In this article I will give a breif summary on different types of aerofoils and why a wing produces lift. This article is mainly based at people who are just getting into the hobby and maybe don't know all that much about the basic principles of flight. This may also apply to people who are intermidiate in the hobby and want to start scratch building but don't know anything about how to make a wing which will produce a descent amount of lift.
Why a wing produces lift:
A wing produces lift because of it's shape, specifically because, in it's most basic form, it's curved top and it's flat bottom. The curved surface on the top produces low pressure.
This is because the air travelling over the top of the wing has longer to travel around the wing than the air which flows underneath, and this means that the air will decrease in pressure as stated in Bernoulli's principle, 'an increase in the speed of the fluid occurs simultaneously with a decrease in pressure'. This is all that lift is, a low pressure area above a high pressure area, this causes the high pressure to push up, and thus lifting your plane off the ground.
Different aerofoils:
There many different aerofoil types, all with there different purposes. I won't go into to much detail on these rather just outline the main different shapes. Underneath there are a series of examples:
Flat bottomed aerofoils are the most simple aerofoil shape and produce quite a lot of lift but aren't the most slippery. They are used a lot in scratch building as they are very easy to reproduce.
Semi-symmetrical aerofoils are probably the most commonly used airfoils on planes as they produce less drag than flat bottomed aerofoils but still a lot of lift.
Symmetrical aerofoils are used on 3d, precision aerobatic and racer planes. They are used on 3d planes as they produce lift inverted and upright and track very straight and are used in racers as they are very slippery in the air. This type of wing generates lift by flying at a slight angle of attack as if it was horizontal, equal amounts of low pressure would form over the top and bottom of the wing.
Under-cambered aerofoils are used in high load planes and slow flyers as they produce a very large amount of lift but a lot of drag.
I hope this article was helpful and if there is anything else you would like to know, comment.
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