Technology: The Wing

In This Module

The technology focus modules in each unit are intended to provide a short "biography" of a technological component--covering the development of that technology and the role(s) that technology has played in our unfolding story of manned flight.  Hopefully this will bring to light some specific innovations that have been transformative for flight in a way that is approachable for a history course and students who have a variety of majors and interests.  These provide a general explanation of related science or engineering concepts as background knowledge.

Before exploring this lesson on the wing, if you are unfamiliar with airplanes in general, this overview of the parts of a plane from NASA is a quick visual summary with explanations of the functions for each part.  Key parts that we will mention during the course are the wings, fuselage, power plant, and cockpit.  The specific uses for the ailerons, flaps, rudder, elevator and other parts of an aircraft mentioned on the NASA site are helpful to understand but not required for this course.  You can also bookmark this page and refer back to it as needed.

After working through this module, you will be able to:

• describe the basic structural components of the wing, including spars, ribs, and bracing

• compare and contrast cloth and wooden wing design during the early years of aviation with aluminum construction used from the 1930s onward

Wing Components

Our previous module on the science of flight showed the importance of the wing in producing lift for an aircraft, so our first technology spotlight in the course will focus on the wing.  Wings generally determine the performance capability and flight characteristics of a plane, and there are different shapes and designs for wings depending on the intended function of the aircraft--for example, high-altitude gliding for spy aircraft, heavy lifting capacity for transport aircraft, or wings that can sweep back for a fighter to cruise more efficiently at supersonic speeds (faster than the speed of sound).  During the first three decades of manned flight, there was continuous experimentation with wings to find the most effective designs and materials for the growing list of functions for an airplane.  We will explore these developments in this lesson.

A wing generally has several characteristics regardless of its size or design:

• a rounded leading edge that leads into a curved upper surface and eventually a sharp, pointed trailing edge (the airfoil shape we observed in the lesson on lift)

• spars that run the length of the wing for internal stability

• ribs that run perpendicular to the spars, also for internal strength and stability

• control surfaces like the wing flap and aileron (pictured below)

Materials and Construction

The Wright Brothers wing design incorporated wooden spars and ribs made of Ash located on the inside of the wing.  They applied a layer of cloth covering the ribs on both the top and bottom surfaces of the wing.  This design was based on their 1899 glider experiments and wind tunnel tests.  Minimizing weight is always a primary concern in aircraft design, and the Wrights used ash ribs with a small block in between the two strips to shape the wings rather than a solid piece of ash for the ribs.  Many aircraft wing ribs have circles or spaces cut out of the center of the ribs to reduce excess materials, and this practice continued even as materials shifted from wood to metal in the early decades of flight.  

You can explore the design of the Wright's wing and other components of the 1903 Wright Flier on this Smithsonian website.

Aircraft build by the Wrights, and those built by others through 1914, relied on this wood and cloth construction for the wings and main body or fuselage of the aircraft.  By World War I, designers started painting cellulose nitrate "dope" onto the wing and fuselage fabric, which would harden and contract the fabric tightly around the wooden frame.  In the carousel of images below, you can see a World War I Curtiss JN4 "Jenny" aircraft wing.  The fabric wing has been doped (with a modern lacquer), and you can see how taut the fabric has become over the wooden ribs.  Subsequent images in the rotation show the wooden spars and wires that help keep the two wings of the biplane stable through tension.  The U.S. government sold many of these aircraft after WWI for $300, and the Jenny became a common staple of barnstormers and backyard pilots throughout the 1920s.

During the 1920s and 1930s, aircraft designers began switching to aluminum in wing construction.  As stress on the wings grew with increasing speed and G-forces during maneuvers, a stronger material for wings was required.  Below is a close-up image of a trainer aircraft with aluminum wings.  Note the rows of rivets along the wing to hold it together.  This design features is still used today for the aluminum skin of commercial aircraft.

Summary

Wings can range in design from long and thin, designed for high-altitude gliding, to short wings designed for maneuverability in air combat.  They almost always share basic components like internal bracing via spars and ribs, control surfaces, and an airfoil shape when viewed in cross-section.  The wings are critical for aircraft because they create the lift that makes flight possible and set the limitations of any aircraft's ability to carry a specific load, achieve certain speeds, and to turn and maneuver in flight.  Although early aircraft used wood and canvas for wing construction, by the 1930s the skin and structures of a wing were increasingly made with aluminum.  Although some alloys are used in aircraft today, especially military aircraft, most modern planes are still construction of aluminum.