Wave drag is an aerodynamics term that refers to a sudden and very powerful form of drag that appears on aircraft and blade tips moving at high-subsonic and supersonic speeds. In Fluid dynamics, drag (sometimes called fluid resistance) is the force that resists the movement of a Solid object through a Fluid (a

Overview

Wave drag is caused by the formation of shock waves around the aircraft. For the music album by Converter see Shock Front For the 1977 horror film see Shock Waves A shock wave (also called Shock waves radiate away a considerable amount of energy, energy that is experienced by the aircraft as drag. Although shock waves are typically associated with supersonic flow, they can form at much lower speeds at areas on the aircraft where, according to Bernoulli's principle, local airflow accelerates to supersonic speeds over curved areas. In Fluid dynamics, Bernoulli's principle states that for an Inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in The effect is typically seen at speeds of about Mach 0.8, but it is possible to notice the problem at any speed over that of the critical Mach of that aircraft's wing. Mach number (\mathrm{Ma} or M (generally ˈmɑːk sometimes /ˈmɑːx/ or /ˈmæk/ is the speed of an object moving through air or any Fluid The Critical Mach number (Mcr of an aircraft is the slowest Mach number at which the airflow over a small region of the wing reaches the speed of sound The magnitude of the rise in drag is impressive, typically peaking at about four times the normal subsonic drag. It is so powerful that it was thought for some time that engines would not be able to provide enough power to easily overcome the effect, which led to the concept of a "sound barrier". WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout

Research

When the problem was being studied, wave drag came to be split into two – wave drag caused by the wing as a part of generating lift, and that caused by other portions of the plane. In 1947, studies into both problems led to the development of "perfect" shapes to reduce wave drag as much as theoretically possible. Year 1947 ( MCMXLVII) was a Common year starting on Wednesday (link will display full 1947 calendar of the Gregorian calendar. For a fuselage the resulting shape was the Sears-Haack body, which suggested a perfect cross-sectional shape for any given internal volume. The Sears-Haack body is generally speaking the body least susceptible to Wave drag. The von Kármán ogive was a similar shape for bodies with a blunt end, like a missile. Given the problem of the Aerodynamic Design of the Nose cone section of any vehicle or body meant to travel through a compressible fluid medium (such as a Rocket Both were based on long narrow shapes with pointed ends, the main difference being that the ogive was pointed on only one end.

Reduction of drag

However a number of new techniques developed during and just after World War II were able to dramatically reduce the magnitude of the problem, and by the early 1950s most fighter aircraft could reach supersonic speeds without too much trouble. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including A fighter aircraft is a Military aircraft designed primarily for air-to-air combat with other Aircraft, as opposed to a Bomber, which is designed For other uses see Supersonic. The term supersonic is used to define a speed that is over the Speed of sound ( Mach 1 If the problem of wave drag is caused by the acceleration of air over curves on the aircraft, the solution is, obviously, to reduce the curves. However this is not always easy, for instance, a wing generates lift at subsonic speeds primarily due to the curvature on the leading edge of the wing. WING "ESPN 1410" is a commercial AM radio station in Dayton Ohio operating with 5000 watts at 1410 kHz with studios offices and transmitter located on David Things are somewhat better for fuselage shaping, but simple things like a cockpit canopy or smoothing off the metal around an air intake can create additional "hot spots".

These research projects were quickly put to use by aircraft designers. One common solution to the problem of wave drag due to the wings was to use a swept-wing, which had actually been developed before WWII and used on some German wartime designs such as the Me-262. A swept-wing is a wing Planform common on high-speed Aircraft, with the wing swept back instead of being set at right angles to the Fuselage. Sweeping the wing to the rear makes it appear thinner and longer in the direction of the airflow, making a "normal" wing shape closer to that of the von Kármán ogive, while still remaining useful at lower speeds where curvature and thickness are important. Given the problem of the Aerodynamic Design of the Nose cone section of any vehicle or body meant to travel through a compressible fluid medium (such as a Rocket

The wing need not be swept as it is possible to build a wing that is extremely thin. This solution was used on a number of designs, perhaps the most obvious being the F-104 Starfighter. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The downside to this approach is that the wing is so thin it is no longer possible to use it for fuel storage or landing gear.

Fuselage shaping was similarly changed with the introduction of the Whitcomb area rule. The Whitcomb area rule, also called the transonic area rule, is a design technique used to reduce an Aircraft 's drag at Transonic and Supersonic Whitcomb had been working on testing various airframe shapes for transonic drag when, after watching a presentation by Adolf Busemann in 1952, he realized that the Sears-Haack body had to apply to the entire aircraft. Adolph Busemann ( 20 April 1901 - 3 November 1986) was a German aerospace engineer and influential early pioneer in This meant that the fuselage needed to be made considerably skinnier where the wings met it, so that the cross-section of the entire aircraft matched the Sears-Haack body, not just the fuselage itself.

Application of the area rule can also be seen in the use of anti-shock bodies on subsonic aircraft, such as jet airliners. Anti-shock bodies or Küchemann carrots are pods placed at the Trailing edge of a Subsonic Aircraft 's wings in order to reduce A jet airliner, sometimes contracted to jetliner, is a passenger Airplane (passenger Aeroplane) that is powered by Jet engines. Anti-shock bodies, which are pods along the trailing edges of the wings, serve the same role as the narrow waist fuselage design of other transonic aircraft. Transonic is an Aeronautics term referring to a range of velocities just below and above the Speed of sound (about mach 0

Other drag reduction methods

Several other attempts to reduce wave drag have been introduced over the years, but have not become common. The supercritical airfoil is a new wing design that results in reasonable low speed lift like a normal planform, but has a profile considerably closer to that of the von Kármán ogive. supercritical airfoil is an Airfoil designed primarily to delay the onset of Wave drag in the Transonic speed range A planform or Plan view is a vertical Orthographic projection of an object on a horizontal plane like a Map. All modern civil airliners use forms of supercritical aerofoil and have substantial supersonic flow over the wing upper surface.

Busemann's Biplane avoids wave drag entirely, but is incapable of generating lift, and has never flown. Busemann's Biplane is a conceptual Airframe design invented by Adolf Busemann which inherently prohibits the formation of N-type Shock waves and thus does