Go into the windows control panel > Game controllers screen
(unless your Saitek uses some other software? I don't have a Saitek so I wouldn't know)
Double click the stick, bring up the window. Use the test screen. Move your stick to full deflections up, down, left, right. Watch the little window. If you're pushing all the way, but the little crosshair is only going halfway, it's a calibration issue. Move your slider fully up and fully down. If it only goes partway up, it's a calibration issue. Do the same for the rudder axis as well.
Calibrate it (use deliberate, careful motions) following the step-by-step instructions, and hit OKAY or FINISH when you're done.
If Saitek has their own software, use that. Calibrate the stick.
Then start up Aces High. Bring up the clipboard, choose (I think) Settings > Controllers > Calibrate (it may be worded similarly) it will give you a screen. Move your stick up, down, left, right, as far as it will go several times (make full circles), slide the throttle fully up and down several times, move your rudder full left and right several times, then move your mouse to click "Okay"
That should do it.