Transcript How Drag Slows an Aircraft

The Physics of Flight
Warm-Up Questions
CPS Questions 1-2
Chapter 1, Lesson 2
Lesson Overview
How lift is generated
 How weight affects flight
 How thrust affects an aircraft’s movement
 How drag slows an aircraft
 How the four forces of flight interact with
each other

Chapter 1, Lesson 2
Quick Write
Octave Chanute’s expertise in designing
bridges gave him the know-how to tackle
some big questions in aviation, such as
the structure of biplane wings.
What skills have you acquired from school
that you could apply to a hobby?
(Note to teacher: Use “Pick a Student” button in CPS)
Chapter 1, Lesson 2
How Lift is Generated
 Upward
force on aircraft
against weight
 Increasing aircraft’s
forward motion
 Increasing airfoil’s angle
of attack – up to stall
speed
 Depends on aircraft’s
shape, size, and velocity
Chapter 1, Lesson 2
Reproduced from NASA/Glenn Research Center
How to Control Lift
Pilots increase angle of
attack to create more lift
 Angle of attack and
velocity must be balanced
to keep flight path level
 Air condition impacts the
need for greater or lesser
velocity to maintain lift

Chapter 1, Lesson 2
Courtesy of NASA/Kim Shiflett
Activity 1: Controlling Lift
 Launch
the airplane you created in
Lesson 1 and observe the lift patterns
 Document
your findings and answer the
questions on the worksheet provided
Chapter 1, Lesson 2
How Weight Affects Flight
Acts through single point center of gravity
 Weight is a gravitational force on an object due
to its mass
 Mass includes airplane parts, fuel, passengers
and freight
 The more mass, the more resistance to moving

Chapter 1, Lesson 2
Adapted from NASA/Glenn Research Center
Weight’s Major Challenges
 Overcoming
an
aircraft’s weight with
lift
 Pilots
constantly adjust
for balance during flight
Chapter 1, Lesson 2
Courtesy of NASA
Learning Check Questions
CPS Questions 3-4
Chapter 1, Lesson 2
Activity 2:
Center of Gravity Limit
 Compute
aircraft weight and center of
gravity
 Answer
questions about your calculations
of moment, weight, and center of gravity
Chapter 1, Lesson 2
How Thrust Affects an
Aircraft’s Movement
 Thrust
is a forward force
that moves an aircraft
through the air
 It’s
opposite force is
drag, the pull or slowing
effect of air on an aircraft
Chapter 1, Lesson 2
Courtesy of USN/PH1 Richard Rosser
Where Thrust Comes From
 Engines
provide powered aircraft’s thrust
 Thrust’s forward motion overcomes drag
so airfoils produce lift
Chapter 1, Lesson 2
Reproduced from NASA/Glenn Research Center
Adjusting Thrust
 Reduction
in engine power while in level
flight, drops thrust and aircraft slows
 When
two forces are equal, pilot will fly at
constant airspeed
Chapter 1, Lesson 2
Adjusting Thrust, cont.
 To
maintain balance between lift and
weight, pilot must coordinate thrust and
angle of attack at any speed
Chapter 1, Lesson 2
Reproduced from US Department of
Transportation/Federal Aviation Administration
How Drag Slows an Aircraft
 As
aircraft moves through air, its boundary
layer changes the shape of airflow over the
aircraft
Chapter 1, Lesson 2
Courtesy of Leon van Dommelen, FAMU-FSU
College of Engineering
Types of Drag

Parasite drag drains flight of needed energy
Form drag includes items like
antennas and engine covers
 Interference drag occurs when
air currents flowing over
various angles of an aircraft
collide
 Skin friction drag can include
anything on an aircraft’s skin
that allows air molecules to stick to

Chapter 1, Lesson 2
© Aaron Kohr/ShutterStock, Inc
Types of Drag, cont.
Wingtip vortices produce
induced drag
 Air flows above the tip
and comes back in a
downwash behind the
wing pulling down and
back on aircraft

Chapter 1, Lesson 2
Courtesy of USAF/TSgt Russell E. Cooley IV
Learning Check Questions
CPS Questions 5-6
Chapter 1, Lesson 2
Activity 3: : FoilSim III Lab
 Conduct
experiments on airfoils in a
virtual wind tunnel using NASA’s
FoilSim III
 Answer
questions pertaining to your
adjustments to lift and drag variables
Chapter 1, Lesson 2
How the Four Forces of
Flight Interact with Each Other
If forces are balanced, aircraft cruises at
constant velocity
 If forces unbalanced, aircraft accelerates in
direction of largest force
 To maintain constant speed, thrust and drag
must remain equal
 For constant altitude, lift and weight must be
equal

Chapter 1, Lesson 2
Activity 4:
Four Forces of Flight
 Label
the appropriate force of flight on
the worksheet illustration
 Write
a short statement describing the
force’s affect on flight
Chapter 1, Lesson 2
Summary
How lift is generated
 How weight affects flight
 How thrust affects an aircraft’s movement
 How drag slows an aircraft
 How the four forces of flight interact with
each other

Chapter 1, Lesson 2
Review Questions
CPS Questions 7-8
Chapter 1, Lesson 2
Next….


Done – the physics of flight
Next – the purpose and function
of airplane parts
Chapter 1, Lesson 2
Courtesy of USAF/CMSgt Gary Emery