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96-490: A flying wing is a tailless fixed-wing aircraft that has no definite fuselage , with its crew, payload, fuel, and equipment housed inside the main wing structure. A flying wing may have various small protuberances such as pods, nacelles , blisters, booms, or vertical stabilizers . Similar aircraft designs, that are not technically flying wings, are sometimes casually referred to as such. These types include blended wing body aircraft and lifting body aircraft, which have

192-424: A bell-shaped lift distribution which minimises induced drag for the aircraft weight. He applied this distribution in the "Prandtl-D" series of designs. By the end of 2017, he had flown three such research models. Directional stability Directional stability is stability of a moving body or vehicle about an axis which is perpendicular to its direction of motion. Stability of a vehicle concerns itself with

288-426: A consequence. The net side force Y on the vehicle is the centripetal force causing the vehicle to change the direction it is traveling: where M is the vehicle mass and V the speed. The angles are all assumed small, so the lateral force equation is: The rotation of the body subjected to a yawing moment N is governed by: where I is the moment of inertia in yaw. The forces and moments of interest arise from

384-432: A conventional wing and long-thin fuselage. This can actually result in higher drag and thus lower efficiency than a conventional design. Typically the solution adopted in this case is to keep the wing reasonably thin, and the aircraft is then fitted with an assortment of blisters, pods, nacelles, fins, and so forth to accommodate all the needs of a practical aircraft. The problem becomes more acute at supersonic speeds, where

480-509: A flying wing, or Nurflügel , design with a pair of Junkers Jumo 004 jet engines in its second, or "V2" (V for Versuch ) prototype airframe; as such, it was the world's first pure flying wing to be powered by twin jet engines , being first reportedly flown in March 1944. V2 was piloted by Erwin Ziller, who was killed when a flameout in one of its engines led to a crash. Plans were made to produce

576-406: A fuselage and no definite wings. A pure flying wing is theoretically the lowest- drag design configuration for a fixed wing aircraft. However, because it lacks conventional stabilizing surfaces and the associated control surfaces, in its purest form the flying wing suffers from being unstable and difficult to control. The basic flying wing configuration became an object of significant study during

672-515: A fuselage nacelle between the planes with rear-mounted pusher propeller and fixed endplate fins between each pair of wing tips. After his Army work had ended, in 1910 the D.5 biplane was witnessed in stable flight by Orville Wright and Griffith Brewer , who submitted an official report to the Royal Aeronautical Society to that effect. It thus became the first aeroplane ever to achieve natural stability in flight, as well as

768-469: A horizontal attitude and so counteract any aerodynamic instability, as in the paraglider . However, in practice this is seldom sufficient to provide stability on its own, and typically is augmented by the aerodynamic techniques described. A classic example is the Rogallo wing hang glider, which uses the same sweepback, washout and conical surface as Dunne. Stability can also be provided artificially. There

864-480: A light weight production vehicle designed around a small engine increases both its directional stability, and its tendency to understeer. The result is an overpowered vehicle with poor cornering performance. Even worse is the installation of an oversized power unit into a rear engined production vehicle without corresponding modification of suspension or mass distribution, as the result will be directionally unstable at high speed. The forces arising from slip depend on

960-446: A more powerful engine, especially at high speeds. If longitudinal (pitch) stability and control can be achieved by some other method (see below), the stabiliser can be removed and the drag reduced. A tailless aeroplane has no separate horizontal stabilizer. Because of this the aerodynamic center of an ordinary wing would lie ahead of the aircraft's center of gravity, creating instability in pitch . Some other method must be used to move

1056-602: A natural solution to the problem of building an airliner large enough to carry a reasonable passenger load and enough fuel to cross the Atlantic in regular service. He believed that the flying wing's potentially large internal volume and low drag made it an obvious design for this role. His deep-chord monoplane wing was incorporated in the otherwise conventional Junkers J 1 in December 1915. In 1919 he started work on his "Giant" JG1 design, intended to seat passengers within

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1152-447: A natural tendency to point in the direction of motion. Arrows, darts, rockets, and airships have tail surfaces (fins or feathers) to achieve directional stability; an airplane uses its vertical stabilizer for the same purpose. A road vehicle does not have elements specifically designed to maintain stability, but relies primarily on the distribution of mass . These points are best illustrated with an example. The first stage of studying

1248-464: A patent for an aero-plane or flying aircraft powered by two propellers and with all the characteristics of a flying wing as we know it today. Tailless aircraft have been experimented with since the earliest attempts to fly. Britain's J. W. Dunne was an early pioneer, his swept-wing biplane and monoplane designs displayed inherent stability as early as 1910. His work directly influenced several other designers, including G. T. R. Hill , who developed

1344-675: A series of experimental tailless aircraft designs, collectively known as the Westland-Hill Pterodactyls , during the 1920s and early 1930s. Despite attempts to pursue orders from the Aviation Ministry , the Pterodactyl programme was ultimately cancelled during the mid 1930s before any order for the Mk. VI was issued. Germany's Hugo Junkers patented his own wing-only air transport concept in 1910, seeing it as

1440-440: A series of tailless aircraft intended to be inherently stable and unstallable. Inspired by his studies of seagulls in flight, they were characterised by swept wings with a conical upper surface. The cone was arranged so that the wing twisted progressively outwards towards the tips creating negative incidence, and hence negative lift, in the outboard sections, creating overall stability in both pitch and yaw. A single control surface on

1536-499: A short fuselage to house the crew and additional passengers. The Soviet Boris Ivanovich Cheranovsky began testing tailless flying wing gliders in 1924. After the 1920s, Soviet designers such as Cheranovsky worked independently and in secret under Stalin . With significant breakthrough in materials and construction methods, aircraft such as the BICh-3 , BICh-14 , BICh-7A became possible. Men like Chizhevskij and Antonov also came into

1632-401: A swept wing as seen in the direction of the airflow depends on the yaw angle relative to the airflow. Yaw increases the aspect ratio of the leading wing and reduces that of the trailing one. With sufficient sweep-back, differential induced drag resulting from the tip vortices and crossflow is sufficient to naturally re-align the aircraft. A complementary approach uses twist or wash-out, reducing

1728-411: A tail fin to keep it straight. Movement of the ailerons creates an adverse yaw pulling it out of the turn, which also has to be compensated by the rudder . While a swept wing is stable in straight flight, it still experiences adverse yaw during a turn. One solution is to give the wing sufficient twist for the outer section to angle downwards and give negative lift. This reverses the adverse yaw action of

1824-557: A thick wing, but two years later the Allied Aeronautical Commission of Control ordered the incomplete JG1 destroyed for exceeding postwar size limits on German aircraft. Junkers conceived futuristic flying wings for up to 1,000 passengers; the nearest this came to realization was in the 1931 Junkers G.38 34-seater Grossflugzeug airliner, which featured a large thick-chord wing providing space for fuel, engines, and two passenger cabins. However, it still required

1920-402: Is a trade-off between stability and maneuverability. A high level of maneuverability requires a low level of stability. Some modern hi-tech combat aircraft are aerodynamically unstable in pitch and rely on fly-by-wire computer control to provide stability. The Northrop Grumman B-2 Spirit flying wing is an example. Many early designs failed to provide effective pitch control to compensate for

2016-436: Is a variable-geometry concept comprising a long-span subsonic wing and a short-span supersonic wing, joined in the form of an unequal cross. Proposed in 2011, the low-speed wing would have a thick, rounded airfoil able to contain the payload and a long span for high efficiency, while the high-speed wing would have a thin, sharp-edged airfoil and a shorter span for low drag at supersonic speed. The craft would take off and land with

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2112-432: Is done progressively along the span of the outer section, it is called tip washout . Dunne achieved it by giving the wing upper surface a conical curvature. In level flight the aircraft should be trimmed so that the tips do not contribute any lift: they may even need to provide a small downthrust. This reduces the overall efficiency of the wing, but for many designs – especially for high speeds – this

2208-634: Is known to have influenced later designers such as John K. Northrop (father of the Northrop Grumman B-2 Spirit stealth bomber). After WWI, pilot Geoffrey T. R. Hill also sought a stable, unstallable design. Dunne gave some help initially and Hill went on to produce the Pterodactyl series of tailless aircraft from the 1920s onwards. Hill also began to develop the theory of the intrinsically stable aerofoil and incorporated it into his designs. German theorists further developed

2304-463: Is larger so enlarged surfaces are not required. The Dassault Mirage tailless delta series and its derivatives were among the most widely used combat jets. However even in the Mirage, pitch control at the high angles of attack experienced during takeoff and landing could be problematic and some later derivatives featured additional canard surfaces. A conventional aeroplane is unstable in yaw and needs

2400-404: Is low, the slip is negative and the body points out of the corner (it understeers ). At a speed given by: The body points in the direction of motion. Above this speed, the body points into the corner ( oversteers ). As an example: Evidently moving the centre of gravity forwards increases this speed, giving the vehicle a tendency to understeer . Note: Installing a heavy, powerful engine in

2496-488: Is made up of the slip of the vehicle as a whole modified by the angular velocity of the body. For the front axle: whilst for the rear axle: Let the constant of proportionality be k. The sideforce is, therefore: The moment is: Denoting the angular velocity ω {\displaystyle \omega } , the equations of motion are: Let θ − ψ = β {\displaystyle \theta -\psi =\beta } (beta),

2592-540: Is outweighed by the reductions in drag, weight and cost over a conventional stabiliser. The long wing span also reduces manoeuvrability, and for this reason Dunne's design was rejected by the British Army. An alternative is the use of low or null pitching moment airfoils , seen for example in the Horten series of sailplanes and fighters. These use an unusual wing aerofoil section with reflex or reverse camber on

2688-425: Is positive, as are the mass, moment of inertia and speed, so the damping is positive, and the directional motion should be dynamically stable. The stiffness term is: If the centre of gravity is ahead of the centre of the wheelbase ( ( b > a ) {\displaystyle (b>a)} , this will always be positive, and the vehicle will be stable at all speeds. However, if it lies further aft,

2784-437: Is positive, so the vehicle will be stable but unsteerable. It follows that the condition of the rear tyres is more critical to directional stability than the state of the front tyres. Also, locking the rear wheels by applying the handbrake, renders the vehicle directionally unstable, causing it to spin. Since the vehicle is not under control during the spin, the ' handbrake turn ' is usually illegal on public roads. Deflecting

2880-409: Is to angle or crank the wing tip sections downward with significant anhedral , increasing the area at the rear of the aircraft when viewed from the side. When combined with sweepback and washout, it can resolve another problem. With a conventional elliptical lift distribution the downgoing elevon causes increased induced drag that causes the aircraft to yaw out of the turn ("adverse yaw"). Washout angles

2976-430: Is to provide large elevator and/or elevon surfaces on the wing trailing edge. Unless the wing is highly swept, these must generate large control forces, as their distance from the aerodynamic center is small and the moments less. Thus a tailless type may experience higher drag during pitching manoeuvres than its conventional equivalent. In a highly swept delta wing the distance between trailing edge and aerodynamic centre

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3072-803: The DINFIA . Similar to the DH.108, the twin-jet powered 1948-vintage Northrop X-4 was one of the series of postwar X-planes experimental aircraft developed in the United States after World War II to fly in research programs exploring the challenges of high-speed transonic flight and beyond. It had aerodynamic problems similar to those of the DH.108, but both X-4 examples built survived their flight test programs without serious incidents through some 80 total research flights from 1950 to 1953, only reaching top speeds of 640 mph (1,035 km/h). The French Mirage series of supersonic jet fighters were an example of

3168-927: The Lockheed Martin RQ-170 Sentinel and the Northrop Grumman Tern . Civilian companies have also experimented with UAVs, such as the Facebook Aquila , as atmospheric satellites . Various prototype unmanned combat aerial vehicles (UCAVs) have been produced, including the Dassault nEUROn , the Sukhoi S-70 Okhotnik-B , the DRDO Ghatak , DRDO SWIFT and the BAE Systems Taranis . Tailless aircraft Theoretical advantages of

3264-516: The Me 163 Komet . It was the only rocket-powered interceptor ever to be placed in front-line service, and was the fastest aircraft to reach operational service during the war. In the 1930s, Walter and Reimar Horten started to build simple tailless gliders, the first of which flew in 1933. The Hortens designed the world's first jet-powered flying wing , the Horten Ho 229 In parallel with Lippisch, in

3360-488: The Tupolev Tu-144 , were tailless supersonic jet airliners, with ogival delta wings. The grace and beauty of these aircraft in flight were often remarked upon. The American Lockheed SR-71 Blackbird strategic reconnaissance aircraft is the fastest jet powered aircraft, achieving speeds above Mach 3. The NASA Preliminary Research Aerodynamic Design To Lower Drag (PRANDTL-D) wing has been developed by Al Bowers at

3456-600: The 1920s, often in conjunction with other tailless designs. In the Second World War , both Nazi Germany and the Allies made advances in developing flying wings. Military interest in the flying wing waned during the 1950s with the development of supersonic aircraft, but was renewed in the 1980s due to their potential for stealth technology . This approach eventually led to the Northrop Grumman B-2 Spirit stealth bomber. There has been continual interest in using it in

3552-541: The 1930s Jack Northrop independently worked on his own designs. The Northrop N-1M , a scale prototype for a long-range bomber, first flew in 1940. In 1941 Northrop was awarded a development contract to build 2 examples of the YB-35 flying wing, a very large 4 engined flying wing with a span of 172'. Development and construction of this aircraft continued throughout World War II. Other 1930s examples of true flying wings include Frenchman Charles Fauvel 's AV3 glider of 1933 and

3648-515: The 1936 summer Olympics in Berlin. In Germany , Alexander Lippisch worked first on tailless types before progressively moving to flying wings, while the Horten brothers developed a series of flying wing gliders through the 1930s. The H1 glider was flown with partial success in 1933, and the subsequent H2 flown successfully in both glider and powered variants. In the United States , from

3744-566: The A.W.52 yielded disappointing results; the first prototype crashed without loss of life on 30 May 1949, the occasion being the first emergency use of an ejection seat by a British pilot. The second A.W.52 remained flying with the Royal Aircraft Establishment until 1954. Projects continued to examine the flying wing during the postwar era. The work on the YB-35 long-range bomber begun in 1941, had continued throughout

3840-475: The Aeronautical Society of Great Britain, Dunne described the effect as "tangential gain". The existence of proverse yaw was not proved until NASA flew its Prandtl-D tailless demonstrator. In some flying wing designs, any stabilizing fins and associated control rudders would be too far forward to have much effect, thus alternative means for yaw control are sometimes provided. One solution to

3936-498: The American Freel Flying Wing glider flown in 1937. featuring a self-stabilizing airfoil on a straight wing. During the Second World War , aerodynamic issues became sufficiently understood for work on a range of production-representative prototypes to commence. In Nazi Germany , the Horten brothers were keen proponents of the flying wing configuration, developing their own designs around it - uniquely for

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4032-551: The NASA Armstrong Flight Research Center . Bowers was inspired by the work of Ludwig Prandtl and, like Dunne, by watching bird flight. As with the Dunne design, it has a wing twist sufficient to set the wing tips at a negative angle and create the same positive roll-yaw coupling. Bowers developed a quantitative analysis of the lifting characteristics, leading to his more general discovery of

4128-537: The US, Jack Northrop was developing his own ideas on tailless designs. The N-1M flew in 1941 and a succession of tailless types followed, some of them true flying wings. In the 1940s, the British aircraft designer John Carver Meadows Frost developed the tailless jet-powered research aircraft called the de Havilland DH.108 Swallow , built using the forward fuselage of the de Havilland Vampire jet fighter. One of these

4224-409: The aerodynamic center backward and make the aircraft stable . There are two main ways for the designer to achieve this, the first being developed by the pioneer aviator J. W. Dunne . Sweeping the wing leading edge back, either as a swept wing or delta wing , and reducing the angle of incidence of the outer wing section allows the outer wing to act like a conventional tailplane stabiliser. If this

4320-543: The aerodynamic centre, which in turn means that the fin is inefficient and to be effective the fin area must be large. Such a large fin has weight and drag penalties, and can negate the advantages of the flying wing. The problem can be minimized by increasing the wing sweepback and placing twin fins outboard near the tips, as for example in a low-aspect-ratio delta wing , but given the corresponding reduction in efficiency many flying wings have gentler sweepback and consequently have, at best, marginal stability. The aspect ratio of

4416-622: The aerodynamic drawbacks of the flying wing to be minimized, making for an efficient and effectively stable long-range bomber. Due to the practical need for a deep wing, the flying wing concept is mostly adopted for subsonic aircraft . There has been continual interest in using it in the large transport role where the wing is deep enough to hold cargo or passengers. A number of companies, including Boeing , McDonnell Douglas , and Armstrong Whitworth , have undertaken design studies on flying wing airliners to date; however, no such airliners have yet been built as of 2023. The bi-directional flying wing

4512-484: The ailerons, helping the plane into the turn and eliminating the need for a vertical rudder or differential-drag spoilers. The bell-shaped lift distribution this produces has also been shown to minimise the induced drag for a given weight (compared to the elliptical distribution, which minimises it for a given span). Between 1905 and 1913, the British Army Officer and aeronaut J. W. Dunne developed

4608-488: The aircraft may be less efficient than a conventional design. Some related aircraft that are not strictly flying wings have been described as such. Some types, such as the Northrop Flying Wing (NX-216H) , still have a tail stabilizer mounted on tail booms, although they lack a fuselage. Many hang gliders and microlight aircraft are tailless. Although sometimes referred to as flying wings, these types carry

4704-414: The angle of attack towards the wing tips, together with a swept-back wing planform. The Dunne D.5 incorporated this principle and its designer J. W. Dunne published it in 1913. The wash-out reduces lift at the tips to create a bell-shaped distribution curve across the span, described by Ludwig Prandtl in 1933, and this can be used to optimise weight and drag for a given amount of lift. Another solution

4800-489: The associated control surfaces, in its purest form the flying wing suffers from the inherent disadvantages of being unstable and difficult to control. These compromises are difficult to reconcile, and efforts to do so can reduce or even negate the expected advantages of the flying wing design, such as reductions in weight and drag . Moreover, solutions may produce a final design that is still too unsafe for certain uses, such as commercial aviation. Further difficulties arise from

4896-497: The car is pointing in a direction θ {\displaystyle \theta } (theta) whilst it is travelling in a direction ψ {\displaystyle \psi } (psi). In general, these are not the same. The tyre treads at the region of contact point in the direction of travel, but the hubs are aligned with the vehicle body, with the steering held central. The tyres distort as they rotate to accommodate this mis-alignment, and generate side forces as

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4992-461: The center of gravity must also be moved forward of the usual position. Due to the Bernoulli effect , reflex camber tends to create a small downthrust, so the angle of attack of the wing is increased to compensate. This in turn creates additional drag. This method allows a wider choice of wing planform than sweepback and washout, and designs have included straight and even circular (Arup) wings. But

5088-511: The coefficient of β {\displaystyle \beta } will be called the 'stiffness', as its function is to return the system to zero deflection, in the same manner as a spring. The form of the solution depends only on the signs of the damping and stiffness terms. The four possible solution types are presented in the figure. [REDACTED] The only satisfactory solution requires both stiffness and damping to be positive. The damping term is: The tyre slip coefficient k

5184-521: The configuration for potential conversion of tanks into temporary gliders . The British Armstrong Whitworth A.W.52 G of 1944 was a glider test bed for a proposed large flying wing airliner capable of serving transatlantic routes. The A.W.52G was later followed up by the Armstrong Whitworth A.W.52 , an all-metal jet-powered model capable of high speeds for the era; great attention was paid to laminar flow . First flown on 13 November 1947,

5280-413: The control problem is differential drag: the drag near one wing tip is artificially increased, causing the aircraft to yaw in the direction of that wing. Typical methods include: A consequence of the differential drag method is that if the aircraft maneuvers frequently then it will frequently create drag. So flying wings are at their best when cruising in still air: in turbulent air or when changing course,

5376-651: The design died with Cheranovsky. Several other nations also opted to undertake flying wing projects. Turkey was one such country, the Turk Hava Kurumu Ucak Fabrikasi producing the THK-13 tailless glider during 1948. Multiple British manufacturers also explored the concept at this time. Early proposals for the Avro Vulcan , a nuclear-armed strategic bomber designed by Roy Chadwick , also explored several flying wing arrangements, although

5472-401: The direction of motion. Without this stability, they may tumble end over end, spin or orient themselves at a high angle of attack , even broadside on to the direction of motion. At high angles of attack, drag forces may become excessive, the vehicle may be impossible to control, or may even experience structural failure. In general, land, sea, air and underwater vehicles are designed to have

5568-428: The distortion of the tyres. The angle between the direction the tread is rolling and the hub is called the slip angle . This is a bit of a misnomer, because the tyre as a whole does not actually slip, part of the region in contact with the road adheres, and part of the region slips. We assume that the tyre force is directly proportional to the slip angle ( ϕ {\displaystyle \phi } ). This

5664-452: The drag inherent in a high angle of attack is generally regarded as making the design inefficient, and only a few production types, such as the Fauvel and Marske Aircraft series of sailplanes, have used it. A simpler approach is to overcome the instability by locating the main weight of the aircraft a significant distance below the wing, so that gravity will tend to maintain the aircraft in

5760-407: The drag of a thick wing rises sharply and it is essential for the wing to be made thin. No supersonic flying wing has ever been built. For any aircraft to fly without constant correction it must have directional stability in yaw. Flying wings lack anywhere to attach an efficient vertical stabilizer or fin. Any fin must attach directly on to the rear part of the wing, giving a small moment arm from

5856-542: The field using a conventional elliptical lift distribution with vertical tail surfaces. During December 1942, Northrop flew the N-9M , a one-third scale development aircraft for a proposed long-range bomber; several were produced, all but one were scrapped following the bomber programme's termination. In Britain, the Baynes Bat glider was flown during wartime; it was a one-third scale experimental aircraft intended to test out

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5952-406: The final design had a fuselage. There has been continual interest in the flying wing for large transport roles for cargo or passengers. Boeing , McDonnell Douglas , and Armstrong Whitworth have undertaken design studies on flying wing airliners ; however, no such airliners have yet been built. Following the arrival of supersonic aircraft during the 1950s, military interest in the flying wing

6048-535: The first practical tailless aeroplane. The later D.8 was license-built and sold commercially by W. Starling Burgess in America as the Burgess-Dunne. He also returned to his monoplane. The D.6 of 1911 was a pusher type high-wing monoplane which also featured pronounced anhedral or droop to the wing tips. The control surfaces now also acted as rudders. Many of Dunne's ideas on stability remain valid, and he

6144-468: The large transport roles for cargo or passengers. Boeing , McDonnell Douglas , and Armstrong Whitworth have undertaken design studies on flying wing airliners ; however, no such airliners have yet been built. The flying wing concept is mostly suited to subsonic aircraft . No supersonic flying wing has ever been built. A flying wing is an aeroplane that has no definite fuselage or tailplane , with its crew, payload, fuel, and equipment housed inside

6240-444: The loading on the tyre as well as the slip angle, this effect has been ignored, but could be taken into account by assuming different values of k for the front and rear axles. Roll motion due to cornering will redistribute the tyre loads between the nearside and offside of the vehicle, again modifying the tyre forces. Engine torque likewise re-distributes the load between front and rear tyres. A full analysis should also take account of

6336-539: The low-speed wing across the airflow, then rotate a quarter-turn so that the high-speed wing faces the airflow for supersonic travel. NASA has funded a study of the proposal. The design is claimed to offer low wave drag, high subsonic efficiency and reduced sonic boom. Since the end of the Cold War , numerous unmanned aerial vehicles (UAVs) featuring the flying wing have been produced. Nations have typically used such platforms for aerial reconnaissance ; such UAVs include

6432-486: The main wing structure. A flying wing may have various small protuberances such as pods, nacelles , blisters, booms, or vertical stabilizers . A clean flying wing is sometimes presented as theoretically the most aerodynamically efficient (lowest drag) design configuration for a fixed wing aircraft. It also would offer high structural efficiency for a given wing depth, leading to light weight and high fuel efficiency . Because it lacks conventional stabilizing surfaces and

6528-427: The main wing. A tailless type may still have a conventional vertical tail fin ( vertical stabilizer ) and rudder . A flying wing is a tailless design which also lacks a distinct fuselage , having the pilot, engines, etc. located wholly or partially in the wing. A conventional fixed-wing aircraft has a horizontal stabiliser surface separate from its main wing. This extra surface causes additional drag requiring

6624-438: The missing stabiliser. Some examples were stable but their height could only be controlled using engine power. Others could pitch up or down sharply and uncontrollably if they were not carefully handled. These gave tailless designs a reputation for instability. It was not until the later success of the tailless delta configuration in the jet age that this reputation was widely accepted to be undeserved. The solution usually adopted

6720-641: The much larger but slower B-36. A reconnaissance version continued in development for some time but the aircraft did not enter production. In the Soviet Union, the BICh-26 , became one of the first attempts to produce a supersonic jet flying wing aircraft in 1948; aviation author Bill Gunston referred to the BICh-26 as being ahead of its time. However, the aeroplane was not accepted by the Soviet military and

6816-419: The net aerodynamic vector (lift plus drag) forwards as the angle of attack reduces and, in the extreme, this can create a net forward thrust. The restoration of outer lift by the elevon creates a slight induced thrust for the rear (outer) section of the wing during the turn. This vector essentially pulls the trailing wing forward to cause "proverse yaw", creating a naturally coordinated turn. In his 1913 lecture to

6912-423: The pilot (and engine where fitted) below the wing structure rather than inside it, and so are not true flying wings. An aircraft of sharply swept delta planform and deep centre section represents a borderline case between flying wing, blended wing body , and/or lifting body configurations. The concept of the flying wing was born on 16 February 1876 when French engineers Alphonse Pénaud and Paul Gauchot filed

7008-470: The problem of fitting the pilot, engines, flight equipment, and payload all within the depth of the wing section. Other known problems with the flying wing design relate to pitch and yaw . Pitch issues are discussed in the article on tailless aircraft . The problems of yaw are discussed below. A wing that is made deep enough to contain the pilot, engines, fuel, undercarriage and other necessary equipment will have an increased frontal area, when compared with

7104-419: The radar receiver is at a specific position relative to the aircraft—a position that changes continuously as the aircraft moves. This approach eventually led to the Northrop Grumman B-2 Spirit , a flying wing stealth bomber. In this case, the aerodynamic advantages of the flying wing are not the primary reasons for the design's adoption. However, modern computer-controlled fly-by-wire systems allow for many of

7200-446: The rear or all of the wing. With reflex camber the flatter side of the wing is on top, and the strongly curved side is on the bottom, so the front section presents a high angle of attack while the back section is more horizontal and contributes no lift, so acting like a tailplane or the washed-out tips of a swept wing. Reflex camber can be simulated by fitting large elevators to a conventional airfoil and trimming them noticeably upwards;

7296-450: The rear tyres produce no significant forces, the side force and yawing moment become: The equation of motion becomes: The coefficient of β {\displaystyle \beta } is negative, so the vehicle will be unstable. Now consider the effect of faulty tyres at the front. The Side force and yawing moment become: The equation of motion becomes: The coefficient of β {\displaystyle \beta }

7392-411: The slip angle for the vehicle as a whole: Eliminating ω {\displaystyle \omega } yields the following equation in β {\displaystyle \beta } : This is called a second-order linear homogeneous equation, and its properties form the basis of much of control theory . We do not need to solve the equation of motion explicitly to decide whether

7488-415: The solution diverges indefinitely or converges to zero following an initial perturbation. The form of the solution depends on the signs of the coefficients. The coefficient of d β d t {\displaystyle {\frac {d\beta }{dt}}} will be called the ' damping ' by analogy with a mass-spring-damper which has a similar equation of motion. By the same analogy,

7584-613: The spotlight of the Communist Party by designing aircraft like the tailless BOK-5 (Chizhevskij) and OKA-33 (the first ever built by Antonov) which were designated as "motorized gliders" due to their similarity to popular gliders of the time. The BICh-11, developed by Cheranovsky in 1932, competed with the Horten brothers H1 and Adolf Galland at the Ninth Glider Competitions in 1933, but was not demonstrated in

7680-405: The stability of a road vehicle is the derivation of a reasonable approximation to the equations of motion. [REDACTED] The diagram illustrates a four-wheel vehicle, in which the front axle is located a distance a {\displaystyle a} ahead of the centre of gravity and the rear axle is a distance b {\displaystyle b} aft of the cg. The body of

7776-436: The steering changes the slip angle of the front tyres, generating a sideforce. With conventional steering, the tyres are deflected by different amounts, but for the purposes of this analysis, the additional slip will be considered equal for both front tyres. The side force becomes: where η {\displaystyle \eta } (eta) is the steering deflection. Similarly, the yawing moment becomes: Including

7872-408: The steering term introduces a forced response: The steady state response is with all time derivatives set to zero. Stability requires that the coefficient of β {\displaystyle \beta } must be positive, so the sign of the response is determined by the coefficient of η {\displaystyle \eta } : This is a function of speed. When the speed

7968-484: The tailless delta , especially for combat aircraft, though the Concorde airliner is also a delta configuration. NASA has used the 'tailless' description for the novel X-36 research aircraft which has a canard foreplane but no vertical fin. A tailless aircraft has no other horizontal surface besides its main wing. The aerodynamic control and stabilisation functions in both pitch and roll are incorporated into

8064-481: The tailless configuration include low parasitic drag as on the Horten H.IV soaring glider and good stealth characteristics as on the Northrop B-2 Spirit bomber. Disadvantages include a potential sensitivity to trim . Tailless aircraft have been flown since the pioneer days; the first stable aeroplane to fly was the tailless Dunne D.5 , in 1910. The most successful tailless configuration has been

8160-644: The tailless delta configuration, and became one of the most widely produced of all Western jet aircraft. By contrast the Soviet Union's equivalent widely produced delta-winged fighter, the Mikoyan-Gurevich MiG-21 , does have a tail stabiliser. In the 1950s, the Convair F2Y Sea Dart prototype became the only seaplane to exceed the speed of sound. Convair built several other successful tailless delta types. The Anglo-French Concorde Supersonic transport , and its Soviet counterpart,

8256-437: The tendency of a vehicle to return to its original direction in relation to the oncoming medium (water, air, road surface, etc.) when disturbed (rotated) away from that original direction. If a vehicle is directionally stable, a restoring moment is produced which is in a direction opposite to the rotational disturbance. This "pushes" the vehicle (in rotation) so as to return it to the original orientation, thus tending to keep

8352-411: The term has the potential of becoming negative above a speed given by: Above this speed, the vehicle will be directionally unstable . If for some reason (incorrect inflation pressure, worn tread) the tyres on one axle are incapable of generating significant lateral force, the stability will obviously be affected. Assume to begin with that the rear tyres are faulty, what is the effect on stability? If

8448-531: The theory of the stable aerofoil. The designer Alexander Lippisch produced his first tailless design, the Delta I, in 1931. He went on to build a series of ever-more sophisticated designs, and at the end of the Second World War was taken to America to continue his work . During the Second World War , Lippisch worked for the German designer Willy Messerschmitt on the first tailless aircraft to go into production,

8544-485: The time using Prandtl's birdlike "bell-shaped lift distribution". One such aircraft they produced was the Horten H.IV glider, which was produced in low numbers between 1941 and 1943. Several other late-war German military designs were based on the flying wing concept, or variations of it, as a proposed solution to extend the range of otherwise very short-range of aircraft powered by early jet engines . The Horten Ho 229 jet fighter prototype first flew in 1944. It combined

8640-485: The trailing edge of each wing tip acted as combined aileron and elevator. Dunne had an advanced qualitative appreciation of the aerodynamic principles involved, even understanding how negative lift at the wing tips, combined with steep downward-angled anhedral, enhanced directional stability. Although originally conceived as a monoplane , Dunne's initial designs for the Army were required to be biplanes , typically featuring

8736-657: The type as the Gotha Go 229 during the closing stages of the conflict. Despite intentions to develop the Go 229 and an improved Go P.60 for several roles, including as a night fighter , no Gotha-built Go 229s or P.60s were ever completed. The unflown, nearly completed surviving "V3," or third prototype was captured by American forces and sent back for study; it has ended up in storage at the Smithsonian Institution . The Allies also made several relevant advances in

8832-404: The vehicle oriented in the original direction. Directional stability is frequently called "weather vaning" because a directionally stable vehicle free to rotate about its center of mass is similar to a weather vane rotating about its (vertical) pivot. With the exception of spacecraft, vehicles generally have a recognisable front and rear and are designed so that the front points more or less in

8928-460: The war with pre-production machines flying in 1946. This was superseded the next year by conversion of the type to jet power as the YB-49 of 1947. Initially, the design did not offer a great advantage in range compared to slower piston bomber designs, primarily due to the high fuel consumption of the early turbojets, however, it broke new ground in speed for a large aircraft. On February 9, 1949, it

9024-468: Was flown from Edwards Air Force Base in California, to Andrews Air Force Base, near Washington, D.C., for President Harry Truman's air power demonstration. The flight was made in four hours and 20 minutes, setting a transcontinental speed record. The YB-49 presented some minor lateral stability problems that were being rectified by a new autopilot system, when the bomber version was cancelled in favour of

9120-489: Was possibly one of the first aircraft ever to break the sound barrier – it did so during a shallow dive, and the sonic boom was heard by several witnesses. All three built were lost in fatal crashes. The DINFIA IA 38 was a 1960s Argentine four-engine experimental tailless transport aircraft , designed under the direction of Reimar Horten and based on the German Horten H.VIII project and built by

9216-427: Was quickly curtailed, as the concept of adopting a thick wing that accommodated the crew and equipment directly conflicted with the optimal thin wing for supersonic flight. Interest in flying wings was renewed in the 1980s due to their potentially low radar reflection cross-sections. Stealth technology relies on shapes that reflect radar waves only in certain directions, thus making the aircraft hard to detect unless

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