F/A-18 flying at transonic speed

Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound (about mach 0. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Aeronautics (from Greek aero which means air or sky and nautis which means sailor i Sound is a vibration that travels through an elastic medium as a Wave. Mach number (\mathrm{Ma} or M (generally ˈmɑːk sometimes /ˈmɑːx/ or /ˈmæk/ is the speed of an object moving through air or any Fluid 8–1. 2). It is defined as the range of speeds between the critical mach number, when some parts of the airflow over an aircraft become supersonic, and a higher speed, typically near Mach 1.2, when all of the airflow is supersonic. 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 For other uses see Supersonic. The term supersonic is used to define a speed that is over the Speed of sound ( Mach 1 Mach number (\mathrm{Ma} or M (generally ˈmɑːk sometimes /ˈmɑːx/ or /ˈmæk/ is the speed of an object moving through air or any Fluid Between these speeds some of the airflow is supersonic,and some is not.

Most modern jet powered aircraft spend a considerable amount of time in the transonic state. specific --->A jet engine is a Reaction engine that discharges a fast moving jet of Fluid to This is particularly important due to an effect known as wave drag, which is prevalent in these speed ranges. 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 Attempts to combat wave drag can be seen on all high-speed aircraft; most notable is the use of swept wings, but another common form is a wasp-waist fuselage as a side effect of the Whitcomb area rule. 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. 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

Severe instability can occur at transonic speeds. Shock waves move through the air at the speed of sound. When an object such as an aircraft also moves at the speed of sound, these shock waves build up in front of it to form a single, very large shock wave. During transonic flight, the plane must pass through this large shock wave, as well as contending with the instability caused by air moving faster than sound over parts of the wing and slower in other parts. The difference in speed is due to Bernoulli's principle. 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

Transonic speeds can also occur at the tips of rotor blades of helicopters and aircraft. Classes of rotorcraft Helicopter See also Helicopter A helicopter is a rotorcraft whose rotors are driven by the engine(s throughout the flight However, as this puts severe, unequal stresses on the rotor blade, it is avoided and may lead to dangerous accidents if it occurs. It is one of the limiting factors to the size of rotors, and also to the forward speeds of helicopters (as this speed is added to the forward-sweeping (leading) side of the rotor, thus possibly causing localized transonics).

Interesting facts

Transonic flow patterns on an airfoil showing flow patterns at and above critical Mach number. An airfoil (in American English) or aerofoil (in British English) is the shape of a Wing or blade (of a Propeller, rotor 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

• At transonic speeds intense low-pressure areas form at various points around an aircraft. If conditions are right (i. e. high humidity) visible clouds will form in these low-pressure areas as shown in the illustration; these are called Prandtl-Glauert singularities. These clouds remain with the aircraft as it travels. It is not necessary for the aircraft as a whole to reach supersonic speeds for these clouds to form. For other uses see Supersonic. The term supersonic is used to define a speed that is over the Speed of sound ( Mach 1

See also

• Critical Mach number
• Speed of sound
• Sound barrier
• Prandtl-Glauert singularity
• Anti-shock body

Other Flow Regimes

• Subsonic flows
• Supersonic flows
• Hypersonic flows

References

Theory of transonic astrophysical flows: Sandip K. 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 Sound is a vibration that travels through an elastic medium as a Wave. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Anti-shock bodies or Küchemann carrots are pods placed at the Trailing edge of a Subsonic Aircraft 's wings in order to reduce For other uses see Supersonic. The term supersonic is used to define a speed that is over the Speed of sound ( Mach 1 In Aerodynamics, hypersonic speeds are speeds that are highly Supersonic. Chakrabarti, World Scientific Publishers , Singapore (1990)