Large aircraft allow the transportation of large and/or heavy payloads over long distances. Making an aircraft design larger can also improve the overall fuel efficiency and man-hours for transporting a given load, while a greater space is available for transporting lightweight cargoes or giving passengers room to move around. However, as aircraft increase in size they pose significant design issues not present in smaller types. These include structural efficiency, flight control response and sufficient power in a reliable and cost-effective installation.
Large aircraft also require specialised ground facilities, and some countries have special regulatory environments for them.
The giant airships of the 1930s remain, as of 2016, the largest aircraft ever constructed, while the Hughes H-4 "Spruce Goose" of 1947 had the largest wingspan of any fixed-wing type. The Hybrid Air Vehicles Airlander 10hybrid airship is the largest aircraft flying today.
Characteristics
The airship Hindenburg compared to the four largest aeroplanes.
Payload space
The lifting capacity of an aircraft depends on the wing size and its "loading", the weight per unit area that the wing can support. Loading is more or less constant for a given level of technology. Thus, as aircraft size increases the lifting capacity increases with the surface area. For a given aerodynamic form, the area in turn increases with the square of the wing span. If structural efficiency can be maintained, the structural weight of the airframe also increases with its surface area and the square of the span. But the internal volume increases with the cube of the span.
For example, if the dimensions are all doubled in size, then the area and lifting capacity increase 2 × 2 = 4 times, while the volume increases 2 × 2 × 2 = 8 times.
For a passenger aircraft, this doubling in size allows up to twice the cabin space per passenger. Alternatively, for a transport it allows up to twice the space to fit in bulky but light cargo. Thus, large aircraft are both more comfortable and operationally flexible in use than smaller types.
Structure
Although a larger wing carries larger forces, it is also thicker. The main spar in the wing approximates an I-beam, whose depth equals the wing thickness. For a given overall load to be carried, the forces in the beam decrease with the square of its depth. If a wing is doubled in span it is also doubled in thickness. This reduces the forces in the spar by a factor of 2 x 2 = 4, allowing a fourfold increase in the overall load. This exactly matches the increased lift available from the larger wing area.
This means that the metal parts of a large aircraft need be no thicker or heavier than those of a smaller aircraft. However, because these parts must cover four times the area they make the aircraft four times heavier. This again exactly matches the increase in laden weight, so there is no structural limit to how large (or small) an aeroplane can be made.
Large aircraft do still pose a design challenge. The structural members may be no thicker, but they are now twice as long, so stiffness becomes a problem, and the design approach must be adapted to ensure adequate overall stiffness. This is typically achieved by making structural members cellular. For example, the wing spar in a small aircraft may in fact be a simple I-beam with a solid cross-section, but in a larger design the upright part of the beam or "web" will be constructed as an open lattice of trusses in a triangulated structure.
Flight control
The effectiveness of a flight control such as an aileron depends mainly on its area and its distance from the centre of the aircraft - its lever arm. If the wingspan is doubled, the area increases fourfold and the lever arm doubles, making the aileron 8 times more effective.
With the aircraft being also four times heavier, and with the weight on average twice as far out, it requires 8 times the effort to achieve the same acceleration of the wing tip.
These balance out, so on a large aircraft the equivalent aileron will accelerate the wing tip up or down at the same speed as a smaller aircraft. But on a wing twice the span, the tip must travel twice as far to achieve the same change in aircraft attitude. This takes longer, so a large aircraft manoeuvres more slowly than the equivalent smaller aircraft.
On very large types such as the Airbus A380, conventional ailerons alone are not enough, and additional lift spoilers are used to reduce the lift of the downward-tipping wing and increase the roll rate to a practical and safe level.
Similar issues occur with the elevator and pitch control. Without extra design measures to ensure adequate control response, any attempt to make a last-minute correction to the flight path is likely to prove too little too late, making a last-minute landing abort and fly-around difficult and dangerous.
Engines
The number of engines on an aircraft affects its reliability and safety. The more engines there are, the safer it is if one engine fails. But on the other hand, the more engines there are, the more likely there is to be a failure of one or more and the greater the workload on the flight engineer. Nowadays, two engines are preferred in practice, with even quite large wide-body aircraft having only two engines. Four is generally accepted as the limit, for both safety and cost reasons.
Barring a few military types, no practical large aircraft has ever had more than four engines. As aircraft get bigger, it therefore becomes necessary to design bigger engines.
The airspeed of a fan blade must be kept below the speed of sound in order to avoid damaging and noisy shock waves. This maximum speed of the tip sets a limit on the rate of rotation. For a given rate of rotation, the tip of a larger fan will travel faster. So to keep down the top speed of a large engine, the fan must spin more slowly. The fan is driven by a turbine off the same shaft, so the turbine blades also spin round more slowly.
Operations
In practice, the operational savings inherent in flying fewer aircraft make larger types more economical on routes which can sustain their size.
However, ground facilities such as runways, handling facilities and hangars must be enlarged to cope, and the expense of this must be offset against the lower operating cost. The limited width available at some airports restricts the wing span achievable on a practical aircraft.
Regulatory definitions
In the regulation of air activity, authorities pose additional rules and restrictions on types above a certain size.
The European Aviation Safety Agency (EASA) defines a large aircraft as either "an aeroplane with a maximum take-off mass of more than 5,700 kilograms (12,600 pounds), a multi-engined helicopter or a gas airship with a volume of more than 15 000 m3."[2]
History
The first practical aircraft were balloons, used for sport and for military observation. In 1901 the giant balloon Preusen (Prussia) of 8,400 cubic metres (300,000cuft) rose to a height of 9,155 metres (30,036ft). Early airships were little more than elongated balloons with an engine slung underneath. These craft were limited in size because their bodies were non-rigid and could not be made too long. The German Count Ferdinand von Zeppelin realised that a rigid frame could support a much larger volume, and in 1900 the Luftschiff Zeppelin 1 of 11,300 cubic metres (400,000cuft) volume and 128 metres (420ft) length took briefly to the air.[3]
Early fixed-wing aeroplanes were mostly single-engined. When the Russian Igor Sikorsky designed and flew his Ilya Muromets in 1913 it became not only the first four-engined aircraft but, with a wing span of 29.8 metres (98ft) and laden weight of 4,600 kilograms (10,100lb), by far the largest and heaviest to date. By comparison the LZ 18 airship, which flew the same year, was 158 metres (518ft) long (the envelope had a capacity of 270,000m3 (9,500,000cuft)) and an empty weight of 20 tonnes.
The Beardmore Inflexible of 1928 had a wingspan of 157ft 6in (48.01m) and an all up weight of 37,000lbs. However, it was underpowered for such a heavy aircraft. It was structurally advanced for its time, being of all-metal stressed-skin construction.[4] The Dornier Do X was the largest, heaviest, and most powerful flying boat in the world when it flew in 1929, having a similar span of 48 m (157ft 6 in) and a maximum takeoff weight of 56,000kg (123,459lb).
During the years between the two World Wars, only the Soviet Tupolev ANT-20Maxim Gorki landplane of 1934 was larger at 63.00 m (206ft 9 in) span, but at 53 metric tons maximum takeoff weight it was not as heavy as the Do X's 56 tonnes.
The largest airship ever built was the Zeppelin LZ 129 "Hindenburg". First flying in 1936, the Hindenburg had a volume of 200,000 cubic metres (7,100,000cuft) and a length of 245 metres (804ft). Its maximum payload, of combined passengers and freight, was 19,000 kilograms (42,000lb). Following the Hindenburg's disastrous end, no airships of this scale have since been built.
By then, larger aeroplanes—especially long-distance flying boats—had exceeded the Ilya Muromets in scale. Then, during World War II, America foresaw a requirement for a large trans-Pacific cargo carrier able to operate from bases with no prepared landing strip. The giant Hughes H-4 Hercules flying boat was constructed from timber, earning it the name the "Spruce Goose". When finally flown briefly in 1947, its 97.82 metres (320ft 11in) wingspan made it the largest plane ever to fly until the Stratolaunch at 117 metres (385ft) was flown for the first time on April 13, 2019. It required 8 Pratt & Whitney R-4360 Wasp Major radial engines to get it into the air. By then, the landplane had taken over long-distance flight and the H-4 - having made no more than a single mile-long flight less than 100ft off the water - never flew again. It is today preserved as a museum piece.
At the start of the Second World War, Barnes Wallis proposed a "Victory Bomber" of 50 tonnes to carry a 10-tonne bomb but it was discounted by the Air Ministry because of its limited application. As the war progressed the British contemplated very large bomber designs (from 75 to 100 tonnes with bombloads of 25 tonnes and six or more engines) but considered the time required to bring them into use, the difficulty of balancing bombload, defensive armament and range, and the success of existing designs (such as the Avro Lancaster) to outweigh any advantages. Some of the work on large aircraft fed into the post-war Bristol Brabazon a 70-m wingspan 130-tonne airliner which would have given its 100 passengers ship-like levels of space and comfort.[5]
With the arrival of the jet age, airliners continued to increase in size. Wide-body types were introduced and, in 1970, the Boeing 747 "Jumbo jet" entered service. It featured a short second, upper deck to provide increased passenger accommodation. Variants of the 747 remained the largest airliners flying for well over thirty years, some with a "stretched" upper deck, until the arrival of the Airbus A380 series in 2007 featuring a full-length upper deck. Both lines continue to be developed, with ever-larger variants being introduced. The largest is currently (2014) the A380-800, capable of seating up to 853 people.
In order to airlift the Buran space shuttle, in 1988 Soviet Union introduced the sole Antonov An-225 Mriya (dream). With a (maximum takeoff weight greater than 640 tonnes (1,410,000lb) and a wing span of 88.4 metres (290ft), it was the largest operational aeroplane in the world. Since the conclusion of Buran flights, the Mriya remained in service as a heavy transport plane until its destruction in the Battle of Antonov Airport during the 2022 Russian invasion of Ukraine.
These lists show the historical progression in size for each major class of aircraft: balloon, airship, aeroplane and rotorcraft. Hybrids are listed under the biggest component whether it be envelope length, wingspan or rotor diameter. -->
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its engines. Common examples of aircraft include airplanes, helicopters, airships, gliders, paramotors, and hot air balloons.
An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air.
The wingspan of a bird or an airplane is the distance from one wingtip to the opposite wingtip. For example, the Boeing 777–200 has a wingspan of 60.93 metres, and a wandering albatross caught in 1965 had a wingspan of 3.63 metres, the official record for a living bird. The term wingspan, more technically extent, is also used for other winged animals such as pterosaurs, bats, insects, etc., and other aircraft such as ornithopters. In humans, the term wingspan also refers to the arm span, which is the distance between the length from the end of an individual's arm to the individual's fingertips on the other arm when raised parallel to the ground at shoulder height.
Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere or through the vacuum of outer space. This can be achieved by generating aerodynamic lift associated with gliding or propulsive thrust, aerostatically using buoyancy, or by ballistic movement.
An aerostat is a lighter-than-air aircraft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships. A balloon may be free-flying or tethered. The average density of the craft is lower than the density of atmospheric air, because its main component is one or more gasbags, a lightweight skin containing a lifting gas to provide buoyancy, to which other components such as a gondola containing equipment or people are attached. Especially with airships, the gasbags are often protected by an outer envelope.
The Kamov Ka-22 Vintokryl was a rotorcraft developed by Kamov for the Soviet Air Force. The experimental transport aircraft combined the capabilities of a helicopter for vertical take-off and landing with those of a fixed-wing aircraft for cruise. The Ka-22 carried a large payload, having a hold comparable in size to the Antonov An-12. Eight world records for altitude and speed were set by the Ka-22 in its class, none of which have since been broken.
An airplane, or aeroplane, informally plane, is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spectrum of uses for airplanes includes recreation, transportation of goods and people, military, and research. Worldwide, commercial aviation transports more than four billion passengers annually on airliners and transports more than 200 billion tonne-kilometers of cargo annually, which is less than 1% of the world's cargo movement. Most airplanes are flown by a pilot on board the aircraft, but some are designed to be remotely or computer-controlled such as drones.
Early flying machines include all forms of aircraft studied or constructed before the development of the modern aeroplane by 1910. The story of modern flight begins more than a century before the first successful manned aeroplane, and the earliest aircraft thousands of years before.
A radio-controlled glider is a type of radio-controlled aircraft that normally does not have any form of propulsion. They are able to sustain continuous flight by exploiting the lift produced by slopes and thermals, controlled remotely from the ground with a transmitter. They can be constructed from a variety of materials, including wood, plastic, polymer foams, and composites, and can vary in wing loading from very light to relatively heavy, depending on their intended use.
The Armstrong Whitworth A.W.52 was an early flying wing aircraft designed and produced by British aircraft manufacturer Armstrong Whitworth Aircraft.
The Royal Aircraft Factory F.E.1 was designed and built in 1910 by the pioneer designer Geoffrey de Havilland. He used it to teach himself to fly during late 1910. After De Havilland was appointed assistant designer and test pilot at the Army Balloon Factory at Farnborough in December 1910 the War Office bought the aircraft for £400. the aircraft was given the designation F.E.1
The British Army Aeroplane No 1 or sometimes Cody 1 was a biplane built by Samuel Franklin Cody in 1907 at the Army Balloon Factory at Farnborough. It made the first recognised powered and sustained flight in the United Kingdom on 16 October 1908.
A subsonic aircraft is an aircraft with a maximum speed less than the speed of sound. The term technically describes an aircraft that flies below its critical Mach number, typically around Mach 0.8. All current civil aircraft, including airliners, helicopters, future passenger drones, personal air vehicles and airships, as well as many military types, are subsonic.
The Bristol B.R.7 was a Romanian-designed single-engine two-seat biplane built by Bristol to a Spanish government order in 1913. It failed to meet its specifications and the order was cancelled.
The Latécoère 350 was a trimotor development of the Latécoère 28, a successful single-engined French monoplane of around 1930. The three engines were intended to provide the reliability needed for overnight flights, but the 350 came out very overweight. Only one was built.
The Wanamaker Triplane or Curtiss Model T, retroactively renamed Curtiss Model 3 was a large experimental four-engined triplane patrol flying boat of World War I. It was the first four-engined aircraft built in the United States. Only a single example (No.3073) was completed. At the time, the Triplane was the largest seaplane in the world.
The Burnelli RB-1 was a US twin engine biplane airliner prototype from 1920, incorporating a lifting body fuselage.
The Schütte-Lanz G.I was a large, twin engine, pusher configuration, experimental biplane built in Germany early in World War I. Only one was completed.
The Dunne-Huntington triplane, sometimes referred to as a biplane, was a pioneer aircraft designed by J. W. Dunne and built by A. K. Huntington. It was of unusual staggered triple-tandem configuration and an early example of an inherently stable aeroplane, flying regularly between 1910 and 1914.
↑ Kössler and Ott, Die großen Dessauer: Junkers Ju 89, 90, 290, 390. Die Geschichte einer Flugzeugfamilie Berlin: Aviatik-Verlag, 1993. ISBN3-925505-25-3.
1 2 Winchester, J. (Ed.); "The Aviation Factfile: Concept Aircraft", Grange (2005).
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