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All ordinary aircraft must have forward speed to fly.

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The reason speed is necessary lies in the shape of the airplane's wings.

3
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A careful examination will show that the wing has been designed so that its upper surface is more curved than its lower surface.

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When the airplane is in motion, air rushes past the wing.

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The air passing the upper surface moves a longer distance in the same time as the air passing the lower surface,

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and therefore moves past the upper surface faster.

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This difference in air speed increases as the airplane itself moves faster,

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and creates a partial vacuum along the upper wing surface.

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The normal air pressure under the wing lifts it into this partial vacuum,

10
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which enables the airplane to fly.

11
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Which enables the airplane to fly.

12
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Which enables the airplane to fly.

13
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Which enables the airplane to fly.

14
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Which enables the airplane to fly.

15
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Which enables the airplane to fly.

16
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Which enables the airplane to fly.

17
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Which enables the airplane to fly.