REVIEW – AIR AND AERODYNAMICS & FLIGHT



REVIEW – AIR AND AERODYNAMICS & FLIGHT

(concepts from Program of Studies)

1. Properties of air: (know examples of where we see these properties demonstrated in everyday life)

a. Air has mass and takes up space

i. inverted jar submerged in water – paper towel in jar doesn’t get wet because of air in that space

ii. full balloon weighs more than empty balloon

b. Air exerts pressure

i. Holding finger over end of straw full of water and water will stay in straw as air pressure in higher pushing up on the water is greater than the pull of gravity)

ii. Index card covering glass of water doesn’t fall off when glass inverted

c. Air is a fluid and can be compressed (this is why we can fill balls and tires with it)

2. Bernoulli’s Principle

a. Faster moving air (fluid) exerts less pressure than slower moving air(fluid)

b. Wings are streamlined forms known as airfoils that make use of a phenomenon called Bernoulli’s principle to maximize upward lift. According to Bernoulli’s principle, as the velocity of a fluid increases, the pressure it exerts decreases. (Remember, air in motion behaves like a fluid.) Because air moves over the curved upper surface of a wing faster than it moves along the underside of a wing, there is less air pressure above the wing, more below and lift is created (see Fig. 2).The same principle is behind the design of golf balls: the tiny dimples act as individual airfoils that accelerate air flow over the ball’s surface and create lift.You can also apply Bernoulli’s principle to generate a downward force by making the airfoil’s lower surface curved (longer) and upper surface flat (shorter). Race cars use this reverse airfoil design to gain increased traction on the road (see Fig. 3).

c. [pic]

i. This applies over the curved surface of a bird’s wing, the curve of a sail on a boat, the camber on a plane’s wing, spoons in running water demo

ii. Rotary- wing aircraft (such as helicopters) utilize airfoils as propeller blades.This allows them to achieve both thrust and lift as the blades turn. Some airplanes can take off vertically, then continue horizontally. Some helicopters can fly horizontally at very high speeds due to specific adaptations.

iii. Bernoulli’s principle also applies for some useful tools such as a paint sprayer .



3. Four forces of flight: Lift/Gravity(Weight) Thrust/Drag

a. In order for devices or living things to fly, they must have sufficient lift to overcome the downward force of gravity

[pic]

b.

c.

d. [pic]

e.

4. Adaptations that enable birds and insects to fly (eg. Birds – hollow wings)

a. The wings of birds, bats and insects serve a similar dual function.They act as both the means of propulsion and as airfoils. Insect wings are often flat when at rest but take on the curved shape of an airfoil once they begin to beat against the air. Likewise, a bird’s entire wing changes shape in the course of a wing stroke in order to maximize the lift and forward motion attained from the down stroke and minimize the drag encountered in the upstroke.

b. In addition to wings, insects and birds have evolved other features that help make them airworthy. Birds have compact, highly streamlined bodies that are perfect for flight.Their collar bones have fused into the familiar “wishbone” in order to provide a rigid skeletal frame that prevents the bird’s body from being squashed when its powerful wing muscles contract. Their light, hollow bones provide maximum strength with minimum weight, and their eyesight is extremely sharp, rapidly delivering an enormous amount of information about the bird’s three-dimensional environment to the brain for processing. Insects have evolved one or two sets of wings that are attached to their thorax (middle body section). Some insects, like a housefly, can take off backwards and sideways, because they can twist their wings.

c.

5. Means of propulsion for aircraft and flying animals (eg. Birds – flapping wings, plane – propellers or engines etc.)

a.

b.

c. Comparing birds to planes:

|Bird |Plane |

|Head |Cockpit |

|Body |Fuselage |

|Wings |Engines (in terms of what part generates thrust) |

| |Wings |

|Tail |Vertical and Horizontal Stabilizer |

|Legs and feet |Landing gear (wheels) |

6. Streamlining reduces drag (think of the shape of the nose of a plane or a rocket)

a. In science, streamlining is the contouring or the shaping of a body so as to reduce the amount of resistance or drag as the body moves through air or water. The body is given a curved shape so as to ease the flow of air or water against it. Streamlining applies to aircraft and also boats and ships and as technology advanced, it was also applied in cars.

7. Air is composed of different gases (78% Nitrogen, 20% Oxygen, 1% Argon, plus traces of other gases – including carbon dioxide, water vapour, hydrogen etc.)Examples:

- Flames need oxygen to burn

- Rusting occurs when certain metals are exposed to water and oxygen

- Animals need oxygen to live

- Plants use carbon dioxide and give off oxygen

- Carbon dioxide will put out a flame

8. Parachutes operate on the principle of drag and work as a result of their mass to surface area ratio. They trap air (create resistance or drag) to reduce the effects of gravity (weight)

a. A hole in the top of the parachute canopy prevents it from wobbling.

b. The larger the surface area of the canopy in relation to the weight of the load, the slower the parachute should descend.

9. Hot air balloons – hot air rises because it is less dense than cold air. (to fall, pilot opens a flap at the top to let hot air escape)

[pic]

Hot air balloons – hot air rises because it is less dense than cold air. (to fall, pilot opens a flap at the top to let hot air escape.

10. Parts of a plane and their functions: (see diagram)

a. Fuselage

b. Wing

c. Vertical and horizontal stabilizer

d. Elevators

e. Rudder

f. Ailerons

11. Understand which surfaces control pitch, roll and yaw and how they do so.

**See link below for animation of these control surfaces working

[pic]



12. Spacecraft (rockets) must carry their own oxygen in order to allow the fuel to burn). Aircraft with jet engines have turbines to keep air coming into the engine where the compressed air mixes with the fuel and is burned.

a. Jet propulsion can provide much greater thrust than propellers.A jet engine takes in ambient (surrounding) air, compresses it, then burns it with fuel in a combustion chamber to produce extremely hot gas that is discharged out of the rear of the jet engine. This provides enormous forward thrust, even at high speeds, where the efficiency of propellers drops off.

Additional Resources:



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[pic]

Ailerons control roll

Elevators (control pitch) (both up or both down)

Rudder (controls yaw) (right or left)

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