This presentation explains all the forces that acts on a flight when flys

1. What Does It Take To Fly?
Explaining The Four Forces Of Flight
Rebin fakhir

2. A force may be thought of as a push or pull in a specific
direction. A force is a vector quantity so a force has both a
magnitude and a direction. When describingforces, we have to
specify both the magnitude and the direction.
FORCE

3. In aircraft in straight and level flight is acted upon by four forces:
Lift Thrust
Gravity Drag
01 02 03 04

4. How do the forces work together?
The opposing forces balance each other: lift equals gravity
and thrust equals drag, any inequality between thrust and
drag while maintaining straight and level flight, will result in
acceleration or deceleration until the two forces again
became balanced

5. 1.What is lift?
To overcomethe weight force, airplanes generatean opposing force called lift. Lift is generated
by the motion of the airplane through the air and is an aerodynamic force."Aero" stands for the
air, and "dynamic" denotes motion. Lift is directedperpendicular to the flight direction. The
magnitude of the lift depends on several factors including the shape, size, and velocity of the
aircraft. As with weight, each part of the aircraftcontributes to the aircraftlift force.

6. 1.What is lift?
Most of the lift is generatedby the wings. Aircraft lift acts through a single point called the
center of pressure. The center of pressure is defined just like the center of gravity, but using the
pressure distribution around the body instead of the weight distribution.
The distribution of lift around the aircraftis important for solving the control problem.
Aerodynamic surfaces are used to control the aircraftin roll, pitch, and yaw.

7. How does lift work?
• The air moving over the wing must travel from A to B in the same
amount of time, therefore, the air is moving faster along the top
of the wing
• This creates a difference in air pressure above and below – a
phenomenon called the Bernoulli effect, the pressure pushing
up is greater than the downward pressure, and lift is created

8. Factors Affecting Lift
Object Motion Air
• Object: At the top of the figure, aircraft wing geometry has a large
effect on the amount of lift generated. The airfoil shape and wing
size will both affect the amount of lift. The ratio of the wing span to
the wing area also affects the amount of lift generated by a wing.

9. Factors Affecting Lift
Object Motion Air
Motion: To generate lift, we have to move the object through
the air. The lift then depends on the velocity of the air and how
the object is inclined to the flow.

10. Factors Affecting Lift
Object Motion Air
Air: Lift depends on the mass of the flow. The lift also depends in a
complex way on two other properties of the air: its viscosity and its
compressibility

11. What is gravity?
Weight is a force that is always directed toward the center of the earth. The magnitude of
the weight depends on the mass of all the airplane parts, plus the amount of fuel, plus any
payload on board (people, baggage, freight, etc.). The weight is distributed throughout the
airplane. But we can often think of it as collected and acting through a single point called
the center of gravity. In flight, the airplane rotates about the center of gravity.

12. What is gravity?
Flying encompasses two major problems; overcoming the weight of an object by some
opposing force,and controlling the objectin flight. Both of these problems are relatedto the
object's weight and the location of the center of gravity. During a flight, an airplane's weight
constantly changes as the aircraftconsumes fuel. The distribution of the weight and the
center of gravity also changes. So the pilot must constantly adjust the controls to keep the
airplane balanced, or trimmed.

13. How does gravity help the flight of a paper airplane?
Gravity helps createlift for paper airplanes. Gravity is the force that pulls objects toward the
Earth. Lift is the forcethat pushes an aircraft into the air. When paper airplanes are thrown
up, gravity pulls them down. This movement causes a differenceof air pressure on the
airplane wings, which then causes lift. Bernoulli's Principle explains how a differenceof air
pressure is caused due to air moving faster on top of the wings than on bottom. It is because
of gravity that paper airplanes are able to produce this differenceand glide!

14. factors that affect gravity
mass distance
Objects with more mass have more gravity. ... So, the closer objects are to
each other, the stronger their gravitational pull is. Earth's gravity comes
from all its mass. All its mass makes a combined gravitational pull on all
the mass in your body.

15. How does gravity help the flight of a paper airplane?
Gravity helps createlift for paper airplanes. Gravity is the force that pulls objects toward the
Earth. Lift is the forcethat pushes an aircraft into the air. When paper airplanes are thrown
up, gravity pulls them down. This movement causes a differenceof air pressure on the
airplane wings, which then causes lift. Bernoulli's Principle explains how a differenceof air
pressure is caused due to air moving faster on top of the wings than on bottom. It is because
of gravity that paper airplanes are able to produce this differenceand glide!

16. What does the small wing on the tail of an airplane do?
The horizontal stabilizer, or rear wing, helps keep the airplane in level flight. This
means it prevents the nose from tilting up or down, keeping the center of lift over the
center of gravity. Without the stabilizer, the airplane's center of gravity is forward of
the wing's center of lift. In other words, the nose tilts down because it's heavier than
the tail, which makes the airplane unbalanced. The horizontal stabilizer also holds
one of the plane's control surfaces known as the elevator.The elevator helps the
airplane pitch up or down. Not all airplanes have a wing in the back, and some don't
have one at all.

17. What Is Thrust?
To overcomedrag, airplanes use a propulsion system to generatea forcecalled thrust. The direction of the
thrust force depends on how the engines are attachedto the aircraft. In the figure shown above, two turbine
engines are locatedunder the wings, parallel to the body, with thrust acting along the body centerline. On
some aircraft, such as the Harrier, the thrust direction can be varied to help the airplane take off in a very
short distance. The magnitude of the thrust depends on many factors associatedwith the propulsion
system including the type of engine, the number of engines, and the throttle setting.

18. What Is Thrust?
For jet engines, it is often confusing to rememberthat aircraftthrust is a reaction to the hot gas
rushing out of the nozzle. The hot gas goes out the back, but the thrust pushes towards the front.
Action <--> reaction is explained by Newton's Third Law of Motion.
The motion of the airplane through the air depends on the relative strength and direction of the
forces shown above. If the forces are balanced,the aircraftcruises at constant velocity. If the
forces are unbalanced, the aircraftaccelerates in the direction of the largest force.

19. How is thrust used during flight?
Thrust is used to overcome the drag of an airplane, and to overcome the
weight of a rocket.

20. FACTORS AFFECTING THRUST
Air Density Altitude Airspeed Ram Effect Engine RPM
Density is the mass of a substance per unit of its volume. According to the thrust equation, if
the mass of airflow increases, thrust will increase. If the density of air increases, mass will
increase, and therefore thrust will increase. As an aircraftoperates at various altitudes and
climates, the ambient air temperatureand pressure will vary. These factors will affect the
density of the air entering the engine, and as a result, will affect thrust.

21. FACTORS AFFECTING THRUST
Air Density Altitude Airspeed Ram Effect Engine RPM
As an aircraftclimbs, pressure and temperaturewill normally drop. From the previous discussion,
thrust will decreasewith a pressure decrease,and thrust will increase with a temperature decrease.
With an increase in altitude, however, the rate of thrust decreases because a pressure drop is greater
than the thrust increase resulting from a temperaturedrop. This means an engine will produce less
thrust as it increases in altitude.

22. FACTORS AFFECTING THRUST
Air Density Altitude Airspeed Ram Effect Engine RPM
In the thrust equation, the differencebetween the inlet and exhaust velocities plays a major
role in determining thrust available. As the inlet velocity (v initial) approaches the magnitude
of the exhaust velocity (v final), thrust is reduced.Therefore, if the mass of air and fuel is held
constant, thrust will decrease as airspeed increases. This decrease in thrust due to an
increase in airspeed is theoretical

23. FACTORS AFFECTING THRUST
Air Density Altitude Airspeed Ram Effect Engine RPM
If we only consider the change in airflow velocity in the thrust equation, then thrust decreases with an
increase in airspeed. Remember, that the thrust equation consists of two variables: mass (m) and
acceleration (v final – v initial). As mentioned, the differencebetween inlet and exhaust velocities
decreases as the aircraft increases speed. However, more and more air is being rammed into the inlet,
increasing the mass and pressure of inlet air. This offsets the decreasein acceleration and results in a
neutral effector slight increase in thrust at subsonic airspeeds.

24. FACTORS AFFECTING THRUST
Air Density Altitude Airspeed Ram Effect Engine RPM
This is due to the compressibility of airflow as velocity increases toward supersonic. As airflow
becomes compressible, mass due to ram effectincreases at an increasing rate. Ram effect is
especially important to high performanceaircraft due to the exceptionallyhigh mass airflow that
occur at supersonic speeds. This results in a significant increase in overall thrust due to ram effect
at supersonic speeds. For many high-performance fighter aircraft,ram effectallows excellent high
altitude performance,although air density is low.

25. FACTORS AFFECTING THRUST
Air Density Altitude Airspeed Ram Effect Engine RPM
One of the most obvious factors that affects the thrust output is the rotational speed of the engine.
With an increase in RPM, there is an increase in thrust. However, at low RPM there is very little
increase in thrust with an increase in throttle. At higher rates of revolution, a small increase in
throttle setting will produce a large increase in thrust. At the lower settings, fuel consumption is high
for the amount of thrust produced. For this reason, gas turbine engines are normally operatedat near
their maximum RPM.

26. What is drag?
As the airplane moves through the air, there is another aerodynamicforce present. The air
resists the motion of the aircraftand the resistance force is called drag. Drag is directedalong
and opposedto the flight direction. Like lift, there are many factors that affectthe magnitude of
the drag force including the shape of the aircraft, the "stickiness" of the air, and the velocity of
the aircraft. Like lift, we collect all of the individual components' drags and combine them into a
single aircraftdrag magnitude. And like lift, drag acts through the aircraftcenter of pressure.

27. Is drag necessary for flight to be achieved?
Drag is the force that pushes planes backwards and slows them down as they fly
through the air. Many current innovations in flight are focused on decreasing drag
on planes as much as possible. With less drag, planes are able to achieve faster
speeds with the same amount of thrust as they had before.

28. Technically, drag is not necessary for flight to be achieved. However, it is impossible to
completelyeliminate drag during flight without eliminating air. Air is needed to generatelift,
so although drag is not completely necessary for flight, an airplane that achieve’s lift will
always experience some form of drag

29. Factors affecting drag force
Object Motion Air
Geometry has a large effect on the amount of drag generated by an object. As with
lift, the drag depends linearly on the size of the object moving through the air. The
cross-sectional shape of an object determines the form drag created by the
pressure variation around the object.

30. Factors affecting drag force
Object Motion Air
The three dimensional plan form shape affects the induced drag of a lifting wing. If we
think of drag as aerodynamicfriction, the amount of drag depends on the surface
roughness of the object; a smooth, waxed surface produces less drag than a roughened
surface. This effectis called skin friction and is usually included in the measured drag
coefficient of the object.

31. Factors affecting drag force
Object Motion Air
Drag is associatedwith the movement of the aircraftthrough the air, so drag
depends on the velocity of the air. Like lift, drag actually varies with the square of
the relative velocity between the objectand the air. The inclination of the object
to the flow also affects the amount of drag generatedby a given shaped object

32. Factors affecting drag force
Object Motion Air
If the object moves through the air at speeds near the speed of sound, shock
waves are formed on the objectwhich create an additional drag component called
wave drag. The motion of the objectthrough the air also causes boundary layers to
form on the object.A boundary layer is a region of very low speed flow near the
surface which contributes to the skin friction.

33. Factors affecting drag force
Object Motion Air
Drag depends directly on the mass of the flow going past the
aircraft. The drag also depends in a complex way on two other
properties of the air: its viscosity and its compressibility.

34. Relationship between those forces
that are required to flight
• Lift must be greater than weight(gravity) for a plane
to take off
• Thrust must be greater than drag for a plane to take
off
• Lift must be less than weight(gravity) for a plane to
land
• Thrust must be less than drag for a plane to land