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56-485: Typical for the era, the Barkley-Grow T8P-1 was a low-wing monoplane of all-metal construction with a twin tail (an additional third tail was installed, à la Lockheed Constellation , when fitted with floats). The T8P (standing for T ransport, 8 P assenger) was designed to be simple and rugged, thus the main units of the tailwheel undercarriage were not retractable, and this may have negatively impacted

112-401: A stability derivative called C l β {\displaystyle \beta } meaning the change in rolling moment coefficient (the " C l ") per degree (or radian) of change in sideslip angle (the " β {\displaystyle \beta } "). The purpose of dihedral effect is to contribute to stability in the roll axis. It is an important factor in

168-476: A B-17 on the Greenland ice shelf. The aircraft was fitted with skis but force-landed on the ice on 22 December 1942 after encountering strong headwinds. The T8P-1 broke through the ice and sank leaving the pilots to be rescued by Inuit tribesmen. Data from General Dynamics Aircraft and their Predecessors General characteristics Performance Related lists Monoplane A monoplane

224-422: A few specialist types. Jet and rocket engines have even more power and all modern high-speed aircraft, especially supersonic types, have been monoplanes. Dihedral (aeronautics) Dihedral angle is the upward angle from horizontal of the wings or tailplane of a fixed-wing aircraft . "Anhedral angle" is the name given to negative dihedral angle, that is, when there is a downward angle from horizontal of

280-627: A light aircraft, the configuration is significant because it offers superior visibility to the pilot. On light aircraft, shoulder-wings tend to be mounted further aft than a high wing, and so may need to be swept forward to maintain correct center of gravity . Examples of light aircraft with shoulder wings include the ARV Super2 , the Bölkow Junior , Saab Safari and the Barber Snark . A high wing has its upper surface on or above

336-440: A low-wing configuration. A side effect of too much dihedral effect, caused by excessive dihedral angle among other things, can be yaw-roll coupling (a tendency for an aircraft to Dutch roll ). This can be unpleasant to experience, or in extreme conditions it can lead to loss of control or can overstress an aircraft. Military fighter aircraft often have near zero or even anhedral angle reducing dihedral effect and hence reducing

392-407: A pendulous fuselage which requires no wing dihedral for stability; and, by comparison with a low-wing, a shoulder-wing's limited ground effect reduces float on landing. Compared to a low-wing, shoulder-wing and high-wing configurations give increased propeller clearance on multi-engined aircraft. On a large aircraft, there is little practical difference between a shoulder wing and a high wing; but on

448-470: A popular configuration for amphibians and small homebuilt and ultralight aircraft . Although the first successful aircraft were biplanes, the first attempts at heavier-than-air flying machines were monoplanes, and many pioneers continued to develop monoplane designs. For example, the first aeroplane to be put into production was the 1907 Santos-Dumont Demoiselle , while the Blériot XI flew across

504-462: A similar but lesser effect. The center of mass , usually called the center of gravity or "CG", is the balance point of an aircraft. If suspended at this point and allowed to rotate, a body (aircraft) will be balanced. The front-to-back location of the CG is of primary importance for the general stability of the aircraft, but the vertical location has important effects as well. The vertical location of

560-465: A strong influence on dihedral effect. Some of these important factors are: wing sweep , vertical center of gravity , and the height and size of anything on an aircraft that changes its sidewards force as sideslip changes. Dihedral angle on an aircraft almost always implies the angle between two paired surfaces, one on each side of the aircraft . Even then, it is almost always between the left and right wings . However, mathematically dihedral means

616-489: A wing of a given size, the weight reduction allows it to fly slower and with a lower-powered and more economical engine. For this reason, all monoplane wings in the pioneer era were braced and most were up until the early 1930s. However, the exposed struts or wires create additional drag, lowering aerodynamic efficiency and reducing the maximum speed. High-speed and long-range designs tend to be pure cantilevers, while low-speed short-range types are often given bracing. Besides

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672-432: Is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes , which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing configuration and is the simplest to build. However, during the early years of flight, these advantages were offset by its greater weight and lower manoeuvrability, making it relatively rare until

728-431: Is not roll stability in and of itself. Roll stability is less-ambiguously termed "spiral mode stability" and dihedral effect is a contributing factor to it. The dihedral angle contributes to the total dihedral effect of the aircraft. In turn, the dihedral effect contributes to stability of the spiral mode . A stable spiral mode will cause the aircraft to eventually return to a nominally "wings level" bank angle when

784-573: Is not caused by yaw rate , nor by the rate of sideslip change . Since dihedral effect is noticed by pilots when "rudder is applied", many pilots and other near-experts explain that the rolling moment is caused by one wing moving more quickly through the air and one wing less quickly. Indeed, these are actual effects, but they are not the dihedral effect, which is caused by being at a sideslip angle, not by getting to one. These other effects are called "rolling moment due to yaw rate" and "rolling moment due to sideslip rate" respectively. Dihedral effect

840-419: Is not the whole picture however. At the same time that angle of sideslip is building up, the vertical fin is trying to turn the nose back into the wind, much like a weathervane, minimizing the amount of sideslip that can be present. If there is no sideslip, there can be no restoring rolling moment. If there is less sideslip, there is less restoring rolling moment. Yaw stability created by the vertical fin opposes

896-410: Is that the fuselage is closer to the ground which eases cargo loading, especially for aircraft with a rear-fuselage cargo door. Military cargo aircraft are predominantly high-wing designs with a rear cargo door. A parasol wing is not directly attached to the fuselage but held above it, supported by either cabane struts or a pylon. Additional bracing may be provided by struts or wires extending from

952-484: Is used by itself it is usually intended to mean "dihedral angle ". However, context may otherwise indicate that "dihedral effect " is the intended meaning. Dihedral angle is the upward angle from horizontal of the wings of a fixed-wing aircraft , or of any paired nominally-horizontal surfaces on any aircraft . The term can also apply to the wings of a bird . Dihedral angle is also used in some types of kites such as box kites. Wings with more than one angle change along

1008-417: Is usually a relatively simple way to adjust the overall dihedral effect. This is to compensate for other design elements' influence on the dihedral effect. These other elements (such as wing sweep, vertical mount point of the wing, etc.) may be more difficult to change than the dihedral angle. As a result, differing amounts of dihedral angle can be found on different types of fixed-wing aircraft. For example,

1064-455: Is visible in Figure 2. As greater angle of attack produces more lift (in the usual case, when the wing is not near stalling), the forward wing will have more lift and the rearward wing will have less lift. This difference in lift between the wings is a rolling moment, and it is caused by the sideslip. It is a contribution to the total dihedral effect of the aircraft. The rolling moment created by

1120-576: The Beriev Be-12 were designed with gull wings bent near the root. Others, such as the Vought F4U Corsair , used an inverted gull wing design, which allowed for shorter landing struts and extra ground clearance for large propellers and external payloads, such as external fuel tanks or bombs. Modern polyhedral wing designs generally bend upwards near the wingtips (also known as tip dihedral ), increasing dihedral effect without increasing

1176-571: The English Channel in 1909. Throughout 1909–1910, Hubert Latham set multiple altitude records in his Antoinette IV monoplane, eventually reaching 1,384 m (4,541 ft). The equivalent German language term is Eindecker , as in the mid-wing Fokker Eindecker fighter of 1915 which for a time dominated the skies in what became known as the " Fokker scourge ". The German military Idflieg aircraft designation system prior to 1918 prefixed monoplane type designations with an E , until

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1232-693: The Fokker D.VIII and Morane-Saulnier AI in the later part of the First World War. A parasol wing also provides a high mounting point for engines and during the interwar period was popular on flying boats, which need to lift the propellers clear of spray. Examples include the Martin M-130 , Dornier Do 18 and the Consolidated PBY Catalina . Compared to a biplane , a parasol wing has less bracing and lower drag. It remains

1288-695: The Tu-134 and Tu-154 . In any case, wing sweepback can also occur with a dihedral configuration. For instance, two small biplanes produced from the 1930s to 1945 by Bücker Flugzeugbau in Germany, the Bücker Jungmann two-seat trainer and the Bücker Jungmeister aerobatic competition biplane, were designed with sweepbacks of approximately 11 degrees, which provided significant dihedral effect – in addition to their small dihedral angles having

1344-451: The braced parasol wing became popular on fighter aircraft, although few arrived in time to see combat. It remained popular throughout the 1920s. On flying boats with a shallow hull, a parasol wing allows the engines to be mounted above the spray from the water when taking off and landing. This arrangement was popular on flying boats during the 1930s; a late example being the Consolidated PBY Catalina . It died out when taller hulls became

1400-422: The keel effect ) and so additional dihedral angle is often not required. Such designs can have excessive dihedral effect and so be excessively stable in the spiral mode, so anhedral angle on the wing is added to cancel out some of the dihedral effect so that the aircraft can be more easily maneuvered. Most aircraft have been designed with planar wings with simple dihedral (or anhedral). Some older aircraft such as

1456-465: The pendulum effect . An extreme example of the effect of vertical CG on dihedral effect is a paraglider . The dihedral effect created by the very low vertical CG more than compensates for the negative dihedral effect created by the strong anhedral of the necessarily strongly downward curving wing. The wing location on a fixed-wing aircraft will also influence its dihedral effect. A high-wing configuration provides about 5° of effective dihedral over

1512-415: The roll axis. Longitudinal dihedral is a comparatively obscure term related to the pitch axis of an airplane. It is the angle between the zero-lift axis of the wing and the zero-lift axis of the horizontal tail. Longitudinal dihedral can influence the nature of controllability about the pitch axis and the nature of an aircraft's phugoid -mode oscillation. When the term "dihedral" (of an aircraft)

1568-725: The 1930s, the cantilever monoplane was fast becoming the standard configuration for a fixed-wing aircraft. Advanced monoplane fighter-aircraft designs were mass-produced for military services around the world in both the Soviet Union and the United States in the early–mid 1930s, with the Polikarpov I-16 and the Boeing P-26 Peashooter respectively. Most military aircraft of WWII were monoplanes, as have been virtually all aircraft since, except for

1624-457: The 1930s. Since then, the monoplane has been the most common form for a fixed-wing aircraft. The inherent efficiency of the monoplane is best achieved in the cantilever wing, which carries all structural forces internally. However, to fly at practical speeds the wing must be made thin, which requires a heavy structure to make it strong and stiff enough. External bracing can be used to improve structural efficiency, reducing weight and cost. For

1680-400: The CG changes the amount of dihedral effect. As the "vertical CG" moves lower, dihedral effect increases. This is caused by the center of lift and drag being further above the CG and having a longer moment arm. So, the same forces that change as sideslip changes (primarily sideforce, but also lift and drag) produce a larger moment about the CG of the aircraft. This is sometimes referred to as

1736-647: The Lockheed entry). Sales in the US were disappointing, only 11 being built, and most machines (seven) were sold to Canada, where the fixed undercarriage was no obstacle to the fitting of skis or pontoons. One was selected for a record flight from Washington D.C. to Peru, and another was used in the Antarctic by the US Navy. In 1942 A T8P-1 flown by Maritime Central Airways was used in the rescue attempt of survivors of

Barkley-Grow T8P-1 - Misplaced Pages Continue

1792-481: The aircraft more manoeuvrable, as on the Spitfire ; but aircraft that value stability over manoeuvrability may then need some dihedral . A feature of the low-wing position is its significant ground effect , giving the plane a tendency to float farther before landing. Conversely, this ground effect permits shorter takeoffs. A mid wing is mounted midway up the fuselage. The carry-through spar structure can reduce

1848-408: The angle between any two planes. So, in aeronautics, in one case, the term "dihedral" is applied to mean the difference in angles between two front-to-back surfaces: Longitudinal dihedral is the difference between the angle of incidence of the wing root chord and angle of incidence of the horizontal tail root chord. Longitudinal dihedral can also mean the angle between the zero-lift axis of

1904-404: The angle of the wings is disturbed to become off-level. If a disturbance causes an aircraft to roll away from its normal wings-level position as in Figure 1, the aircraft will begin to move somewhat sideways toward the lower wing. In Figure 2, the airplane's flight path has started to move toward its left while the nose of the airplane is still pointing in the original direction. This means that

1960-412: The angle the wings meet at the root, which may be restricted to meet other design criteria. Polyhedral is seen on gliders and some other aircraft. The McDonnell Douglas F-4 Phantom II is one such example, unique among jet fighters for having dihedral wingtips. This was added after flight testing of the flat winged prototype showed the need to correct some unanticipated spiral mode instability – angling

2016-525: The approval of the Fokker D.VIII fighter from its former "E.V" designation. However, the success of the Fokker was short-lived, and World War I was dominated by biplanes. Towards the end of the war, the parasol monoplane became popular and successful designs were produced into the 1920s. Nonetheless, relatively few monoplane types were built between 1914 and the late 1920s, compared with the number of biplanes. The reasons for this were primarily practical. With

2072-563: The dihedral angle is usually greater on low-wing aircraft than on otherwise-similar high-wing aircraft. This is because "highness" of a wing (or "lowness" of vertical center of gravity compared to the wing) naturally creates more dihedral effect itself. This makes it so less dihedral angle is needed to get the amount of dihedral effect needed. Dihedral effect is defined simply to be the rolling moment caused by sideslip and nothing else. Rolling moments caused by other things that may be related to sideslip have different names. Dihedral effect

2128-422: The full span are said to be polyhedral . Dihedral angle has important stabilizing effects on flying bodies because it has a strong influence on the dihedral effect. Dihedral effect of an aircraft is a rolling moment resulting from the vehicle having a non-zero angle of sideslip . Increasing the dihedral angle of an aircraft increases the dihedral effect on it. However, many other aircraft parameters also have

2184-402: The fuselage sides. The first parasol monoplanes were adaptations of shoulder wing monoplanes, since raising a shoulder mounted wing above the fuselage greatly improved visibility downwards, which was useful for reconnaissance roles, as with the widely used Morane-Saulnier L . The parasol wing allows for an efficient design with good pilot visibility, and was adopted for some fighters such as

2240-433: The general variations in wing configuration such as tail position and use of bracing, the main distinction between types of monoplane is where the wing is mounted vertically on the fuselage . A low wing is one which is located on or near the bottom of the fuselage. Placing the wing low allows good visibility upwards and frees the central fuselage from the wing spar carry-through. By reducing pendulum stability, it makes

2296-415: The low engine powers and airspeeds available, the wings of a monoplane needed to be large in order to create enough lift while a biplane could have two smaller wings and so be made smaller and lighter. Towards the end of the First World War, the inherent high drag of the biplane was beginning to restrict performance. Engines were not yet powerful enough to make the heavy cantilever-wing monoplane viable, and

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2352-410: The norm during World War II, allowing a high wing to be attached directly to the hull. As ever-increasing engine powers made the weight of all-metal construction and the cantilever wing more practical — first pioneered together by the revolutionary German Junkers J 1 factory demonstrator in 1915–16 — they became common during the post–World War I period, the day of the braced wing passed, and by

2408-407: The oncoming air is arriving somewhat from the left of the nose. The airplane now has sideslip angle in addition to the bank angle. Figure 2 shows the airplane as it presents itself to the oncoming air. In Figure 2, the sideslip conditions produce greater angle of attack on the forward-yawed wing and smaller angle of attack on the rearward-yawed wing. This alteration of angle of attack by sideslip

2464-456: The runway on rotation/touchdown. In military aircraft dihedral angle space may be used for mounting materiel and drop-tanks on wing hard points, especially in aircraft with low wings. The increased dihedral effect caused by this design choice may need to be compensated for, perhaps by decreasing the dihedral angle on the horizontal tail. During design of a fixed-wing aircraft (or any aircraft with horizontal surfaces), changing dihedral angle

2520-412: The sideslip (labeled as "P") tends to roll the aircraft back to wings level. More dihedral effect tries to roll the wings in the "leveling" direction more strongly, and less dihedral effect tries to roll the wings in the "leveling" direction less strongly. Dihedral effect helps stabilize the spiral mode by tending to roll the wings toward level in proportion to the amount of sideslip that builds up. It

2576-475: The stability of the spiral mode which is sometimes called "roll stability". The dihedral effect does not contribute directly to the restoring of "wings level", but it indirectly helps restore "wings level" through its effect on the spiral mode of motion described below. Aircraft designers may increase dihedral angle to provide greater clearance between the wing tips and the runway. This is of particular concern with swept-wing aircraft, whose wingtips could hit

2632-535: The stability of the spiral mode, although there are other factors that affect it less strongly. Factors of design other than dihedral angle also contribute to dihedral effect. Each increases or decreases total aircraft dihedral effect to a greater or lesser degree. Wing sweepback also increases the dihedral effect, for roughly 1° of effective dihedral with every 10° of sweepback. This is one reason for anhedral configuration on aircraft with high sweep angle, as well as on some airliners, even on low-wing aircraft such as

2688-422: The stability of the spiral mode. This increases maneuverability which is desirable in fighter-type aircraft. Anhedral angles are also seen on aircraft with a high mounted wing, such as the very large Antonov An-124 and Lockheed C-5 Galaxy cargo aircraft. In such designs, the high mounted wing is above the aircraft's center of gravity which confers extra dihedral effect due to the pendulum effect (also called

2744-412: The tendency for dihedral effect to roll the wings back level by limiting sideslip. The spiral mode is the tendency to slowly diverge from, or the tendency to slowly return to wings level. If the spiral mode is stable, the aircraft will slowly return to wings-level, if it is unstable, the aircraft will slowly diverge from wings-level. Dihedral effect and yaw stability are the two primary factors that affect

2800-453: The top of the fuselage. It shares many advantages and disadvantages with the shoulder wing, but on a light aircraft, the high wing has poorer upwards visibility. On light aircraft such as the Cessna 152 , the wing is usually located above the cabin, so that the wing spar passes over the occupants' heads, leaving the wing in the ideal fore-aft position. An advantage of the high-wing configuration

2856-403: The type's reception in the marketplace. A novel design feature, however, was the wing structure. Barkley used what might be called a "horizontal cell" technique that has no ribs or spars. Long tapered strips of aluminium were bent to form V shapes which were then riveted tip to tip to form an "X". These "X"s are riveted inside the wing side by side to produce the long "cells". This wing structure

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2912-406: The usage " di hedral" evolved to mean the positive, up angle between the left and right wings, while usage with the prefix "an-" (as in " an hedral") evolved to mean the negative, down angle between the wings. The aerodynamic stabilizing qualities of a dihedral angle were described in an influential 1810 article by Sir George Cayley . In analysis of aircraft stability, the dihedral effect is also

2968-439: The useful fuselage volume near its centre of gravity, where space is often in most demand. A shoulder wing (a category between high-wing and mid-wing) is a configuration whereby the wing is mounted near the top of the fuselage but not on the very top. It is so called because it sits on the "shoulder" of the fuselage, rather than on the pilot's shoulder. Shoulder-wings and high-wings share some characteristics, namely: they support

3024-457: The wing and the zero-lift axis of the horizontal tail instead of between the root chords of the two surfaces. This is the more meaningful usage because the directions of zero-lift are pertinent to trim and stability while the directions of the root chords are not. This measurement is also often referred to as decalage . In geometry, dihedral angle is the angle between two planes. Aviation usage differs slightly from usage in geometry. In aviation,

3080-454: The wings or tailplane of a fixed-wing aircraft. Dihedral angle has a strong influence on dihedral effect , which is named after it. Dihedral effect is the amount of roll moment produced in proportion to the amount of sideslip . Dihedral effect is a critical factor in the stability of an aircraft about the roll axis (the spiral mode ). It is also pertinent to the nature of an aircraft's Dutch roll oscillation and to maneuverability about

3136-633: Was unique to the Barkley-Grow and according to mechanics who worked on the aircraft it was very light, very stiff, very expensive to build, and difficult to repair if damaged, but it gave no problems in service. Like its two main competitors, the Lockheed Model 12 Electra Junior and the Beech 18 , the T8P-1 was originally designed to a 1935 Bureau of Air Commerce specification (eventually won by

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