Centrifugal compressors, sometimes called radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. They achieve a pressure rise by adding kinetic energy/velocity to a continuous flow of fluid through the rotor or impeller; this kinetic energy is converted to an increase in potential energy/static pressure by slowing the flow through a diffuser. The pressure rise in the impeller is in most cases equal to the rise in the diffuser. In the case where flow passes through a straight pipe to enter a centrifugal compressor the flow is straight and has no vorticity, ie swirling motion, so the swirl angle α1 = 0° as illustrated; as the flow passes through the centrifugal impeller, the impeller forces the flow to spin faster as it gets further from the rotational axis. According to a form of Euler's fluid dynamics equation, known as the pump and turbine equation, the energy input to the fluid is proportional to the flow's local spinning velocity multiplied by the local impeller tangential velocity.
In many cases, the flow leaving the centrifugal impeller is travelling near the speed of sound. It flows through a stationary compressor causing it to decelerate; the stationary compressor is ducting with increasing flow-area where energy transformation takes place. If the flow has to be turned in a rearward direction to enter the next part of the machine, eg another impeller or a combustor, flow losses can be reduced by directing the flow with stationary turning vanes or individual turning pipes; as described in Bernoulli's principle, the reduction in velocity causes the pressure to rise. Over the past 100 years, applied scientists including Stodola, Hawthorne, Shepard and Japikse, have educated young engineers in the fundamentals of turbomachinery; these understandings apply to all dynamic, continuous-flow, axisymmetric pumps, fans and compressors in axial, mixed-flow and radial/centrifugal configurations. This relationship is the reason advances in turbines and axial compressors find their way into other turbomachinery including centrifugal compressors.
Figures 1.1 and 1.2 illustrate the domain of turbomachinery with labels showing centrifugal compressors. Improvements in centrifugal compressors have not been achieved through large discoveries. Rather, improvements have been achieved through understanding and applying incremental pieces of knowledge discovered by many individuals. Figure 1.1 represents the aero-thermo domain of turbomachinery. The horizontal axis represents the energy equation derivable from The first law of thermodynamics; the vertical axis, which can be characterized by Mach Number, represents the range of fluid compressibility. The Z-axis, which can be characterized by Reynolds number, represents the range of fluid viscosities. Mathematicians and physicists who established the foundations of this aero-thermo domain include: Isaac Newton, Daniel Bernoulli, Leonhard Euler, Claude-Louis Navier, George Stokes, Ernst Mach, Nikolay Yegorovich Zhukovsky, Martin Kutta, Ludwig Prandtl, Theodore von Kármán, Paul Richard Heinrich Blasius, Henri Coandă.
Figure 1.2 represents the mechanical domain of turbomachinery. Again, the horizontal axis represents the energy equation with turbines generating power to the left and compressors absorbing power to the right. Within the physical domain the vertical axis differentiates between high speeds and low speeds depending upon the turbomachinery application; the Z-axis differentiates between axial-flow geometry and radial-flow geometry within the physical domain of turbomachinery. It is implied that mixed-flow turbomachinery lie between radial. Key contributors of technical achievements that pushed the practical application of turbomachinery forward include: Denis Papin, Kernelien Le Demour, Daniel Gabriel Fahrenheit, John Smeaton, Dr. A. C. E. Rateau, John Barber, Alexander Sablukov, Sir Charles Algernon Parsons, Ægidius Elling, Sanford Alexander Moss, Willis Carrier, Adolf Busemann, Hermann Schlichting, Frank Whittle and Hans von Ohain. Centrifugal compressors are similar in many ways to other turbomachinery and are compared and contrasted as follows: Centrifugal compressors are similar to axial compressors in that they are rotating airfoil-based compressors.
Both are shown in the adjacent photograph of an engine with 5 stages of axial compressor and one stage of centrifugal compressor. The first part of the centrifugal impeller looks similar to an axial compressor; this first part of the centrifugal impeller is termed an inducer. Centrifugal compressors differ from axials as they use a significant change in radius from inlet to exit of the impeller to produce a much greater pressure rise in a single stage than does an axial stage; the 1940s-era German Heinkel HeS 011 experimental engine was the first aviation turbojet to have a compressor stage with radial flow-turning part-way between none for an axial and 90 degrees for a centrifugal. It is known as a mixed/diagonal-flow compressor. A diagonal stage is used in the Whitney Canada PW600 series of small turbofans. Centrifugal compressors are similar to centrifugal fans of the style shown in neighboring figure as they both increase the flows energy through increasing radius. In contrast to centrifugal fans, compressors operate at higher speeds to generate greater pressure rises.
In many cases the engineering methods used to design a centrifugal fan are the same as those to design a centrifugal compressor, so they can look similar. This relationship is less true in comparison to the squirrel-cage fan shown in the accompanying figure. For purposes o
The Yakovlev AIR-1 was a 1920s Soviet two-seat light biplane, the first aircraft designed and built by Aleksandr Sergeyevich Yakovlev. Yakovlev designed his first aircraft while working at the Zhukovsky Military Aviation Academy. Although the directors of the Academy were opposed to the design, the aircraft was built in the Academy Club on his own time. Designated VVA-3 Yakovlev redesignated it the AIR-1 in honour of Alexei Ivanovich Rykov, the country's premier and the president of the Osoviakihm; the first flight on 12 May 1927 was flown by Yakovlev's friend J. I. Piontkovsky, who rated the flying qualities as excellent. In 1928 Yakovlev produced an improved variant, the AIR-2. One aircraft powered by a Siemens engine was designated AIR-2S and was fitted with floats designed by V B Shavrov. AIR-1 Prototype with a 60 hp ADC Cirrus engine. AIR-2 Improved variant fitted with either a Walter NZ-60 or NAMI M-23 radial engine. AIR-2S AIR-2 fitted with two wooden floats. VVA-3 Original designation of the AIR-1 Data from The History of Soviet Aircraft from 1918.
General characteristics Crew: two Length: 6.9 m Wingspan: 8.85 m Wing area: 18.7 m2 Empty weight: 335 kg Gross weight: 535 kg Powerplant: 1 × ADC Cirrus, 45 kW Performance Maximum speed: 140 km/h Range: 1240 km Service ceiling: 3850 m Armament Yakovlev AIR-1
An interceptor aircraft, or interceptor, is a type of fighter aircraft designed to attack enemy aircraft bombers and reconnaissance aircraft, as they approach. There are two general classes of interceptor: lightweight aircraft built for high performance, heavier aircraft designed to fly at night or in adverse weather and operate over longer ranges. For daytime operations, conventional fighters fill the interceptor role, as well as many other missions. Daytime interceptors have been used in a defensive role since the World War I era, but are best known from several major actions during World War II, notably the Battle of Britain where the Supermarine Spitfire and Hawker Hurricane developed a good reputation. Few aircraft can be considered dedicated daytime interceptors. Exceptions include the Messerschmitt Me 163B—the only rocket-powered, manned military aircraft to see combat—and to a lesser degree designs like the Mikoyan-Gurevich MiG-15, which had heavy armament intended for anti-bomber missions.
Night fighters and bomber destroyers are, by definition, interceptors of the heavy type, although they were referred to as such. In the early Cold War era the combination of jet-powered bombers and nuclear weapons created air forces' demand for capable interceptors. Examples of classic interceptors of this era include the F-106 Delta Dart, Sukhoi Su-15, English Electric Lightning. Through the 1960s and 1970s, the rapid improvements in design led to most air-superiority and multirole fighters, such as the Grumman F-14 Tomcat and McDonnell Douglas F-15 Eagle, having the performance to take on the interceptor role, the strategic threat moved from bombers to intercontinental ballistic missiles. Dedicated interceptor designs became rare, with the only used examples designed after the 1960s being the Tornado F3, Mikoyan MiG-25 "Foxbat", Mikoyan MiG-31 "Foxhound", the Shenyang J-8 "Finback"; the first interceptor squadrons were formed during World War I to defend London against attacks by Zeppelins and against fixed-wing long-range bombers.
Early units used aircraft withdrawn from front-line service, notably the Sopwith Pup. They were told about their target's location before take-off from a command centre in the Horse Guards building; the Pup proved to have too low performance to intercept Gotha G. IV bombers, the superior Sopwith Camels supplanted them; the term "interceptor" was in use by 1929. Through the 1930s, bomber aircraft speeds increased so much that conventional interceptor tactics appeared impossible. Visual and acoustic detection from the ground had a range of only a few miles, which meant that an interceptor would have insufficient time to climb to altitude before the bombers reached their targets. Standing combat air patrols were only at great cost; the conclusion at the time was that "the bomber will always get through". The invention of radar made possible early, long-range detection of aircraft on the order of 100 miles, both day and night and in all weather. A typical bomber might take twenty minutes to cross the detection zone of early radar systems, time enough for interceptor fighters to start up, climb to altitude and engage the bombers.
Ground controlled interception required constant contact between the interceptor and the ground until the bombers became visible to the pilots and nationwide networks like the Dowding system were built in the late 1930s. The introduction of jet power increased speeds from 400 miles per hour to 600 miles per hour in a step and doubled operational altitudes. Although radars improved in performance, the gap between offense and defense was reduced. Large attacks could so confuse the defense's ability to communicate with pilots that the classic method of manual ground controlled interception was seen as inadequate. In the United States, this led to the introduction of the Semi-Automatic Ground Environment to computerize this task; the introduction of the first useful surface-to-air missiles in the 1950s obviated the need for fast reaction time interceptors as the missile could launch instantly and air forces turned to much larger designs, with enough fuel for longer endurance, to avoid the need for rapid reaction.
In the 1950s, during the Cold War, a strong interceptor force was crucial for the great powers as the best means to defend against an unexpected nuclear attack by strategic bombers. Hence for a brief period of time they faced rapid development. At the end of the 1960s, a nuclear attack became unstoppable with the introduction of ballistic missiles capable of approaching from outside the atmosphere at speeds as high as 5–7 km/s; the doctrine of mutually assured destruction replaced the trend of defense strengthening, making interceptors less strategically logical. The utility of interceptors waned as the role merged with that of the heavy air superiority fighter, dominant in military thinking; the interceptor mission is, by its nature, a difficult one. Consider the desire to protect a single target from attack by long-range bombers; the bombers have the advantage of being able to select the parameters of the mission – attack vector and altitude. This results in an enormous area. In the time it takes for the bombers to cross the distance from first detection to being on their targets, the interceptor must be able to start, take off, climb to altitude, maneuver for attack and attack the bomber.
A dedicated interceptor aircraft sacrifices the capabilities of the air superiority fighter and multirole fighter (i.e. countering enemy fighter airc
The Yakovlev UT-1 was a single-seater trainer aircraft used by the Soviet Air Force from 1937 until the late 1940s. The Yakovlev UT-1 was designed as a single-seater advanced trainer and aerobatic airplane by the team led by Alexander Sergeyevich Yakovlev; the first prototype, designated the AIR-14, was flown in early 1936. The AIR-14 was a small low-winged monoplane with a fixed tailwheel undercarriage, with a welded steel fuselage and wooden wings. After some changes, the AIR-14 was accepted for production. Among other improvements, the 75 kW Shvetsov M-11 radial was changed to the more powerful 86 kW M-11G; the plane received the designation UT-1. The UT-1 was used as a transitional type between the UT-2 and fighters like the I-16, it was not easy to fly, requiring precise piloting, thus forming an ideal intermediate between basic trainers and the maneuverable but difficult-to-fly I-16. In 1939 the plane was modified by moving the engine 26 cm forward. During production, the 112 kW M-11E engine was used.
Soviet pilots broke several records with the UT-1 before World War II, some with its floatplane variant. In total, 1,241 aircraft were built between December 1936 and 1940. During World War II, from 1941, the UT-1 was used for reconnaissance; some were used as improvised combat machines, after fitting with underwing machine guns or two unguided rockets. In February 1942, about 50 UT-1 were converted in workshops as improvised UT-1B ground-attack planes, fitted with two machine guns and two-four rockets, they were next used in Black Sea Fleet aviation in Caucasus. The survivors were disarmed in December 1942. There were a large number of variants, the most numerous or noteworthy were: AIR-14 - Prototype of UT-1 AIR-18 - UT-1 with a 104 kW Renault Bengali 4 inline engine and closed canopy, retractable undercarriage. AIR-21 - UT-1 with 164 kW Renault Bengali 6 engine, tested in 1938-39, fixed undercarriage. UT-1B - Wartime attack version with two ShKAS machine guns and two or four RS-82 rockets. UT-1E - (UT-1 For tests at TsAGI.
UT-1 Floatplane - with M-11Ye engine which became standard in the majority of UT-1's. Soviet UnionSoviet Air Force Soviet Naval Aviation ChinaChinese Nationalist Air Force Data from Gordon 2005 and Gunston 1995General characteristics Crew: one Length: 5.75 m Wingspan: 7.3 m Height: 2.34 m Wing area: 9.58 m2 Empty weight: 429 kg Gross weight: 597.5 kg Powerplant: 1 × Shvetsov M-11Ye, 111 kW Performance Maximum speed: 257 km/h Range: 670 km Service ceiling: 7,120 m Rate of climb: 7.4 m/s Armament 2 x 7.7mm ShKAS machine guns 2 or 4 x RS-82 Related development Yakovlev UT-2 Related lists List of Interwar military aircraft Gordon, Yefim.. OKB Yakovlev. London: Ian Allan. Pp. 36 to 45. Gunston, Bill; the Osprey Encyclopedia of Russian Aircraft 1875-1995. London: Osprey
An autocannon or automatic cannon is a large automatic, rapid-fire projectile weapon that fires armour-piercing or explosive shells, as opposed to the bullet fired by a machine gun. Autocannons have a larger calibre than a machine gun, but are smaller than a field gun or other artillery; when used on its own, the word "autocannon" indicates a single-barrel weapon. When multiple rotating barrels are involved, the word "rotary" is added, such a weapon is referred to as a "rotary autocannon". Modern autocannons are not single soldier-portable or stand-alone units, rather they are vehicle-mounted, aircraft-mounted, or boat-mounted, or remote-operated as in some naval applications; as such, ammunition is fed from a belt to reduce reloading or for a faster rate of fire, but a magazine remains an option. They can use a variety of ammunition: common shells include high-explosive dual-purpose types, any variety of armour-piercing types, such as composite rigid or discarding sabot types. Although capable of generating a high rate of fire, autocannons overheat if used for sustained fire, are limited by the amount of ammunition that can be carried by the weapons systems mounting them.
Both the US 25 mm Bushmaster and the British 30 mm Rarden have slow rates of fire so as not to use ammunition too quickly. The rate of fire of a modern autocannon ranges from 90 rounds per minute, to 2,500 rounds per minute with the GIAT 30. Systems with multiple barrels can have rates of fire of over 10,000 rounds per minute; such high rates of fire are employed by aircraft in air-to-air combat and close air support attacks on ground targets, where the target dwell time is short and weapons are operated in brief bursts. The first modern autocannon was the British QF 1 pounder known as the "pom-pom"; this was an upscaled version of the Maxim gun, the first successful automatic machine gun, requiring no outside stimulus in its firing cycle other than holding the trigger. The pom-pom fired 1 pound gunpowder-filled explosive shells at a rate of over 200 rounds a minute: much faster than conventional artillery while possessing a much longer range and more firepower than the infantry rifle. In 1913, Reinhold Becker and his Stahlwerke Becker firm designed the 20mm Becker cannon for the German Empire's perceived need for heavy-calibre aircraft armament, was assisted by the Imperial Government's Spandau Arsenal in perfecting the ordnance - although only about 500+ examples of the original Becker design were made during World War I, the design's patent was acquired by the Swiss Oerlikon Contraves firm in 1924, with the Third Reich's Ikaria-Werke firm of Berlin using Oerlikon design patents in creating the MG FF wingmount cannon ordnance, in Imperial Japan, their navy's adoption and production of the Type 99 cannon in 1939 was based on the Becker/Oerlikon design's principles.
During the First World War, autocannons were used in the trenches as an anti-aircraft gun. The British used pom-pom guns as part of their air defences to counter the German Zeppelin airships that made regular bombing raids on London, but they were of little value, as their shells neither ignited the hydrogen of the Zeppelins, nor caused sufficient loss of gas to bring them down. Attempts to use them in aircraft failed as the weight limited both speed and altitude, thus making successful interception impossible; the more effective QF 2 pounder naval gun would be developed during the war to serve as an anti-aircraft and close range defensive weapon for naval vessels. Autocannons would serve in a much greater capacity during the Second World War. During the inter-war years, aircraft underwent an evolution and the all-metal monoplane, pioneered as far back as the end of 1915 replaced wood and fabric biplanes; the subsequent increase in speed and durability reduced the window of opportunity for defence.
Heavier anti-aircraft cannon had difficulty tracking fast-moving aircraft and were unable to judge altitude or distance, while machine guns possessed insufficient range and firepower to bring down aircraft consistently. Weapons such as the Oerlikon 20 mm and the Bofors 40 mm would see widespread use by both sides during the second World War. Continued ineffectiveness against aircraft despite the large numbers installed during the second World War led, in the West, to the removal of all shipboard anti-aircraft weapons in the early post-war period; this was only reversed with the introduction of computer-controlled systems. The German Panzer II light tank, one of the most numerous in German service during the invasion of Poland and the campaign in France, used a 20 mm autocannon as its main armament. Although ineffective against tank armour during the early years of the war, the cannon was effective against light-skinned vehicles as well as infantry and was used by armoured cars. Larger examples, such as the 40 mm Vickers S, were mounted in ground attack aircraft to serve as an anti-tank weapon, a role to which they were suited as tank armour is lightest on top.
Polish 20 mm. Unlike the Oerlikon, it was effective against all the tanks fielded in 1939 because it was built as an upgrade to the Oerlikon, Hispano—Suiza, Madsen. It, with great difficulty, proved capable of knocking out early Panzer IIIs and IVs. Only 55 were produced by the time of the Polish Defensive War. In airc