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The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips.

In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack.

The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing.

Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

The critical Mach number, lift-to-drag ratio and drag force play important role in the performance of the wings. This paper aims to investigate the effect of taper stacking, which has been used to generalize wing sweeping, on those parameters.

The results obtained are based on steady-state turbulent flowfields computations. The baseline wing is ONERA M6. Various wing planforms are generated by linearly or parabolically varying the spanwise stacking location. The critical Mach number is determined by changing the freestream Mach number for a fixed angle of attack. On the other hand, the analysis of the drag force is carried out by changing the angle of attack to keep the lift force constant.

By changing the stacking location, the critical Mach number and the corresponding lift-to-drag ratio have increased by around 7 and 3%, respectively. A reduction of 12.8% in total drag force has been observed in one of the analyzed cases. Moreover, there exist some cases in which the values of drag reduce significantly while the lift is the same.

The results of this new stacking approach have implied that the drag force can be decreased without decreasing the lift. This outcome is valuable for increasing the range and endurance of an aircraft.

This work generalizes wing sweeping by modifying the taper stacking along the span. In literature, wing sweep is enhanced using segmented stacking of taper distribution. The present study is further enhancing this concept by introducing continuous stacking (infinite number of stacking segments) for the first time.

THE change from the parallel wings of the now obsolescent biplane to the tapered wings of the monoplane, usually fitted with flaps, raised a great number of problems, both aerodynamic and structural. Work on these has been pursued vigorously during the past few years, but the designer is still some considerable distance from having all his questions answered. For instance, further information is required as to the relation between wing thickness and profile drag before it can be decided what is the maximum thickness which can be used, taking both aero‐dynamical and structural considerations into account. This question is complicated by the fact that, so far as the tip sections are concerned,. the indications are that the thickness ratio has important effects on the nature of the stall, violent or gentle. So, too, will such factors as centre line camber and position of maximum ordinate affect the nature of the stall in greater or Jess degree. Added to these factors there is, of course, the important one of the taper itself, including—as is now realised—the question as to the way in which the tapering is done, that is, whether by sweeping the trailing edge forward or the leading edge back, or, as is more usual, a combination of the two.

The purpose of this paper is to improve autonomous flight performance of an unmanned aerial vehicle (UAV) having actively sweep angle morphing wing using simultaneous UAV and flight control system (FCS) design.

An UAV is remanufactured in the ISTE Unmanned Aerial Vehicle Laboratory. Its wing sweep angle can vary actively during flight. FCS parameters and wing sweep angle are simultaneously designed to optimize autonomous flight performance index using a stochastic optimization method called as simultaneous perturbation stochastic approximation (SPSA). Results obtained are applied for flight simulations.

Using simultaneous design process of an UAV having actively sweep angle morphing wing and FCS design, autonomous flight performance index is maximized.

Authorization of Directorate General of Civil Aviation in Turkey is crucial for real-time UAV flights.

Simultaneous UAV having actively sweep angle morphing wing and FCS design process is so beneficial for recovering UAV autonomous flight performance index.

Simultaneous UAV having actively sweep angle morphing wing and FCS design process achieves confidence, high autonomous performance index and simple service demands of UAV operators.

Composing a novel approach to improve autonomous flight performance index (e.g. less settling and rise time, less overshoot meanwhile trajectory tracking) of an UAV and creating an original procedure carrying out simultaneous UAV having actively sweep angle morphing wing and FCS design idea.

THE complexity of the problems which are associated with the lateral stability and directional control of tailless aeroplanes was not realized until rather late.

The development of variable geometry in general is traced as applied to aircraft wings with particular emphasis on variable sweepback, including discussion of some experimental aircraft. The characteristics of swept wings illustrate the reason for variable sweep in some advanced aircraft and a comparison made with jet lift. Some of the implications and problems involved in variable sweep design are discussed in detail and some observations made on the weight aspect. To illustrate the discussion, three sketch designs of aircraft with variable sweep are presented.

IN 1955 Hamburger Flugzeugbau began to reconstruct its Finkenwerder plant and develop its aeronautical activities, following the period of in‐activity after the Second World War. Production began with an order from the West German Federal Defence Ministry for components for the S.N.C.A.N. 2501 Noratlas built under licence for the West German Air Force. Final assembly and flight testing of this twin‐engined transport were also carried out at Finkenwerder. The next stage of development involved participation in the European licence production of the Lockheed F.104G Starfighter, and in the design and construction of the Franco‐German C.160 Transall transport. By J 958, HFB had completed the project stage of the design of a turbojet airliner—the HFB 314. This was a short /medium‐range airliner designed to carry 70 tourist class passengers over ranges up to 1,250 miles. Although Hamburger Flugzeugbau had designed the aircraft in close co‐operation with Lufthansa, West Germany's largest airline, and were fully prepared to produce the aircraft in consort with other German or European companies, development costs would have amounted to some £5 million and since no Government financial support was forthcoming, the project was abandoned. Determined to reassert its authority as a design agency, HFB turned to the jet executive field in 1960 and designed the twin‐jet HFB 320 Hansa. The most distinctive feature of this aircraft is without doubt its sweptforward wing and it is this feature which is dealt with in detail in this article. The decision to utilize such a wing was based to some extent on Hamburger Flugzeugbaus‘ technical experience in the development of the Junkers Ju 287 sweptforward wing dating back to the Second World War. The HFB 320 Hansa is powered by two General Electric CJ 610–1 turbo‐jets, each of which has a weight of 355 lb. and a thrust of 2,850 lb. The engine's eight‐stage axial compressor has a mass flow of 565 at. ft. I sec. at 16,500 r.p.m. At gross weights of 16,000 to 18,000 lb., the Hansa will cruise at 500 m.p.h. over ranges up to 1,600 miles with full reserves. Well over 2,000 hours of model testing have been carried out in wind tunnels at the Aerodynamische Versuchsanstalt, (Goettingen), National Luchten Ruimtvaartlaboratorium (Amsterdam), Torrejon (Madrid), Emmen (Switzerland) and Modane (France).‐ Static testing is underway on an airframe structural specimen including: test for maximum cabin pressure, windshield strength test—bird impact, investigation of ground and landing loads, and investigation of loading at the extremes of the flight envelope. Later this summer, HFB will commence a programme of loading tests of a dynamic test airframe utilizing the water tank technique, involving pressurization cycles and gust loading to simulate 50,000 flights. Assembly of the first prototype HFB 320 Hansa was completed on March 18, 1964, and was followed by ground resonance tests, and engine ground’ running prior to the aircraft's maiden flight on April 21. The prototype, which carries extensive flight test instrumentation and is not equipped with the production‐type cabin, made its first public appearance at the Deutsches Luftfahrtschau at Hanover‐Langenhagen a few days later. The full flight test programme is currently being pursued.

This paper presents a broad survey of the structural problems associated with variable geometry for aircraft. Variable sweep allows an aircraft to fly throughout a broad regime of speed and altitude efficiently and without excessive power requirements. Tailored lift drag, improved ride quality, lessening of fatigue damage, and reasonable control sensitivities are advantages. Structural problems fall into two general categories: (1) Because of the number of wing positions, the equivalent of many fixed‐wing aircraft must be investigated, analysed and tested; (2) there are unusual problems which have heretofore not been important considerations in design. Category (1) presents the problem of managing and assimilating large amounts of data. Computer pogrammes and a family of cross‐plots assist greatly. Category (2) presents new fail‐safe criteria, a large lumber of possible flutter‐critical configurations, unavoidable free play in mechanisms which affect flutter speeds, dynamic loads, pivot mechanism bearing life, and requires high reliability in materials. Analyses and wind‐tunnel tests have shown that free play in mechanical joints may or may not cause significant service problems depending upon the mechanical arrangement selected and the actual degree of free play under service conditions.

Thus, consider an unstaggered biplane at, say, 40 dug. incidence. At values of rotational speed likely to be expected in a spin it will have a iairly large positive value of rolling moment, which means, as we have seen, an inward sideslip. This means in turn less sideslip at the tail leading to difficulty in preserving the spin at a low incidence. ? monoplane spinning at the same incidence would do so with outward sideslip, thereby augmenting the sideslip due to rotation. Inertia moments enter into the question as well, and, in fact, the aerodynamic and inertia moments and the eitects of sideslip are so interwoven as to make any simple separation of cause and effect extremely difficult. An opinion has been expressed that the ordinaiy autorotation experiment has no bearing on the fully developed spin at all but may be important as regards the incipient spin. In the wind tunnel spins have been observed on monoplanes at incidences quite outside the autorotation range.

THE OBJECTIVES of this article are twofold, firstly to argue the case for variable configuration aircraft, i.e. aircraft whose planform can be adjusted in flight to give optimum performance in differing roles; and secondly, to put forward proposals for a wing suspension designed to overcome the handicaps inherent in the method so far employed in mounting the wings of variable configuration aircraft.