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DarkAlman t1_iyf202d wrote

TLDR: no

The short answer is planes can't hover because they need air flowing over their wings to fly. If they were to have zero ground speed they would immediately crash.

To achieve what's called a Geo-synchronous orbit (where the GPS satellites are), meaning that you are hovering directly above a specific spot and stay there, you actually need to go very high into space and speed up a lot to get there and stay there. It has to do with orbital mechanics, and outside the scope of this ELI5.

The long answer is that you have to factor in is momentum.

The reason we have a hard time conceptualizing this is because humans don't feel how fast we are moving, we feel acceleration and deceleration. That's why when a car or a plane gets up to speed you feel the same as if you are standing still. You only feel it when the vehicle is speeding up or slowing down.

You sitting still is actually moving around at around 1000mph because that's the speed the Earth is turning. You are also moving at around 30km per sec because that's how fast the Earth orbits the sun, etc etc

That's why we have to speak in relative terms. You sitting still means you aren't moving relative to the Earth spinning, because everything you are comparing yourself against in terms of movement is also spinning around at 1000mph.

If you were to suddenly remove all the momentum an object has relative to the Earth, the Sun, the Galaxy, etc it would go flying off into space at several thousand meters per second... because everything else would fly away from it in an instant.

If you really want to blow your mind, The Earth is rotating from West to East, so when you move East you are moving the speed you are walking + the rotation of the Earth. But when you are moving West you are moving the speed of the Earths Rotation minus you walking speed. So a person walking due West is moving slower than a person sitting still. It's all relative to how you measure it.

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Invisabowl t1_iyf4eel wrote

>The short answer is planes can't hover because they need air flowing over their wings to fly. If they were to have zero ground speed they would immediately crash.

I’m sure you already know this and were just simplifying it to make your point but planes don’t care about ground speed. It’s not super common but planes can hover if they have enough wind. It’s called perching. As you said they require airflow.

Some aircraft have a very low stall airspeed such as STOL aircraft so it doesn’t take more than about 45-50 knots of wind to start perching. In some cases they can even fly backwards lol.

Some other interesting things that happen are the transatlantic commercial flights that end up with a supersonic ground speed because of very high tailwinds in the jet stream, yet if the plane was actually supersonic it would destroy the aircraft.

Again, not bringing this up to detract from your well explained comment. I just really like planes lol.

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JoyGodLives OP t1_iyf2ux3 wrote

Wow, that's cool. Thank you! I feel dizzy now. In a good way!

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greenvillain t1_iyf4qg2 wrote

Look at non-stop flights from Tokyo to Chicago (I've taken this flight a few times). Note the local departure and arrival times. The plane arrives in Chicago before it leaves Tokyo.

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RSwordsman t1_iyf4599 wrote

> If they were to have zero ground speed they would immediately crash.

Just some clarification here you probably mean zero airspeed. If the wind is blowing 70mph and a plane's stall speed is 60, it could very well hover above the ground while the gauge reads 70mph.

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