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Explaining four forces which affect aircraft performance and how they relate to each other.

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Van, I want you to meet my friend. This is Mike Logan.

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Hi. Hi, Van.

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He works here at NASA Langley Research Center in Hampton, Virginia, designing aircraft.

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Oh. So, Van, Jennifer tells me you're having a problem with your vehicle.

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Oh, I sure am. I belong to a band called The Noodles, and we bought a van to carry our equipment to our performances, but it keeps breaking down.

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Jennifer says it might be an aerodynamic problem. Can you help?

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Sure. We here at the NASA Langley Research Center have been studying aerodynamics since 1917.

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Every aircraft is designed with a specific purpose in mind, like carrying people or cargo.

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No matter what the purpose is, all aircraft designs must consider four basic forces, lift, weight, thrust, and drag.

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Lift is the force that moves an airplane up when the air flows across the wings.

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Weight is the effect of gravity pulling an airplane down.

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The force that pushes a plane forward is called thrust. It's usually created by a plane's engine or propeller.

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The last force, drag, slows an airplane down as air rubs against the plane's surfaces.

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It's a lot like the friction created when a tire skids across the road.

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We measure these forces by creating scale models of our designs and then testing them in wind tunnels.

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At NASA Langley alone, we test designs in over 20 different wind tunnels.

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So, Van, exactly what happens when you take your vehicle out?

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Well, every time we load the equipment on top of the van, it doesn't have enough power.

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And every time we load our stuff inside the van, it helps a little, but it's still a slug.

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Aerodynamically speaking, it sounds like you may be having a problem with drag, which is causing your engine to overwork.

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I think a wind tunnel test might help us to understand your problem better.

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I'll call a colleague of mine, Hector Soto, who designs measurement tools used in wind tunnels and arrange for the two of you to meet.

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In the meantime, I'll go back to my office and work on some possible solutions to your problem.

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All right. Yep.