I find the way flying seaplane

[VSUN77]

I tried many many times to fly the seaplane. I believe many of you have similar problems as well. The plane still taxi on the water and the engine turns slowly, even if keeping press W or number keys not working. I suppose that is because the setting of the graphs. I changed my visual effect to medium, frame rate to unlocked, and resolution to 1440*900, after doing this, the plane took off easily. You could have a try, hope that works for you , too

[Kinski]

If you hold mouse button 1 and pull the mouse up/down you can control the rear wing to either dive/rise with the plane.
It's really not self-explaining and totally different than in later GTA parts.
But once you know it you can at least finish these missions.