Misplaced Pages

#10989

85-461: The user of the base is the French Air and Space Force with several operational units on the base, including: The base also hosts a helicopter squadron and a large repair and training facility. In addition, it also includes EPNER (École du Personnel Navigant d’Essais et de Réception); test facilities for DGA Essais en vol, Dassault Aviation , SNECMA , Thales and some aeronautical units of

170-525: A constitutive relation between a turbulent flux and the gradient of a mean variable similar to the relation between flux and gradient that exists for molecular transport. In the best case, this assumption is only an approximation. Nevertheless, the turbulent diffusivity is the simplest approach for quantitative analysis of turbulent flows, and many models have been postulated to calculate it. For instance, in large bodies of water like oceans this coefficient can be found using Richardson 's four-third power law and

255-601: A contingency landing site for the Space Shuttle in the case of a Transoceanic Abort Landing (TAL). The base's runway is 3,750 metres (12,300 ft) long and 60 metres (200 ft) wide. An additional overrun area 1,200 metres (3,900 ft) long was built for Airbus Industries in 1992. It has the same characteristics as the runway, making it the longest runway in Western Europe and thus suited to Shuttle landings. Built prior to World War II , Istres Air Base

340-416: A mean value: and similarly for temperature ( T = T + T′ ) and pressure ( P = P + P′ ), where the primed quantities denote fluctuations superposed to the mean. This decomposition of a flow variable into a mean value and a turbulent fluctuation was originally proposed by Osborne Reynolds in 1895, and is considered to be the beginning of the systematic mathematical analysis of turbulent flow, as

425-453: A new unit tasked with keeping German observation craft from over the French lines. The ad hoc unit commandeered all available Morane-Saulniers and Nieuport 11s , as well as the 15 best pilots regardless of posting. This ad hoc unit patrolling the skies over Verdun was the first French Groupement de Chasse . The Groupement was successful despite Tricornet's death in a mishap. Under

510-457: A statistical description is needed. The Russian mathematician Andrey Kolmogorov proposed the first statistical theory of turbulence, based on the aforementioned notion of the energy cascade (an idea originally introduced by Richardson ) and the concept of self-similarity . As a result, the Kolmogorov microscales were named after him. It is now known that the self-similarity is broken so

595-400: A sub-field of fluid dynamics. While the mean values are taken as predictable variables determined by dynamics laws, the turbulent fluctuations are regarded as stochastic variables. The heat flux and momentum transfer (represented by the shear stress τ ) in the direction normal to the flow for a given time are where c P is the heat capacity at constant pressure, ρ is the density of

680-443: A third hypothesis of Kolmogorov was that at very high Reynolds number the statistics of scales in the range η ≪ r ≪ L are universally and uniquely determined by the scale r and the rate of energy dissipation ε . The way in which the kinetic energy is distributed over the multiplicity of scales is a fundamental characterization of a turbulent flow. For homogeneous turbulence (i.e., statistically invariant under translations of

765-485: A total of 19 squadrons of Mirage III, Jaguars, two squadrons flying the Mirage 5 F (EC 2/13 and EC 3/13, both at Colmar ), and a squadron flying the Mirage F.1 CR. CoTAM counted 28 squadrons, of which ten were fixed-wing transport squadrons, and the remainder helicopter and liaison squadrons, at least five of which were overseas. CAFDA numbered 14 squadrons mostly flying the Mirage F.1 C. Two other commands had flying units,

850-434: A universal constant. This is one of the most famous results of Kolmogorov 1941 theory, describing transport of energy through scale space without any loss or gain. The Kolmogorov five-thirds law was first observed in a tidal channel, and considerable experimental evidence has since accumulated that supports it. Outside of the inertial area, one can find the formula below : In spite of this success, Kolmogorov theory

935-445: A vector r (since the turbulence is assumed isotropic, the flow velocity increment depends only on the modulus of r ). Flow velocity increments are useful because they emphasize the effects of scales of the order of the separation r when statistics are computed. The statistical scale-invariance without intermittency implies that the scaling of flow velocity increments should occur with a unique scaling exponent β , so that when r

SECTION 10

#1732790432011

1020-448: A wide range of length scales and the hierarchy can be described by the energy spectrum that measures the energy in flow velocity fluctuations for each length scale ( wavenumber ). The scales in the energy cascade are generally uncontrollable and highly non-symmetric. Nevertheless, based on these length scales these eddies can be divided into three categories. The integral time scale for a Lagrangian flow can be defined as: where u ′

1105-430: Is a factor in developing turbulent flow. Counteracting this effect is the viscosity of the fluid, which as it increases, progressively inhibits turbulence, as more kinetic energy is absorbed by a more viscous fluid. The Reynolds number quantifies the relative importance of these two types of forces for given flow conditions, and is a guide to when turbulent flow will occur in a particular situation. This ability to predict

1190-466: Is a range of scales (each one with its own characteristic length r ) that has formed at the expense of the energy of the large ones. These scales are very large compared with the Kolmogorov length, but still very small compared with the large scale of the flow (i.e. η ≪ r ≪ L ). Since eddies in this range are much larger than the dissipative eddies that exist at Kolmogorov scales, kinetic energy

1275-405: Is at present under revision. This theory implicitly assumes that the turbulence is statistically self-similar at different scales. This essentially means that the statistics are scale-invariant and non-intermittent in the inertial range. A usual way of studying turbulent flow velocity fields is by means of flow velocity increments: that is, the difference in flow velocity between points separated by

1360-410: Is characterized by a hierarchy of scales through which the energy cascade takes place. Dissipation of kinetic energy takes place at scales of the order of Kolmogorov length η , while the input of energy into the cascade comes from the decay of the large scales, of order L . These two scales at the extremes of the cascade can differ by several orders of magnitude at high Reynolds numbers. In between there

1445-431: Is characterized by the following features: Turbulent diffusion is usually described by a turbulent diffusion coefficient . This turbulent diffusion coefficient is defined in a phenomenological sense, by analogy with the molecular diffusivities, but it does not have a true physical meaning, being dependent on the flow conditions, and not a property of the fluid itself. In addition, the turbulent diffusivity concept assumes

1530-647: Is commonly observed in everyday phenomena such as surf , fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason, turbulence is commonly realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. The onset of turbulence can be predicted by

1615-400: Is considerable evidence that turbulent flows deviate from this behavior. The scaling exponents deviate from the ⁠ n / 3 ⁠ value predicted by the theory, becoming a non-linear function of the order n of the structure function. The universality of the constants have also been questioned. For low orders the discrepancy with the Kolmogorov ⁠ n / 3 ⁠ value

1700-419: Is essentially not dissipated in this range, and it is merely transferred to smaller scales until viscous effects become important as the order of the Kolmogorov scale is approached. Within this range inertial effects are still much larger than viscous effects, and it is possible to assume that viscosity does not play a role in their internal dynamics (for this reason this range is called "inertial range"). Hence,

1785-473: Is governed by the random walk principle. In rivers and large ocean currents, the diffusion coefficient is given by variations of Elder's formula. Via this energy cascade , turbulent flow can be realized as a superposition of a spectrum of flow velocity fluctuations and eddies upon a mean flow . The eddies are loosely defined as coherent patterns of flow velocity, vorticity and pressure. Turbulent flows may be viewed as made of an entire hierarchy of eddies over

SECTION 20

#1732790432011

1870-757: Is organized in accordance with Chapter 4, Title II, Book II of the Third Part of the French Defense Code ( French : code de la Défense ), which replaced decree n° 91-672 dated 14 July 1991. Under the authority of the Chief of Staff of the French Air and Space Force (CEMAAE) in Paris , the Air and Space Force includes: The Air and Space Force headquarters, employing 150 personnel, are located alongside

1955-422: Is scaled by a factor λ , should have the same statistical distribution as with β independent of the scale r . From this fact, and other results of Kolmogorov 1941 theory, it follows that the statistical moments of the flow velocity increments (known as structure functions in turbulence) should scale as where the brackets denote the statistical average, and the C n would be universal constants. There

2040-447: Is sufficiently high. Thus, Kolmogorov introduced a second hypothesis: for very high Reynolds numbers the statistics of small scales are universally and uniquely determined by the kinematic viscosity ν and the rate of energy dissipation ε . With only these two parameters, the unique length that can be formed by dimensional analysis is This is today known as the Kolmogorov length scale (see Kolmogorov microscales ). A turbulent flow

2125-401: Is the mean turbulent kinetic energy of the flow. The wavenumber k corresponding to length scale r is k = ⁠ 2π / r ⁠ . Therefore, by dimensional analysis, the only possible form for the energy spectrum function according with the third Kolmogorov's hypothesis is where K 0 ≈ 1.5 {\displaystyle K_{0}\approx 1.5} would be

2210-505: Is the velocity fluctuation, and τ {\displaystyle \tau } is the time lag between measurements. Although it is possible to find some particular solutions of the Navier–Stokes equations governing fluid motion, all such solutions are unstable to finite perturbations at large Reynolds numbers. Sensitive dependence on the initial and boundary conditions makes fluid flow irregular both in time and in space so that

2295-466: Is very small, which explain the success of Kolmogorov theory in regards to low order statistical moments. In particular, it can be shown that when the energy spectrum follows a power law with 1 < p < 3 , the second order structure function has also a power law, with the form Since the experimental values obtained for the second order structure function only deviate slightly from the ⁠ 2 / 3 ⁠ value predicted by Kolmogorov theory,

2380-823: The Division Aerienne fought until war's end. By the time of the Battle of Saint-Mihiel , the French could commit 27 fighter squadrons to the effort, along with reconnaissance and bombing squadrons. The 1,137 airplanes dedicated to the battle were the most numerous used in a World War I battle. When the 11 November 1918 armistice came, French air power had expanded to 336 squadrons, 74 of which were SPAD fighter squadrons. France had 3,608 planes in service. Confirmed claims of 2,049 destroyed enemy airplanes included 307 that had been brought down within French lines. French airmen had also destroyed 357 observation balloons . However, 5,500 pilots and observers were killed out of

2465-657: The Groupement d'Unités Aériennes Spécialisées . Also created in 1964 was the Escadron des Fusiliers Commandos de l'Air (EFCA), seemingly grouping all FCA units. The Dassault Mirage IV , the principal French strategic bomber, was designed to strike Soviet positions as part of the French nuclear triad . In 1985, the Air Force had four major flying commands, the Strategic Air Forces Command ,

2550-532: The Fusiliers Commandos de l'Air command was reestablished under a different form. The French Air Force entered a phase of inventory replacement and expansion. The Air Force ordered the Airbus A400M military transport aircraft, then in development. By November 2016, 11 had already been delivered to ET00.061 at Orleans-Bricy, and integration of the new Dassault Rafale multi-role jet fighter

2635-472: The 324th Fighter Group to the airfield on 2 September, with Republic P-47 Thunderbolts . However the 324th only remained a few days before moving forward to Amberieu on 6 September. The main USAAF use of Istres was by the 64th Troop Carrier Group , which operated Douglas C-47 Skytrain transports from the airfield from September to November 1944. When the combat units moved north into eastern France, Istres

Istres-Le Tubé Air Base - Misplaced Pages Continue

2720-762: The Air Force Training Command , and the Air Force Transmissions Command, with four squadrons and three trials units. Dassault Aviation led the way mainly with delta-wing designs, which formed the basis for the Dassault Mirage III series of fighter jets . The Mirage demonstrated its abilities in the Six-Day War , Yom Kippur War , Falklands War , and Gulf War , becoming one of the most popular jet fighters of its day and being widely sold. In 1994,

2805-831: The Battle of France in 1940. The Vichy French Air Force had later a significant presence in the French Levant . The engagement of the Free French Air Forces from 1940 to 1943, and then the engagement of the aviators of the French Liberation Army , were also important episodes in the history of the French Air Force. The sacrifices of Commandant René Mouchotte and Lieutenant Marcel Beau illustrated their devotion. After 1945, France rebuilt its aircraft industry. The French Air Force participated in several colonial wars during

2890-404: The C n constants, are related with the phenomenon of intermittency in turbulence and can be related to the non-trivial scaling behavior of the dissipation rate averaged over scale r . This is an important area of research in this field, and a major goal of the modern theory of turbulence is to understand what is universal in the inertial range, and how to deduce intermittency properties from

2975-710: The Chief of the Defence Staff (CEMA) on the deployment, manner, and use of the Air and Space Force. They are responsible for the preparation and logistic support of the French Air and Space Force. The CEMAA is assisted by a Deputy Chief, the Major Général de l'Armée de l'Air . Finally, the CEMAA is assisted by the Inspectorate of the French Air and Space Force (IAA) and by the French Air and Space Force Health Service Inspection (ISSAA). The Air and Space Force

3060-588: The Chief of the Defence Staff 's offices (EMA) and the Army and Navy headquarters at the Balard armed forces complex in Paris. The new site replaced the former Paris Air Base (BA 117) which served as air staff headquarters until 25 June 2015. The French Air and Space Force has had three commands: two grand operational commands (CDAOA and CFAS) and one organic command (CFA). These last two brigades belonged until 2013 to

3145-560: The French Navy . More than 5,000 personnel work on the base. Secondary users occasionally include the United States Air Force (USAF), during Allied operations engaging United States and France. During Operation Allied Force , USAF Boeing KC-135 Stratotankers and Lockheed U-2s operated out of the base. Istres was the home of U-2 detachment OL-FR (Operating Location-FRance). Istres was also designated by NASA as

3230-523: The Reynolds number , which is the ratio of inertial forces to viscous forces within a fluid which is subject to relative internal movement due to different fluid velocities, in what is known as a boundary layer in the case of a bounding surface such as the interior of a pipe. A similar effect is created by the introduction of a stream of higher velocity fluid, such as the hot gases from a flame in air. This relative movement generates fluid friction, which

3315-772: The Strategic Air Forces Command , COTAM, the Air Command of Aerial Defense Forces ( Commandement Air des Forces de Défense Aérienne , CAFDA), and the Force aérienne tactique (FATac). In 1964, the Second Tactical Air Command was created in Nancy to take command of air units stationed in France but not assigned to NATO . The Military Air Transport Command had previously been formed in February 1962 from

3400-640: The kinetic energy is significantly absorbed due to the action of fluid molecular viscosity gives rise to a laminar flow regime. For this the dimensionless quantity the Reynolds number ( Re ) is used as a guide. With respect to laminar and turbulent flow regimes: The Reynolds number is defined as where: While there is no theorem directly relating the non-dimensional Reynolds number to turbulence, flows at Reynolds numbers larger than 5000 are typically (but not necessarily) turbulent, while those at low Reynolds numbers usually remain laminar. In Poiseuille flow , for example, turbulence can first be sustained if

3485-480: The 17,300 engaged in the conflict, amounting to 31%. A 1919 newspaper article reported that the French Air Force had suffered losses of 61%. Military aeronautics was established as a "special arm" by the law of 8 December 1922. It remained under the auspices of the French Army . It was not until 2 July 1934, that the "special arm" became an independent service and was totally independent. The initial air arm

Istres-Le Tubé Air Base - Misplaced Pages Continue

3570-493: The 1960s, there were five air regions (RA). The number was then reduced to four by a decree of 30 June 1962 with the disestablishment of the 5th Aerial Region ( French North Africa ). The decree of 14 July 1991 reduced the air regions to three: « RA Atlantic », « RA Mediterranean » and «  RA North-East ». On 1 July 2000 was placed into effect an organization consisting of « RA North » (RAN) and « RA South » (RAS). The territorial division

3655-532: The Air Force Support Command (CSFA), which maintained the arms systems, equipment, information and communication systems (SIC) as well as infrastructure. The CSFA supported the human element, the military logistics (supply and transport), wherever, previously, forces of the French Air and Space Force operated or trained. These two brigades are now subordinate to the CFA. The official designation of

3740-491: The Air and Space Force (DRH-AAE) recruits, trains, manages, administers, and converts personnel of the Air and Space Force. Since January 2008, the DRH-AAE groups the former Air Force directorate of military personnel (DPMMA) and some tasks of the former Air Force Training Command . The directorate is responsible for Air and Space Force recruitment via the recruiting bureau. French joint defence service organisations, supporting

3825-754: The Empire such as French Indochina after the Second World War. Since 1945, the French Air Force was notably engaged in Indochina (1945–1954). The French Air Force was active in Algeria from 1952 until 1962 and Suez (1956), later Mauritania and Chad , the Persian Gulf (1990–1991), ex- Yugoslavia and more recently in Afghanistan , Mali and Iraq . From 1964 until 1971

3910-558: The French Air Force had the unique responsibility for the French nuclear arm via Dassault Mirage IV or ballistic missiles of Air Base 200 Apt-Saint-Christol on the Plateau d'Albion. Accordingly, from 1962, the French political leadership shifted its military emphasis to nuclear deterrence , implementing a complete reorganisation of the Air Force, with the creation of four air regions and seven major specialised commands, among which were

3995-542: The French Air Force. On 10 September 2020, it assumed its current name, the French Air and Space Force, to reflect an "evolution of its mission" into the area of outer space . The number of aircraft in service with the French Air and Space Force varies depending on the source; the Ministry of Armed Forces gives a figure of 658 aircraft in 2014. According to 2018 data, this figure includes 210 combat aircraft: 115 Dassault Mirage 2000 and 95 Dassault Rafale . As of 2021,

4080-552: The French Air and Space Force employs a total of 40,500 regular personnel, with a reserve element of 5,187 in 2014. The Chief of Staff of the French Air and Space Force (CEMAAE) is a direct subordinate of the Chief of the Defence Staff (CEMA), a high-ranking military officer who in turn answers to the civilian Minister of the Armed Forces . The founding of the Service Aéronautique began in 1909, when

4165-539: The French War Minister approved the purchase of a Wright Biplane . The following year, another Wright biplane, a Bleriot , and two Farmans were added to the lone acquisition. On 22 October 1910, General Pierre Roques was appointed Inspector General of what was becoming referred to as the Cinquieme Arme, or Fifth Service. In March 1912, the French parliament enacted legislation to establish

4250-754: The Invasion of Southern France in August 1944 and was repaired and placed into operational use by the United States Army Air Forces XII Engineer Command, being turned over to Twelfth Air Force on 27 August 1944. The airfield was designated by the Americans as Istres/Le Tubé Airfield or Advanced Landing Ground Y-17 . It was also given the AAF designation of USAAF Station 196 . Twelfth Air Force initially assigned

4335-493: The Reynolds number is larger than a critical value of about 2040; moreover, the turbulence is generally interspersed with laminar flow until a larger Reynolds number of about 4000. The transition occurs if the size of the object is gradually increased, or the viscosity of the fluid is decreased, or if the density of the fluid is increased. When flow is turbulent, particles exhibit additional transverse motion which enhances

SECTION 50

#1732790432011

4420-667: The Tactical Air Forces Command, the Military Air Transport Command , and CAFDA (air defence). CFAS had two squadrons of S2 and S-3 IRBMs at the Plateau d'Albion, six squadrons of Mirage IV As (at Mont de Marsan , Cazaux, Orange, Istres, St Dizier, and EB 3/94 at Luxeuil - Saint-Sauveur Air Base ), and three squadrons of C-135F , as well as a training/reconnaissance unit, CIFAS 328, at Bordeaux . The tactical air command included wings EC 3, EC 4, EC 7, EC 11, EC 13, and ER 33, with

4505-570: The air and space force, include: Commanded by a Lieutenant-colonel or Colonel, the Escadre is a formation that assembles various units and personnel dedicated to the same mission. In 1932, the "regiment" designation was replaced with "Escadre", which until 1994 was a unit consisting of the following: Escadres ( wings ) were dissolved from 1993 as part of the Armées 2000 reorganisation, were reestablished in 2014. The problems caused by having

4590-596: The air arm. It was projected to consist of three distinct branches based on aircraft missions—reconnaissance, bombing, or countering other aircraft. France was one of the first states to start building aircraft. At the beginning of World War I , France had a total of 148 planes (eight from French Naval Aviation ( Aéronautique Navale )) and 15 airships . In August 1914, as France entered World War I, French airpower consisted of 24 squadrons ( escadrilles ) supporting ground forces, including three squadrons assigned to cavalry units. By 8 October, expansion to 65 squadrons

4675-508: The aircraft had passed mandatory maintenance and was overloaded. French Air and Space Force The French Air and Space Force ( French : Armée de l'air et de l'espace , lit.   ' Army of Air and Space ' ) is the air and space force of the French Armed Forces . Formed in 1909 as the Service Aéronautique , a service arm of the French Army , it became an independent military branch in 1934 as

4760-424: The aircraft maintenance units not responsible to the flying squadrons they supported eventually forced the change. Turbulence In fluid dynamics , turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity . It is in contrast to laminar flow , which occurs when a fluid flows in parallel layers with no disruption between those layers. Turbulence

4845-523: The civilian population. The last remaining squadron of Dassault Mirage F1s retired the aircraft in July 2014 and replaced them with Dassault Rafales . On 13 July 2019, President Emmanuel Macron announced the creation of a space command, which would come into being within the French Air Force by September 2019, and the transformation of the French Air Force into the French Air and Space Force. According to Defense Minister Florence Parly , France reserves

4930-492: The dimensionless Reynolds number , the ratio of kinetic energy to viscous damping in a fluid flow. However, turbulence has long resisted detailed physical analysis, and the interactions within turbulence create a very complex phenomenon. Physicist Richard Feynman described turbulence as the most important unsolved problem in classical physics. The turbulence intensity affects many fields, for examples fish ecology, air pollution, precipitation, and climate change. Turbulence

5015-401: The end of the French accumulation of air power. On 14 May 1918, they were grouped into the Division Aerienne . As bombing aircraft were also being concentrated into larger units, the new division would also contain Escadre de Bombardement No. 12 and Escadre de Bombardement No. 13 . The bombing units were both equipped with 45 Breguet 14 bombers. The last addition to the new division

5100-581: The first." A similar witticism has been attributed to Horace Lamb in a speech to the British Association for the Advancement of Science : "I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather more optimistic." The onset of turbulence can be, to some extent, predicted by

5185-499: The fluid, μ turb is the coefficient of turbulent viscosity and k turb is the turbulent thermal conductivity . Richardson's notion of turbulence was that a turbulent flow is composed by "eddies" of different sizes. The sizes define a characteristic length scale for the eddies, which are also characterized by flow velocity scales and time scales (turnover time) dependent on the length scale. The large eddies are unstable and eventually break up originating smaller eddies, and

SECTION 60

#1732790432011

5270-582: The inventories of the French. With the Groupes success, the French were encouraged to amass airpower into still larger tactical units. On 4 February 1918, Escadre de Combat No. 1 was created out of Groupe de Combat 15 , Groupe de Combat 18 , and Groupe de Combat 19 . It was followed by Escadre de Combat No. 2 , formed on the 27th from Groupe de Combat 11 , Groupe de Combat 13 , and Groupe de Combat 17 . Each groupe would be stocked with 72 fighters. The escadres were not

5355-399: The kinetic energy of the initial large eddy is divided into the smaller eddies that stemmed from it. These smaller eddies undergo the same process, giving rise to even smaller eddies which inherit the energy of their predecessor eddy, and so on. In this way, the energy is passed down from the large scales of the motion to smaller scales until reaching a sufficiently small length scale such that

5440-619: The leadership of new commander Captain Auguste de Reverand, such flying aces as Georges Guynemer , Charles Nungesser , and Albert Deullin began their careers. Encouraged by the success of their original Groupement , the French massed several squadrons for the Battle of the Somme . The burgeoning French aircraft inventory afforded the formation of Groupement de Combat de la Somme under Captain Felix Brocard . The Groupement

5525-498: The onset of turbulent flow is an important design tool for equipment such as piping systems or aircraft wings, but the Reynolds number is also used in scaling of fluid dynamics problems, and is used to determine dynamic similitude between two different cases of fluid flow, such as between a model aircraft, and its full size version. Such scaling is not always linear and the application of Reynolds numbers to both situations allows scaling factors to be developed. A flow situation in which

5610-460: The particular geometrical features of the boundaries (the size characterizing the large scales will be denoted as L ). Kolmogorov's idea was that in the Richardson's energy cascade this geometrical and directional information is lost, while the scale is reduced, so that the statistics of the small scales has a universal character: they are the same for all turbulent flows when the Reynolds number

5695-421: The rate of energy and momentum exchange between them thus increasing the heat transfer and the friction coefficient. Assume for a two-dimensional turbulent flow that one was able to locate a specific point in the fluid and measure the actual flow velocity v = ( v x , v y ) of every particle that passed through that point at any given time. Then one would find the actual flow velocity fluctuating about

5780-586: The reference frame) this is usually done by means of the energy spectrum function E ( k ) , where k is the modulus of the wavevector corresponding to some harmonics in a Fourier representation of the flow velocity field u ( x ) : where û ( k ) is the Fourier transform of the flow velocity field. Thus, E ( k ) d k represents the contribution to the kinetic energy from all the Fourier modes with k < | k | < k + d k , and therefore, where ⁠ 1 / 2 ⁠ ⟨ u i u i ⟩

5865-476: The right to arm French satellites with lasers for defensive purposes. The official renaming occurred on 24 July 2020, with the new Air and Space Force logo unveiled on 11 September 2020. On 26 July 2023, FASF conducted its first ever joint fighter exercise with Japan , continuing its defense ties between the two countries. The Chief of Staff of the French Air and Space Force (CEMAAE) determines French Air and Space Force doctrines application and advises

5950-607: The service was changed in July 2019 from Air Army ( Armée de l'Air ) to Air and Space Army ( Armée de l'air et de l'espace ), when the previous joint Inter-Service Space Command ( Commandement interarmées de l'espace ( CIE )) under the French General Staff was transformed into the Space Command ( Commandement de l'espace ( CDE )) and absorbed into the Air and Space Force as its fourth command. All air regions were disestablished on 1 January 2008. In

6035-400: The statistical description is presently modified. A complete description of turbulence is one of the unsolved problems in physics . According to an apocryphal story, Werner Heisenberg was asked what he would ask God , given the opportunity. His reply was: "When I meet God, I am going to ask him two questions: Why relativity ? And why turbulence? I really believe he will have an answer for

6120-403: The value for p is very near to ⁠ 5 / 3 ⁠ (differences are about 2% ). Thus the "Kolmogorov − ⁠ 5 / 3 ⁠ spectrum" is generally observed in turbulence. However, for high order structure functions, the difference with the Kolmogorov scaling is significant, and the breakdown of the statistical self-similarity is clear. This behavior, and the lack of universality of

6205-400: The viscosity of the fluid can effectively dissipate the kinetic energy into internal energy. In his original theory of 1941, Kolmogorov postulated that for very high Reynolds numbers , the small-scale turbulent motions are statistically isotropic (i.e. no preferential spatial direction could be discerned). In general, the large scales of a flow are not isotropic, since they are determined by

6290-496: The wing in turbulence at 35,000 feet (11,000 m). The aircraft performed a flapless , downwind landing with a touch-down speed of nearly 200 knots (370 km/h; 230 mph) and the right wing on fire from the pouring fuel. The gear failed and the aircraft slid off the far end of the runway , but the crew of five survived and the cargo was saved. The incident brought to light severe deficiencies in Kabo Air 's operations —

6375-470: Was abolished by decree n°2007-601 of 26 April 2007. From 2008 to 2010 the French Air Force underwent the "Air 2010" streamlining process. The main targets of this project were to simplify the command structure, to regroup all military and civil air force functions and to rationalise and optimise all air force units. Five major commands, were formed, instead of the former 13, and several commands and units were disbanded. The Directorate of Human Resources of

6460-410: Was assigned four Nieuport fighter squadrons; again, each was sent to support a different French field army . On 10 January 1918, Groupe de Combat 16 was formed from four SPAD squadrons. In February, five more Groupe de Combats were founded from SPAD squadrons: Groupes de Combats number 17, 18, 19, 20, and 21. The various Nieuport models were now being phased out as the new SPADs filled

6545-487: Was being planned. By December, the plans called for 70 new squadrons. Meanwhile, even as procurement efforts scaled up, inventive airmen were trying to use various light weapons against opposing airplanes. Roland Garros invented a crude method of firing a machine gun through the propeller arc by cladding his propeller with metal wedges deflecting any errant bullets. After destroying three German airplanes, Garros came down behind enemy lines on 18 April 1915. His secret weapon

6630-623: Was first used by the French Air Force during the early part of the war, and after the 1940 Battle of France and the June Armistice with Nazi Germany , became part of the limited ( French : Armée de l'Air de Vichy ) air force of the Vichy Government . It was attacked on several missions by Allied bombers based in England while under German control after November 1942. It was seized by Allied forces during Operation Dragoon ,

6715-630: Was five protection squadrons, operating 75 Caudron R.11 gunships to fly escort for the Breguets. On 25 June 1918, Groupe de Combat 22 was founded. Groupe de Combat 23 followed soon thereafter. A couple of night bombardment groupes were also founded. Then, on 15 July 1918, the Division was committed to the Second Battle of the Marne . From then on, whether in whole or in part,

6800-521: Was formed on 1 July 1916 with a posting of four Nieuport squadrons: Squadron N.3 , N.26 , N.73 , and N.103 . Three other squadrons-- Squadron N.37 , N.62 , and N.65 were temporarily attached at various times. On 19 October 1916, three fixed Groupes de Combat were established, each to consist of four squadron. Numbered 11 , 12 , and 13 , they were only the first three Groupements . During March 1917, Groupe de Combat 14 and Groupe de Combat 15 were formed. Again, each new Groupe

6885-668: Was host to the Royal Air Force Liaison Party, that serviced transient British and Commonwealth military aircraft staging to and from the United Kingdom. In May 1958, the Royal Air Force Liaison Party, moved to Base Aérienne 115 Orange-Caritat where it continued into the early 1960s. On 31 March 1992, Trans-Air Service Flight 671 , a Boeing 707 , made an emergency landing at Istres after engines 3 and 4 had separated from

6970-669: Was the cradle of French military parachuting , responsible for the first formation of the Air Infantry Groups ( Groupements de l'Infanterie de l'Air ) in the 1930s, out of which the Air Parachute Commandos ( commandos parachutistes de l'air ) descended. The French Air Force maintained a continuous presence across the French colonial empire , particularly from the 1920s to 1943. The French Air Force played an important role in WWII, most notably during

7055-544: Was thus exposed, and Anthony Fokker came up with the synchronization gear that by July 1, 1915 , turned airplanes into flying gun platforms. On 21 February 1916, the Verdun Offensive began. New weapons demanded new tactics. Commandant Charles de Tricornet de Rose was the original French pilot, having learned to fly in March 1911. This experienced flier was given a free hand to select pilots and airplanes for

7140-698: Was underway; the first 20-aircraft squadron became operational in 2006 at Saint-Dizier . In 2009, France rejoined the NATO Military Command Structure , having been absent since 1966. France was a leading nation, alongside the United States , United Kingdom and Italy in implementing the UN sponsored no-fly zone in Libya (NATO Operation Unified Protector ), deploying 20 fighter aircraft to Benghazi in defense of rebel-held positions and

7225-579: Was used by Air Transport Command as a transshipment point for supplies and Allied personnel, being administratively controlled by the 1411th Army Air Force Base Unit. With the end of the war, the Americans used Istres as a staging point between Occupied Germany and Morocco for air transport of personnel back to the United States. It was returned to full French control in October 1945. Sometime after World War II, until May 1958, Base Aérienne 125

#10989