I have an old single stage Badger airbrush that I use for the detail painting and an "EBay Special" for the large areas. The EBay special is an HVLP electric spray unit. (High Volume Low Pressure) I get nice results with them. They are not show quality, but they are above average.

The amount of painting you plan to do and your budget will determine the type of equipment you get.

If you do not have a compressor, get one. It will come in handy for a variety of things besides painting.

Depending on your budget, a 2 stage airbrush is the top of the line and will provide the most detailed results. Almost any compressor will handle an airbrush.

For the large areas, I would suggest a decent "Detail Gun". These hold anywhere from 4 - 16 oz of paint depending on brand/style. An 8oz capacity should be plenty for the majority of the models you will paint.

For the detail gun I like an HVLP type, because the amount of overspray is minimal compared to a regular type gun and the feet per minute/pressure required are less. These USUALLY have the paint container above the gun, however you can achieve excellent results with a regular gun also.

What you need to ESPECIALLY CAREFUL of is the rating of the spray gun and the compressor. The gun will be rated for "X" amount of air at "X" pressure (this information is usually on the box). You need to make sure the compressor is capable of providing this. I have seen several halfway decent, inexpensive detail guns that require only about 3 - 4 feet per minute at 40 psi. Many require around 7 feet per minute at 70 - 90 psi.

The rating of the gun and how long you plan to spray will determine the compressor/unit size. Using a gun that needs 3 - 4 feet @ 40 psi, you can probably get away with a 100 psi compressor with a 2 - 4 gallon tank. For the other type guns, you will need a MINIMUM of a 125 psi unit with a MINIMUM of a 6 gallon tank.

FWIW, the HVLP setup I bought off EBay new was about $90. I find it does what I want quite nicely. I spray latex and water base polyurethane with it. Usually I paint the whole plane it's "base" color, then mask off and use the airbrush for the contrasting/detailing. If I were to build show models, or be doing a lot of painting, I would spring for the detail gun, a 2 stage airbrush and a good compressor.

The area my HVLP can paint in 1 minute, will take about 30 minutes (or longer) with an airbrush to achieve the same level of coverage.

If you decide to go with the electric HVLP unit, do not get a compressor designed just for airbrushes - for the same money as a good airbrush comprssor you can get a 100 psi 2 gallon regular compressor.

BEFORE you start painting the plane, practice using the airbrush/spray gun on scrap pieces of wood, paper, etc to determine proper paint thickness, pressure needed, speed of the stroke, spray pattern, distance, etc.

A good tip for spraying is to start the painting BEFORE the item to be painted and end the stroke AFTER the item. This will eliminate/minimize and build up.

Hope this helps.