How do Hydrofoils work? Explained!
Hey friends, Happy Wednesday!
Tweet of the week
I just joined Twitter a while back. And am planning to share a cool fact about gadgets every day. Follow me if you’d like daily dose of gadgets in no time. Thank you!
Answer to the question I posed last week
We discussed electric bikes in the previous issue. There are bikes that power-assist using a motor once you start pedaling irrespective of the pedaling force. Here is how it works! As you pedal, the rotation sensor detects that the angular position changes as your crankset is rotating (you pedal in a circular fashion). Once this change in the angular position is detected, the motor is commanded to provide additional torque to the wheels thereby assisting you in the effort.
This week, let’s look at what are hydrofoils and how they work. But why hydrofoils? Maybe this is why - I’ve always wanted to swim since I was a kid. I tried learning through summer camps but never made it as I was afraid of water back then. And also, surfing has been on my bucket list for a very long time.
My experience using a hydrofoil will be different as I now know how it works. And so will be yours! 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 do Hydrofoils work?
Hydrofoils are surfboards with an inverted T-shaped structure (submerged in water most of the time) attached to the bottom, which helps the board fly above the waterline beyond a certain speed.
Figure: T-shaped structure submerged in water. Aerofoil shape of the foil wings.
Why fly above the waterline?
There is lesser drag force and friction as the entire surface area of the board is not in contact with the water like in a regular surfboard. In this way, you can travel at higher speeds. This technology has been used in several passenger boats for decades.
How do they fly above the waterline?
In short, it’s because of Newton’s third law: Any force has an equal and opposite reaction.
It’s similar to how an airplane generates lift. The foil wing at the bottom is aerofoil shaped similar to an aircraft wing. So when the hydrofoil is at a high speed with the surfboard pointed upwards at an angle of attack of around 3 to 4 degrees, the water is deflected downwards at an angle due to the aerofoil shape of the foil wing. This causes an equal and opposite force, pushing the foil wing upward, and effectively driving the board over the waterline.
And this is exactly how hydrofoils work!
Read my full blog post from the link attached in the later section of this newsletter issue to fully understand the nuances and different types.
Gadget of the Week
Self-driving stroller: A Canadian startup Glüxkind developed a stroller called Ella AI. It can drive independently and detect incoming obstacles using built-in sensors, sounds, and flashing lights to alert the parents. I’m in no way recommending this, just sharing the cool tech out there :P
Blog posts
The full blog post-S2E2 on how hydrofoils work is out! Read it here, happy learning!
Read S2E2: How do Hydrofoils work?
My next episode S2E3 is coming out next week. Feel free to reply to this email if you’d like to read about a specific gadget/device. And I’ll write about it :)
Thank you for reading.
Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur
