On December 17th, 1903 the history of aviation was changed forever when the Wright brothers made the world's first successful flight. You might think that their design was so simple. The propeller moves the aircraft forward, the wings produce the lift and the aircraft stays in the air. But when you examine it closely you will be amazed by the numerous ingenious technologies these high school dropouts developed 100 years ago. Their design was so complete that even the current modern aircraft use the same principles of flight. In this article I will explain in detail how the Wright Brothers succeeded in designing the first Airplane flight.
What do you think makes an aircraft fly? For the very first you have to overcome the pull of gravity or in other words, you have to produce a lift force (Fig.1). The Wright brothers borrowed the idea of lift generation from their own earlier experience on gliders. They knew that when air flowed over a curved surface it generated a lift force. The higher the speed, the more would be the lift force. An increase in angle of attack also increased the lift force.
To make the aircraft move forward, 2 propeller blades were used (Fig.2A). They produced thrust force again from the same Airfoil principle (Fig.2B). The thin propeller blades were a clever design choice. Until then the common belief was that an aircraft propeller should be something like that of a ship's propeller. However, the Wright Brothers proved that to work efficiently in air, a high-speed narrow blade was the ideal choice. Moreover, it was noticed that the blades were rotating in opposite directions. This was another crucial design decision. Without this, control of the aircraft would not have been possible. The blades were driven by an engine which sat on the wing.
To fly an Aircraft, you have to go with some force equations of flight (Fig.3). To come up with an Aircraft design which satisfied force equations, the Wright Brothers developed their own lift data by abandoning all the wrong lift data that was available at that time. The Wright Brothers designed wing had the top point near the leading edge. This design produced much more lift than the top at center design used at that time.
They found that with this optimized wing design alone, the aircraft would not lift up from the ground. The Wright brothers realized that the existing heavy automobile engines being used were the main villains. They had to make the engine lighter without compromising its power output. Only a powerful engine could give the aircraft a good speed. As I explained earlier, the more the speed, the more the lift. Since they didn’t find any such engine, with the help of their mechanic, the Wright brothers designed and built their own engine, a lightweight 12 HP petrol engine. Before the new engine development the Wright brothers had calculated that they needed an engine of less than 200 pounds in weight, with at least 8 horsepower to meet the equations of flight. To reduce weight, they even cast the crankcase with aluminum, a first at that time (Fig.4). They painted the crankcase black so that their competitors would not know about the construction material. You know what? Interestingly, Chain and sprocket mechanism was used to transfer power from the engine to the propeller blades.
With the design formed, at proper airplane speed, the lift force would overtake the gravitational pull and it will help in taking off. Can you guess any idea for the perfect take off? There was another clever design decision from the Wright Brothers. They knew that it was impossible to get a good airplane speed in the sandy terrain. So, they used a 60-foot-long rail track arrangement for a smooth take off (Fig.5).
The Wright brothers main innovation was the development of successful flight controls. Aircraft crashes were common issues in those days and nobody knew how to control them. To have a successfully controlled flight they have to control their plane in 3 axes - Pitch, Roll and Yaw (Fig.6).
They again relied on the principles of the airfoil to accomplish this task. To pitch the airplane the Wright Flier had an elevator arrangement at the front (Fig.7A). By moving the lever, a rope mechanism changed the angle of the elevator. If the elevators rotated up, there would be an upward lift force as per the airfoil principle. The torque produced by this lift force could push the whole aircraft up. To push the aircraft nose down, they just did the reverse. In modern airplanes the elevators are fitted at the back.
To roll the aircraft Wilbur Wright had a great idea, wing warping. It was clear that by twisting the wing along its length at one end the angle of attack would be positive and at the other end it would be negative. This would obviously create a lift differential and the airplane would roll. The pilot controls a cradle using his hip, which in turn controls two separate cables attached to it. The cable movement makes the wing warp through a clever mechanism. In modern aircraft ailerons are used to generate the lift differential.
I hope you got this article meaningful. In the next article I will let you know further details of first flight.