U.S. Navy F/A-18 breaking the sound barrier. The white halo is formed by condensed water droplets which are thought to result from a drop in air pressure around the aircraft (see Prandtl-Glauert Singularity). ^[1][2]

In aerodynamics, the sound barrier usually refers to the point at which an aircraft moves from transonic to supersonic speed. The term came into use during World War II when a number of aircraft started to encounter the effects of compressibility, a grab-bag of unrelated aerodynamic effects. The term fell out of use in the 1950s when aircraft started to routinely "break" the sound barrier. Refer to the speed of sound for the science behind the velocity referred to as the sound barrier. Image File history File links Download high resolution version (2100x1500, 1416 KB) U.S. Navy F/A-18 at transonic speed. ... Image File history File links Download high resolution version (2100x1500, 1416 KB) U.S. Navy F/A-18 at transonic speed. ... The McDonnell Douglas (now Boeing) F/A-18 Hornet is a modern all-weather carrier-capable strike fighter jet, designed to attack both ground and aerial targets. ... F/A-18 demonstrating singularity effect The Prandtl-Glauert singularity, at which point a sudden drop in air pressure occurs, is generally accepted as the cause of the visible condensation cloud that often surrounds an airplane traveling at transonic speeds, though there remains some debate. ... Sound barrier may refer to: Sound barrier, the transition at transonic speeds from subsonic to supersonic travel, usually referring to flight. ... For the Daft Punk song, see Aerodynamic (song). ... Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound. ... A United States Navy F/A-18E/F Super Hornet in transonic flight. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... Flying machine redirects here. ... Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in... For other uses, see Speed of sound (disambiguation). ...

History

The bullwhip, or sparewhip, was the first known human-made object to move faster than sound. The tip of the whip breaks the sound barrier and causes a sharp crack — literally a sonic boom. Many forms of ammunition also achieve supersonic speeds. A bullwhip is a single-tailed whip, usually made of braided leather, which was originally used as a farmers tool for working with livestock. ... For other uses, see Sonic boom (disambiguation). ... Ammunition, often referred to as ammo, is a generic term meaning (the assembly of) a projectile and its propellant. ...

Early problems

The tip of the propeller on many early aircraft may reach supersonic speeds, producing a noticeable buzz that differentiates such aircraft. This is particularly noticeable on the Stearman, and noticeable on the T-6 Texan when it enters a sharp-breaking turn. This is undesirable as the transonic air movement creates disruptive shock waves and turbulence. It is due to these effects that propellers are known to suffer from dramatically decreased performance as they approach the speed of sound. It is easy to demon…strate that the power needed to improve performance is so great that the weight of the required engine grows faster than the power output of the propeller. This problem was one of the issues that led to early research in jet engines, notably by Frank Whittle and Hans von Ohain, who were led to their research specifically in order to avoid these problems in high-speed flight. For other uses, see Propeller (disambiguation). ... Boeing Stearman PT-17 Stearman Aircraft Corporation was an aircraft manufacturer established by Lloyd Stearman at Wichita, Kansas in 1927. ... This article is about the first T-6 Texan. ... For other uses, see Speed of sound (disambiguation). ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... Frank Whittle speaking to employees of the Flight Propulsion Research Laboratory (Now known as the NASA Glenn Research Center), USA, in 1946 Air Commodore Sir Frank Whittle, OM, KBE, FRS, Hon FRAeS (1 June 1907–9 August 1996) was an English Royal Air Force officer and is seen as the... Hans Joachim Pabst von Ohain (December 14, 1911 – March 13, 1998) was one of the inventors of jet propulsion. ...

Propeller aircraft were nevertheless able to approach the speed of sound in a dive. However this led to numerous crashes for a variety of reasons. These included the rapidly increasing forces on the various control surfaces, which led to the aircraft becoming difficult to control to the point where many suffered from powered flight into terrain when the pilot was unable to overcome the force on the control stick. The Mitsubishi Zero was infamous for this problem, and several attempts to fix it only made the problem worse. In the case of the Supermarine Spitfire, the wings suffered from low torsional stiffness, and when ailerons were moved the wing tended to flex in a such a way to counteract the control input, leading to a condition known as control reversal. This was solved in later models with changes to the wing. The P-38 Lightning suffered from a particularly dangerous interaction of the airflow between the wings and tail surfaces in the dive that made it difficult to "pull out", a problem that was later solved with the addition of a "dive flap" that upset the airflow under these circumstances. Flutter due to the formation of shock waves on curved surfaces was another major problem, which led most famously to the breakup of de Havilland Swallow and death of its pilot, Geoffrey de Havilland Jr. Mitsubishi A6M5 Zero Model 52 The Mitsubishi A6M was a light-weight carrier-based fighter aircraft employed by the Imperial Japanese Navy from 1940 to 1945. ... The Supermarine Spitfire was a British single-seat fighter, which was used by the Royal Air Force and many other Allied countries during the Second World War, and into the 1950s. ... Control reversal is an adverse affect on the controllability of aircraft. ... P-38 redirects here. ... Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ... The first DH. 108 built - TG283. ... Geoffrey de Havilland Junior, (b. ...

All of these effects, although unrelated in most ways, led to the concept of a "sound barrier" that makes it difficult for an aircraft to break the speed of sound.^[3]

Early claims

There are, however, several claims that the sound barrier was broken during World War II. Hans Guido Mutke claimed to have broken the sound barrier on 9 April 1945 in a Messerschmitt Me 262. Mütke reported not just transonic buffeting but the resumption of normal control once a certain speed was exceeded, then a resumption of severe buffeting once the 262 slowed again. He also reported engine flame out. However, this claim is widely disputed by various experts believing the Me 262's structure could not support high transonic, let alone supersonic flight.^[4] The lack of area ruled fuselage and 10 percent thick wings did not prevent other aircraft from exceeding Mach 1 in dives. Yeager's Bell X1, the F86 sabre and the Convair Seadart seaplane exceeded Mach 1 without area rule fuselages. Computational tests carried out by Professor Otto Wagner of the München Technical University in 1999 suggest the Me262 was capable of supersonic flight during steep dives. Recovering from the dive and the resumption of severe buffeting once subsonic flight was resumed would have been very likely to damage the craft terminally. Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... Dr. Hans Guido Mutke (March 25, 1921 in Neiße – April 8, 2004 in Munich, Germany) was a fighter pilot for the German Luftwaffe during World War II. He claimed to be the first person to break the sound barrier and to achieve supersonic flight, although this claim is... is the 99th day of the year (100th in leap years) in the Gregorian calendar. ... Year 1945 (MCMXLV) was a common year starting on Monday (link will display the full calendar). ... The Messerschmitt Me 262 Schwalbe (German: Swallow) was the worlds first operational turbojet fighter aircraft. ...

On page 13 of the "Me 262 A-1 Pilot's Handbook" issued by Headquarters Air Materiel Command, Wright Field, Dayton, Ohio as Report No. F-SU-1111-ND on 10 January 1946: "Speeds of 950 km/h (590 mph) are reported to have been attained in a shallow dive 20° to 30° from the horizontal. No vertical dives were made. At speeds of 950 to 1000 km/h (590 to 620 mph) the air flow around the aircraft reaches the speed of sound, and it is reported that the control surfaces no longer effect the direction of flight. The results vary with different airplanes: some wing over and dive while others dive gradually. It is also reported that once the speed of sound is exceeded, this condition disappears and normal control is restored" . The comments about restoration of flight control and cessation of buffeting above Mach 1 are very significant in a 1946 document.

In his book Me-163, former Me-163 pilot Mano Ziegler claims that his friend, test pilot Heini Dittmar, broke the sound barrier when steep-diving the rocket plane and that several on the ground heard the sonic bangs. Heini Dittmar had been accurately and officially recorded at 1004.5km/hr (623.8mph) in level flight on October 2nd, 1941 in the prototype Me163a V4. He reached this speed at less than full throttle as he was concerned by the transonic buffeting. The craft's Walter RII-203 rocket engine produced 7.34 kN (750 kgp / 1,650 lbf) thrust. The flight was made after a drop launch from a carrier plane to conserve fuel, a record that was kept secret till war's end. The craft's potential performance in a powered dive is unknown but the production version of the rocket plane had an even more powerful engine. Ziegler claims that on 6 July 1944, Heini Dittmar flying a production comet Me 163BV18 VA + SP was measured travelling at a speed of 1130km/h. Similar claims for the Spitfire and other propeller aircraft are more suspect. It is now known that traditional airspeed gauges using a pitot tube give inaccurately high readings in the transonic, apparently due to shock waves interacting with the tube or the static source. This led to problems then known as "Mach jump".^[5] The Messerschmitt Me 163 Komet was the only operational rocket fighter aircraft. ... A Pitot tube is a measuring instrument used to measure fluid flow. ...

Attempts to break the sound barrier

The first self propelled vehicle to break the sound barrier was probably the first successful test launch of the German V-2 ballistic missile on 3 October 1942, at Peenemunde in Germany. By September 1944, the V-2s routinely achieved Mach 4 (4,900 km/h) during terminal descent. German test launch. ... Diagram of V-2, the first ballistic missile. ... is the 276th day of the year (277th in leap years) in the Gregorian calendar. ... Year 1942 (MCMXLII) was a common year starting on Thursday (the link will display the full 1942 calendar) of the Gregorian calendar. ... Peenemündes position in Germany Peenemünde is a village in the northeast of the German island of Usedom on the Peene river, on the easternmost part of the German Baltic coast. ...

In 1942 the United Kingdom's Ministry of Aviation began a top secret project with Miles Aircraft to develop the world's first aircraft capable of breaking the sound barrier. The project resulted in the development of the prototype Miles M.52 jet aircraft, which was designed to reach 1,000 mph (417 m/s; 1,600 km/h) at 36,000 feet (11 km) in 1 minute 30 sec. The Ministry of Aviation was a department of the United Kingdom government, established in 1959. ... Miles Aircraft was a British manufacturer of light civil and military aircraft. ... Miles M.52 The Miles M.52 was a supersonic research aircraft project which was undertaken in top secret conditions between 1942 and 1945. ...

The aircraft's design introduced many innovations which are still used on today's supersonic aircraft. The single most important development was the all-moving tailplane, giving extra control to counteract the Mach tuck which allowed control to be maintained at supersonic speeds. In the immediate post-war era new data from captured German records suggested that major savings in drag could be had through a variety of means such as swept wings, and Director of Scientific Research, Sir Ben Lockspeiser, decided to cancel the project in light of this new information. Later experimentation on the Miles M.52 design proved that the aircraft would indeed have broken the sound barrier, with an unpiloted 3/10 scale replica of the M.52 achieving Mach 1.5 in October 1948. Tailplane or horizontal stabilizer of a Boeing 737 A tailplane, also known as horizontal stabilizer, is a small lifting surface located behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed wing aircraft such as helicopters and gyroplanes. ... Mach tuck is an aerodynamic effect, whereby the nose of an aircraft tends to pitch downwards as the airflow around the wing reaches speeds close to Mach 1. ... An object moving through a gas or liquid experiences a force in direction opposite to its motion. ... The swept wing of an airliner: British Midland Airbus A320-200 A swept-wing is a wing planform used on high-speed aircraft that spend a considerable portion of their flight time in the transonic. ... Sir Ben Lockspeiser (March 9, 1891 - October 18, 1990) was the first President of CERN. Quote about the establishment of CERN. Scientific research lives and flourishes in an atmosphere of freedom - freedom to doubt, freedom to enquire and freedom to discover. ...

U.S. efforts started soon after Britain had disclosed all its research and designs to the U.S. government, on the promise that U.S. information would be shared the other way. The U.S. failed to disclose any information in return, stating the Pentagon had deemed the project Top Secret. They took the technological information provided by the British and began work on the Bell XS-1. The final version of the Bell XS-1 has many design similarities to the original Miles version. Also featuring the all-moving tail, the XS-1, later known as the X-1. It was in the X-1 that Chuck Yeager was the first person to break the sound barrier in level flight on 14 October 1947, flying at an altitude of 45,000 ft (13.7 km). This article is about the United States military building. ... The Bell X-1, originally designated XS-1, was a joint NACA-U.S. Army Air Forces/US Air Force supersonic research project and the first aircraft to exceed the speed of sound in controlled, level flight. ... Charles Elwood Chuck Yeager (born February 13, 1923) is a retired Brigadier General in the United States Air Force and a noted test pilot. ... is the 287th day of the year (288th in leap years) in the Gregorian calendar. ... Year 1947 (MCMXLVII) was a common year starting on Wednesday (link will display full 1947 calendar) of the Gregorian calendar. ...

George Welch made a plausible but officially unverified claim to have broken the sound barrier on 1 October 1947, while flying an XP-86 Sabre. He also claimed to have repeated his supersonic flight on 14 October 1947, 30 minutes before Chuck Yeager broke the sound barrier in the Bell X-1 using the adjustable tail concept. Although evidence from witnesses and instruments strongly imply that Welch achieved supersonic speed, the flights were not properly monitored and cannot be officially recognized. (The XP-86 officially achieved supersonic speed on 26 April 1948.) Welch with his XP-86 Sabre George Welch, Major, USAF (May 10, 1918 – October 12, 1954) was a World War II flying ace, a Medal of Honor nominee, and an experimental aircraft pilot after the war. ... is the 274th day of the year (275th in leap years) in the Gregorian calendar. ... Year 1947 (MCMXLVII) was a common year starting on Wednesday (link will display full 1947 calendar) of the Gregorian calendar. ... The North American F-86 Sabre (sometimes called the Sabrejet) was a transonic combat aircraft developed for the US Air Force. ... is the 287th day of the year (288th in leap years) in the Gregorian calendar. ... Year 1947 (MCMXLVII) was a common year starting on Wednesday (link will display full 1947 calendar) of the Gregorian calendar. ... is the 116th day of the year (117th in leap years) in the Gregorian calendar. ... Year 1948 (MCMXLVIII) was a leap year starting on Thursday (link will display the 1948 calendar) of the Gregorian calendar. ...

The sound barrier was first broken in a vehicle in a sustained way on land in 1948 by a rocket-powered test vehicle at Muroc Air Force Base (now Edwards AFB) in California, United States. It was powered by 6,000 pounds (27 kN) of thrust, reaching 1,019 mph (1,640 km/h).^[6] Edwards Air Force Base is a base located on the border of Kern County and Los Angeles County, California in the Antelope Valley, northeast of Lancaster. ...

Jackie Cochran was the first woman to break the sound barrier on 18 May 1953, in a Canadair Sabre, with Yeager as her wingman. Jacqueline Cochran Jacqueline Cochran (born Bessie Lee Pittman on May 11, 1906, died August 7, 1980), was a pioneer American aviatrix. ... is the 138th day of the year (139th in leap years) in the Gregorian calendar. ... Year 1953 (MCMLIII) was a common year starting on Thursday (link will display full calendar) of the Gregorian calendar. ... The Canadair Sabre was a fighter jet built by Canadair under licence from California-based North American Aviation Inc. ...

The Sound Barrier fades

As the science of high-speed flight became more widely understood, a number of changes led to the eventual disappearance of the "sound barrier". Among these were the introduction of swept wings, the area rule, and engines of ever increasing performance. By the 1950s many combat aircraft could routinely break the sound barrier in level flight, although they often suffered from control problems when doing so (Mach tuck). Modern aircraft can transition through the "barrier" without it even being noticeable. The swept wing of an airliner: British Midland Airbus A320-200 A swept-wing is a wing planform used on high-speed aircraft that spend a considerable portion of their flight time in the transonic. ... Junkers patent drawing from March 1944. ... Mach tuck is an aerodynamic effect, whereby the nose of an aircraft tends to pitch downwards as the airflow around the wing reaches speeds close to Mach 1. ...

By the late 1950s the issue was so well understood that many companies started investing in the development of supersonic airliners, or SST's, believing that to be the next "natural" step in airliner evolution. History has proven this not to be the case, at least yet, but the Concorde and Tupolev Tu-144 both entered service in the 1970s regardless. The Concorde supersonic transport has a delta wing, a slender fuselage and four underslung Olympus engines. ... For other uses, see Concorde (disambiguation). ... The Tupolev Tu-144 (NATO reporting name: Charger) was the first supersonic transport aircraft (SST), constructed under the direction of the Soviet Tupolev design bureau headed by Alexei Tupolev (1925–2001). ...

Although the Concorde and Tu-144 were the first aircraft to carry commercial passengers at supersonic speeds, they were not the first or only commercial airliners to break the sound barrier. On 21 August 1961 a Douglas DC-8 broke the sound barrier at Mach 1.012 or (1,240 km/h, 660 mph) while in a controlled dive through 41,088 feet (12,510 m). The purpose of the flight was to collect data on a new leading-edge design for the wing.^[7] A China Airlines 747 almost certainly broke the sound barrier in an unplanned descent from 41,000 ft (12,500 m) to 9,500 feet (2,900 m) after an in-flight upset on 19 February 1985. It also reached over 5g. ^[8] is the 233rd day of the year (234th in leap years) in the Gregorian calendar. ... Year 1961 (MCMLXI) was a common year starting on Sunday (link will display full calendar) of the Gregorian calendar. ... The Douglas DC-8 is a four-engined jet airliner, manufactured from 1958 to 1972. ... China Airlines Flight 006 was a daily non-stop flight departing from Taipei at 4:40 pm and arriving in Los Angeles at 1:25pm local time. ... [[Media:Italic text]]{| style=float:right; |- | |- | |} is the 50th day of the year in the Gregorian calendar. ... This article is about the year. ...

On 15 October 1997, in a vehicle designed and built by a team led by Richard Noble, driver Andy Green became the first person to break the sound barrier in a land vehicle. The vehicle called the ThrustSSC ("Super Sonic Car"), captured the record exactly 50 years and one day after Yeager's flight. is the 288th day of the year (289th in leap years) in the Gregorian calendar. ... For the band, see 1997 (band). ... Richard Noble, OBE (born March 6, 1946, in Edinburgh, Scotland) was a holder of the land speed record, and was the project director of the ThrustSSC, which currently holds the land speed record which was set at Black Rock Desert. ... Wing Commander Andy Green OBE (born 1962), a British RAF pilot, is the current holder of the land speed record and the first person to break the sound barrier on land. ... ThrustSSC at Black Rock Desert, Nevada, USA. The ThrustSSC is built with highly protected aluminium wheels The team with ThrustSSC. ThrustSSC (SuperSonic Car) is a British designed and built jet propelled car developed by Richard Noble and Ron Ayers, which holds the world land speed record. ...

Media

References

Notes

Bibliography

Modern Marvels introductory title. ... Oxford University Press (OUP) is a highly-respected publishing house and a department of the University of Oxford in England. ...

External links

Wikimedia Commons has media related to:

Sound barrier

• collection of tutorials by Dr. Mark S. Cramer, Ph.D. at Fluid Mechanics
• Breaking the Sound Barrier with an Aircraft by Carl Rod Nave, Ph.D. at http://HyperPhysics.phy-astr.gsu.edu (Sound).
• a video of a Concorde reaching Mach 1 at intersection TESGO taken from below.