn -0.3° and -9.5°I am really questioning the -0.3° max. UPTRIM... when I could set that to 0° or +1° all problems would be solved? But the cert. says -> NO only negative? ;-) If anyone even has the time to take a testflight, I can send you a link to the current acf. Your help and ideas are very welcome!