The Epic LT took me about a year. I mapped and remapped ever square inch of that thing, did the airfiles over and over and over, made the textures a easy to repaint system with layers, then create a group of repaints for the main package. Not to mention the soundpack.
So, a high detail 3D virtual model will probably take you much longer then creating a actual scaled 'model' of a plane, but thats for a high detail plane. There are ways to quickly whip out a mesh model, use existing gauges, sounds, basic textures, etc. Kazunori Ito is a good example of a lightning fast modellor who has developed some good shortcut techniques that work well for him.
Bill