You might be wondering if you can understand aerodynamics without a strong maths background. It's true that maths plays a significant role in understanding aerodynamics, but you can still grasp the concepts without advanced maths. Thinking practically about the subject can help you design airplanes effectively. That being said, here's a brief introduction to the principles of RC airplane aerodynamics, focusing on wings and lift, as well as some common rules and guidelines to follow.
Lift
Rule 1: Most things will fly if you have:
- Airspeed
- Wing area
- Air
You might notice that many very simple RC planes have completely flat wings. This is because some planes really doesn't require an airfoil to fly and are instead kept simple, being made from simple flat materials like foam board. Other models do have simple airfoils, again often made from foam, but folded to form crude airfoils that again do a perfectly good job. 
The way lift works is complex, but a basic working theory can guide you. Wings create lift by generating differences in air pressure. Bernoulli's Principle explains that the curved surface of an airfoil accelerates air passing over the top of the wing, creating lower pressure and causing the wing to lift.
The bottom of the wing experiences higher pressure due to the wing's angle of attack. This difference in pressure helps generate lift. You can design a plane with a flat wing at a positive angle of attack to achieve lift. For example, the Viggen uses angled front canards to lift the nose during flight.
It's important to recognize that these explanations are simplified—lift is a complex topic. However, for basic model aviation, this understanding is sufficient.
Lift depends on:
- The airfoil shape
- The wing area
- The density of the air
- The speed of the oncoming air
- The angle of attack
Wing to Fuselage Ratio
The wing-to-fuselage ratio may seem mathematical, but it refers to the size relationship between the fuselage and the wing. This ratio affects an airplane's characteristics. Generally, if you increase one, you should increase the other to maintain stability. Stability is crucial for safe flight.
For example, a small, stubby plane may be fast but can suffer from low directional stability on the yaw axis. Increasing the distance between the wing and tail, reducing weight, and adjusting wing loading can improve stability.
Here's a plane I designed and built a while ago. It was small, stubby and (supposed to be) fast. There was a problem though: it was incredibly unstable.
A small, stubby plane may be fast but can suffer from low directional stability on the yaw axis. Increasing the distance between the wing and tail, reducing weight, and adjusting wing loading can improve stability.
compare with this similar model, an FT Scout, which has greater wing area, lower wing loading, and a longer fuselage. This results in better longitudinal and directional stability.
Taking it a step further, a longer wingspan and tail, as seen in the Avro Monoplane model, offer excellent stability.
- Wingspan should usually be greater than fuselage length
- Increase wing area if you increase weight to keep wing loading the same
- Dihedral/polyhedral is useful for keeping you flying level
- Thinner wings create less drag (think about what a traditional glider looks like)
- Longer tails have better longitudinal and directional stability
- Longer wings have better lateral stability
- Smaller stubbier planes are generally less stable than longer thinner planes.
I hope this article helped you to understand model aircraft wings a little better! They don't always have to be that complex, but you can get it a bit wrong if you choose the wrong shape. If you want to read more about simplified aerodynamics for model planes, check out these articles.