"Supersonic aircraft A supersonic aircraft is an aircraft able to fly faster than the speed of sound (Mach number 1). Supersonic aircraft were developed in the second half of the twentieth century and have been used almost entirely for research and military purposes. Only two, Concorde and the Tupolev Tu-144, ever entered service for civil use as airliners. Fighter jets are the most common example of supersonic aircraft. The aerodynamics of supersonic flight is called compressible flow because of the compression (physics) associated with the shock waves or ""sonic boom"" created by any object travelling faster than sound. Aircraft flying"
"Bullet bow shockwave A bullet bow shockwave is a physical and audible wave created in the air when a bullet travels at supersonic speeds; meaning faster than the speed of sound. The bullet bow shockwave is the result of air being greatly compressed at the front-most tip of the bullet as it slices through the air. As the bullet moves forward a broadening wave of compressed air trails out diagonally from the bullet tip. The sides of the bullet create a conical waveform. This conical waveform may be audible to a witness as a whip-crack sound. If the bullet passes"
"by the U.S. Bureau of Mines and other agencies. The power, or volume, of the shock wave depends on the quantity of air that is being accelerated, and thus the size and shape of the aircraft. As the aircraft increases speed the shock cone gets ""tighter"" around the craft and becomes weaker to the point that at very high speeds and altitudes no boom is heard. The ""length"" of the boom from front to back depends on the length of the aircraft to a power of 3/2. Longer aircraft therefore ""spread out"" their booms more than smaller ones, which leads"
"United States and eventually in other countries around the world with airspace the aircraft was supposed to fly through. This opposition made it impossible for Concorde to be a commercial success. The sonic boom issue was also a significant factor in the eventual cancellation of the Boeing 2707. Shock waves develop around aircraft as they near Mach 1 (1225.0 km/h). At ground level, these are perceived as a loud double boom or bang. Their intensity varies due to factors such as weather, refraction from different layers of atmospheric density, and size of the aircraft, but in general, from a supersonic"
"The crack of a supersonic bullet passing overhead or the crack of a bullwhip are examples of a sonic boom in miniature. Sonic booms due to large supersonic aircraft can be particularly loud and startling, tend to awaken people, and may cause minor damage to some structures. They led to prohibition of routine supersonic flight over land. Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle the nuisance due to them may be reduced to the point that overland supersonic flight may become a practical option. A supersonic transport (SST) is a civil aircraft"
"about five times the altitude); that is, an aircraft flying supersonic at will create a lateral boom spread of about . For steady supersonic flight, the boom is described as a carpet boom since it moves with the aircraft as it maintains supersonic speed and altitude. Some manoeuvers, diving, acceleration or turning, can cause focusing of the boom. Other manoeuvers, such as deceleration and climbing, can reduce the strength of the shock. In some instances weather conditions can distort sonic booms. Depending on the aircraft's altitude, sonic booms reach the ground two to 60 seconds after flyover. However, not all"
"a small area around the object's leading edge. (Fig.1b) Fig. 1. ""Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)."" When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this."
"of sound, so that the sound waves leaving the aircraft pile up on one another, similar to a traffic jam on a motorway. When a shock wave forms, the local air pressure increases and then spreads out sideways. Because of this amplification effect, a shock wave can be very intense, more like an explosion when heard at a distance (not coincidentally, since explosions create shock waves). Analogous phenomena are known outside fluid mechanics. For example, particles accelerated beyond the speed of light in a refractive medium (where the speed of light is less than that in a vacuum, such as"
"is sometimes called an airfoil, which is a device that creates lift when air flows across it. Supersonic flight is flight faster than the speed of sound. Supersonic flight is associated with the formation of shock waves that form a sonic boom that can be heard from the ground, and is frequently startling. This shockwave takes quite a lot of energy to create and this makes supersonic flight generally less efficient than subsonic flight at about 85% of the speed of sound. Hypersonic flight is very high speed flight where the heat generated by the compression of the air due"
"the deafening sonic waves from the combined liquid and solid-fuel rockets used to propel the vehicle. Standing shock waves in the rocket exhaust produce continuous supersonic shock waves (a continuous ""sonic boom""). The auditory dynamics of two roaring rocket exhausts, combined with the pounding physical effects of such intense sound waves over the short distance to the observers, made it questionable whether close observers could have differentiated the vehicle's sonic boom from the general cacophony of background noise. No boom was heard at greater distances either, in marked contrast to the runs of ThrustSSC, which generated extensive and well attested"
"involved in such an event, that the sound you hear from a suppressed weapon will not be from the point of origin. Most humans will perceive the sound as being omnidirectional or as emanating from the bullet as it passes by. Bullet bow shockwave A bullet bow shockwave is a physical and audible wave created in the air when a bullet travels at supersonic speeds; meaning faster than the speed of sound. The bullet bow shockwave is the result of air being greatly compressed at the front-most tip of the bullet as it slices through the air. As the bullet"
"is a sharper ""bang"" or ""crack"". The sound is much like that of mortar bombs, commonly used in firework displays. It is a common misconception that only one boom is generated during the subsonic to supersonic transition; rather, the boom is continuous along the boom carpet for the entire supersonic flight. As a former Concorde pilot puts it, ""You don't actually hear anything on board. All we see is the pressure wave moving down the aeroplane - it gives an indication on the instruments. And that's what we see around Mach 1. But we don't hear the sonic boom or"
"a region in the shape of a geometrical cone behind the object. As the object moves, this conical region also moves behind it and when the cone passes over the observer, they will briefly experience the ""boom"". When an aircraft passes through the air it creates a series of pressure waves in front of the aircraft and behind it, similar to the bow and stern waves created by a boat. These waves travel at the speed of sound and, as the speed of the object increases, the waves are forced together, or compressed, because they cannot get out of each"
"boom was produced by an F-4 flying just above the speed of sound at an altitude of . In recent tests, the maximum boom measured during more realistic flight conditions was 1,010 Pa (21 psf). There is a probability that some damage — shattered glass, for example — will result from a sonic boom. Buildings in good condition should suffer no damage by pressures of 530 Pa (11 psf) or less. And, typically, community exposure to sonic boom is below 100 Pa (2 psf). Ground motion resulting from sonic boom is rare and is well below structural damage thresholds accepted"
"to a less powerful boom. Several smaller shock waves can and usually do form at other points on the aircraft, primarily at any convex points, or curves, the leading wing edge, and especially the inlet to engines. These secondary shockwaves are caused by the air being forced to turn around these convex points, which generates a shock wave in supersonic flow. The later shock waves are somewhat faster than the first one, travel faster and add to the main shockwave at some distance away from the aircraft to create a much more defined N-wave shape. This maximizes both the magnitude"
"is termed the “blast wave.” The blast wave is characterized by an almost instantaneous rise from ambient pressure to a peak incident pressure (Pi). This pressure increase or “shock front,” travels radially outward from the detonation point, with a diminishing velocity that is always in excess of the speed of sound in that medium. Gas molecules making up the front move at lower velocities. This velocity, which is called the “particle velocity,” is associated with the “dynamic pressure,” or the pressure formed by the winds produced by the shock front. As the shock front expands into increasingly larger volumes of"
"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. 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 contend with the instability caused by air moving faster than"
"Jet noise In aeroacoustics, jet noise is the field that focuses on the noise generation caused by high-velocity jets and the turbulent eddies generated by shearing flow. Such noise is known as broadband noise and extends well beyond the range of human hearing (100 kHz and higher). Jet noise is also responsible for some of the loudest sounds ever produced by mankind. The primary sources of jet noise for a high-speed air jet (meaning when the exhaust velocity exceeds about 100 m/s) are ""jet mixing noise"" and, for supersonic flow, shock associated noise. Also, acoustic sources within the ""jet pipe"""
"air in front of the aircraft begins to compress. This creates a force known as wave drag. This wave drag increases steeply until the whole aircraft is supersonic and then reduces. However, shock waves can form on some parts of an aircraft at a speed where the aircraft is moving at less than M=1.0 because the ""local"" speed of sound is determined by air temperature. A rapid drop in air density caused by aircraft contours will reduce the local air temperature and will correspondingly cause a drop in the local speed of sound that can cause shock waves to form."
"barrel, thus preventing any backward travel from the projectile into the barrel.) Sound waves travel in an ever-expanding bubble emanating from the muzzle when the propellant gases are traveling at supersonic speeds. This is called the ""muzzle blast."" Except in extremely low pressure loads, the exiting propellant gasses generate much higher sound pressure levels (dBa) than any other aspect of the weapon firing. (e.g., hammer, sear, bolt, supersonic flight signature, etc.) The supersonic ""ballistic crack"" is typically 136-138 dB, whereas ""muzzle blast"" may reach 168 dB. By encircling the muzzle, the shroud funnels and focuses the sound waves along the"
"Sound barrier The sound barrier or sonic barrier is the sudden increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first began to be able to reach close to the speed of sound, these effects were seen as constituting a barrier making faster speeds very difficult or impossible. The term ""sound barrier"" is still sometimes used today to refer to aircraft reaching supersonic flight. In dry air at 20 °C (68 °F), the speed of sound is 343 metres per second (about 767 mph, 1234"
"booms are heard at ground level. The speed of sound at any altitude is a function of air temperature. A decrease or increase in temperature results in a corresponding decrease or increase in sound speed. Under standard atmospheric conditions, air temperature decreases with increased altitude. For example, when sea-level temperature is 59 degrees Fahrenheit (15 °C), the temperature at drops to minus 49 degrees Fahrenheit (−45 °C). This temperature gradient helps bend the sound waves upward. Therefore, for a boom to reach the ground, the aircraft speed relative to the ground must be greater than the speed of sound at"
"Shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the"
"the pressure returns to normal. This leads to a distinctive ""double boom"" from a supersonic aircraft. When the aircraft is maneuvering, the pressure distribution changes into different forms, with a characteristic U-wave shape. Since the boom is being generated continually as long as the aircraft is supersonic, it fills out a narrow path on the ground following the aircraft's flight path, a bit like an unrolling red carpet, and hence known as the ""boom carpet"". Its width depends on the altitude of the aircraft. The distance from the point on the ground where the boom is heard to the aircraft"
"moves through water: just as the bow wave is produced for the entire journey of the ship, so the sonic shockwave occurs throughout the duration of a supersonic flight. In subsonic flight, the plane pushes the air ahead of it out of the way as it moves. When a plane is traveling faster than the speed of sound (i.e. faster than air molecules normally travel) the air ahead of it is not pushed out of the way: the air remains still until the plane has approached to within half an inch, at which point the air is forced aside in"
"km/h or 1,125 ft/s). The term came into use during World War II when pilots of high-speed fighter aircraft experienced the effects of compressibility, a number of adverse aerodynamic effects that deterred further acceleration, seemingly impeding flight at speeds close to the speed of sound. These difficulties represented a barrier to flying at faster speeds. In 1947 it was demonstrated that safe flight at the speed of sound was achievable in purpose-designed aircraft thereby breaking the barrier. By the 1950s new designs of fighter aircraft routinely reached the speed of sound, and faster. Some common whips such as the bullwhip"
"aircraft of the size of a civilian airliner, the overpressure created at ground level is enough to rattle windows. For example, the sonic boom from the Concorde traveling at a speed of Mach 2 (2450 km/h) was about Because of sonic boom intensity, many countries now prohibit supersonic overflight over land or population centres. The FAA prohibits supersonic flight over land, except in special military flight corridors. The Quiet Spike is able to suppress sonic booms a little, but a Quiet Spike alone is not effective enough to circumvent the current ban on supersonic overflight. Various structural approaches have been"
"a few millionths of a second. This creates extreme local compression and heating, and a shockwave spreads outwards in a cone. This pressure wave extends as much as 25 miles on either side of the flight path, and may be experienced as a loud sound, with accompanying vibration severe enough in close proximity to break windows and damage buildings. Development had begun before the effects of sonic boom tests had been conducted. During 1961 and 1962, 150 supersonic flights were made over St Louis, Missouri, in 1964, flights were made over Oklahoma City for five months, and in 1965, there"
"times heating increase at vehicle surface, (5)interacting with other structures, such as boundary layers, to produce new flow structures such as flow separation, transition, etc. Shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic flows, additional increased expansion may be"
"of a 75 boom, lower than Concorde’s 105 PNLdB. It should not be louder at takeoff than current airliners like the Boeing 777-300ER. Supersonic jets could be exempted from the FAA takeoff noise regulations, reducing their fuel consumption by 20-30% using narrower engines optimised for acceleration over limiting noise. In 2017, Honeywell and NASA tested predictive software and cockpit displays showing the sonic booms en route, to minimize its disruption overland. Boom wants to use moderate bypass turbofans without afterburners, unlike Concorde's Rolls-Royce/Snecma Olympus. The only available are jet fighter engines, which have neither the fuel economy nor the reliability"
"shock wave associated with a return to subsonic flow behind the aircraft. Since the local Mach number is not uniform over the aircraft, parts of the aircraft may be supersonic while others remain subsonic — a flight regime called transonic flight. In addition to making the shock waves themselves visible, water condensation can also occur in the trough between two crests of the shock waves produced by the passing of the object. However, this effect does not necessarily coincide with the acceleration of an aircraft through the speed of sound or Mach 1. These condensation clouds can often be seen"
"routine supersonic flight over land. Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle the nuisance due to them may be reduced to the point that overland supersonic flight may become a practical option. A sonic boom does not occur only at the moment an object crosses the speed of sound; and neither is it heard in all directions emanating from the speeding object. Rather the boom is a continuous effect that occurs while the object is travelling at supersonic speeds. But it only affects observers that are positioned at a point that intersects"
"given by: where formula_3 is the inverse formula_4 of the plane's Mach number (formula_5). Thus the faster the plane travels, the finer and more pointed the cone is. There is a rise in pressure at the nose, decreasing steadily to a negative pressure at the tail, followed by a sudden return to normal pressure after the object passes. This ""overpressure profile"" is known as an N-wave because of its shape. The ""boom"" is experienced when there is a sudden change in pressure; therefore, an N-wave causes two booms – one when the initial pressure-rise reaches an observer, and another when"