Assignment One: Aerofoils - How Wings Work
Task 1
Describe three common misconceptions about lift?
There are many misconceptions about lift like, the design curve of the air-foil has to be more curved then the lower surface, the only reason wings create lift is because the bottom is flat and the top is curved and lifting force is due partly Newton and Bernoulli Effect. All of these misconceptions are incorrect, let me explain.
1.
The design curve of the air-foil has to be more curved then the lower surface: Wrong
An air-foil can have all sorts of designs, like there are flat wings made out of paper, plywood and fabric. On acrobatic aircraft the wings are symmetrical that means both sides of the wings are the same. A kite has lots of different…show more content… The only reason wings create lift is because the bottom is flat and the top is curved: Wrong
There are lots of wings that create lift, where the top is flat and the bottom is curved or the wing is symmetrical or supercritical. No matter what the design the wing is the air flow of the top does move faster but it doesn’t reach the end of the wing at the same time as the air along the bottom. If an airplane would fly upside down the forces of the lift would still be there.
3.
Lifting force is due partly Newton and Bernoulli Effect: Wrong
Lifting force is always 100% Newton and 100% of lift is through the Bernoulli equation. No matter the wings design no matter its degree of tilt or the shape. The reason for Bernoulli equation to be a 100% effect for lifting force is all about the pressure in the air and the velocity change around the object. Now for Newton (third law of motion) it’s all about the aerodynamic force on an object.
Task 2
Explain how an aerofoil really generates…show more content… When traveling through air in the boundary layer around the wing or the object viscous drag is being created. To avoid viscous drag the best thing to do is to shorten the object by its cross-section and the length. The other way of reducing the friction on the skin is to get a laminar flow by shaping the object like a wing (aerofoil).
The Interference drag
Lift-induced drag
Wave drag
Task 6
What is a boundary layer?
Task 7
What are wingtip vortices and what causes them?
Trailing, lift-induced or wingtip vortices are caused as a wing of a plane generates lift, air from each wing tip is being rotated behind the wing which have circular patterns and that’s what they call a wingtip vortex. When a plane is moving and generating lift, the top of the wing has a lower air pressure than the bottom of the wing. The air underneath the wing flow out and round the tip of the top of the wing which creates a spiral which is called a wingtip vortex.
Task 8
What are the common formulas for Lift & Drag? (What do they depend on? Give example use of the equations.)
Task 9
Task 10
From the plots in section question 9;
a) What angle gives zero lift?
b) What angle gives maximum lift?
c) If it flies upside down, what is the maximum lift, and at what