Why can headwind assist planes when taking off and landing? Why does tailwind not help with takeoff?
For takeoff, you need a certain velocity of air under your wings. Lets say for simple math that it’s 50km/h. If you have no wind at all, you have to roll your plane on the ground up to 50km/h before the wings will give you lift.
But the important part is it’s not the ground speed that matters – it’s the speed of the air the plane is going through.
So if you have a 20km/h headwind, and get your ground speed up to 30km/h, now the air is moving across your wings at 50km/h and you can fly. If you have a 20km/h tailwind, you’re actually starting at a negative -20km/h air speed. You have to get the plane up to 70km/h on the ground to get your 50km/h of air over the wings.
Airplanes generate lift by the passage of air from the front of a plane across the shaped wings to the back of a plane, which causes lower air pressure above the wing, generating lift.
A headwind pushes air across them faster, decreasing pressure above the wing further and making lift easier. A tailwind does the opposite, which means you need more speed to generate that lift. That’s a problem when taking off, because you need to go faster to generate the lift to get off the ground, but it’s also a problem when landing because it means your approach needs to be faster to land properly. Since runways are typically of finite length and you need to take off/stop before you reach the end of said finite length, headwinds are better.
Crosswinds are the really shitty ones though.
Because the important number when you’re taking off is “air speed” not “ground speed”. Aka, how fast are you going relative to the air. This is because lift comes from the air moving over the wings, and it doesn’t matter if it’s the air moving over a wing or the wing slicing through air. They both mean the same thing for lift.
So if you have a headwind, the wind is adding to the air speed, making it easier to take off. And conversely, a tailwind *subtracts* from the air speed, meaning that the plane has to reach a significantly faster actual speed before it reaches the required air speed.
Others have already explained why. Here’s a video of a plane landing in a strong headwind that will tie it all together for you. https://www.youtube.com/shorts/7vP13XPMNfc
Okay so the shape of the wing is what makes the plane go up. The top is curved out. This makes the top longer than the bottom. Because of this the air pushes on the bottom, and gets spread out on the top making less pressure on top. The head wind increases the force pushing on the bottom and so makes take off easier. Tailwind does the reverse