berry jackie
TRANSCRIPT
-
8/12/2019 Berry Jackie
1/12
Low Speed Aerodynamics
By Jackie Berry
http://www.coolhdwallpapers.com/small_airplane_flying-wallpapers
-
8/12/2019 Berry Jackie
2/12
Topics to Cover
History of Flight How Airplanes Fly Lift
Thrust
Drag
Characteristics ofLow Speed Aerodynamics
-
8/12/2019 Berry Jackie
3/12
The History of Flight Prior to the 17th century, very little was discovered
concerning the nature of flight.
1505 Da Vinci discovered that the center of gravity is notthe same as the center of pressure and sketched a flyingmachine that resembled a bird (ornithopter).
Newton developed the first theory for air resistance. Hethought that drag was due to the shape of the flying object,
the density of the fluid, and the velocity of the object(squared). Correct for low flow speeds.
Newton developed an equation for the drag force: F =SV2sin2(). But only works for hypersonic flow speeds.
-
8/12/2019 Berry Jackie
4/12
The History of Flight (cntd)
Sir George Cayley separated forces of lift and drag.He knew that a flying machine would need somekind of propulsion to fly. He researched shapes with
less drag and investigated the cross section of atrout.
Francis H. Wenham constructed the first wind tunnelin 1871.
1889: Charles Renard predicted the necessaryamount of power for sustained flight.
1903: The Wright brothers flew the first poweredaircraft. (http://www.youtube.com/watch?v=uT2dQB_OgFE&feature=related)
http://www.youtube.com/watch?v=uT2dQB_OgFE&feature=relatedhttp://www.youtube.com/watch?v=uT2dQB_OgFE&feature=related -
8/12/2019 Berry Jackie
5/12
The History of Flight (cntd x2)
Kutta-Joukowski condition(early 20th century)
described thecharacteristics of flow
around an airfoil. This
contributed to the creationof the Joukowski airfoil
which we use for airplanes
today.
QuickTime and aTIFF (Uncompressed) decompressor
are needed to see this picture.
www.viswiki.com/ en/Joukowsky_transform
-
8/12/2019 Berry Jackie
6/12
How Airplanes Fly
http://www.allstar.fiu.edu/aero/fltmidfly.htm
-
8/12/2019 Berry Jackie
7/12
Four main forces on an airplane: thrust, drag,lift, and weight.
Thrust and lift forces must be greater than
drag and weight forces for the plane to takeoff.
During level flight with constant speed, thenet force on the aircraft is zero. So,
thrust=drag and lift=weight.
How Airplanes Fly
-
8/12/2019 Berry Jackie
8/12
Lift
ksnn.larc.nasa.gov/ pokemon/unseen/main.html
Lift is generated when
the velocity of the fluid
over the wing is greater
than the velocity of the
fluid under the wing.
The higher the velocity,
the lower the pressureand the lower the
velocity, the higher the
pressure. Thus, thepressure under the wing
is greater than above,
generating LIFT!
-
8/12/2019 Berry Jackie
9/12
Thrust
Thrust is the force created by the engines tocounteract the drag force.
A propulsion system generates thrust byaccelerating a mass of gas: the thrust is in the
opposite direction from the gas.
In aircrafts, thrust is produced by propellers orjet engines.
-
8/12/2019 Berry Jackie
10/12
Drag
All parts of airplanes produce drag when the airplane is inmotion (the drag force is produced when there is adifference in velocity between fluid and object).
Drag is opposite to the direction of motion.
Similar to friction. The magnitude of force depends on the
properties of the surface material and the viscosity of thefluid.
Drag is caused by the shape of the body (shape alters thevelocity and pressure).
Induced drag is produced when the airplane generates lift.The magnitude depends on how much lift is created and theshape of the wing tips.
-
8/12/2019 Berry Jackie
11/12
Characteristics of Low Speed Aerodynamics
Low speed aerodynamics = subsonic aerodynamics.Sometimes are also called inviscid, incompressible, andirrotational.
Characterized by objects moving through fluids ofconstant density (incompressible). Only works if the fluidhas a low speed.
Subsonic aerodynamics have mach
-
8/12/2019 Berry Jackie
12/12
Sources of Information
http://en.wikipedia.org/wiki/Aerodynamics
http://www.grc.nasa.gov/WWW/K-12/airplane/thrust1.html
http://www.grc.nasa.gov/WWW/K-
12/airplane/drag1.html http://www.grc.nasa.gov/WWW/K-
12/airplane/mach.html
http://www.allstar.fiu.edu/aero/fltmidfly.htm