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Current time:0:00Total duration:3:33

Video transcript

(Abhi) Hundreds of years ago, James Watt decided that my friend, Helga, could lift five-hundred fifty pounds a foot in the air in one second. And that's the definition of a horsepower. (Luke) This lawn mower has six horsepower. (Abhi) This car has a hundred and thirty horsepower. (Luke) This Cessna has two-hundred and thirty horsepower. (Abhi) And this jet has eighty-five thousand horsepower. All of these engines produce power by forcing a mixture of fuel and air into a tight space and then burning it. (Luke) But they do it in different ways. (Abhi) A car uses a piston engine. This is a piston engine that's been cut into a halve so you can look into it. A mixture of fuel and air enters through these valves into this metal cylinder. It's compressed when the piston pushes up onto it. And then, this mixture is burned through a spark plug, causing the mixture to expand, and the piston comes back down. And this happens over and over again. There are multiple pistons in car, and they're connected through a series of linkages to the wheels, causing them to turn. (Luke): This is a plane, so you might think its closest cousin is a jumbo jet. (Abhi) But actually, it's more closely related to a car because it uses a piston engine. (Abhi) Here is the piston engine, just like in the car. But instead of it being attached to the wheels, it's attached to the propeller. (Luke) A small plane, like this Cessna, actually weighs about the same as most cars, so it needs about the same amount of horsepower to roll down the runway and get off the ground. (Abhi) But a Boeing 777 - with all its passengers, cargo, and fuel - is about two-hundred times the weight of a Cessna. So it needs a LOT more horsepower. (Luke) You could provide that horsepower by using a ton of pistons, but you'd need sixty-seven of the most powerful piston engines ever built to fly a 777 at cruising speed. And that won't work. (Abhi) What you really need is one engine that can produce enough horsepower to fly the plane. A 'turbine engine' is capable of much more horsepower than a piston engine because of the way it uses giant fans to compress the air. (Luke) At the front of the turbine engine is an intake fan which spins and brings a huge amount of air into the front of the engine. As we move backwards through the engine, a series of compressor blades makes that air more and more compressed until we get here. And here, fuel is introduced and burned. And that hot, high-pressure flow gets sent out the back of the engine and that makes the thrust of the engine. But at the same time, that flow passes through a series of four or five turbine blades, and those blades are connected directly to a shaft in the middle of the engine. That shaft runs all the way back to the front and spins the intake fan. And that's what keeps the engine running. We've gone from one horsepower to two-hundred ninety thousand horsepower. So Helga, I guess we don't need you anymore. Run free, join your herd! (Carol) That's Brandon, he's domesticated.