How Far Can a Paper Airplane Fly if You Add a Motor? How Do Planes Really Fly?

Okay, today I'm going to be seeing if I can get a paper airplane to actually fly by sticking a motor on the back. And then I'm going to be explaining the real reason why planes fly and what you might have been taught in school that's actually wrong. So first, let's make my paper airplane. So before I take my plane up for its flight, you may know that next week it's the 4th of July in the United States, and in order to celebrate that, I'm giving a special for my Action Lab subscription box. So if you use the link in my description, theactionlab.com slash fireworks, you'll be able to get $4 off your subscription. So go get your box if you haven't yet. The first box is going to be your very own vacuum chamber. Now let's go fly the plane. Okay, so you've all flown a paper airplane before. You can make them pretty good so that they glide for quite a while, but the problem is they're just gliding. They have no power, so they always end up falling. But what happens if I were to stick a little motor on the airplane? Do you think it would still be able to fly? Well, one problem that we have is that these plane wings are flat. Normal plane wings have a curve in them. And if you've ever attended a basic physics class, they probably taught you that due to the curve of the wing, it causes lower pressure below and higher pressure above, and that's what lifts the plane in the air. So if that's true, then a flat wing plane shouldn't fly, especially a paper airplane. But let's try it out and see if we can actually get it to fly. Okay, so if you want any chance of being able to fly a paper airplane, you need some power. But you can't have all the weight at the back. You need the weight in the front. And also, you need a way to control it because any airplane with just power and no way to change the rudder or change which way it tilts will ultimately just end up going in a spiral down to the ground because no matter what, it's going to end up imbalanced. So what's cool about this system here is it's connected through Bluetooth to my phone here. So notice how when I tilt my phone, the rudder changes. So you can see it changing as I turn my phone. So this way, this lets you control the plane while it's in the air. And then also you have your throttle here. And so this controls the speed of the motor. And it's pretty strong, it easily moves the plane. But the question is, with just a fuselage and wings made out of paper, can you actually get it to fly? Is there going to be too much weight from the motor and the electronics? Or can we get it to fly? Well, let's give it a try. So I'm going to give it a try with my red plane that I made here. Let's see if we can get it to fly. Okay, let's see if we can actually get the paper airplane to fly. Here we go. Okay, we're clear for takeoff. Oh, try again. Hey, there it goes. Oh no. Cleared for takeoff. Throttle up. Whoa. Whoa. There it goes. Holy cow. Whoa. Oh, I ran into a building. That was awesome. It totally worked. So just by sticking a little propeller on the end, even with flat wings, you can get it to work. Try to catch it. Okay, so there you go. Flat wing planes can fly. So we can see that the explanation that the reason why planes fly is because they have a curved surface, and so the air has to travel faster on the top than the bottom. It's just not true. I mean, you can see that you don't even need a curved wing in order to produce lift. But how does a plane actually fly? So how a plane actually flies is that it flies into the air, and it pushes air downward, and it pushes the same weight of air downward as the weight of the plane. So when the plane is just flying steady and not increasing in altitude, that means it's throwing the same weight of air down as the weight of the entire plane. So how much air does a plane actually throw down as it flies through the air? Well, I calculated that for a fully laden A380 Airbus flying at an attack angle of around 30 degrees, it would throw down around 50,000 kilograms per second of air. So if you've never heard the true reason why planes fly, this may be surprising to learn that planes actually throw air downwards. But it's not surprising if you've ever seen a helicopter fly. So helicopters and plane wings are actually not so different. In fact, a helicopter blade is just simply a rotating wing. And because it's rotating and staying in the same general location, you can stick your hand under it and you can feel the air blowing downwards. In fact, if you take a drone and you weigh it on a scale, you'll find that as it lifts up and flies, the scale does not change weight. So let's see what happens when I lift the drone up. So if I lift it up, it weighs 21 grams less. Set it back down, back to zero. So this drone weighs around 21 grams. Okay, we're at zero. Okay, let's see what the scale says when I take off. Three, two, one. It's staying right at zero. So now let's do a bigger drone on just this glass plate here and see if we see the same effect. Okay, so I have it zeroed right now. If I lift the drone off, it's 743 grams lighter. So it didn't quite stay at zero. It was about 20 grams off. But that's because in order for the scale to feel all the weight of the air, it has to be collecting all the air that's moving down. But because the drone is so big, some of the entrapped air is hitting the ground and not this glass plate here. And so it doesn't exactly feel all the way. But for the most part, it did feel most of the weight of the drone. And the same would be true for a plane flying also, except it's harder to do because it would be a fleeting moment as it passed over the scale. And most scales don't have that quick of resolution to be able to capture it. In fact, now that you know the real reason why planes fly, you can actually see whenever a plane flies through a cloud, if you were to see it from above, you would see the air being thrown downward behind it. So why is it that you are most likely always taught that the reason a plane flies is because there's higher pressure below the wing and lower pressure above it. And that causes the pressure to push up the wing. Well, the reason you were taught that is because that explanation ends up being true, but for the wrong reason. So when the wing of an airplane throws the air downward, it actually creates a pressure difference. It does create higher pressure on the bottom and lower pressure on the top. Well, the air on the bottom gets bunched up because it's squishing the same mass of air into a smaller volume. Meanwhile, on the top, the air on the top is getting stretched out because the air has to travel up and over the wing. And so the same mass of air is getting expanded into a larger volume. So truly the correct thing to say is it's the velocity of the air over the wing that's causing the high and low pressure and the air being squirted out the back downward that's causing the plane to fly. Hey everybody, thanks for watching another episode of the Action Lab. I hope you enjoyed it. If you did and you're not subscribed yet, hit that subscribe button and hit the bell to be notified of my latest videos out. And if you haven't got your Action Lab subscription box, hit this link here and you can head to theactionlab.com. And thanks for watching and I'll see you next time.