this post was submitted on 26 Jun 2024
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Science Memes

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Mythbusters (mander.xyz)
submitted 3 months ago by [email protected] to c/[email protected]
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[–] FuglyDuck 16 points 3 months ago (20 children)

My favorite is planes on a treadmill.

Mostly because fans still argue about it and it’s hit the point they had to ban PoaT comments.

Which is insane as it’s not that difficult to understand. When a plane is on the ground, its gear/wheels will roll at ground speed, but the wings provide lift at airspeed.

If the ground is being moved under the plane (as on a treadmill,) the wheels will just roll faster.

Sure they’re not zero friction and some of that needs to be overcome; but this is something encountered on a daily basis all across the world- or rather, the opposite.

If the wind is coming from ahead, its airspeed is increased and the plane needs a lower ground speed to get into the air where if the wind is coming from behind, then they need more.

(This is why carriers set course into the wind when launching jets,)

At no point is ground speed and airspeed necessarily the same (i suppose you could have a calm day, but most days, the wind is blowing at least some.)

[–] Arrkk 3 points 3 months ago (2 children)

Plane on a treadmill is really interesting because if you understand how planes work its so obvious what will happen you don't need to test it. Planes move on the ground by running their engines, which push against the air, the wheels provide zero motive force. It's also why planes need tugs to move away from the gate, you can't run the engines in reverse. Planes are not cars, but people tend to assume the thing they don't understand works like the thing they do understand, and refuse to believe their hasty assumption is wrong even when told directly their hasty assumption is wrong.

[–] Hildegarde 2 points 3 months ago

You actually can run the engines in reverse. They have thrust reversers. There's very good reasons that they do not reverse the plane from the stand using the engines, but it is possible.

[–] FuglyDuck 1 points 3 months ago

my criticism of PoaT actually has to do with the scale model they used to prove it.

scale aircraft have ridiculous power-to-weight ratios

but that's just me being a stickler.

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