AERODYNAMICS
The wind design can increase the airplane’s lift force; the most common design option for the wings includes the tilting of the wings to increase the angle of attack and increase the ratio of wingspan to the wing area. The amount of lift always depends on air density. To generate more lift force, the needs to be more angle of attack of the wings. This is attained through the design of the wings by pushing the tail of the aircraft downwards. The aerodynamic performance will be increased since speeding up implies that the wings will force more air downwards and increases the lift force. This is simply known as the tilting of the wings. Tilting the wings upwards will increase the angle of attack; thus, it will increase the angle of attack until a given point.
In case the tilting is too much, then the airflow will pull away from the upper surface, which will result in a smooth flow turning into a turbulent flow. If this occurs, then there will be a lot of viscous drag to the aircraft, which will highly reduce its speed and also reduces the force of lift. At this point, the wings will abruptly lose the lift, which is a condition known as a stall. The wings can be tilted upwards to increase the lift force as it will decrease the airspeed around the wings. With the increased angle of attack, the aerodynamics performance will be affected in two ways: the lift component of the aerodynamic force and the component of the drag of the aerodynamic force will increase. For task 2, where the angle of attack is given as 100, it is advisable to increase this angle of attack to realize a higher lift force of the airplane, which will increase the aerodynamics performance. This can be proved mathematically as below,
The lift coefficient ( CL) = ………………………………………………………. 1
Where a is the angle of attack
And lift L can be given by equation 2 below;
L= …………………………………………………………………. 2
Where d is the air density, s is the area of the wings in square feet, v is the aircraft’s velocity in feet per second, L is the lift, and CL is the lift coefficient.
Equation 1 can be substituted in equation 2 to obtain equation 3
L= ……………………………………………………………3
Thus holding other parameters constant L α
From equation 3 above, it can be seen that increasing the angle of attack will increase the force of lift.
For the same angle of attack ( holding the angle of attack constant), an increased ratio of wingspan to the wing area will increase the lift force but with limits just like for the angle of attack. This ratio is the ratio of span to the chord, and it is illustrated in figure 1 below. The lift fore depends on the size, shape, flow conditions, and inclination. The ratio of wingspan to the wing area ( Span ratio) increases the force of lift since a slender and long wing reduces the pressure above the plane, thus resulting in higher pressure at the bottom. The pressure difference from top to bottom of the wing causes spillage around the wingtips. This will automatically result in increased force of lift for any analyzed in question 2.
Figure 1: Showing a span ratio in an aircraft ( https://aerotoolbox.com/intro-wing-design/)
Mathematically this can be proved as below;
The coefficient of lift (CL) = …………………………………………………….4
CL is the lift coefficient, Cio is the stream lift coefficient, and AR is the span ratio.
From equation 4, CL is directly proportional to AR, which means when AR is increased, the CL will also increase. And as seen in equation 2 above, CL is directly proportional to L; therefore, the AR will also be directly prerational to L.
References
Field, E. D. M., 2014. Structural Analysis and Design of Airplanes. 2nd ed. Hull: Watchmaker Publishing.
Palmer, W., 2011. Transonic Investigation at Lifting Conditions of Streamline Contouring in the Sweptback-wing-fuselage Juncture in Combination with the Transonic Area Rule. 2nd ed. Chicago: National Advisory Committee for Aeronautics.
Shyy, W., 2013. An Introduction to Flapping Wing Aerodynamics. 2nd ed. Liverpool: Cambridge University Press.
Torenbeek, E., 2013. Advanced Aircraft Design: Conceptual Design, Analysis, and Optimization of Subsonic Civil Airplanes. 2nd ed. Liverpool: John Wiley & Sons.
Torenbeek, E., 2013. Synthesis of Subsonic Airplane Design: An introduction to the preliminary design of subsonic general aviation and transport aircraft, with emphasis on layout, aerodynamic design, propulsion, and performance. 3rd ed. Chicago: Springer Science & Business Media.
Wood, R., 2013. The Natural Flow Wing-design Concept. 2nd ed. Liverpool: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program.