In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, may take the form of strut, which act in compression or tension as the need arises, and/or wires, which act only in tension. In general, bracing allows a stronger, lighter structure than one, unbraced, but external bracing in particular adds drag which slows down the aircraft and raises more design issues than internal bracing. Another disadvantage of bracing wires is that they require routine checking and adjustment, or rigging when located internally. During the early years of aviation, bracing was a universal feature of all forms of aeroplane, including the monoplanes and biplanes which were equally common. Today, bracing in the form of lift struts is still used for some light commercial designs where a high wing and light weight are more important than ultimate performance. Bracing works by creating a triangulated truss structure which resists twisting.
By comparison, an unbraced cantilever structure bends unless it carries a lot of heavy reinforcement. Making the structure deeper allows it to be much lighter and stiffer. To reduce weight and air resistance, the structure may be made hollow, with bracing connecting the main parts of the airframe. For example, a high-wing monoplane may be given a diagonal lifting strut running from the bottom of the fuselage to a position far out towards the wingtip; this increases the effective depth of the wing root to the height of the fuselage, making it much stiffer for little increase in weight. The ends of bracing struts are joined to the main internal structural components such as a wing spar or a fuselage bulkhead, bracing wires are attached close by. Bracing may be used to resist all the various forces which occur in an airframe, including lift, weight and twisting or torsion. A strut is a bracing component stiff enough to resist these forces whether they place it under compression or tension. A wire is a bracing component able only to resist tension, going slack under compression, is nearly always used in conjunction with struts.
A square frame made of solid bars tends to bend at the corners. Bracing it with an extra diagonal bar would be heavy. A wire would stop it collapsing only one way. To hold it rigid, two cross-bracing wires are needed; this method of cross-bracing can be seen on early biplanes, where the wings and interplane struts form a rectangle, cross-braced by wires. Another way of arranging a rigid structure is to make the cross pieces solid enough to act in compression and to connect their ends with an outer diamond acting in tension; this method was once common on monoplanes, where the wing and a central cabane or a pylon form the cross members while wire bracing forms the outer diamond. Most found on biplane and other multiplane aircraft, wire bracing was common on early monoplanes. Unlike struts, bracing wires always act in tension The thickness and profile of a wire affect the drag it causes at higher speeds. Wires may be made of multi-stranded cable, a single strand of piano wire, or aerofoil sectioned steel.
Bracing wires divide into flying wires which hold the wings down when flying and landing wires which hold the wings up when they are not generating lift. Thinner incidence wires are sometimes run diagonally between fore and aft interplane struts to stop the wing twisting and changing its angle of incidence to the fuselage. In some pioneer aircraft, wing bracing wires were run diagonally fore and aft to prevent distortion under side loads such as when turning. Besides the basic loads imposed by lift and gravity, bracing wires must carry powerful inertial loads generated during manoeuvres, such as the increased load on the landing wires at the moment of touchdown. Bracing wires must be rigged to maintain the correct length and tension. In flight the wires tend to stretch under load and on landing some may become slack. Regular rigging checks are required and any necessary adjustments made before every flight. Rigging adjustments may be used to set and maintain wing dihedral and angle of incidence with the help of a clinometer and plumb-bob.
Individual wires are fitted with turnbuckles or threaded end fittings so that they can be adjusted. Once set, the adjuster is locked in place. Internal bracing was most significant during the early days of aeronautics when airframes were frames, at best covered in doped fabric which had no strength of its own. Wire cross-bracing was extensively used to stiffen such airframes, both in the fabric-covered wings and in the fuselage, left bare. Routine rigging of the wires was needed to maintain structural stiffness against bending and torsion. A particular problem for internal wires is access in the cramped interior of the fuselage. Providing sufficient internal bracing would make a design too heavy, so in order to make the airframe both light and strong the bracing is fitted externally; this was common in early aircraft due to the limited engine power available and the need for light weight in order to fly at all. As engine powers rose through the 1920s and 30s, much heavier airframes became practicable and most designers abandoned external bracing in order to allow for increased speed.
Nearly all biplane aircraft have their upper and lower planes connected by interplane struts, with the upper wing running across above the fuselage and connected to it by shorter cabane struts. These struts divide the wings into bays which are brace
The leading edge is the part of the wing that first contacts the air. The first is the second a structural one; as an example of the distinction, during a tailslide, from an aerodynamic point of view, the trailing edge becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged. The structural leading edge may be equipped with one or more of the following: Leading edge boots Leading edge cuffs Leading edge extensions Leading edge slats Leading edge slots Krueger flaps Stall strips Vortex generators. Associated terms are leading edge stagnation point. Seen in plan the leading edge may be curved. A straight leading edge may be swept or unswept, the latter meaning that it is perpendicular to the longitudinal axis of the aircraft; as wing sweep is conventionally measured at the 25% chord line an unswept wing may have a swept or tapered leading edge. Some aircraft, like the General Dynamics F-111, have swing-wings where the sweep of both wing and leading edge can be varied.
In high-speed aircraft, compression heating of the air ahead of the wings can cause extreme heating of the leading edge. Heating was a major contributor to the destruction of the Space Shuttle Columbia during re-entry on February 1, 2003; when sailing into the wind, the dynamics that propel a sailboat forward are the same that create lift for an airplane. The term leading edge refers to the part of the sail. A fine tapered leading edge that does not disturb the flow is desirable since 90% of the drag on a sailboat owing to sails is a result of vortex shedding from the edges of the sail. Sailboats utilize a mast to support the sail. To help reduce the drag and poor net sail performance, designers have experimented with masts that are more aerodynamically shaped, rotating masts, wing masts, or placed the mast behind the sails as in the mast aft rig
The Hanriot HD.2 was a biplane floatplane fighter aircraft produced in France during the First World War, used after the war for testing the use of aircraft from warships. The design was based on that of the HD.1, but was a purpose-built floatplane. It had a shorter wingspan with greater area. Like its predecessor, though, it was a conventional single-bay biplane with staggered wings of unequal span; the prototype had a twin pontoon undercarriage, with a small third pontoon under the tail. The third pontoon was discarded on production machines, though; the HD.2 was developed as an interceptor to defend flying boat bases, but soon was used as an escort fighter to protect French reconnaissance flying boats. The United States Navy bought 10 examples with wheeled undercarriages, designated HD.2C. Both the French and United States navies used these aircraft in early experiments in launching fighters from warships; the United States Navy replicated the French trials where a HD.1 had been launched from a platform built atop one of the turrets of the battleship Paris and built a similar platform on the USS Mississippi to launch a HD.2 from.
The French Navy converted some of their HD.2s to wheeled configuration and used them for trials on the new aircraft carrier Béarn. A final experiment in launching a HD.2 from a ship was carried out in 1924 with two new-built examples designated H.29. An unorthodox launching system was developed where the aircraft were equipped with three small pulley-wheels, one on each tip of the upper wing, one at the tip of the tail fin; these ran along metal rails, attached to project horizontally from the mast of the battleship Lorraine. This did not work. Further trials were discontinued. HD.2 floatplane fighter with Clerget 9B engine HD.2C HD.2 with wheeled undercarriage HD.12 fitted with wheeled landing gear, powered by a 170-hp Le Rhône 9R rotary piston engine. HD.27 powered by a 180-hp Hispano-Suiza 8Ac engine. H.29 powered by a Hispano-Suiza 8Ab engine and fitted for launch from a warship FranceFrench Navy Aéronavale United StatesUnited States Navy General characteristics Crew: one pilot Length: 7.00 m Wingspan: 8.51 m Height: 3.10 m Wing area: 18.4 m2 Empty weight: 495 kg Gross weight: 700 kg Powerplant: 1 × Clêrget 9B, 100 kW Performance Maximum speed: 182 km/h Range: 300 km Service ceiling: 4,800 m Armament 2 × fixed, forward-firing.303 Vickers machine guns Aircraft of comparable role and era Sopwith Baby Taylor, Michael J. H..
Jane's Encyclopedia of Aviation. London: Studio Editions. P. 469. World Aircraft Information Files. London: Bright Star Publishing. Pp. File 896 Sheet 11
The Hanriot HD.22 was a racer aircraft built by Hanriot in the early 1920s. The HD.22 was a high-wing monoplane intended for the Coupe Deutsch de la Meurthe. It had an all-metal fuselage. Data from General characteristics Crew: 1 Length: 5.93 m Wingspan: 6.38 m Height: 2.20 m Wing area: 7.50 m2 Gross weight: 800 kg Powerplant: 1 × Hispano-Suiza 8Fb V-8 water-cooled piston engine, 220 kW Propellers: 2-bladed fixed-pitch propellerPerformance Maximum speed: 133 km/h at sea level. It is not certain if these performance figures relate to the MS.180 or the MS.181. Cruise speed: 360 km/h
Bezons French pronunciation: is a commune in the northwestern suburbs of Paris, France. It is located 12.6 km from the centre of Paris. An extension of the tramway line T2 to Pont de Bezons opened in 2012. With Bezons not served by any stations on the Paris Métro, RER, or suburban rail network, the extension has enhanced the connectivity of Bezons to the Paris public transport network; the journey time to the La Défense business district and transport hub is estimated at 12 minutes. The closest train station is Houilles – Carrières-sur-Seine located in the neighbouring commune of Houilles, 2.4 km from the town centre of Bezons. It is served by the RER Transilien Paris -- Saint-Lazare rail lines. In March 2013, the convicted killer of Israeli tourism minister Rehavam Ze'evi, Majdi Al-Rimawi, was named a "honorary resident" of Bezons. Majdi Al-Rimawi is a member of the Popular Front for the Liberation of Palestine, sentenced to life in prison for his role in the 2008 murder of Rehavam Ze'evi. According to Bezons monthly newsletter, the honouring of Rimawi was the result of a unanimous decision by the Bezons local council, which described his crime as "defending his town and its inhabitants, calling for the application of international law for the establishment of Palestine to the 1967 borders as recognised by the United Nations, Jerusalem as its capital."
The decision and the newsletter made no mention of Ze'evi's killing. In February 2013, Rimawi's son and wife were presented with the plaque honouring Rimawi at the ceremony attended by Lesparre; the Mayor of Bezons, Dominique Lesparre, a member of the French Communist Party who has supported left-wing figures, stated that honouring Rimawi is a "strong political act" related to the "colonisation of the Palestinian people". On his website, Lesparre describes Rimawi as being "jailed for 10 years for taking part with his people in the struggle to resist the occupation of their country"; the website contains no mention of Rehavam Ze'evi's murder. Lesparre claimed that "For these acts of resistance, he was jailed in 2002 for life + 80 years" and described him as one of many Palestinians, "imprisoned for daring to defend their country". Lesparre stated that "Majdi draws his strength from the Palestinian struggle and the solidarity demonstrations throughout the world". Lesparre stated that honouring Al-Rimawi was part of a "tradition of peace and cooperation with the Palestinian people".
Lesparre was criticized by Moshe Kantor, who stated that "It is inconceivable that an elected official can be so ignorant as to call a cold-blooded murderer a victim" and described the decision "outrageous and horrific". The Israeli Foreign Ministry criticized the decision, stating that it was "humanly outrageous to honor a convicted murderer, no political view can justify it". Ron Prosor, who serves as Israel's ambassador to the United Nations condemned what he described as the "glorification of terrorists who deliberately murder innocent civilians" and questioned whether or not Bezons' will grant citizenship to Anders Breivik or Osama bin Laden. Abraham Foxman of the Anti-Defamation League stated, "This award is an insult to the French concept of justice and liberty and a perversion of French values" and charged that Bezons "is callously encouraging more violence against Jews". Lesparre subsequently accused critics of the town's decision of "hatred" and "complicity in occupation" while claiming that "It strengthens our resolve to defend the noble and just Palestinian cause".
Regarding Israel's opposition to the Bezons' honouring of Al-Rimawi, Lesparre stated: In December 2014, a court ruled that the town must remove the plaque honoring Al Rimawi and declared that the Bezons' grant of honorary citizenship to Al Rimawi was invalid. There are eight preschools: Marcel-Cachin, Paul-Vaillant-Couturier, Paul-Langevin, Karl-Marx, Louise-Michel, Gabriel-Péri, Jacques-Prévert, Victor-Hugo. Mickaël Gaffoor, footballer Communes of the Val-d'Oise department INSEE Association of Mayors of the Val d’Oise Official website Mérimée database – Cultural heritage Land use
The Hanriot HD.15 was a French two seat fighter aircraft fitted with a supercharger for good high altitude performance, built in the 1920s. Three were lost at sea during delivery; the Hanriot HD.15 was designed in response to a government call for a turbo-supercharged high altitude fighter-reconnaissance aircraft. It was powered by a Hispano-Suiza 8Fb 8-cylinder upright water-cooled V-8 engine fitted with a Rateau turbo-supercharger intended to maintain sea level powers to altitudes up to 5,000 m. Structurally the HD.15 was an all-metal aircraft, though the flying surfaces and rear fuselage were fabric covered. The wings had rectangular section Duralumin box spars, assisted by tubular auxiliary spars forward and aft of them. In plan they were straight edged, unswept and of constant chord and thickness; the lower wing had a greater span. The wing tips were square, except that the horn balances of the short span ailerons on both upper and lower wings projected beyond. There was no stagger; the HD.15 had unusual interplane struts: instead of the familiar division of the wing into bays by struts braced with crossed flying and landing wires, it had a rigid, spanwise, X-shaped strut on each side, linking the upper and lower spars.
Vertical wires maintained the interplane gap and the location of the crossing point, below mid-gap. The inboard end of each upper X-strut met the wing at the top of the aft member of a pair of cabane struts; the lower ends of the X-strut met the wing further outboard, at the bottom of a strut that ran to the upper fuselage longeron. The empennage of the HD.15 was like those used on earlier Emile Dupont designs, with a braced, rectangular tailplane mounted on top of the fuselage and a small, curved edged fin. Both carried balanced control surfaces, the elevator's balances projecting beyond the tailplane tips, the low but broad chord, curved edge, deep rudder reaching down to the keel and moving within an elevator cut-out; the rather tubby fuselage of the HD.15 had tubular cross-section longerons with similar, triangularly arranged, cross bracing. The pilot's open cockpit was just behind the main wing spar, under a deep trailing edge cut-out to improve his upwards and forward vision. Close behind was the observer's cockpit, fitted with a mounted pair of swivelling machine guns.
The fuselage was fabric covered from the pilot's cockpit aft. The Hispano engine, enclosed under a metal cowling, was cooled with a pair of circular cross-section radiators mounted ventrally between the undercarriage legs; the HD.15 had a fixed conventional undercarriage, with mainwheels on a single axle mounted on the lower fuselage longerons by two pairs of V-struts. The HD.15 first flew in April 1922 and should have been in competition with the Gourdou-Leseurre GL.50, but the two seat reconnaissance fighter programme had been abandoned before this date. The whole high altitude fighter project, which included single seaters, was dropped with the inability of Rateau to deliver reliable superchargers in quantity because of high temperature material problems. Nonetheless, the Japanese Army became interested in supercharger-engined fighters and in 1926 the prototype HD.15 was sold and delivered to them. An order for three more followed, but the ship taking them to Japan was sunk by a tidal wave en voyage.
Data from Green & Swanborough p.278General characteristics Crew: Two Length: 7.60 m Wingspan: 11.40 m Height: 2.57 m Wing area: 32.48 m2 Empty weight: 1,050 kg Gross weight: 1,750 kg Powerplant: 1 × Hispano-Suiza 8Fb 8-cylinder upright water-cooled supercharged V-8, 220 kW Propellers: 2-bladedPerformance Maximum speed: 180 km/h Range: 800 km Service ceiling: 10,250 m Armament Guns: 2 × fixed, forward-firing 7.7 mm Darne machine guns.
A tailplane known as a horizontal stabiliser, is a small lifting surface located on the tail behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplanes. Not all fixed-wing aircraft have tailplanes. Canards and flying wing aircraft have no separate tailplane, while in V-tail aircraft the vertical stabilizer and the tail-plane and elevator are combined to form two diagonal surfaces in a V layout; the function of the tailplane is to provide control. In particular, the tailplane helps adjust for changes in position of the center of pressure or center of gravity caused by changes in speed and attitude, fuel consumption, or dropping cargo or payload; the tailplane comprises the tail-mounted fixed horizontal movable elevator. Besides its planform, it is characterised by: Number of tailplanes - from 0 to 3 Location of tailplane - mounted high, mid or low on the fuselage, fin or tail booms. Fixed movable elevator surfaces, or a single combined stabilator or flying tail.
Some locations have been given special names: Cruciform: mid-mounted on the fin T-tail: high-mounted on the fin A wing with a conventional aerofoil profile makes a negative contribution to longitudinal stability. This means that any disturbance which raises the nose produces a nose-up pitching moment which tends to raise the nose further. With the same disturbance, the presence of a tailplane produces a restoring nose-down pitching moment, which may counteract the natural instability of the wing and make the aircraft longitudinally stable; the longitudinal stability of an aircraft may change when it is flown "hands-off". In addition to giving a restoring force a tailplane gives damping; this is caused by the relative wind seen by the tail as the aircraft rotates around the center of gravity. For example, when the aircraft is oscillating, but is momentarily aligned with the overall vehicle's motion, the tailplane still sees a relative wind, opposing the oscillation. Depending on the aircraft design and flight regime, its tailplane may create positive lift or negative lift.
It is sometimes assumed that on a stable aircraft this will always be a net down force, but this is untrue. On some pioneer designs, such as the Bleriot XI, the center of gravity was between the neutral point and the tailplane, which provided positive lift; however this arrangement can be unstable and these designs had severe handling issues. The requirements for stability were not understood until shortly before World War I - the era within which the British Bristol Scout light biplane was designed for civilian use, with an airfoiled lifting tail throughout its production run into the early World War I years and British military service from 1914-1916 — when it was realised that moving the center of gravity further forwards allowed the use of a non-lifting tailplane in which the lift is nominally neither positive nor negative but zero, which leads to more stable behaviour. Examples of aircraft from World War I and onwards into the interwar years that had positive lift tailplanes include, the Sopwith Camel, Charles Lindbergh's Spirit of St. Louis, the Gee Bee Model R Racer - all aircraft with a reputation for being difficult to fly, the easier-to-fly Fleet Finch two-seat Canadian trainer biplane, itself possessing a flat-bottom airfoiled tailplane unit not unlike the earlier Bristol Scout.
But with care a lifting tailplane can be made stable. An example is provided by the Bachem Ba 349 Natter VTOL rocket-powered interceptor, which had a lifting tail and was both stable and controllable in flight. In many modern conventional aircraft, the center of gravity is placed ahead of the neutral point; the wing lift exerts a pitch-down moment around the centre of gravity, which must be balanced by a pitch-up moment from the tailplane. A disadvantage is. Using a computer to control the elevator allows aerodynamically unstable aircraft to be flown in the same manner. Aircraft such as the F-16 are flown with artificial stability; the advantage of this is a significant reduction in drag caused by the tailplane, improved maneuverability. At transonic speeds, an aircraft can experience a shift rearwards in the center of pressure due to the buildup and movement of shockwaves; this causes. Significant trim force may be needed to maintain equilibrium, this is most provided using the whole tailplane in the form of an all-flying tailplane or stabilator.
A tailplane has some means allowing the pilot to control the amount of lift produced by the tailplane. This in turn causes a nose-up or nose-down pitching moment on the aircraft, used to control the aircraft in pitch. Elevator A conventional tailplane has a hinged aft surface called an elevator, Stabilator or all-moving tail In transonic flight shock waves generated by the front of the tailplane render any elevator unusable. An all-moving tail was developed by the British for the Miles M.52, but first saw actual transonic flight on the Bell X-1. This saved the program from a time-consuming rebuild of the aircraft. Transonic and supersonic aircraft now have all-moving tailplanes to counterac