l l Regional Gliding School Lift Weight Thrust

l l Regional Gliding School Lift Weight Thrust Drag

l The upward force that sustains the aircraft in flight. Regional Gliding School

Newton’s Three Laws of Motion ¬ ® For every action there is an equal and opposite reaction An object when in motion tends to remain in motion An external force must be applied to alter that state of uniform motion Regional Gliding School

Bernoulli’s Principle l The total energy in any system remains constant. If one element increases, another must decrease to counter balance it. Regional Gliding School

Air flowing over the wing’s upper surface accelerates as it passes through the constricted area just as it does in the venturi tube (Newton’s Laws of Motion and Bernoulli’s Principle). The result is a decrease in pressure on the upper surface of the wing that results in the phenomena known as lift. Regional Gliding School

Downwash is the flow of air downward towards the trailing edge of the wing. Also, the airflow passing under the wing is deflected downward by the bottom surface of the wing. The wing receives an upward force, therefore, downwash contributes to lift. Regional Gliding School

l l l The downward force due to gravity, directly opposed to lift. The weight of an aircraft acts through the Centre of Gravity (C of G). It is the point through which the resultant of the weights of all the various parts of the aircraft pass in every attitude it can assume. Regional Gliding School

NOTE: You must use the buttons in the Confirmation Stage Regional Gliding School

Theory of Flight Four Forces Acting on a Aircraft Let's try a few review questions on Theory of Flight: Question #1 - Regional Gliding School Which is not a force acting on a aircraft? A Lift B Weight C Torque D Drag

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Theory of Flight Four Forces Acting on a Aircraft Let's try a few review questions on Theory of Flight: Question #2 - Regional Gliding School Name the scientist who theorized “The total energy in any system remains constant. If one element increases, another must decrease to counter balance it. ” A Newton B Bernoulli C Ventri D Coriolis

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l The force exerted by the engine and its propeller which pushes air backward with the object of causing a reaction, or thrust, in the forward direction. Regional Gliding School

l The effect is the same whether the thrust is produced by a propeller moving a large mass of air backward at a relatively slow speed or by a jet moving a small mass of air backward at a high speed. Regional Gliding School

l Resistance an aircraft experience when moving forward through the air. Regional Gliding School

There are two main types of drag they are: 1 Parasite Drag – is the term given to the drag of all those parts of the aircraft which do not contribute to lift (e. g. the fuselage, wheels, antennas, etc. ) Regional Gliding School

Parasite drag may be divided into two components: ¶ Form Drag – refers to the drag created by the form or shape of a body as it resists motion through the air. Streamlining the exterior components of the aircraft helps reduce this type of drag. Regional Gliding School

Parasite drag may be divided into two components: · Skin Friction – refers to the tendency of air flowing over a body to cling to its surface; dirt, mud or ice that has accumulated on the aircraft contributes to skin friction. Regional Gliding School

There are two main types of drag they are: 2 Induced Drag – is caused by those parts of the aircraft which are active in producing lift (e. g. the wing). Therefore, it is always present and cannot be eliminated. Regional Gliding School

The greater the lift, the greater the induced drag. Airflow over the top of an airfoil tends to flow inward, airflow under the bottom of the wing tends to flow outwards, at the trailing edge, small eddies are created. These tend to move to the tips resulting in wing tip vortices which are the chief contributors to induced drag. Regional Gliding School

NOTE: You must use the buttons in the Confirmation Stage Regional Gliding School

Theory of Flight Four Forces Acting on a Aircraft Let's try a few review questions on Theory of Flight: Question #3 - Regional Gliding School What are the two main types of drag? A Induced & form B Induced & parasite C Parasite & skin friction D Parasite & form

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Theory of Flight Four Forces Acting on a Aircraft Let's try a few review questions on Theory of Flight: Question #4 - Regional Gliding School Name the drag that refers to the shape of a body. A Parasite B Induced C Form D Skin friction

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Theory of Flight Four Forces Acting on a Aircraft Congratulations!! You have now completed the Four Forces Acting on a Aircraft lesson of the Theory of Flight Module. Of course, this lesson is always available to you for future reference if required. You are now ready to move along to the next Theory of Flight lesson you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam. Good Luck! Regional Gliding School