Transcript[]
Text reads: The Mysteries of Life with Tim and Moby
An animation shows Moby standing on the roof of a house. He is holding onto a rod that has a pair of wings attached to it. On the ground below, Tim is watching him.
TIM: Don't do it!
Moby jumps off the roof and disappears from view. A loud thud is heard. Tim reads from a typed letter.
TIM: Dear Tim & Moby, how does flight work? From T.J.
An animation shows Tim and Moby standing on the lawn in front of their house. Moby is wearing his broken wings and looking very sad.
MOBY: Beep.
TIM: Well, birds and bugs can fly by flapping their wings cause their bodies are so light.
Moby flaps his arms but does not lift off the ground. A bird flies across the screen, flapping its wings.
TIM: Airplanes are too heavy for that, so they need to rely on a different technique.
An animation shows a pilot in a small make-shift aircraft with large, flapping wings. The aircraft does not get very far and falls down into the lake below. The sound of a splash is heard.
TIM: There are four forces that affect a plane: weight, drag, lift, and thrust.
A diagram shows an airplane, facing left. As Tim mentions the four forces, arrows appear on the diagram. The arrow labeled "weight" appears below the airplane and points down toward the earth. The arrow labeled "drag" appears behind the airplane and points to the right. The arrow labeled lift appears above the airplane and points up toward the sky. The arrow labeled "thrust" appears in front of the airplane and points to the left.
TIM: Weight is the downward force that Earth's gravity exerts on all objects.
An animation of a person standing on a bathroom scale shows a close-up of the person's feet and the readout. The dial spins and finally stops on the number 90.
TIM: Drag is the resistance of air against anything that moves through it. If you've ever walked against a really strong wind, you've felt the force of drag.
An animation shows Tim walking in a heavy wind. There is a barn in the background. Leaves are seen being blown by the wind in the direction opposite to the direction Tim is walking in.
TIM: Weight and drag both work against a plane’s ability to fly.
The diagram of the plane (with the four arrows) is shown again. The arrows labeled "weight" and "drag" are highlighted. The arrow labeled "weight" moves down and the arrow labeled "drag" moves to the right.
TIM: That’s where lift and thrust come in. Lift is just what it sounds like — an upward pull.
The arrow labeled "lift" is now highlighted. It is moving up toward the sky.
TIM: And thrust is any force that moves a plane forward.
The arrow labeled "thrust" is now highlighted. It is moving left, away from the front of the plane.
TIM: In order for a plane to be able to fly, lift has to be greater than or equal to weight.
The lift arrow becomes thicker than the weight arrow. The plane begins to rise.
TIM: To move forward, thrust has to be greater than or equal to drag.
The thrust arrow becomes thicker than the drag arrow. The plane starts moving to the left.
TIM: Thrust can be generated by propellers, jets, or rockets.
Three inserts appear on the screen. One shows a plane with propellers. Another shows a plane with a blue jet stream behind it. The third shows a rocket moving upward, with a yellow stream of gas under it.
MOBY: Beep?
TIM: Well, lift is a little bit trickier. Most planes' wings are built in a shape called an airfoil, similar to a bird’s wing.
An animation shows a close-up of the wing of a plane. A cross section shows an oval shape. A caption reads: airfoil. The front (facing left) of the shape is curved, and the rear is pointed. White circles representing air molecules can be seen moving from left to right. Some are above the airfoil and some are below.
TIM: As it moves forward, the airfoil's curved shape makes air passing above the wing move faster than the air passing below.
The air molecules can be seen moving faster above the airfoil.
TIM: Fast-moving air has lower pressure than slow-moving air, so the higher pressure below the wing overcomes the plane’s weight, pushing it up into the low-pressure zone.
In the animation, an arrow pointing up appears and moves upward. The airfoil moves up as well.
TIM: The airfoil shape also lessens the wing's drag by causing air molecules to "stick" close to its surface.
The air molecules move closer to the surface of the wing.
TIM: This streamlining means less drag and more lift. For thrust, most small planes use propellers, but bigger planes are usually powered by jet engines. Jets suck air in the front of the engine and spit it out the back.
An animation shows a close-up of a jet engine at the end of a wing. Arrows show air entering from the front and leaving from the rear.
TIM: This powerful action and reaction forces the plane forward.
The animation shows the plane moving forward.
TIM: Barbara here is a flight instructor, and she’s gonna show us how to fly a plane!
An animation now shows the cockpit of a small plane. In the front are Tim and Barbara. Moby is sitting in the centre rear seat.
BARBARA: Howdy!
TIM: The pilot's job is to control all the parts of the plane that make it climb, dive, and turn. This control column is connected to hinged flaps called ailerons and elevators.
The animation shows Barbara pushing various controls. A diagram shows a hand holding a control column. A schematic of a plane with a propeller is also shown. Red flaps are shown on the outer rear portion of the main wings and are labeled "ailerons". Red flaps on the tail wings appear and are labeled "elevators".
TIM: And the pedals activate the rudder, another movable flap on the plane’s fin.
The animation shows two feet pressing on pedals. A diagram of the side view of an airplane shows a red flap on the side of the rear wing. It is labeled "rudder". Tim starts pressing buttons in the cockpit, and Barbara frowns then smacks Tim’s hands away from the controls.
TIM: Ow! Sorry.
The animation shows a side view of the plane moving on the runway. The plane begins to take off.
TIM: Let's climb!
The animation shows a hand pulling back on a control column.
TIM: The air pushes against the raised elevators, turning the nose of the plane upwards.
In the animation, the elevators at the rear of the plane tilt upward and arrows show wind pushing into them. The plane’s nose tilts up, and the plane starts to rise.
BARBARA: Left or right, Moby?
MOBY: Beep!
Moby points to his left.
TIM: That's left, Moby.
The animation shows a hand moving the control column to the left.
TIM: The rudder and ailerons control turns.
The animation shows a rear view of the plane. On the main wings, the left flap moves up and the right flap moves down. On the side of the rear wing, the rudder moves to the left. The plane tilts to the left and disappears off the left side of the screen.
MOBY: Beep?
TIM: How about it Barbara?
BARBARA: One dive, comin' right up.
The animation shows the elevator flaps tilt down and then the cockpit again.
TIM: When the elevators on the tail lower, the nose drops and… AHHHHHHH!!!!
The animation shows the plane diving down into the bottom of the screen. Tim and Moby are back on the ground and Moby waves at the plane, flying overhead. Moby turns to face Tim. He looks very sick, like he's about to throw up.
MOBY: Beep?
TIM: Uh, I think-I think that's enough flying...for me...for a while.
Tim groans, then suddenly throws up.
TIM: (Barf!)
MOBY: Beep!!
Moby offers Tim an air sickness bag.