Scale Facts-Aircraft flaps.

[wonwinglo]

Aircraft flaps can rougly be divided into three different types,first we have the basic contour changing variety whereby the aft portion of the wing hinges downwards to change the aerofoil section,then we have split trailing edge flaps which lower from beneath the wing trailing edge,Junkers used a floating flap which was hinged aft of the wing trailing edge and being lower than the wing itself created a useful slot effect.Flaps are sometimes confused with air brakes which are something entirely different,usually these are the split variety and are used on landing to reduce the aircrafts landing speed,then we encounter air brakes such as used on wartime dive bombers, sometimes these exit from the top of the wing ( also on sailplanes and gliders) or are fitted as perforated panels beneath the wing,another very different variation is a type of flap which is used to control the aircraft laterally called flaperons,these work much like ailerons but give adverse drag on one side without the effect of lifting the wing itself,an example of this is the Noble Hardman Snowbird aircraft.Airliners also use a vast combination of flaperons and airbrakes peculier to each machine.So we can see there are overlaps where designers have used flaps as a means of control,however the main purpose is to reduce the flying speed without inducing the stall especially at high angles of attack or with the nose of the aircraft downward.

There are many other factors which affect flaps and the above is a generalisation to get a better understanding.

 

[Kiwi]

I'm suprised you didn't mention the Fowler Flap whereby the flap moves backwards as it moves down therby giving an increase in wing area which improves handling as the aircraft slows down. Examples are numerous, HS 748, P-38, Hudson, Constellation and numerous others.