Unit 24 - Bernoulli Principal And Flight

Unit 24

History of Flight and Bernoulli’s Principal

The pressure exerted by a moving stream of fluid is less than its

surrounding fluid.

Therefore, as the speed of the fluid increases its pressure decreases.

Feather and Flaps

They both act to change the angle of air over the wing to

control lift

There are many forces acting on an aircraft.

The thrust must be sufficient to overcome drag to give enough lift to overcome gravity

How Do Birds Do It?

• They have hollow bones to be very light weight and their strongest muscles are their breast muscles to generate thrust.

Use of Lift by Animals• Riding “thermals” condors and hawks can soar for

hours without flapping their wings.

Use of Lift by Animals• Riding “ocean breezes” albatrosses can literally fly for

days between wing flaps just feet above the water.

Use of Lift by Animals• Flying fish use their fins as wings to fly above the

water. This reduces drag, allowing them to go faster and to avoid predators.

• Penguins use their wings to “fly” underwater at high velocity

Variations on the ThemeOther Examples of Bernoulli’s Principal

• Paper airplanes, frisbees, and boomerangs are all examples of using Bernoulli’s Principal to get lift.

Variations on the ThemeOther Examples of Bernoulli’s Principal

• Hydroplanes use lift to reduce the boat’s drag in the water, allowed them to hit speeds in excess of 150 mph

Variations on the ThemeOther Examples of Bernoulli’s Principal

• Hydroplanes use lift to reduce the boat’s drag in the water, allowed them to hit speeds in excess of 150 mph

• However, if they get too far out of the water, it can be bad news.

Hydrofoils

• Hydrofoils use “wings” underwater to create lift, to reduce drag, for high speed ferries.

Variations on the ThemeOther Examples of Bernoulli’s Principal

• The Stealth Fighter and Stealth Bomber are so unstable to fly, that pilots do not actually control them.

• They are controlled almost completely by computers

Variations on Flight Today

The Harrier can rotate its jets downward to take off or land vertically, or can flight like a normal plane

Helicopters push air downward to rise The osprey is half-helicopter half-airplane

History of Flight

1000 BC to Present

1000 BC

• Chinese Invent Kites

15th Century

• Leonardo Da Vinci, using the basic principals of flight, draws and explains various possible aircraft types.

• He never built or attempted to fly them himself.

1670’s

• Giovanni Borelli, a mathematician calculates human muscles are not strong enough for flight.

• Many attempted before and some still try afterwards.

1783

• Jean François Pilâtre de Rozier and Marquis d'Arlandes make first successful flight in hot air balloon in France.

• They used the concept of bouyancy of gases and density changes with temperature.

1797

• André Jacques Garnerin is first to successfully descend to the ground on a parachute.

1852

• Henri Giffard makes first steam powered airship that can be propelled and controlled.

1891

• Otto Lilienthal starts flying first successful gliders

1902

• Orville and Wilbur Wright begin flying gliders in preparation for their powered flight attempts.

1903• The Wright Brothers make first successful

powered flights at Kittyhawk, NC• First flight only lasted 12 seconds and went

120 feet. The longest was 893 feet.

So Much More Has Occurred Since

• It took many years before flying was common.• In doing your assignment, look up advances in

flight technology that occurred after the Wright Brothers.