All sizes of the plastic and diecast model kits are terrific sources of detail and proper shapes of the various parts of aircraft.
Good quality kits will have all the hatches and panels as well as the rivet placement, antena's, etc in all the right places.
Many of these kits are very accurate in the scale reproduction of the aircraft they are modeled after.
I have had great luck scanning the decals from these kits into my computer and enlarging them to the size required for my RC Planes.
If you like to build rc models these are also fun to build as well as a source for how your rc model can be finished.
Below are some links to a few sources online for these kits.
Amazon has a great collection of plastic Revell Models
Amazon also has a great collection of plastic Academy Models
Another great source for great deals on plastic models is
There are a few well detailed scale models in diecast as well, the good ones tend to be expensive compared to there plastic counter parts. If collecting these is also part of your hobby. Motormint is one such company.