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What Makes a Plane Fly?By Sharon Fabian

What makes a plane fly? Ifyou want to become anairplane pilot, someday youwill probably need to learnthe full explanation in all ofits mathematical details.But for the rest of us whojust enjoy traveling in aplane once in a while, asimpler explanation willprobably do.

A plane's ability to get off the ground depends on four main forcesand how they interact with each other. These four forces are thrust,drag, lift, and weight.

Thrust is the force created by the plane's engine that pushes itforward. It is similar to the force of a car's engine pushing the cardown the road.

Drag is the force of the wind pushing back on the plane. Airplanesmust contend with the force of drag whether or not it is a windy daybecause, even on a still day, the effect of air movement is created asthe plane flies through the air. Drag pushes the plane in the oppositedirection from the direction of thrust.

Lift is caused by the shape of the plane's wings, and it is onlyproduced when the plane is moving. Airplane wings have a specialshape that looks something like a curved raindrop when you view across section of the wing. This shape is known as an aerofoil. With anaerofoil, lower air pressure is created on the top side of the wing. Thehigher pressure on the bottom side of the wing pushes the planeupward.

Weight is the force of gravity pulling the plane back down to earth.Weight pulls in the opposite direction from lift.

To get off the ground and stay in the air, a plane needs enough thrustand lift to overcome the forces of gravity and drag.

Airplane pilots control their plane's direction and speed by usinginstruments in the cockpit to manipulate the balance of the four forcesof thrust, lift, drag, and weight. The instruments in the cockpit mayinclude control wheels, throttle levers, rudder pedals, a radar display,a systems information display, a direction finder, and an altitudeindicator.

A control wheel looks something like the steering wheel in a car.Like a car's steering wheel, it can be turned to make the plane turn. Todo this it moves the ailerons, the small flaps on the ends of the wings.The control wheel can also be pushed forward or pulled back to movethe elevators, the moveable parts on either side of the plane's tail.Elevators are used for takeoffs and landings.

The throttle lever controls the power from the plane's engine like thegas pedal does in a car. The engine in a large airplane can burnthousands of gallons of fuel in just one trip.

The rudder pedal controls the rudder, located on the middle part ofthe plane's tail, which is also used for turning.

Once the plane is cruising in the sky, the moveable parts, includingthe ailerons and the large flaps on the wings, are kept in a neutralposition to minimize air resistance. The plane's streamlined shape alsohelps it to cut through the air with as little drag as possible.

By manipulating these four main forces - thrust, drag, lift, and weight- in just the right ways, pilots can lift a huge Boeing 747 weighinghundreds of thousands of pounds off the ground. They can make itspeed up to hundreds of miles per hour, turn, and slow down, all whilecarrying hundreds of passengers and tons of cargo. And they canbring it all back down for a smooth landing.

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What Makes a Plane Fly?

Questions

1. The force created by a plane's engine that pushes it forward iscalled ______.

A. thrustB. weightC. liftD. drag

2. The force of moving air that pushes back on a moving plane iscalled ______.

A. dragB. weightC. liftD. thrust

3. The force caused by gravity pulling down on a plane is called______.

A. weightB. liftC. thrustD. drag

4. The difference in air pressure above and below the wing of amoving plane produces ______

A. dragB. thrustC. weightD. lift

5. A control wheel is ______.

A. a plane's landing gearB. a wheel on the vehicle that pulls a plane out onto the

runwayC. a plane's wheelD. like a steering wheel on a plane

6. ______ are small flaps at the ends of a plane's wings.

A. elevatorsB. throttlesC. ruddersD. ailerons

7. Name the four forces that are important in making a plane fly.

8. Why are airplanes made in a streamlined shape?

Have you ever flown in an airplane? If so, describe your experience. Ifnot, write a paragraph predicting what it would be like to fly.

NameSome people are good at one type of job, and some people are good atanother. What are some characteristics that you think a good airplanepilot should have?