Hafif siklet bir uçağın kesme-eğilme ve burulmaya göre kanat hesabı

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Fen Bilimleri Enstitüsü
Bu tez çalışmasında, daha önce ön boyutlandırılması yapılmış, yüklenme durumları, belirlenmiş İstanbul-Antalya arasında seyehat edecek iki kişilik tek piston motorlu genel kullanım amaçlı bir uçağın FAR 23 nizamnamesi ve NACA teknik bültenlerine bağlı olarak dikdörtgen platformlu, sökülebilir konsol kiriş alttan kanadın kanada gelen yükler dolayısıyla kanatta oluşan kesme yükleri ve eğilme momentleri hesaplanmış; bu yükler altında ana spar dizaynı yapılmıştır. Daha sonra kanat burulma kontrolleri yapılmıştır. Bu çalışma L.Pazmany'nin iki kişilik akrobatik bir uçak için yapmış olduğu hesapların iki kişilik genel kullanım amaçlı bir uçak için adaptasyonu ve uygulaması şeklinde olup Uluslararası Havacılık Birliği (ICAO) 'nun ticari amaçla dizayn ve imalatı yapılacak olan hafif uçak kanatları için koyduğu standartlar harfiyen uygulanmaktadır.
According To The Shear Loeds, Bending And Light Airplane Design Torsional Moments The aim of this research is to give some knowledge about the preliminary design stage of the design of the light aircraft. Usually Direct Operating Costs (DOC), Indirect Operating Costs (IOC), technical renovation, passenger request and the number and the size of the aircraft required determine the properties during the preliminary design stage. If an international marketing is thought, it must be determined that the aircraft will show in accord to the rules of FAR or BCAR before beginning the design of the civil transport aircaft. The rules of FAR and CAR differ in detail. After the general regularity is realized, the design of the fuselage, wing and tail are done, the recent tecnique of the engine is estimated, the engine and theproller if required are chosen and put into the suitable^ place, the design performance is provided, the weight of the aircraft is analized and balanced, the under carriage is put into the place suited, analysis of aerodynamic and operational characteristics are discussed and at least the summary of the preliminary design is estimated. In this research because we have not enough time and page to investigate everything, it will be showed the aerodynamic analysis and operational characteristics and the. definition and calculation of the takeoff field length required for civil transport aircraft more detaily than the others procedures of the preliminary design stage of the aircraft. The primary aim of the chapter named aerodynamic analysis and operational characteristics is to verify whether the design meets the initial specification. Generally speaking, this comparison will reveal that design improvements are required but experience gained during the design stage may lead to the conclusion that the design specification should be changed instead of or in combination with aircraft. In any case, the design analysis and evaluation will finally result in an irfitial baseline design which takes into account the most recent views on the design requirements. -vi- Although many aspects can only considered after detailed study and testing, estimates are usually made of several performance aspects, such as cruising performance, airfield performance, design speeds and DOC. A report on the background information for a design study might contain the following elements. a- A prediction of the lift curve, the drag polar and pitching moment curve for representative cruising conditions. b- Calculation of the cruising speed and/or maximum flight speed and the specific range (i.e distance traveled per unit weight of fuel) for several flight speeds and/or cruising altitudes. c- Considerations for choosing the most relevant structural design speeds (V and V") and determining the limitations of operational speeds vs pressure altitude, i.e. the flight envelope. d- Calculations of V-n diagrams for maneuvering and gust loads for several representative operational conditions. e- Computations of the maximum rate of climb, ceilings with all engines operating and with a failed engine (appropriate). f- Aprediction of the lift curve and the airplane drag polar for several positions of the high-lift devices, with under carriage up or down. g- Limits for the takeoff and landing weght, based on the airworthiness requirements in relation to climb performance, i.e. Wat curves. h- Calculations of the takeoff and landing field length required in accordance with the airworthiness rules appropriate to the particular airplane category. j- Pay load-range diagrams for several cruising conditions, due allowances being made for reserve fuel. k- An estimate of the operating costs as a function of the stage length, using a suitable standart method. Many other questions can be raised and the designer must make a decision on the basis of what he considers necessary and appropriate in the preliminary design stage. For example, a detailed study of some principal stability and control characteristics can be carried out, particulary if there are sound reasons for doubting the adequacy of the empennage and control surface design. However, the designer should -vxx- also realize that many assumptions have to be made which must be verifi ed later on anddecide whether much time should be spent in studies the conclusions of which are subjet to considerable inaccuracy. Several topics in this chapter will be touched upon in a rather super ficial manner since a thorough treatment might necessitate as many chapters as there are sections in this chapter.. The outline of the wing, both in platform and in the cross- sectional shape, must be suitable for housing a structure which is capable of doing its job. As soonas the basic wing shape has been decided, a preliminary layout of the wing structure must be indicated wich is expected to lead, after further refinement and detail design, to a suffieciently strong, stiff and light solution, with a minimum of manufacturing problems. This thesis has been devoted to the wing design for light Airplane of which were identified the determination of air loads at diffefent points of V-n diagram and their disturbution on main parts of the Dimensions and weights of entire aircraft and its parts have been assigned by utilizing some well-known aircrafts with similar characteristics to the proposed design. As the basic structural and skin metarial, the aluminum alloy was used. The uniformity in quality is better than plywood or spruce. A relativly thick skin on the leading edge allows the use of countersunk rivets, and also reduces the wrinkles. Both conditions are very desirable to obtain some laminarity in the flow, at last upto the maximum thickness of the airfoil. This is an ideal condition difficult to each, but if obtained, will result in a general improvement in the performance [ 1 ]. Whith 15 % chord-thickness ratioairfoil, it is possible to build a cantilever wing with a weight comparable to a strut braced. It is not only the weight of the basic members that must be considered in the comparision, but also the extra fittings, bolts, turnbuckles etc., along with the added loss in aerodynamic efficiency due to the additional parasite and interference drag. So the cantilever wing has been selected for the airplane to be designed [ 1 ]. As the location of the wing, low-wing hasbeen selected. The most dangerous parts of everyf light probably are take off, landing and flying the pattern. Visibility in a turn is greatly desired during these maneuvers. In a high wing aircraft, the visibility during these critical moments is reduced mostly toward the inside of the turn. These considerations alone will decide the choise between high wing and low wing, but there are many others that can be enumerated. Aircraft accident investigations and simple reasoning indicated that the more structure between the occupants and the ground, in cose of crash, the hig her are dissipated in the wing before starting with the passengers. From aerodynamic viewpoints, the fuselage cross- section area of alow wing airplane could be made smaller than of a high -viii- wing; the accuponts could be seated over the wing. The leads carried by wing are diveded in two types. The firsttype is named disturbuted loads which are consisted of aerodynamic loads, chordwise loodsspanwise distribution normal laads spanwise distribution at ony flight contidion (symmetrical and unsymmetrical) have been calculated foreach point of V-n diagram JAPPENDIX D], Plapextended and Flap retracted conditions, un symmetrical wing loods, loods due to dounaileron and their distribution, and The inertiloads. The second one is named concentrated loads which are consisted of wing tip fuel tanks weight and main landing gear weight. The shear loads and Bending moments due to the aboue loads are calculated in different wing stations as a first step this wing design. In chapter 3, According to the shear loads and bending moments spanwise distribution which are calculated in chapter 2 and the mechanical ppoperties of the material the main spar lower and upper Caps' crosssection dimensions are determined. In order to assure high margin of safety and to manufectue the spar easy the calculated thickness of spar lower and uppe caps are enlarged with the constant slope. In chapter 4, The main Spar design is made accarding to the NACA Method of Strength Analysis For Semi-Tension Field Beams Flat Webs. To place the web and stiff ener design on a more rational or truer basis. The NACA carried on a comprehesive study and testing program to develop better understanding of semi-tension filed beam action and to present a design procedure for using by the aeronautical structures engineer under light of the NACA methads. The skin thickness and critical and permanent shear flows which are carried by the skin, are determined according to the shear and bending moments which are calculated in chapter 3. And Then, the spar web and skin shear flows are calculated and compared with the critical and permanent shear flows in the same panels thraughout the wing. Allowable streses in uprights ( stiff eners on each side of web are calculated according to two types of failure; column failure and Forced crippling failure column failure in the usual meaning of the word (failure due to instability, without previous bowing) are possible only in double uprights. When column bowing begins. The uprights will force the web out of its original plan. The web tensile forces will then develop components normal to the plane of the web which tend to force the uprights back. In the forced crippling failure at uprights, the shear buckles inthe web will force buckling of upright in a leg attached to the web, particulary if the upright leg is thinner than the web. These buckles give a lever arm to the compressive force acting in the leg and there fore produce a severe stress condition. The buckles in the attached leg will in turn induce buckling of the outstanding leg. -IX- For design purposes of web, the peak values of the nominal web shear stress within a bay is calculated according to the NACA methods. The allowable shear stress is determined by tests and depends on the value of the diagonal-tension faktör k as well as on the details of the web to flange and web to upright festenings. A check for the development of permanent shear Buckles of web can be made using Appendix B [figure Cll. 46]. Web to flange, web to upights and upright to flange ivets, types and avantities are detemined according to the loads whieh are carried by the attaehments which are calculated in preveus chapters. The lightining holes of the spar webs ' locations and dimensions are determinedn by using of WRb shear spanwise dustribution which are calculeted inchapter 4, The last paragraph of this chapter of this chapter is the design of the wing tip fueltank attachment to the main spar.
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1991
Anahtar kelimeler
uçak mühendisliği, ana spar tasarımı, eğilme momenti, kanat burulması, kesme yükü, uçaklar, Aircraft Engineering, Main spar design, Bending moment, Wing torsion, Shearing load, Airplanes