This is a short course on how to build a good plane. I have been in the situation where I have felt frustrated by my terrible planes.

STABILITY: If your plane is not taking off or is extremely unstable, it might be the Center Of Mass and the Center Of Lift. The tutorials don't stress enough the importance of the COM being slightly in front of the COL.

LANDING GEAR: Early on in my airplanes I had a problem where my plane would veer off to the side during takeoff. This was because I had the large retractable gear where I should have had large back landing gear.

MANEUVERABILITY: If your plane is stable and can take off, you may find it pitches horribly. I have found a basic formula on the 'secret' to maneuverability. It is as follows:

Wing Area times Propulsion minus Weight minus Drag

I hope this basic tutorial helped, as I know there are a ton of players I find that have difficulty making a plane that works well.