How aircraft generates lift & Bladeless fan!
Hey friends, Happy Wednesday!
Answer to the question I posed last week
Last week, I asked about the behavior of the water stream when you place the curved surface of the spoon vertically underneath. What happens is that water bends due to the Coanda effect. As the water stream hits the spoon, it bends the water to flow along the shape of the spoon before gravity takes over.
We’ll discuss how an aircraft generates lift to fully understand bladeless fans. I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for your food, etc. Let’s jump in!
How does an aircraft generate Lift?
The answer is not “entirely” due to Bernoulli’s principle. Let’s walk through this and settle it once and for all.
Assume that an aircraft is gaining speed on a runway - Here is how it generates lift!
REACTION LIFT (Newton’s third law)
The upper portion of an aircraft wing is a Coanda surface (discussed last week). The lower surface is pretty much flat. Let’s assume we have an Airstream that hits the wing horizontally against it. The air stream that travels below the wing exits in a downward direction due to the angle of the airfoil (or) it’s flat and pretty much unchanged. But, the direction of the airstream that travels above the wing exits angled downwardly due to the Coanda surface bending it. Thus, on a whole, it effectively deflects the airstream from a horizontal direction to an inclined downwards one. From Newton’s third law - Every action has an equal and opposite reaction. As the force by the wing on the airstream is acting downwards as it pushed the air downside, there should be a force by the air on the wing which pushes the wing upwards. This force is the Reaction lift!
Fun Fact: 80% of the lift generated by a Boeing 747 is due to this kind!!
2. BERNOULLI LIFT
This is a more popular explanation for how an aircraft generates lift - The air travels faster above the wing compared to the air below the wing. Thus, due to Bernoulli’s principle, the faster-moving air above the wing produces less pressure than the slower-moving air below the wing. This difference in pressure, causes the wing to lift upwards.
A “combination” of both these types contributes to the lift of an aircraft!
Source - For the love of physics by Walter Lewin
Question of the week
Why does air travel faster above the wing compared to the air below the wing of an aircraft? Share your thoughts by replying to this email, and we can have a discussion. I’ll answer this in next week’s issue.
Blog post
My blog post S1E3 on the bladeless fan is out! It’s not going to take more than 3 minutes to read after following this and my previous newsletter issue. Read it HERE, happy learning!
Back to algorithms - My next episode S1E4: Heart rate monitoring algorithm on a fitness watch is coming out next Wednesday. Also, let me know if you’d like to read about a specific gadget/device.
Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur
