Who Says You Cannot Make your Own Airplane? Series #1: Understanding The Mechanism Behind Airplanes And The Misconceptions

Welcome to this page. You might be one of those guys who hate reading with utmost passion, but trust me, you are not in control to stop yourself from reading this article. In fact, you will soon start to enjoy reading more than playing video games. I do not want to brag.., okay, I do want to, but not now.

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Looking at those flying machines that convey passengers over a long distance at a speed faster than that of sound, we all love to understand the mystery behind them and may be build one from scratch. Having money to purchase one is one thing, understanding the Science behind it gives undeniable pleasure, something money could not buy.

You believe you do not have the potential to create something that outstanding, that I am aware of. But much of that was thought of the Wright brothers before they printed their names on the 'greatest of all time' list. Or are you thinking about not having any academic certificate on aero-engineering? I will request you check this my post where I explained the relationship between intelligence and creativity and why dropouts from normal academic institutions have been known to emerge as great inventors later later In life while I take a cup of coffee. Coffee time!

Understanding the mechanism behind flight

Oh I'm back! No more coffee sipping I guess. There was a time as a kid when I believed that there is something spiritual about flight. Then, I thought there should be some kind of witchy juju thing behind heavy metals conveying loads of several pounds and flying in that great speed over a long distance. May be it was because I am a black man. "Black man mentality"? You are permitted to joke with that. But an average Nigerian would understand what I mean because most of us had that thought as a kid.

But now I have come to understand it, that the witchy juju behind aeroplane and other flying devices is Science. Nothing less, nothing more. For every technological device, there exist a certain mechanism guiding it. When we look into airplane, there is a certain mechanism responsible for its operations. You might be thinking that planes could fly because of the engine, trust me you'd be wrong. Things that do not have engines fly. Kite and paper planes have no engine and yet they fly. The engine in planes is there to propel it forward, that is, moving in a horizontal position. Something else is responsible for the ability of an airplane to lift itself up and make the heavier-than-air object to look like it has no weight whatsoever and fly in the air.

How Do Planes Fly

I will not make this boring. So, I will be explaining this concept like I am really tutoring you. Just pay attention and we are all going to get this pretty well, pretty quick.

Like you could have read in several books, the principles behind flight is directed to Isaac Newton's laws of motion. Most especially, the third law of motion which simply states:

For every action, there is an equal and opposite reaction.

As simple as that looks, it is responsible for aircraft movement. As the propelling engine pushes a massive air backward, there is an equal force that moves the airplane forward. This is called thrust. There are four forces of flight. We have already mentioned thrust. Others are drag, lift and weight. Thrust and drag are opposite forces as are lift and weight. That is how Newton's third law of motion comes in play.

Out of the four forces of flight, the most complicated one where people get it wrong is lift. Okay, wings are responsible for lift which is the basic concept of flight, not the engine like I mentioned earlier, but what really lift the airplane from the ground is the turning of the airflow. You will understand this soon. Just stay with me, bud.

Misconceptions surrounding wings and lift

One of the most common but incorrect theory which is taught is something called Longer Path or Equal Transit Time which is based on Bernoulli's theory. This theory simply states that:

As the speed of a moving fluid (could be liquid or gas) increases, the pressure within the fluid decreases.

The explanation that this theory, with respect to flight gives is that the air flow; the air which is hitting the wings splits as it hits the front of the wing. The air passes over and under the wing and rejoins at the back of the wing at the same time. So for this to happen, the air flowing over the wing has a longer distance to cover over the curved surface, therefore it speeds up. As the air speeds off, it causes an area of low air pressure above the wing. The air which passes underneath the wing slows down because it has a shorter distance to travel and this causes high air pressure below the wing. The end result this theory states is that it is the pressure difference above and below the wing which causes the wings to move upward. And this upward force is what we call lift.

There are few aspects of this theory which are true but it does not tell the full story. So, I am going to give you the correct answer first and try to explain what is going on after. Pardon me as I take a sip from my coffee cup. Be gentle with me, okay?

Oh.. Alright, I am back.

The correct answer is that lift is created because a wing is turning the air flow and directing it downwards. It is not the pressure difference which creates lift. Here comes my attempt to explain this again. So the airflow hits the front of the wing and splits, the same as before. Also, Bernoulli was correct when he talked about the difference in air pressure above and below the wing. And he was also correct in saying that the air which flows over the top of the wing speeds up, that the air which passes at the top of the wing kind of sticks to the top of the wing and follows the curve of the wing upper surface. This sticking phenomenon is known as the Coander effect. As the airflow leaves the wing at the back, it leaves a slight downward angle because of that curve. That downward deflection also push after the air which passes under the wing and also turns it in the downward direction. It is this turning of the airflow which causes the lift.

You can generate more lift in two ways. The first is by increasing the speed at which the air passes around the wing. This is generally attained by simply firing faster, like increase the speed of the airplane. Another way is by increasing something called the angle of attack. This is the angle of the wing relative to the air flow. This creates more lift because the air flow is turned downward at its upper angle. Now there is a danger to increasing the angle of attack. If you increase that angle too much, there will come a point when the air flow cannot turn and follow the top of the wing. When this happens, the air flow will separate from the top of the wing. This is what happens when an aircraft stalls. There is no steady flow of air at the top of the wing. Therefore the wings stop producing lift and the airplane eventually falls out of the sky.

There are couple of devices used on an aircraft which help increase the amount of lift that the wing can generate. The main one, we have flaps. The flaps on aircraft are designed to increase the amount of lift that a wing can produce by increasing the surface area of the wing. This allows the plane to take off and land at slower speed, yet still produce enough lift for safe flight. The downside of flaps is that it causes increase in drag in mid-flight. Normally, flaps are constructed and integrated into the overall shape of the wing. Then they extend backwards at the back of the wing. This increases the overture for airflow around the wing. On most of the aircraft, you will see something called a slotted flap. when extended, this has a small gap between the wing and the flap itself where air can pass from underneath of the main wing through a small slot and over the flap. This helps the air flow of the main wing stay attached at higher angle of attack. If you really want to solidify your understanding of flaps, I will recommend you take a look at some pictures of aircraft flaps online, you will notice that the flaps are actually mini-wings . They have a similar shape and structured to the main wing.

Another device which is the most commonly found on commercial jets is the leading-edge slat. This device stays at the leading edge of the front of the wing and can extend forward to increase the surface area of the wing. Again, closing the wing to produce more lift at slower speed. This can also have a slot where air passes underneath the leading-edge slat and then flow over the main wing. As with flaps, this can be retracted to reduce the amount of drag or wind resistance allowing your plane to fly faster.

Now there is this one more device that is normally integrated with the wing, however its purpose is to reduce the amount of lift that wing produces. These are the spoilers. These are normally flat panels which extends up from the top of the wing. They are called spoilers because they spoil the air flowing over the top of the wing and reduce the amount of lift that it produces. These are mostly used on landing to ensure that the aircraft touches the ground safely and to prevent it from taking off again. They also have a secondary effect, that they create a lot of drag or wind resistance, resisting the plane of slowing down to safe speed on the ground. They may also be used in flight to help a plane descend faster, however, they would only be partially extended. The main issue with these is that they create a lot of turbulent which makes the wings of the plane to vibrate. It also leads to super rushing winds noise. These two might be uncomfortable for passengers.

Conclusion

So I hope that explains the basics of how wings produces lift. Of course there is a lot more to it. One of which is understanding how atmospheric pressure plays its part in keeping the air flow connected to the surface of the wing, understanding the lift coefficient and honestly, the Physics behind these may give you headaches. And I do not want you getting confused. Hence, a need for a break for now. But do not worry, we are getting there gradually.

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References

• Airplane
• Aircraft
• Bernoulli's Principle
• Flap

Till we meet again on my next post, well I am not changing my name. I am @teekingtv and I write STEM!

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