Dassault Mirage III
The Dassault Mirage III is a family of single-seat, single-engine, fighter aircraft developed and manufactured by French aircraft company Dassault Aviation. It was the first Western European combat aircraft to exceed Mach 2 in horizontal flight. During 1952, the French government issued its specification, calling for a lightweight, all-weather interceptor. Amongst the respondents were Dassault with their design known as the MD.550 Mystère-Delta and renamed as the Mirage I. Following favourable flight testing held during 1955, in which speeds of up to Mach 1.6 were attained, it was decided that a larger follow-on aircraft would be required to bear the necessary equipment and payloads. An enlarged Mirage II proposal was considered, as well as MD 610 Cavalier, but was discarded in favour of a further-developed design, powered by the newly developed Snecma Atar afterburning turbojet engine, designated as the Mirage III. During October 1960, the first major production model, designated as the Mirage IIIC, performed its maiden flight.
Initial operational deliveries of this model commenced during July 1961. The Mirage IIIC was followed by numerous other variants; the Mirage III was produced in large numbers for both the French Air Force and a wide number of export customers. Prominent overseas operators of the fighter included Argentina, South Africa and Israel, as well as a number of non-aligned nations. Considered to be a second-generation fighter aircraft, the Mirage III experienced a lengthy service life with several of these operators. During its service with the French Air Force, the Mirage III was armed with assorted air-to-ground ordnance or R.550 Magic air-to-air missiles. Its design proved to be versatile, allowing the fighter model to have been adapted to serve in a variety of roles, including trainer and ground-attack versions, along with several more extensive derivatives of the aircraft, including the Dassault Mirage 5, Dassault Mirage IIIV and Atlas Cheetah; some operators have undertaken extensive modification and upgrade programmes of their flights, such as Project ROSE of the Pakistan Air Force.
The Mirage III has been used in active combat roles in multiple conflicts by a number of operators. The Israeli Air Force was the most prolific operator of the fighter outside of France itself. Ace of ace Giora Epstein achieved all of his kills flying either the Mirage III or the Nesher. During the South African Border War, the Mirage III formed the bulk of the South African Air Force's fleet, comprising a cluster of Mirage IIICZ interceptors, Mirage IIIEZ fighter-bombers and Mirage IIIRZ reconnaissance fighters; the Argentine Air Force utilised the Mirage IIIEA during the Falklands War, but their lack of an aerial refueling capability limited their usefulness in the conflict. Using drop tanks, the Mirages only had an endurance of five minutes within the combat area around the British fleet; the Mirage III family has its origins within a series of studies conducted by the French Defence Ministry which had commenced during 1952. At the time, several nations had taken an interest in the prospects of a light fighter, motivated by combat experiences acquired during the Korean War the Soviet-built Mikoyan-Gurevich MiG-15 jet-propelled fighter aircraft which had drawn considerable attention internationally.
Western nations were keen to explore the performance of a uncomplicated and armed jet-powered swept wing fighter, inspired by the rapid advances in aircraft capabilities, made by the Soviet Union. France was one of the quickest governments of several nations, including the United Kingdom, the United States, Italy, to embark on encouraging the development of such an aircraft. During 1952, the French government issued its specification, calling for a lightweight, all-weather interceptor, capable of climbing to 18,000 meters in 6 minutes along with the ability to reach Mach 1.3 in level flight. Three separate French manufacturers decided to respond to the specification, these being Dassault Aviation, Sud-Est, Sud-Ouest, offering the MD.550 Mystère-Delta, SE.212 Durandal and SO.9000 Trident, respectively. Dassault's submission, which became known as the MD.550 Mystère-Delta, was a diminutive and sleek-appearing aircraft, principally powered by a pair of 9.61 kN Armstrong Siddeley MD30R Viper afterburning turbojet engines.
The basic layout of the Mystère-Delta featured a tailless delta configuration, possessing a 5 per cent thickness and 60° sweep, complete with a large vertical stabilizer and rudder. However, the tailless delta configuration imposed a number of limitations, includi
Dassault Mirage G
The Dassault Mirage G was a French two-seat twinjet variable-geometry prototype fighter, built by Dassault Aviation in the late 1960s. The type was further developed into the twin-engine Mirage G4 and G8 variants as a multi-role jet fighter capable of both interception and nuclear strike missions. Although Dassault built and flew prototypes, the entire programme was terminated in the 1970s without the aircraft entering production. In 1964 the French defence ministry requested a development programme on variable-sweep wing aircraft for dual land and aircraft carrier use. France had participated with the Anglo-French Variable Geometry aircraft before abandoning their interest; the first variable-sweep aircraft from Dassault emerged as the single-engined, two-seat Mirage G fighter in 1967 a swing wing version of the Mirage F2. The wings were swept at 22 degrees when forward and 70 degrees when aft and featured full-span double-slotted trailing edge flaps and two-position leading edge flaps. Flight trials were successful but no production order ensued, the Mirage G programme being cancelled in 1968.
Flying with the Mirage G continued however until 13 January 1971 when the sole prototype was lost in an accident. Single-engined initial version, first flight 18 November 1967. Crashed 13 January 1971; the basic Mirage G was developed into a twin-engine, two-seat nuclear strike fighter, the Mirage G4 after a separate contract was issued in 1968 for two aircraft to be built. These aircraft were intended to be powered by Snecma M53 turbofans in production. While the aircraft were under construction the requirements changed and the French military requested that the design be converted into a dedicated interceptor, the Mirage G8. Mirage G4-01 was redesignated G8-01 and remained a two-seat aircraft with the second aircraft, G4-02 becoming a single-seat version, G8-02; the G8 variants were equipped with Thomson-CSF radar and a low-altitude navigational-attack system based on that used in the SEPECAT Jaguar and Dassault Milan. As no funding was included for the Mirage G8 in the 1971-1976 French defence budget the aircraft did not enter production.
The Ling-Temco-Vought company was in search of skills on the variable-geometry wings, within the framework of the program Light Weight Fighter and in search of the VFX. This company decided to cooperate with the Avions company Marcel Dassault, which had just made a success of the development of the Mirage G. Two agreements were signed in 1968, for general cooperation and other one on the variable-geometry wings. For the competition VFX, the prototype LTV V-507, inspired by the Mirage G, was rejected to the benefit of the Grumman F-14 Tomcat. In the reading of the file of the LTV V-507, the Grumman company asked for numerous further information, in front of the interest of the technical solutions held for the Mirage G; the Pentagon envisaged this plane as basis for the program Light Weight Fighter, but other solutions were used. Dassault Mirage G8-01 is on public display at the Musée de l’air et de l’espace near Paris. Dassault Mirage G8-02 is on public display at the Musée Européen de l'Aviation de Chasse, Montélimar.
General characteristics Crew: 1 Length: 18.8 m Wingspan: 15.4 m Lower wingspan: 8.7 m swept Height: 5.35 m Empty weight: 14,740 kg Powerplant: 2 × SNECMA Atar 9K50 after-burning turbojet engines, 49.03 kN thrust each dry, 70.1 kN with afterburnerPerformance Maximum speed: Mach 2.2 Range: 3,850 km Service ceiling: 18,500 m Related development Dassault Mirage F2Aircraft of comparable role and era General Dynamics F-111 Aardvark Grumman F-14 Tomcat Mikoyan-Gurevich MiG-23 Panavia Tornado Related lists List of fighter aircraft List of military aircraft of France Flight International - October 1971 - Mirage G
Dassault/Dornier Alpha Jet
The Dassault/Dornier Alpha Jet is a light attack jet and advanced jet trainer co-manufactured by Dassault Aviation of France and Dornier Flugzeugwerke of Germany. It was developed to perform the trainer and light attack missions, as well as to perform these duties more ideally than the first generation of jet trainers that preceded it. Following a competition, a design submitted by a team comprising Breguet Aviation, Dassault Aviation, Dornier Flugzeugwerke designated as the TA501, was selected and subsequently produced as the Alpha Jet. Both the French Air Force and German Air Force procured the Alpha Jet in large numbers, the former principally as a trainer aircraft and the latter choosing to use it as a light attack platform; as a result of post-Cold War military cutbacks, Germany elected to retire its own fleet of Alpha Jets in the 1990s and has re-sold many of these aircraft to both military and civilian operators. The Alpha Jet has been adopted by a number of air forces across the world and has seen active combat use by some of these operators.
In the early 1960s, European air forces began to consider their requirements for the coming decades. One such area of consideration was the requirement for a new generation of jet-powered trainer aircraft to replace such aircraft as the US-built Lockheed T-33 Shooting Star and French-built Fouga Magister. Britain and France established a collaborative program to pursue development of what was intended to become a supersonic jet aircraft; this aircraft was to be produced in two distinct variants for different roles: trainer and light attack aircraft. The result of this collaboration, the SEPECAT Jaguar, proved to be an excellent aircraft, but its definition had changed in the interim, the type emerged as a full-sized, nuclear-capable strike fighter, whose two-seat variants were used for operational conversion to the type; as such, the Jaguar was not well suited for the general training mission. This left the original requirement unfulfilled. West Germany was keen to participate in such talks, having long held an interest in conducting joint training operations with France along with a desire for strengthening positive political relations between the two nations.
France valued military cooperation with West Germany, wanting to break a perceived German ideological preference for American aircraft. In 1968, a joint specification was produced out of these talks. One substantial change to the requirements was that the sought trainer was now specified to be subsonic, supersonic trainer aircraft having proven to be superfluous to practical requirements. In July 1969, a joint development and production agreement was signed between West Germany and France. At one point, both the German government and the German Air Force had been keen to relocate pilot training activities from the United States to France as part of the project. In 1971, this was abandoned over fears of a hostile US reaction and West Germany's offset obligations to the United States making such a move unpalatable. While the joint Franco-German training proposal was abandoned, the German government felt obligated to proceed with the aircraft program. Accordingly, Germany proposed that the aircraft be built in two distinct versions, as an inexpensive trainer for the French requirement, as a close air support platform for the German requirement.
An initial point of contention whether to use a French or American powerplant for the aircraft was settled, with France agreeing to finance the development of the French-built Larzac engine while Germany agreed to adopt the same powerplant. A total of three groups of manufacturers produced proposals in response to the requirement; each of these proposals were to be powered by twin SNECMA Turbomeca Larzac turbofan engines. The German Air Force had insisted that the trainer have two engines after having suffered from severe aircraft attrition rates due to the high accident rate of the single-engine Lockheed F-104 Starfighter. On 23 July 1970, the Breguet-Dassault-Dornier TA501 was declared the winner of the competition. In February 1971, the project definition phase was formally completed and the integrated design team was formally set up at Saint-Cloud, France. In February 1972, the approval to proceed with full development was issued. In May 1972, the first project meeting was held in Bordeaux, at which the order for the four prototypes was formally placed.
By November 1972, the project had passed its first mock-up review. Dassault was designated as the'pilot' company for the project and possessed final authority on design and management decisions, this approach to project management has been claimed to have been a efficient manner of running the program. Two prototypes were to be built by Dassault in France and a further two were to be built by Dornier in Germany. On 26 October 1973, the first French prototype performed its first flight at Istres, Marseill
Dassault Mirage 5
The Dassault Mirage 5 is a supersonic attack aircraft designed in France by Dassault Aviation during the 1960s and manufactured in France and a number of other countries. It was derived from Dassault's popular Mirage III fighter and spawned several variants of its own, including the IAI Kfir; the aircraft is capable of nuclear weapons delivery. The Mirage 5 grew out of a request to Dassault from the Israeli Air Force. Since the weather over the Middle East is clear and sunny most of the time, the Israelis suggested removing avionics located behind the cockpit, from the standard Mirage IIIE to reduce cost and maintenance, replacing them with more fuel storage for attack missions. In September 1966, the Israelis placed an order for 50 of the new aircraft; the first Mirage 5 flew on 19 May 1967. It looked much like the Mirage III, except that it had a long slender nose that extended the aircraft's length by about half a metre. A pitot tube was distinctively moved from the tip of the nose to below the nose in the majority of Mirage 5 variants.
The Mirage 5 retained the IIIE's twin DEFA guns, but added two additional pylons, for a total of seven. Maximum warload was 4,000 kg. Provision for the SEPR rocket engine was deleted. Rising tensions in the Middle East led French President Charles de Gaulle to embargo the Israeli Mirage 5s on 3 June 1967; the Mirages continued to roll off the production line though they were embargoed, by 1968 the batch was complete and the Israelis had provided final payments. In late 1969, the Israelis, who had pilots in France testing the aircraft, requested that the aircraft be transferred to Corsica, in theory to allow them to continue flight training during the winter; the French government became suspicious when the Israelis tried to obtain long-range fuel tanks and cancelled the move. The Israelis gave up trying to acquire the aircraft and accepted a refund; some sources claim that cooperation with France resumed outside the public's eye and Israel received 50 Mirage 5s in crates from the French Air Force, while the French took over the 50 aircraft intended for Israel, as Mirage 5Fs.
Israel claimed to have built the aircraft after obtaining complete blueprints, naming them IAI Nesher. Like the Mirage IIIE, the Mirage 5 was popular with export customers, with different export variants fitted with a wide range of different avionics. While the Mirage 5 had been oriented to the clear-weather attack role, with some avionic fits it was refocused to the air-combat mission; as electronic systems became more compact and powerful, it was possible to provide the Mirage 5 with increased capability though the rear avionics bay had been deleted, therefore in some sub-versions, the result was a "reinvented" Mirage IIIE. Reconnaissance and two-seat versions of the Mirage 5 were sold, with the designation Mirage 5R, Mirage 5D respectively; the Mirage 5 was sold to Abu Dhabi, Colombia, Gabon, Pakistan, Peru and Zaire, with the usual list of subvariant designations and variations in kit. The Belgian aircraft were fitted with US avionics, Egyptian aircraft fitted with the MS2 attack avionics system from the Dassault-Dornier Alpha Jet.
In 1978 and 1980, Israel sold a total of 35 of their Neshers plus 4 Nesher trainer aircraft to Argentina, where they were locally known first as Daggers and after their last upgrade as Fingers. The Argentines lost two IIIEAs and eleven Daggers during the Falklands War in 1982, and, as a measure of solidarity, the Peruvians transferred ten of their Mirage 5s to Argentina, under the name Mirage Mara, to help alleviate its losses. South Africa purchased five Nesher trainers for trials during its own Atlas Cheetah fighter programme. All the aircraft were upgraded to Cheetah D standard. Chile incorporated some Mirage 5s under name Mirage Elkan. A total of 582 Mirage 5s were built, including 51 Israeli Neshers. In 1968, the Belgian government ordered 106 Mirage 5s from Dassault to re-equip No 3 Wing at Bierset air base. All aircraft but the first one were to be license-built by SABCA in Belgium. Component production at the SABCA Haren plant near Brussels was followed by assembly at the SABCA plant at Gosselies airfield, near Charleroi.
The ATAR engines were produced by FN Moteurs at this company's Liège plant. SABCA production included three versions: Mirage 5BA for the ground-attack role, Mirage 5BR for the reconnaissance role and Mirage 5BD for training and conversion. By the end of the 1980s, a MIRage Safety Improvement Program was agreed to by parliament, calling for 20 low-time Mirages to be upgraded. Initial plans included a new more powerful engine; the upgrade included a new state-of-the-art cockpit, a new ejection seat, canards to improve takeoff performance and overall maneuverability. A new government canceled the MIRSIP but SABCA, having a watertight contract, were allowed to carry out the update. After completion, the Belgian government sold all 20 aircraft to Chile at a loss; the new Atar 09K-50 engine, was still an improvement, fitment of this engine led to the next Mirage variant, the Mirage 50, during the 1970s. The uprated engine gave the Mirage 50 better takeoff and climb characteristics than its predecessors.
While the Mirage 50 incorporated new avionics, such as a Cyrano IV radar system, it did not prove popular in export sales, as the first-generation Mirage series was becoming obsolete. Chile ordered a quantity of Mirage 50s, receiving both new production as well as updated Armée de l'Air Mirage 5s; the Chilean aircraft were modernised along the lines of the IAI Kfir as the ENAER Pantera. The Pantera incorporates fixed canards and other aerodynamic improvements, as well as advanced avioni
The Hawker 800 is a mid-size twinjet corporate aircraft. It is a development of the British Aerospace BAe 125, was assembled by Hawker Beechcraft. In April 1981, the British Aerospace Board sanctioned the programme to improve the British Aerospace 125-700 series. By May 1983 the new aircraft was ready for its first test flight; the BAe 125-800 series has a number of modifications and changes over the 700, the most noticeable being the redesigned cockpit windscreen. Accompanying this are a modified rear fuselage fairing, as well as a glass cockpit and uprated Garrett TFE731-5R-1H engines. British Aerospace improved the wing by incorporating new outer wing sections; this helped to improve aerodynamic efficiency. The 125-800 series would become a sales success. From the first BAe 125 flight in August 1961 it took nineteen years until the 500th airframe was sold. In a little over five years, British Aerospace were registering the 200th sale of the 800 series. In 1994 Raytheon acquired Corporate Jets.
The new entity being known as Raytheon Aircraft. In March 2007, Raytheon divested its aircraft manufacturing business to Hawker Beechcraft Corp. a company formed and controlled by GS Capital Partners and Onex Partners of Canada. The last version was the Hawker 850XP, certified for operation in March 2006; the 850XP is identical to the 800XP except that it includes winglets, which have extended its operating range by 100 nautical miles. This version incorporates upgraded avionics and a redesigned interior; the Hawker 850XP fills the gap left behind by the Hawker 1000 when production of that aircraft ceased. Two new variants were announced in October 2006 for future deliveries: The Hawker 750, in which the ventral fuel tank is replaced by an externally accessed baggage pannier, which reduces range slightly; the Hawker 900XP, using new Honeywell TFE731-50BR engines for increased rangeAfter the 2013 bankruptcy of Hawker Beechcraft, the surviving company, discontinued its business jet range, including the 800 series, although the designs are still supported for parts.
By 2018, a 1980s-era 700s was priced for less than $500,000, a 1995 800A at $1.02 million and a 2012 900XP at $6 million. The Hawker 800 is similar to most modern airframes in requiring sub-assemblies to be constructed away from the final point of manufacture; the fuselage sections and control surfaces are manufactured and assembled in the United Kingdom in a combination of Hawker Beechcraft's own facility and those owned by Airbus UK, which inherited much of BAE Systems's civil aircraft manufacturing capacity. These sections are fitted out and installed with control surfacing and major systems before being shipped to Hawker Beechcraft's main manufacturing site in Wichita, Kansas for final assembly, fitting out and testing. Japan uses a maritime search and rescue variant of the Hawker 800, it is designated the U-125A in Japan Air Self-Defense Force service. This variant has large observation windows, a flare and marker-buoy dispenser system, life-raft and emergency equipment dropping system and enhanced salt water corrosion prevention.
The aircraft has a Toshiba 360-degree search radar, Melco thermal imaging equipment and other military communications equipment for its mission. A military version of the Hawker 800XP is in use by South Korea for tactical aerial reconnaissance, surveillance and SIGINT tasks, 8 specially equipped aircraft were delivered in 2000; the Republic of Korea Air Force calls them RC-800s, they are based at Seoul Air Base. Hawker 750With 48 built, this lower-cost, lighter-weight and shorter-range version of the 800XP competes with the Citation XLS and Learjet 60. In November 2017, used prices range from $2.2 million for early 2008 models to 3.8 million for late 2011 models. Its larger 604 cu ft cabin is configured with eight seats in double club or a four chair club followed by a three-place divan facing a single seat, is pressurized by 8.5 psi to provides a 7,500 ft cabin altitude at FL 410. Its 1,500 lb ventral fuel tank is replaced with a 47 cu ft external baggage compartment, leaving 8,500 lb of fuel in the wet wings.
The cockpit has four-screen Rockwell Collins Pro Line 21 avionics and FMS-6000. It takes off in 4,696 ft at MTOW/Sea level. With a 20° quarter chord wing sweep, its maximum speed is Mach 0.80, it cruises at Mach 0.74 to 0.78 and long-range cruise is Mach 0.70 at 1,214 lb per hour midweight. First hour fuel burn is 1,900 lb, second hour is 1,200 lb for subsequent hours. B-checks are every 800 h, C-checks every 1,600 h and D-checks every 3,200 h and there are yearly maintenance checks; the landing gear is overhauled every 12 years. Its 4,750 lbf Honeywell TFE731-5BR have 2,100 h MPI and 4,200 h CZI inspection intervals, extendable to 2,500 h / 5,000 h with optional service bulletins, MSP per engine. Hawker 800 Hawker 800XPAble to fly nine passengers over 2,400 nmi, 475 Hawker 800XP have been sold for $10-13.5 million between 1995 and 2005. By July 2018, 467 were still in service, valued $1.4-2.4 million. Hawker 800XP Pro Line Hawker 800XPi Hawker 850XP Hawker 900XP U-125 RC-800 C-29 The aircraft is operated by private individuals and executive charter operators, in fractional ownership programs.
BrazilBrazilian Air Force JapanJapan Air Self-Defense Force U-125A MalawiMilitary of Malawi Mozambique Mozambique Air Force NigeriaNigerian Air Force PakistanPakistan Navy Saudi ArabiaRoyal Saudi Air Force South KoreaRepublic of Korea Air Force 10 November 2015: A Hawker 800 crashed into an apartment complex in Akron, Ohio shortly before 15:00 EST
The turbofan or fanjet is a type of airbreathing jet engine, used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the turbo portion refers to a gas turbine engine which achieves mechanical energy from combustion, the fan, a ducted fan that uses the mechanical energy from the gas turbine to accelerate air rearwards. Thus, whereas all the air taken in by a turbojet passes through the turbine, in a turbofan some of that air bypasses the turbine. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust; the ratio of the mass-flow of air bypassing the engine core divided by the mass-flow of air passing through the core is referred to as the bypass ratio. The engine produces thrust through a combination of these two portions working together. Most commercial aviation jet engines in use today are of the high-bypass type, most modern military fighter engines are low-bypass. Afterburners are not used on high-bypass turbofan engines but may be used on either low-bypass turbofan or turbojet engines.
Modern turbofans have either a smaller fan with several stages. An early configuration combined a low-pressure fan in a single rear-mounted unit. Turbofans were invented to circumvent an awkward feature of turbojets, that they were inefficient for subsonic flight. To raise the efficiency of a turbojet, the obvious approach would be to increase the burner temperature, to give better Carnot efficiency and fit larger compressors and nozzles. However, while that does increase thrust somewhat, the exhaust jet leaves the engine with higher velocity, which at subsonic flight speeds, takes most of the extra energy with it, wasting fuel. Instead, a turbofan can be thought of as a turbojet being used to drive a ducted fan, with both of those contributing to the thrust. Whereas all the air taken in by a turbojet passes through the turbine, in a turbofan some of that air bypasses the turbine; because the turbine has to additionally drive the fan, the turbine is larger and has larger pressure and temperature drops, so the nozzles are smaller.
This means. The fan has lower exhaust velocity, giving much more thrust per unit energy; the overall effective exhaust velocity of the two exhaust jets can be made closer to a normal subsonic aircraft's flight speed. In effect, a turbofan emits a large amount of air more whereas a turbojet emits a smaller amount of air, a far less efficient way to generate the same thrust; the ratio of the mass-flow of air bypassing the engine core compared to the mass-flow of air passing through the core is referred to as the bypass ratio. The engine produces thrust through a combination of these two portions working together. Most commercial aviation jet engines in use today are of the high-bypass type, most modern military fighter engines are low-bypass. Afterburners are not used on high-bypass turbofan engines but may be used on either low-bypass turbofan or turbojet engines; the bypass ratio of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core.
A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for every 1 kg of air passing through the core. Turbofan engines are described in terms of BPR, which together with overall pressure ratio, turbine inlet temperature and fan pressure ratio are important design parameters. In addition bpr is quoted for turboprop and unducted fan installations because their high propulsive efficiency gives them the overall efficiency characteristics of high bypass turbofans; this allows them to be shown together with turbofans on plots which show trends of reducing specific fuel consumption with increasing BPS. BPR can be quoted for lift fan installations where the fan airflow is remote from the engine and doesn't physically touch the engine core. Bypass provides a lower fuel consumption for the same thrust. If all the gas power from a gas turbine is converted to kinetic energy in a propelling nozzle, the aircraft is best suited to high supersonic speeds. If it is all transferred to a separate big mass of air with low kinetic energy, the aircraft is best suited to zero speed.
For speeds in between, the gas power is shared between a separate airstream and the gas turbine's own nozzle flow in a proportion which gives the aircraft performance required. The trade off between mass flow and velocity is seen with propellers and helicopter rotors by comparing disc loading and power loading. For example, the same helicopter weight can be supported by a high power engine and small diameter rotor or, for less fuel, a lower power engine and bigger rotor with lower velocity through the rotor. Bypass refers to transferring gas power from a gas turbine to a bypass stream of air to reduce fuel consumption and jet noise. Alternatively, there may be a requirement for an afterburning engine where the sole requirement for bypass is to provide cooling air; this sets the lower limit for bpr and these engines have been called "leaky" or continuous bleed turbojets and low bpr turbojets. Low bpr has bee
Croatia the Republic of Croatia, is a country at the crossroads of Central and Southeast Europe, on the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east and Herzegovina, Montenegro to the southeast, sharing a maritime border with Italy, its capital, forms one of the country's primary subdivisions, along with twenty counties. Croatia has an area of 56,594 square kilometres and a population of 4.28 million, most of whom are Roman Catholics. Inhabited since the Paleolithic Age, the Croats arrived in the area in the 6th century and organised the territory into two duchies by the 9th century. Croatia was first internationally recognized as an independent state on 7 June 879 during the reign of duke Branimir. Tomislav became the first king by 925, elevating Croatia to the status of a kingdom, which retained its sovereignty for nearly two centuries. During the succession crisis after the Trpimirović dynasty ended, Croatia entered a personal union with Hungary in 1102.
In 1527, faced with Ottoman conquest, the Croatian Parliament elected Ferdinand I of Austria to the Croatian throne. In October 1918, in the final days of World War I, the State of Slovenes and Serbs, independent from Austria-Hungary, was proclaimed in Zagreb, in December 1918 it was merged into the Kingdom of Serbs and Slovenes. Following the Axis invasion of Yugoslavia in April 1941, most of the Croatian territory was incorporated into the Nazi-backed client-state which led to the development of a resistance movement and the creation of the Federal State of Croatia which after the war become a founding member and a federal constituent of the Socialist Federal Republic of Yugoslavia. On 25 June 1991, Croatia declared independence, which came wholly into effect on 8 October of the same year; the Croatian War of Independence was fought for four years following the declaration. The sovereign state of Croatia is a republic governed under a parliamentary system and a developed country with a high standard of living.
It is a member of the European Union, the United Nations, the Council of Europe, NATO, the World Trade Organization, a founding member of the Union for the Mediterranean. As an active participant in the UN peacekeeping forces, Croatia has contributed troops to the NATO-led mission in Afghanistan and took a non-permanent seat on the UN Security Council for the 2008–2009 term. Since 2000, the Croatian government has invested in infrastructure transport routes and facilities along the Pan-European corridors. Croatia's economy is dominated by service and industrial sectors and agriculture. Tourism is a significant source of revenue, with Croatia ranked among the top 20 most popular tourist destinations in the world; the state controls a part of the economy, with substantial government expenditure. The European Union is Croatia's most important trading partner. Croatia provides a social security, universal health care system, a tuition-free primary and secondary education, while supporting culture through numerous public institutions and corporate investments in media and publishing.
The name of Croatia derives from Medieval Latin Croātia. Itself a derivation of North-West Slavic *Xrovat-, by liquid metathesis from Common Slavic period *Xorvat, from proposed Proto-Slavic *Xъrvátъ which comes from Old Persian *xaraxwat-; the word is attested by the Old Iranian toponym Harahvait-, the native name of Arachosia. The origin of the name is uncertain, but is thought to be a Gothic or Indo-Aryan term assigned to a Slavic tribe; the oldest preserved record of the Croatian ethnonym *xъrvatъ is of variable stem, attested in the Baška tablet in style zvъnъmirъ kralъ xrъvatъskъ. The first attestation of the Latin term is attributed to a charter of Duke Trpimir from the year 852; the original is lost, just a 1568 copy is preserved, leading to doubts over the authenticity of the claim. The oldest preserved stone inscription is the 9th-century Branimir Inscription found near Benkovac, where Duke Branimir is styled Dux Cruatorvm; the inscription is not believed to be dated but is to be from during the period of 879–892, during Branimir's rule.
The area known as Croatia today was inhabited throughout the prehistoric period. Fossils of Neanderthals dating to the middle Palaeolithic period have been unearthed in northern Croatia, with the most famous and the best presented site in Krapina. Remnants of several Neolithic and Chalcolithic cultures were found in all regions of the country; the largest proportion of the sites is in the river valleys of northern Croatia, the most significant cultures whose presence was discovered include Baden, Starčevo, Vučedol cultures. The Iron Age left traces of the Celtic La Tène culture. Much the region was settled by Illyrians and Liburnians, while the first Greek colonies were established on the islands of Hvar, Korčula, Vis. In 9 AD the territory of today's Croatia became part of the Roman Empire. Emperor Diocletian had a large palace built in Split to which he retired after his abdication in AD 305. During the 5th century, the last de jure Western emperor last Western Roman Emperor Julius Nepos ruled his small realm from the palace after fleeing Italy to go into exile in 475.
The period ends with Avar and Croat invasions in the first half of the 7th century and destruction of all Roman towns. Roman survivors retreated to more favourable sites on the coast and mountains; the city of Dubrovnik was founded by such survivors from Epidaurum. The ethnogenesis of Croats is uncertain an