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61-627: By mid-20th century, Lockheed had established a strong position in commercial airliner production with its piston-engined Constellation series . Further development brought turboprop engines to the Constellation airframe with the Lockheed L-1249 Super Constellation . In 1951, Lockheed was approached by Capital Airlines to develop a new turboprop airliner, which was designated the YC-130, but no other carriers had any interest, so

122-435: A balance wheel , pendulum , or quartz crystal . The natural frequency of the very simple mechanical system consisting of a weight suspended by a spring is: where m is the mass and k is the spring constant . For a given mass, stiffening the system (increasing k {\displaystyle k} ) increases its natural frequency, which is a general characteristic of vibrating mechanical systems. A swing set

183-532: A rotating motion . This article describes the common features of all types. The main types are: the internal combustion engine , used extensively in motor vehicles ; the steam engine , the mainstay of the Industrial Revolution ; and the Stirling engine for niche applications. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine , where the spark plug initiates

244-557: A Model 188A, first flew on December 6, 1957, two months ahead of schedule. Lockheed was awarded a type certificate by the Civil Aeronautics Administration (CAA) on 22 August 1958. The first delivery – to Eastern Air Lines – was on October 8, 1958, but it did not enter service until January 12, 1959. In 1957, the United States Navy issued a requirement for an advanced maritime patrol aircraft . Lockheed proposed

305-597: A capacity of 1,820 L (64 cu ft), making a total capacity of 25,480 L (900 cu ft) for the largest versions. For piston engines, an engine's capacity is the engine displacement , in other words the volume swept by all the pistons of an engine in a single movement. It is generally measured in litres (l) or cubic inches (c.i.d., cu in, or in ) for larger engines, and cubic centimetres (abbreviated cc) for smaller engines. All else being equal, engines with greater capacities are more powerful and consumption of fuel increases accordingly (although this

366-528: A complex excitation, such as an impulse or a wideband noise excitation. In effect, it is filtering out all frequencies other than its resonance. In the example above, the swing cannot easily be excited by harmonic frequencies, but can be excited by subharmonics , such as pushing the swing every second or third oscillation. Various examples of mechanical resonance include: Resonance may cause violent swaying motions in constructed structures, such as bridges and buildings. The London Millennium Footbridge (nicknamed

427-469: A cylinder to drive a reciprocating engine in a local-pollution-free urban vehicle. Torpedoes may use a working gas produced by high test peroxide or Otto fuel II , which pressurize without combustion. The 230 kg (510 lb) Mark 46 torpedo , for example, can travel 11 km (6.8 mi) underwater at 74 km/h (46 mph) fuelled by Otto fuel without oxidant . Quantum heat engines are devices that generate power from heat that flows from

488-600: A development of the Electra that was later placed into production as the P-3 Orion, which had much greater success – the Orion has been in continual front-line service for more than 50 years. The Model 188 Electra is a low-wing cantilever monoplane powered by four wing-mounted Allison 501-D13 turboprops. It has a retractable tricycle landing gear and a conventional tail . It has a cockpit crew of three and can carry 66 to 80 passengers in

549-418: A dozen cylinders or more. Cylinder capacities may range from 10 cm or less in model engines up to thousands of liters in ships' engines. The compression ratio affects the performance in most types of reciprocating engine. It is the ratio between the volume of the cylinder, when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke. The bore/stroke ratio

610-570: A four-engine design for 75 passengers with 2,000 miles (3,200 km) range. Lockheed proposed a new design, the CL-310 with a low wing and four Rolls-Royce Darts or Napier Elands . The CL-310 design met the American Airlines requirements, but failed to meet those of another interested carrier, Eastern Air Lines . Its requirements were for a longer range, a minimum cruising speed of 350 miles per hour (560 km/h), and increased seating capacity to

671-407: A fuel air mixture ( internal combustion engine ) or by contact with a hot heat exchanger in the cylinder ( Stirling engine ). The hot gases expand, pushing the piston to the bottom of the cylinder. This position is also known as the bottom dead center (BDC), or where the piston forms the largest volume in the cylinder. The piston is returned to the cylinder top (top dead center) (TDC) by a flywheel ,

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732-406: A hot to a cold reservoir. The mechanism of operation of the engine can be described by the laws of quantum mechanics . Quantum refrigerators are devices that consume power with the purpose to pump heat from a cold to a hot reservoir. In a reciprocating quantum heat engine, the working medium is a quantum system such as spin systems or a harmonic oscillator. The Carnot cycle and Otto cycle are

793-615: A large number of unusual varieties of piston engines that have various claimed advantages, many of which see little if any current use: Mechanical resonance Mechanical resonance is the tendency of a mechanical system to respond at greater amplitude when the frequency of its oscillations matches the system's natural frequency of vibration (its resonance frequency or resonant frequency ) closer than it does other frequencies. It may cause violent swaying motions and potentially catastrophic failure in improperly constructed structures including bridges, buildings and airplanes. This

854-521: A million flights on the route before the type was replaced by Boeing 737-300 and Fokker 100 jets in 1992. The Electra became so iconic on that route that its retirement caused a commotion in Brazil, with extensive press coverage and many special tributes. During the mid-1970s, several secondhand Electras were bought by travel clubs, including Nomads, Adventurers and Shillelaghs. Others were retired from passenger service into air-cargo use, 40 being modified by

915-452: A mixed-class arrangement, although 98 could be carried in a high-density layout. The first variant was the Model 188A, followed by the longer-range 188C with room for 1,000 US gallons (3,800 L) more fuel and maximum take-off weight 15000 KG / 33069 lbs. American Airlines was the launch customer. Eastern Air Lines , Braniff Airways , and Northwest Airlines followed. The Electra suffered

976-480: A sequence of strokes that admit and remove gases to and from the cylinder. These operations are repeated cyclically and an engine is said to be 2-stroke , 4-stroke or 6-stroke depending on the number of strokes it takes to complete a cycle. The most common type is 4-stroke, which has following cycles. The reciprocating engine developed in Europe during the 18th century, first as the atmospheric engine then later as

1037-538: A subsidiary of Lockheed from 1968 with one or two large doors in the left side of the fuselage and a reinforced cabin floor. Air California and Pacific Southwest Airlines (PSA) were still operating Electras for scheduled passenger service during the late 1970s primarily into the Lake Tahoe Airport located in the Sierra Nevada mountains of California, as this airfield had banned scheduled jet aircraft flights at

1098-489: A troubled start. Passengers of early aircraft complained of noise in the cabin forward of the wings, caused by propeller resonance. Lockheed redesigned the engine nacelles , tilting the engines upwards 3°. The changes were incorporated on the production line by mid-1959 or as modification kits for the aircraft already built, and resulted in improved performance and a better ride for passengers. Three aircraft were lost in fatal accidents between February 1959 and March 1960. After

1159-407: A vibratory force for determining qualities, characteristics, or conditions thereof, or sensing, studying or making analysis of the vibrations otherwise generated in or existing in the article or mechanism. Devices include right methods to cause vibrations at a natural mechanical resonance and measure the frequency and/or amplitude the resonance made. Various devices study the amplitude response over

1220-445: Is a phenomenon known as resonance disaster. Avoiding resonance disasters is a major concern in every building, tower and bridge construction project. The Taipei 101 building for instance relies on a 660-ton pendulum —a tuned mass damper —to modify the response at resonance. The structure is also designed to resonate at a frequency which does not typically occur. Buildings in seismic zones are often constructed to take into account

1281-438: Is another simple example of a resonant system with which most people have practical experience. It is a form of pendulum. If the system is excited (pushed) with a period between pushes equal to the inverse of the pendulum's natural frequency, the swing will swing higher and higher, but if excited at a different frequency, it will be difficult to move. The resonance frequency of a pendulum, the only frequency at which it will vibrate,

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1342-472: Is common to classify such engines by the number and alignment of cylinders and total volume of displacement of gas by the pistons moving in the cylinders usually measured in cubic centimetres (cm or cc) or litres (l) or (L) (US: liter). For example, for internal combustion engines, single and two-cylinder designs are common in smaller vehicles such as motorcycles , while automobiles typically have between four and eight, and locomotives and ships may have

1403-492: Is given approximately, for small displacements, by the equation: where g is the acceleration due to gravity (about 9.8 m/s near the surface of Earth ), and L is the length from the pivot point to the center of mass. (An elliptic integral yields a description for any displacement). Note that, in this approximation, the frequency does not depend on mass . Mechanical resonators work by transferring energy repeatedly from kinetic to potential form and back again. In

1464-586: Is not to be confused with fuel efficiency , since high efficiency often requires a lean fuel-air ratio, and thus lower power density. A modern high-performance car engine makes in excess of 75 kW/L (1.65 hp/in ). Reciprocating engines that are powered by compressed air, steam or other hot gases are still used in some applications such as to drive many modern torpedoes or as pollution-free motive power. Most steam-driven applications use steam turbines , which are more efficient than piston engines. The French-designed FlowAIR vehicles use compressed air stored in

1525-412: Is not true of every reciprocating engine), although power and fuel consumption are affected by many factors outside of engine displacement. Reciprocating engines can be characterized by their specific power , which is typically given in kilowatts per litre of engine displacement (in the U.S. also horsepower per cubic inch). The result offers an approximation of the peak power output of an engine. This

1586-401: Is often used to ensure smooth rotation or to store energy to carry the engine through an un-powered part of the cycle. The more cylinders a reciprocating engine has, generally, the more vibration-free (smoothly) it can operate. The power of a reciprocating engine is proportional to the volume of the combined pistons' displacement. A seal must be made between the sliding piston and the walls of

1647-516: Is proportional to the bob's mass and to the square of its speed. When the bob is at the bottom of its travel, it has maximum kinetic energy and minimum potential energy. The same process then happens in reverse as the bob climbs towards the top of its swing. Some resonant objects have more than one resonance frequency, particularly at harmonics (multiples) of the strongest resonance. It will vibrate easily at those frequencies, and less so at other frequencies. It will "pick out" its resonance frequency from

1708-532: Is simply the distance between the TDC and the BDC, or the greatest distance that the piston can travel in one direction. In some designs the piston may be powered in both directions in the cylinder, in which case it is said to be double-acting . In most types, the linear movement of the piston is converted to a rotating movement via a connecting rod and a crankshaft or by a swashplate or other suitable mechanism. A flywheel

1769-394: Is the fictitious pressure which would produce the same amount of net work that was produced during the power stroke cycle. This is shown by: where A p {\displaystyle A_{p}} is the total piston area of the engine, S {\displaystyle S} is the stroke length of the pistons, and V d {\displaystyle V_{d}}

1830-459: Is the ratio of the diameter of the piston, or " bore ", to the length of travel within the cylinder, or "stroke". If this is around 1 the engine is said to be "square". If it is greater than 1, i.e. the bore is larger than the stroke, it is "oversquare". If it is less than 1, i.e. the stroke is larger than the bore, it is "undersquare". Cylinders may be aligned in line , in a V configuration , horizontally opposite each other, or radially around

1891-425: Is the total displacement volume of the engine. Therefore: Whichever engine with the larger value of MEP produces more net work per cycle and performs more efficiently. In steam engines and internal combustion engines, valves are required to allow the entry and exit of gases at the correct times in the piston's cycle. These are worked by cams, eccentrics or cranks driven by the shaft of the engine. Early designs used

Lockheed L-188 Electra - Misplaced Pages Continue

1952-423: Is then fed through one or more, increasingly larger bore cylinders successively, to extract power from the steam at increasingly lower pressures. These engines are called compound engines . Aside from looking at the power that the engine can produce, the mean effective pressure (MEP), can also be used in comparing the power output and performance of reciprocating engines of the same size. The mean effective pressure

2013-452: The D slide valve but this has been largely superseded by piston valve or poppet valve designs. In steam engines the point in the piston cycle at which the steam inlet valve closes is called the cutoff and this can often be controlled to adjust the torque supplied by the engine and improve efficiency. In some steam engines, the action of the valves can be replaced by an oscillating cylinder . Internal combustion engines operate through

2074-481: The Wobbly Bridge ) exhibited this problem. A faulty bridge can even be destroyed by its resonance (see Broughton Suspension Bridge and Angers Bridge ). Mechanical systems store potential energy in different forms. For example, a spring /mass system stores energy as tension in the spring, which is ultimately stored as the energy of bonds between atoms . In mechanics and construction a resonance disaster describes

2135-469: The cylinder so that the high pressure gas above the piston does not leak past it and reduce the efficiency of the engine. This seal is usually provided by one or more piston rings . These are rings made of a hard metal, and are sprung into a circular groove in the piston head. The rings fit closely in the groove and press lightly against the cylinder wall to form a seal, and more heavily when higher combustion pressure moves around to their inner surfaces. It

2196-420: The steam engine . These were followed by the Stirling engine and internal combustion engine in the 19th century. Today the most common form of reciprocating engine is the internal combustion engine running on the combustion of petrol , diesel , liquefied petroleum gas (LPG) or compressed natural gas (CNG) and used to power motor vehicles and engine power plants . One notable reciprocating engine from

2257-404: The 1940 collapse of "Galloping Gertie", the original Tacoma Narrows Bridge , is sometimes characterized in physics textbooks as a classic example of resonance. The catastrophic vibrations that destroyed the bridge were due to an oscillation caused by interactions between the bridge and the winds passing through its structure—a phenomenon known as aeroelastic flutter . Robert H. Scanlan , father of

2318-742: The 85-to-90-passenger level. Lockheed redesigned the CL-310 to use the Allison 501-D13 turboprop engine, a civilian version of the T56 developed for the Lockheed C-130 Hercules military transport. The airframe was stretched to allow for more seats and handle the increased performance. This design was launched as the Model 188 with an order for 35 by American Airlines on June 8, 1955. This was followed by Eastern Air Lines with an order for 40 on September 27, 1955. The first aircraft took 26 months to complete, and by that time Lockheed had orders for 129. The prototype,

2379-732: The Argentine Navy's Electras, known locally as L-188E Electron , is preserved at the Argentine Naval Aviation Museum ( Museo de la Aviación Naval ) at Bahía Blanca . By July 2018, only two Electras in the world were transporting cargo, both with Buffalo Airways . Thirteen other aircraft remained in service as air tankers nine with Air Spray ( aerial firefighting ) and four with Buffalo Airways (cargo/bulk fuel and aerial firefighting). As of 2024, no passenger flights are taken on Electras, with Air Spray and Buffalo Airways still operating 13 cargo and firefighting planes. Of

2440-597: The Australian mainland state capital cities, and later to Port Moresby , from 1959 until 1971. Ansett had its three Electras converted to freighters in 1970–71 and continued to fly them until 1984. Qantas also operated four Electras on its routes to Hong Kong and Japan, to New Caledonia , and to New Guinea (until the New Guinea route was handed to Ansett and TAA); then later across the Indian Ocean to South Africa, and across

2501-537: The Electra had highly successful operations, such as those of Lloyd Aéreo Boliviano and Líneas Aéreas Paraguayas ; in both cases, the Electra ensured the airlines' international operations before they started using jets. Most notably, Brazilian flag carrier airline Varig operated flawlessly a fleet of 14 Electras on the extremely busy Rio de Janeiro - São Paulo shuttle service (the so-called Ponte Aérea – or "Air Bridge" in Portuguese) for 30 years, completing over half

Lockheed L-188 Electra - Misplaced Pages Continue

2562-494: The Tasman in competition with TEAL after that airline became 100% New Zealand-owned. The divestiture of TEAL's 50%-Australian shareholding was itself prompted by the Electra order, as TEAL wanted jet aircraft, but was forced by the Australian government to order Electras in order to standardise with Qantas. Three Qantas Electras were retired in the mid-1960s and the fourth in 1971. Some Electras were sold to South American airlines, where

2623-483: The World War II era was the 28-cylinder, 3,500  hp (2,600 kW) Pratt & Whitney R-4360 Wasp Major radial engine. It powered the last generation of large piston-engined planes before jet engines and turboprops took over from 1944 onward. It had a total engine capacity of 71.5 L (4,360 cu in), and a high power-to-weight ratio . The largest reciprocating engine in production at present, but not

2684-414: The combustion; or a compression-ignition (CI) engine , where the air within the cylinder is compressed, thus heating it , so that the heated air ignites fuel that is injected then or earlier . There may be one or more pistons. Each piston is inside a cylinder , into which a gas is introduced, either already under pressure (e.g. steam engine ), or heated inside the cylinder either by ignition of

2745-470: The crankshaft. Opposed-piston engines put two pistons working at opposite ends of the same cylinder and this has been extended into triangular arrangements such as the Napier Deltic . Some designs have set the cylinders in motion around the shaft, such as the rotary engine . In some steam engines, the cylinders may be of varying size with the smallest bore cylinder working the highest pressure steam. This

2806-557: The design was dropped. Subsequently, Capital Airlines went on to order 60 British Vickers Viscounts . In 1954, as a result of American Airlines ' interest in developing a twin-engined aircraft, the idea resurfaced and the company offered a twin-engined design now designated the CL-303. This newer design was a high-wing type and would allow for 60 to 70 passengers. This design was also shelved for lack of interest from other carriers. The following year, American Airlines revised its requirement to

2867-435: The destruction of a building or a technical mechanism by induced vibrations at a system's resonant frequency, which causes it to oscillate . Periodic excitation optimally transfers to the system the energy of the vibration and stores it there. Because of this repeated storage and additional energy input the system swings ever more strongly, until its load limit is exceeded. The dramatic, rhythmic twisting that resulted in

2928-407: The element or apply mechanical energy produced by the element to an external load. The United States Patent Office classifies devices that tests mechanical resonance under subclass 579, resonance , frequency , or amplitude study, of Class 73, Measuring and testing . This subclass is itself indented under subclass 570, Vibration. Such devices test an article or mechanism by subjecting it to

2989-405: The engine mounts and the wing structures supporting the mounts were strengthened, and some of the wing skins were replaced with thicker material. All Electras were modified by the factory at Lockheed's expense, with the modifications taking 20 days for each aircraft. The changes were incorporated in later aircraft as they were built. However, the damage had been done, and the public lost confidence in

3050-460: The field of bridge aerodynamics, wrote an article about this. Various method of inducing mechanical resonance in a medium exist. Mechanical waves can be generated in a medium by subjecting an electromechanical element to an alternating electric field having a frequency which induces mechanical resonance and is below any electrical resonance frequency. Such devices can apply mechanical energy from an external source to an element to mechanically stress

3111-588: The largest ever built, is the Wärtsilä-Sulzer RTA96-C turbocharged two-stroke diesel engine of 2006 built by Wärtsilä . It is used to power the largest modern container ships such as the Emma Mærsk . It is five stories high (13.5 m or 44 ft), 27 m (89 ft) long, and weighs over 2,300 metric tons (2,535 short tons ; 2,264 long tons ) in its largest 14 cylinders version producing more than 84.42 MW (113,209 bhp). Each cylinder has

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3172-410: The ones most studied. The quantum versions obey the laws of thermodynamics . In addition, these models can justify the assumptions of endoreversible thermodynamics . A theoretical study has shown that it is possible and practical to build a reciprocating engine that is composed of a single oscillating atom. This is an area for future research and could have applications in nanotechnology . There are

3233-478: The only European airline to order the type from Lockheed was KLM , which used 12 between September 1959 and January 1969 in Europe and east to Saigon and Kuala Lumpur. In the South Pacific, Tasman Empire Airways Limited (TEAL) and its successor Air New Zealand flew the Electra on trans-Tasman flights. In Australia Trans Australia Airlines (TAA) and Ansett each operated three Electras on trunk routes between

3294-478: The oscillating frequencies of expected ground motion. Engineers designing objects that have engines must ensure that the mechanical resonant frequencies of the component parts do not match driving vibrational frequencies of the motors or other strongly oscillating parts. Many resonant objects have more than one resonance frequency. Such objects will vibrate easily at those frequencies, and less so at other frequencies. Many clocks keep time by mechanical resonance in

3355-503: The outboard engine nacelles. When the oscillation was transmitted to the wings and the flutter frequency decreased to a point where it was resonant with the outer wing panels (at the same frequency, or harmonically related ones), violent up-and-down oscillation increased until the wings would tear off. The company implemented an expensive modification program (the Lockheed Electra Achievement Program, LEAP) in which

3416-401: The pendulum, for example, all the energy is stored as gravitational energy (a form of potential energy) when the bob is instantaneously motionless at the top of its swing. This energy is proportional to both the mass of the bob and its height above the lowest point. As the bob descends and picks up speed, its potential energy is gradually converted to kinetic energy (energy of movement), which

3477-434: The power from other pistons connected to the same shaft or (in a double acting cylinder ) by the same process acting on the other side of the piston. This is where the piston forms the smallest volume in the cylinder. In most types the expanded or " exhausted " gases are removed from the cylinder by this stroke . The exception is the Stirling engine , which repeatedly heats and cools the same sealed quantity of gas. The stroke

3538-568: The third crash, the FAA limited the Electra's speed until the cause could be determined. After an extensive investigation, two of the crashes (in September 1959 and March 1960) were found to be caused by an engine-mount problem. The mounting of the gearbox cracked, and the reduced rigidity enabled a phenomenon called "whirl mode flutter" (analogous to the precession of a child's Spinning Top as it slows down, an interaction of propellers with airflow) that affected

3599-692: The time. In 1973, the Argentine Navy bought three Electras equipped with cargo doors. These were used during the " Dirty War " to toss political prisoners into the Rio de La Plata in the infamous death flights . The Electras were also used for transport duties during the Falklands War in 1982. In 1983, after the retirement of its last SP-2H Neptune , the Argentine Navy bought further civilian Electra airframes, modified several for maritime patrol , and widely used them until their replacement by P-3s in 1994. One of

3660-511: The total of 170 Electras built, as of June 2011, 58 have been written off because of crashes and other accidents. Data from Lockheed Aircraft since 1913 General characteristics Performance Related development Aircraft of comparable role, configuration, and era Piston-engine A reciprocating engine , also often known as a piston engine , is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into

3721-468: The type. This and the smaller jets that were being introduced eventually relegated Electras to the smallest airlines. Production ended in 1961 after 170 had been built. Losses to Lockheed have been estimated as high as $ 57 million, not counting an additional $ 55 million in lawsuits. Electras continued to carry passengers into the 1990s, but most now in use are freighters. Several airlines in the US flew Electras, but

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