One of the most common types of airplanes in use today is the jet, which has largely replaced traditional aircraft powered by propellers. Although propeller planes are still used in some instances, jets dominate commercial and private air travel due to their greater speed, ability to fly at higher altitudes and mechanical reliability.
General Airplane History
While efforts toward powered flight date back to the earliest inventors, the first successful flight of a fixed-wing aircraft was performed famously by the Wright brothers in 1903. Their plane, known as the Wright Flyer I, was made of wood and used a gasoline engine to spin a pair of wooden propellers. Over the next several years, the Wright brothers continued to refine the design that would provide the basis for aircraft over the coming decades.
World War I provided a major incentive for the design and construction of better airplanes. Planes were originally used purely for surveying the enemy's positions. This led to aerial bombardment with heavy objects and hand grenades. Finally, guns were mounted to planes (which by now were made of metal and capable of sustained level flight). Following the war, the civilian aviation industry began, promoted by hero pilots like Charles Lindbergh in the 1920s.
The key difference between jets and the combustion engines used on propeller planes is that jets produce thrust through the discharge of gas instead of powering a drive shaft that is linked to a propeller. Jets based on rockets or steam engines were used to power gliders invented by the ancient Greeks. For many years, most efforts at aircraft development went into propeller-driven planes.
Jets generate thrust by discharging a fluid in the opposite direction of the intended motion. Air enters a jet engine through its induction fan and is then compressed until it attains a high pressure state. The pressurized air is mixed with fuel and combustion occurs. Heated gasses leaving the combustion chamber drive a series of turbines and are rapidly expelled through an exhaust nozzle, producing forward thrust.
Jet aircraft have several distinct advantages over traditional propeller planes. The largest of these advantages is that jets can travel much faster than propeller planes, up to and beyond the speed of sound. Jets can also travel at higher altitudes due to different air quality needs for the different types of propulsion systems. Propellers require dense air for the spinning blades to engage with, whereas jets employ turbochargers to compress even the thin air that exists in the stratosphere until it is suitable for combustion in the jet engine. Flying higher allows planes to avoid the turbulence that occurs at lower altitudes and also allows air traffic patterns to increase the number of planes in the sky if they can operate at different altitudes. Jets can also use their greater power to propel larger aircraft, including the class of oversized "jumbo jets." This advantage also makes jet engines suitable for cargo and military aircraft where heavy payloads are routine.
Development of Jet Planes
Jet-powered aircraft have existed as experimental models or designs on paper since the earliest days of aviation. British and German engineers turned more attention to the development of jet aircraft following World War I, when aviation had proven so vitally important. The onset of the second World War galvanized their efforts. The first practical plane to be fully powered by jet engines was the German Heinkel He 178 in 1939. Meanwhile, the first Italian-designed jet, the Campini N.1, first flew in 1940 and the British Gloster E.28/39 had been proven in test runs in 1941. The United States entered the jet race with its Bell XP-59 in 1942. Useful jet planes were too late in coming to prove effective in World War II, where propeller planes still dominated. Jets would be important to the Korean War and all wars thereafter. Commercial jet service began in the early 1950s and today jets are used for the majority of medium- and long-distance flights around the world.
Use of Propeller Planes Today
Despite the popularity of jet planes, there are still certain areas where propeller planes are in use today. Most major airlines use propeller planes for short regional flights. These planes are less expensive to maintain and operate. Declining revenues experienced by most airlines during hard economic times has led to cancellation of jet service to many smaller airports, and in some cases this is replaced by propeller plane service. This, however, represents a challenge to airlines who must combat a negative public view of propeller planes. Passengers complain about the turbulence and noise of propeller planes, as well as the perceived lack of safety and slower speed of travel. Still, their small size and lower fuel consumption make propeller planes a vital part of operations for airlines struggling to lower their costs while maintaining a broad service network.