Since installing this aircraft, whichever aircraft I choose at the start of my sim session, it steers to the right when I accelerate until I correct with opposite rudder one time. Then all is well. Upon aircraft startup, I notice the aircraft bobbing up and down slightly, but there is no flutter. The flutter starts when the aircraft leaves the ground.
A couple possibilities here: First and foremost, is your default flight, and plane, the original FSX default? IE: The trike over Friday Harbour. If not, try making it that and see what happens.
Second: Make sure that, once you get the engines fired up, and both generators on-line, press the FCS Reset switch, left side panel, aft the throttles. Then, just before you take off, when you're on the runway, all systems fired up, BIT checked, and ready to fly, just before you advance the throttles, "wipe" the controls. Move the stick in a full throw fore-n-aft, left-n-right, and waggle the rudders full throw, left-n-right. This is a habit ALL Naval Aviators get drilled into their skull housing groups from day 1 of flight school. It should be YOUR habit as well. In the real-world, wherever that may be, it gives a last check to make sure the controls are free-n-clear, nothings jammed up by a bit of FOD, which can crash a plane with no notice, no systems have failed on you, whatever. In the sim, it can clear previous settings that may have been held over from a previous flight, and so on. Some of the more religiously inclined Aviators say the Trinity to as they wipe the controls, ie: Forward=Father, aft=Son, etc. Most, however, just go with forward=testicles, aft=spectacles, left=watch, right=wallet. Handy little mnemonic
For the Flutter, try this: Make a back-up of it, then open the plane's aircraft.cfg file with NotePad. Scan down through it for the heading
[HornetFCS] . Under that, find the line that reads
AoAScalar=1.500. Change it to 1.35. Save the file, exit NotePad, and reload the plane. I don't know why, and it shouldn't, actually, but that stops the flutter. Give it a try. If it doesn't help, you can always restore the original easily enough. It worked for me, any way.
Hope this helps a little...
Pat☺