This is an airplane I made in cycles, trying to achieve photo realism but something is missing…
The final render will have more samples, and simplify is on.
The final render will have more samples, and simplify is on.
If you want some realism, you need to use real textures! Texture Lib and CG Textures are one of my favorite texture sites. They have a wide variety from snow to desert. You can also just use Google image search, I found good textures this way.
You should also enable full global illumination and use a sun lamp with the size of 7mm and colored slightly yellow
This is very typical what I see most of times when people start doing their 3d-stuff.
Look at the sizes of your elements and how they are related to each other. for example if we think that the window of the plane is something like 80cm high, then how come that corrugated iron is that thigh on the roof? Also you could not make it support that big area by itself without support. The “waves” of the tin should be at the same wide on every piece you have in the scene, or it is not logical. Then there is that bell(?) or lamp on the wall. How big it is? If the plane is at correct dimension, then that bell is about the size of a man.
So, fix first your measurements (scene) and then fix the materials and textures and then lighting. Or something like that. Good luck. That plane model is very cool and you have nice idea. 
