Due to IT
security concerns, many users are currently experiencing problems running NASA Glenn
educational applets. The applets are slowly being updated, but it is a lengthy process.
If you are familiar with Java Runtime Environments (JRE), you may want to try downloading
the applet and running it on an Integrated Development Environment (IDE) such as Netbeans or Eclipse.
The following are tutorials for running Java applets on either IDE:
Netbeans Eclipse
You can download your own copy of this applet by pushing the following button:
The program is downloaded in .zip format. You must save the file to disk and
then "Extract" the files. Click on
"Warp.html" to run the program off-line.
One of the major breakthroughs of the Wright brothers was the ability
to
control
and maneuver their
aircraft.
Roll
control was provided by a unique idea called wing warping.
The tips of their wings could by twisted relative to the rest of
the wing by a series of cables.
On this page we have a Java program which allows you to explore all the
aspects of wing warping so that you can better understand how it works.
The program shows a computer drawing of the Wright brothers'
1900
aircraft.
To the right of the drawing are some buttons which allow you to consider
the various aspects of wing warping. At the bottom is a slider which
lets you change the amount of deflection of the right wing tip or the
left wing tip, as viewed from the front of the aircraft.
Mechanics
The mechanics of wing warping is shown with the aircraft fixed in space.
The central cells of the wing are held in place by wire rigging so that
the vertical struts can not move relative to the wings. But the outer cell
of each wing is wired differently. There are no cross wires on the outer
struts except at the front. The leading edge of each wing is kept
straight by the rigging wires, but the rear portion of each wing can
move relative to the rest of the wing. There are additional control wires
at the rear of the wing which connect the wing tips to a pedal at the foot
of the pilot. As the pilot pushes the pedal, the wire pulls on the wing
tip and the shape of the outer panel changes. (Push the "Mechanics" button
and move the slider to see the change in shape)
Lift Force
As described on the shape effects slide,
changing the angle of deflection at the rear of an airfoil will
change the amount of lift generated by the foil. With greater
downward deflection, the lift will increase in the upward direction.
If you select the "Lift Force" button you will see the distribution
of lift across the wing. We represent the lift by a series of red arrows
whose length is proportional to the lift in that section of the wing.
If the tip of the right wing, as viewed
from the front of the aircraft, is deflected down, the tip of the
left wing is deflected slightly upward.
Therefore, the lift on the right wing is
increased, while the lift on the left wing is decreased.
We display these forces and the wing deflection with the aircraft fixed
in space. In response to the unequal forces on each wing, the aircraft
will rotate about its
center of gravity and change
its attitude as it moves through the air.
Attitude
Because of unequal forces on the wings of the aircraft, the
aircraft will
roll
or bank in the direction of the smaller
force. (The wing with the higher lift will move upward, the wing with
the lower lift will move downward.)
There is a
slide
available which shows the directions of the forces and the resulting
motion.
You can investigate this behavior with the Java program by pushing
the "Attitude" button and then move the slider.
The orientation of the aircraft as a result of the varying lift forces
is displayed in the graphics.
Forces
When the aircraft banks or rolls to one side, the balance of forces on
the aircraft is changed and the aircraft moves in a new direction. The
weight force is always directed towards
the center of the earth. In a wings-level cruise condition, the
lift is perpendicular to the flight
direction and opposes the weight. The lift acts nearly perpendicular to the
wing surface. When the aircraft (and the wing) rolls to one side, the
lift remains perpendicular to the flight path and the wing surface. A large
portion of the lift still opposes the weight, but there is now a
component of the lift which produces a side force on the aircraft.
You can investigate this side force by pushing the "Forces" button
on the program and moving the slider.
Resulting Motion
The side force is unopposed by any other force and so the aircraft
moves in that direction in accordance with Newton's
first law of motion.
The side force is a centralized force; it is always perpendicular
to the flight path because it is a component of the lift. An object
subjected to a centralized force moves in a
circular path.
This animation shows the motion of the
1901
aircraft when the right wing tip as viewed from the front is deflected down.
If the aircraft is rolled in the opposite direction, the plane turns
in the opposite direction.
Notice that banking an aircraft to one side causes the aircraft to
turn
in that direction. The turning is not the result of
a rudder input as it would be on a boat. The 1901 aircraft had no rudder.
Airplanes are turned by
banking or rolling. The rudder on an airplane is just used to keep
the nose pointed in the correct direction in order to eliminate
a condition called adverse yaw and to bring the thrust vector
into the turn on high performance aircraft.
The Wright brothers used wing warping for roll control on their
1901
and
1902 gliders
and on the successful 1903
flyer.
Modern airliners and fighter planes, however,
no longer use wing warping for roll control. They typically use either
ailerons or spoilers
which are moving sections on the wing of the aircraft.
When you travel on an airliner, watch
the wings during turns. The pilot rolls the aircraft in the direction
of the turn. You will probably be surprised at how little deflection
is necessary to bank (roll) a large airliner. You can
tell whether an airliner is using spoilers or ailerons by noticing
where the moving part is located. At the trailing edge, it's an
aileron; between the leading and trailing edges, it's a spoiler.
You can view a short
movie
of "Orville and Wilbur Wright" explaining how wing warping
was used to roll their aircraft. The movie file can
be saved to your computer and viewed as a Podcast on your podcast player.
