Is airbrush needed for painting airplanes? How do I paint an airplane with pencils or airbrush to get nice effects like this?

Personally I use a Badger 175 and love it. It is a double action allowing air flow and paint flow control. It comes with three needles Large medium and fine. These give you a wide array of coverage options. The body is a metal and has lasted very well. I think if you keep it clean it'll last forever.

Is it needed....no. Can you get by without one....yes. Can you replicate the planes above without one...yes, but it would be much easier with an airbrush. I painted my models with spray can paint for a long time before moving onto an airbrush. Some of the effects seen above (streaking, exhaust stains, chipped paint) can be accomplished without an airbrush using items such as pastel chalks for the stains and tape for the paint chips (a silver gel pen works good for paint chips too). The big problem you run into with using a rattle can for painting is the area coverage. When the paint comes from a can the paint distributes over a wide area which makes painting details and soft-edge camo difficult (hard-edge camo can be painted pretty easily with a spray can).

So, I guess the answer is no, you don't need an airbrush but it would certainly make things easier if you got one and practiced with it. A simple airbrush isn't too expensive either. I use the same Paasch H I bought 10 years ago and it's still going strong. It's a single action brush that will cost you anywhere from $40-$50 now. Hope this helps you out.

You don't have to buy an AB, bit I guarantee that your results will be superior. I use an Aztek 4709 dual action.
It is superb.
You will not be able to simulate some of the advanced modelling techniqiues with a brush.
Do your research on AB's before buying one, they are individual things.....

Thanks for the answers guys,

I haven't afford to buy an airbrush, for the moment (tight budget!).

Before I buy an airbrush-set I will research a little, to see what's best for me...

Thanks again!