AIRCRAFT DESIGN PROJECT - I Heavy Business Jet

Transcription

1 AIRCRAFT DESIGN PROJECT - I Heavy Business Jet A PROJECT REPORT Submitted by VIGNESH. M VINCENT KEVIN MORRIS ARAVIND. C in partial fulfillment for the award of the degree of BACHELOR OF ENGINEERING in AERONAUTICAL ENGINEERING RAJALAKSHMI ENGINEERING COLLEGE, THANDALAM ANNA UNIVERSITY: CHENNAI APRIL 2014

2 ANNA UNIVERSITY: CHENNAI BONAFIDE CERTIFICATE Certified that this project report DESIGN OF HEAVY BUSINESS JET is the bonafide work of VIGNESH. M ( ), VINCENT KEVIN MORRIS ( ) and ARAVIND. C () who carried out the project work under my supervision. SIGNATURE Mr. Yogesh Kumar Sinha HEAD OF THE DEPARTMENT SIGNATURE Mr. Surendra Bogadi SUPERVISOR Assistant Professor Aeronautical Engineering Rajalakshmi Engineering College, Aeronautical Engineering Rajalakshmi Engineering College, Thandalam, Chennai Thandalam, Chennai Internal Examiner External Examiner

3 ACKNOWLEDGEMENTS We owe a debt of gratitude to Mr. Yogesh Kumar Sinha, Head of the Department, Department of Aeronautical Engineering, for being a source of constant encouragement and a pillar of support in all that we do, be it academic or extracurricular. We would like to extend our heartfelt thanks to Mr. Surendra Bogadi for his constant help, erudite guidance and immense passion which enthused us to do the project better. A warm token of appreciation to the management at Rajalakshmi Engineering College, Thandalam for providing us with the amenities and a congenial atmosphere to work in.

4 ABSTRACT The aim of this project is to design and conceptualize a heavy corporate/business jet that can cater to a wide range of clientele ranging from business conglomerates to private organizations and individual parties. Business jet, private jet or, colloquially bizjet is a term describing a jet aircraft, usually of smaller size, designed for transporting groups of business people or wealthy individuals. The project involves the design of a heavy business jet that can accommodate about 40 passengers at full seating layout, providing the amenities and level of comfort that a business jet is expected to provide while incorporating the design specifications and performance parameters of a long range commercial airliner. The aircraft allows for long range transport with better efficiency and reduced fuel consumption and noise levels owing to a state of the art engine and design features. iv

5 TABLE OF CONTENTS CHAPTER NO. TITLE PAGE NO. ABSTRACT LIST OF TABLES LIST OF FIGURES LIST OF SYMBOLS AND ABBREVIATIONS iv vii viii x 1. INTRODUCTION TO DESIGN Defining a new design Aircraft Purpose Design Motivation Design Process Conceptual Design Design Process Breakdown INTRODUCTION TO BUSINESS JETS Classification of Business Jets Need for Business Jets COMMON COMPARATIVE STUDY COMPARATIVE DATA SHEET COMPARATIVE GRAPHS 22 v

6 6. WEIGHT ESTIMATION WING LOADING AIRFOIL SELECTION DRAG ESTIMATION POWERPLANT SELECTION LANDING GEAR DESIGN PERFORMANCE CHARACTERISTICS CENTRE OF GRAVITY ESTIMATION STABILITY AND CONTROL VIEW DIAGRAM FINALIZED DESIGN PARAMETERS CONCLUSION REFERENCES 96 vi

7 List of Tables Page no. 1. Design Process breakdown Common Comparative study Comparative Data Sheet (Business Jets) Gross Weight Iteration Table Wing Parameters Comparison of Turbofan Engines Performance Parameters Approximate Group Weights Method Wing Location and c.g. of the Airplane Finalized Design Parameters 94 vii

8 List of Figures Page no. 1. Design Process flow chart Cruise Speed vs. Range Cruise speed vs. Altitude Cruise Speed vs. Wing Loading Cruise Speed vs. Gross Weight Cruise Speed vs. Aspect Ratio Range vs. Aspect ratio Wing loading vs. Aspect ratio Wing Loading vs. Takeoff run Wing Loading vs. R/Cmax Aspect ratio vs. R/Cmax Mission Profile Weight Distribution Chart Wing loading Airfoil Geometry Angle of Attack NACA 63A-514 (Root airfoil) NACA (Midspan airfoil) 46 viii

9 19. NACA (Tip airfoil) Maximum Thickness Taper Ratio Wing Sweep Effective Mach no Winglets Pratt & Whitney PW1000G Landing Gear System Performance Characteristics a. climbing flight 69 b. gliding flight Static Longitudinal Stability Longitudinal stability Fuselage directional stability coefficient Directional stability Lateral stability View Diagram 92 ix

10 List of Symbols and Abbreviations - Angle of attack - Climb angle - Density factor - Density of air - Dihedral angle - Glide angle - Turn angle - Turn rate - Wing thickness ratio correction factor - Yaw angle 1/4 - Quarter chord sweep angle C m / e - Elevator control power C n / r - Rudder control power fuel - Density of fuel (L/D) cruise - Lift-to-drag ratio at cruise (L/D) loiter - Lift-to-drag ratio at loiter ac - Aerodynamic centre APU - Auxiliary Power Unit AR - Wing aspect ratio x

11 a t - Lift curve slope of tail a v - Lift curve slope of vertical tail a w - Lift curve slope of wing b - Wing span c - Chord length ĉ - Mean chord c.g. - Centre of gravity CAEP - Committee of Aviation Environmental Protection C D - Drag coefficient C D0 - Zero lift drag co-efficient C fe - Skin friction coefficient C l - Rolling moment coefficient C lf - Function of airfoil chord over which the flow in laminar C Lmax - Maximum Lift coefficient C m - Pitching moment coefficient C n - Yawing moment coefficient c R - Root chord c T - Tip chord D - Drag force d - Tire diameter xi

12 E Endurance e - Oswald efficiency factor g - Acceleration due to gravity K tf - Factor allowed for trapped fuel L - Lift force LE - Leading edge of wing l f - Length of fuselage L t - Load on tyre l v - Aerodynamic centre of vertical tail to the airplane s centre of gravity M - Mach number MTOW - Maximum Takeoff Weight N 0 - Neutral point N e - Number of engines located on top surface of wing q - Dynamic pressure R - Turn radius R/C - Rate of climb R r - Rolling radius of tyre S - Wing area SFC - Specific Fuel Consumption S LO - Takeoff run distance xii

13 S ref - Wing reference area S TD - Landing run distance S wet - Wing wetted area T - Thrust force t/c - Wing thickness ratio T/W - Thrust loading T f - A factor which is unity for streamlined shape V - Velocity of air/aircraft V cruise - Velocity at cruise V f - Volume of fuel V stall - Velocity at stall w - Tyre width W/S - Wing loading W 0 - Gross weight of aircraft W crew - Crew weight W e - Empty weight of aircraft W f - Weight of fuel W payload Aircraft payload weight x lew - Distance of location of wing from nose of the aircraft λ - Taper ratio of wing xiii

14 1. INTRODUCTION TO DESIGN Modern aircraft are a complex combination of aerodynamic performance, lightweight durable structures and advanced systems engineering. Air passengers demand more comfort and more environmentally friendly aircraft. Hence many technical challenges need to be balanced for an aircraft to economically achieve its design specification. Aircraft design is a complex and laborious undertaking with a number of factors and details that are required to be checked to obtain optimum the final envisioned product. The design process begins from scratch and involves a number of calculations, logistic planning, design and real world considerations, and a level head to meet any hurdle head on. Every airplane goes through many changes in design before it is finally built in a factory. These steps between the first ideas for an airplane and the time when it is actually flown make up the design process. Along the way, engineers think about four main areas of aeronautics: Aerodynamics, Propulsion, Structures and Materials, and Stability and Control. Aerodynamics is the study of how air flows around an airplane. In order for an airplane to fly at all, air must flow over and under its wings. The more aerodynamic, or streamlined the airplane is, the less resistance it has against the air. If air can move around the airplane easier, the airplane's engines have less 1

15 work to do. This means the engines do not have to be as big or eat up as much fuel which makes the airplane more lightweight and easier to fly. Engineers have to think about what type of airplane they are designing because certain airplanes need to be aerodynamic in certain ways. For example, fighter jets maneuver and turn quickly and fly faster than sound (supersonic flight) over short distances. Most passenger airplanes, on the other hand, fly below the speed of sound (subsonic flight) for long periods of time. Propulsion is the study of what kind of engine and power an airplane needs. An airplane needs to have the right kind of engine for the kind of job that it has. A passenger jet carries many passengers and a lot of heavy cargo over long distances so its engines need to use fuel very efficiently. Engineers are also trying to make airplane engines quieter so they do not bother the passengers onboard or the neighborhoods they are flying over. Another important concern is making the exhaust cleaner and more environmentally friendly. Just like automobiles, airplane exhaust contains chemicals that can damage the earth's environment. Structures and Materials is the study of how strong the airplane is and what materials will be used to build it. It is really important for an airplane to be as lightweight as possible. The less weight an airplane has, the less work the engines have to do and the farther it can fly. It is tough designing an airplane that is lightweight and strong at the same time. In the past, airplanes were 2

16 usually made out of lightweight metals like aluminum, but today a lot of engineers are thinking about using composites in their designs. Composites look and feel like plastic, but are stronger than most metals. Engineers also need to make sure that airplanes not only fly well, but are also easy to build and maintain. Stability and Control is the study of how an airplane handles and interacts to pilot input and feed. Pilots in the cockpit have a lot of data to read from the airplane's computers or displays. Some of this information could include the airplane's speed, altitude, direction, and fuel levels as well as upcoming weather conditions and other instructions from ground control. The pilot needs to be able to process the correct data quickly, to think about what kind of action needs to be taken, and to react in an appropriate way. Meanwhile, the airplane should display information to the pilot in an easy-to-read and easy-to-understand way. The controls in the cockpit should be within easy reach and just where the pilot expects them to be. It is also important that the airplane responds quickly and accurately to the pilot's instructions and maneuvers. A beautiful aircraft is the expression of the genius of a great engineer who is also a great artist. Neville Shute, British Aeronautical Engineer and Novelist, From, No Highway,

17 When you look at aircraft, it is easy to observe that they have a number of common features: wings, a tail with vertical and horizontal wing sections, engines to propel them through the air, and a fuselage to carry passengers or cargo. If, however, you take a more critical look beyond the gross features, you also can see subtle, and sometimes not so subtle, differences. This is where design comes into play. Each and every aircraft is built for a specific task, and the design is worked around the requirement and need of the aircraft. The design is modeled about the aircraft role and type and not the other way around. Thus, this is why airplanes differ from each other and are conceptualized differently. Aircrafts that fall in the same category may have similar specifications and performance parameters, albeit with a few design changes. Design is a pivotal part of any operation. Without a fixed idea or knowledge of required aircraft, it is not possible to conceive the end product. Airplane design is both an art and a science. In that respect it is difficult to learn by reading a book; rather, it must be experienced and practiced. However, we can offer the following definition and then attempt to explain it. Airplane design is the intellectual engineering process of creating on paper (or on a computer screen) a flying machine to (1) meet certain specifications and requirements established by potential users (or as perceived by the manufacturer) and/or (2) pioneer innovative, new ideas and technology. An example of the former is the design of most commercial transports, starting at least with the Douglas DC-1 in 1932, 4

18 which was designed to meet or exceed various specifications by an airplane company. (The airline was TWA, named Transcontinental and Western Air at that time.) An example of the latter is the design of the rocket-powered Bell X- 1, the first airplane to exceed the speed of sound in level or climbing flight (October 14, 1947). The design process is indeed an intellectual activity, but a rather special one that is tempered by good intuition developed via experience, by attention paid to successful airplane designs that have been used in the past, and by (generally proprietary) design procedures and databases (handbooks, etc) that are a part of every airplane manufacturer. 1.1 Defining a new design The design of an aircraft draws on a number of basic areas of aerospace engineering. These include aerodynamics, propulsion, light-weight structures and control. Each of these areas involves parameters that govern the size, shape, weight and performance of an aircraft. Although we generally try to seek optimum in all these aspects, with an aircraft, this is practically impossible to achieve. The reason is that in many cases, optimizing one characteristic degrades another. There are many performance aspects that can be specified by the mission requirements. These include: The aircraft purpose or mission profile 5

19 The type(s) and amount of payload The cruise and maximum speeds The normal cruise altitude The range or radius with normal payload The endurance The take-off distance at the maximum weight The purchase cost Aircraft Purpose The starting point of any new aircraft is to clearly identify its purpose. With this, it is often possible to place a design into a general category. Such categories include combat aircraft, passenger or cargo transports, and general aviation aircraft. These may also be further refined into subcategories based on particular design objectives such as range (short or long), take-off or landing distances, maximum speed, etc. The process of categorizing is useful in identifying any existing aircraft that might be used in making comparisons to a proposed design. With modern military aircraft, the purpose for a new aircraft generally comes from a military program office. For example, the mission specifications for the X-29 pictured in figure 1.1 came from a 1977 request for proposals from the U.S. Air Force Flight Dynamics Laboratory in which they were seeking a research aircraft that would explore the forward swept wing 6

20 concept and validate studies that indicated such a design could provide better control and lift qualities in extreme maneuvers. With modern commercial aircraft, a proposal for a new design usually comes as the response to internal studies that aim to project future market needs. For example, the specifications for the Boeing commercial aircraft (B-777) were based on the interest of commercial airlines to have a twin-engine aircraft with a payload and range in between those of the existing B-767 and B-747 aircraft. Since it is not usually possible to optimize all of the performance aspects in an aircraft, defining the purpose leads the way in setting which of these aspects will be the design drivers. For example, with the B-777, two of the prominent design drivers were range and payload. 1.2 Design Motivation Fundamentally, an aircraft is a structure. Aircraft designers design structures. The structures are shaped to give them desired aerodynamic characteristics, and the materials and structures of their engines are chosen and shaped so they can provide needed thrust. Even seats, control sticks, and windows are structures, all of which must be designed for optimum performance. Designing aircraft structures is particularly challenging, because their weight must be kept to a minimum. There is always a tradeoff between structural strength and weight. A good aircraft structure is one which provides all the strength and rigidity to 7

21 allow the aircraft to meet all its design requirements, but which weighs no more than necessary. Any excess structural weight often makes the aircraft cost more to build and almost always makes it cost more to operate. As with small excesses of aircraft drag, a small percentage of total aircraft weight used for structure instead of payload can make the difference between a profitable airliner or successful tactical fighter and a failure. Designing aircraft structures involves determining the loads on the structure, planning the general shape and layout, choosing materials, and then shaping, sizing and optimizing its many components to give every part just enough strength without excess weight. Since aircraft structures have relatively low densities, much of their interiors are typically empty space which in the complete aircraft is filled with equipment, payload, and fuel. Careful layout of the aircraft structure ensures structural components are placed within the interior of the structure so they carry the required loads efficiently and do not interfere with placement of other components and payload within the space. Choice of materials for the structure can profoundly influence weight, cost, and manufacturing difficulty. The extreme complexity of modern aircraft structures makes optimal sizing of individual components particularly challenging. An understanding of basic structural concepts and techniques for designing efficient structures is essential to every aircraft designer 8

22 1.3 Design Process The process of designing an aircraft and taking it to the point of a flight test article consists of a sequence of steps, as illustrated in the figure. It starts by identifying a need or capability for a new aircraft that is brought about by (1) a perceived market potential and (2) technological advances made through research and development. The former will include a market-share forecast, which attempts to examine factors that might impact future sales of a new design. These factors include the need for a new design of a specific size and performance, the number of competing designs, and the commonality of features with existing aircraft. As a rule, a new design with competitive performance and cost will have an equal share of new sales with existing competitors. The needs and capabilities of a new aircraft that are determined in a market survey go to define the mission requirements for a conceptual aircraft. These are compiled in the form of a design proposal that includes (1) the motivation for initiating a new design and (2) the technology readiness of new technology for incorporation into a new design. It is essential that the mission requirements be defined before the design can be started. Based on these, the most important performance aspects or design drivers can be identified and optimized above all others. Following the design proposal, the next step is to produce a conceptual design. The conceptual design develops the first general size and configuration for a new aircraft. It involves the estimates of the weights 9

23 and the choice of aerodynamic characteristics that will be best suited to the mission requirements stated in the design proposal. Research, Development and Market Analysis Mission Requirements Conceptual Design No Requirements Satisfied Yes Preliminary Design Stop Final Evaluation Go Detailed Design Test Article Fabrication Flight Test Design Process flow chart 10

24 The conceptual design is driven by the mission requirements, which are set in the design proposal. In some cases, these may not be attainable so that the requirement may need to be relaxed in one or more areas. This is shown in the iterative loop in the flow chart. When the mission requirements are satisfied, the design moves to the next phase, which is the preliminary design. 1.4 Conceptual Design This article deals with the steps involved in the conceptual design of an aircraft. It is broken down in to several elements, which are followed in order. These consist of: 1. Literature survey 2. Preliminary data acquisition 3. Estimation of aircraft weight a. Maximum take-off weight b. Empty weight of the aircraft c. Weight of the fuel d. Fuel tank capacity 4. Estimation of critical performance parameters a. Wing area b. Lift and drag coefficients c. Wing loading d. Power loading e. Thrust to weight ratio 5. Engine selection 6. Performance curves 7. 3 View diagrams 11

25 1.5 Design Process Breakdown Conceptual Design: - Competing concepts evaluated What drives the design? - Performance goals established Will it work/meet requirement? - Preferred concept selected What does it look like? Preliminary Design: - Refined sizing of preferred concept Do serious wind tunnel tests tests - Design examined data/establish parameters Make actual cost estimate - Some changes allowed Detail Design: - Final detail design Certification process - Drawings released Component/systems tests - Detailed performance Manufacturing - Only tweaking of design allowed Flight control system design 12

26 2. INTRODUCTION TO BUSINESS JETS A business jet is a jet that is owned by a private company or individual that is used primarily for transporting the people who own the aircraft. That being said a lot of planes that were developed to be used as business jets are also used for other purposes. In addition there are also companies that are set up exclusively to operate business jets. Therefore the lines between a business aircraft and a commercial one have become somewhat blurred. Over the last few years business jets have become a very popular way to travel. They offer great comfort of travel and service, with the option of having the aircraft at your beck and call whenever you require it. A private business jet trumps regular commercial transport in a number of areas. Nowadays, organizations and individuals who can afford the heavy expenses that a private jet entails are willing to invest in one. Greater ease of travel, ease of access, faster and hassle free transit and high comfort levels are some of the advantages of business jet transport. In most cases a business jet will be quite a bit smaller than a commercial jet. The most common ones carry fewer than twenty passengers since this allows them to operate under a different set of rules from the ones that are required for airliners. There are however now quite a few business jets that are the size of 13

27 airliners and in many cases they are airliners that have been adapted for the purpose. Nevertheless most business jets are quite small and only carry a small number of people. Business jets have a much more luxurious interior, with a number of amenities and services that a normal airliner would not have. Airliners are designed to carry large numbers of people, most of who are looking for the lowest cost possible. Business jets on the other hand are designed to carry people in a much higher level of comfort. The people who travel by business jet are almost always quite well off and expect this level of comfort when they travel. 2.1 Classification of Business Jets The business jet industry groups these jets into four loosely-defined classes Mid-sized jets Combining flight distance, speed and comfort, these mid-sized jets are ideal for intimate trips. Number of Passengers: 8-10 Sample Aircraft: Gulfstream 200, Embraer Legacy 450, Cessna Citation X, Bombardier Challenger

28 Large-cabin jets These aircraft are fast, comfortable, and can accommodate a medium-sized group. Number of Passengers: 8-15 Sample Aircraft: Gulfstream 550, Embraer Legacy 650, Dassault Falcon 7X Light jets Light jets have been a staple of the business jet industry since the advent of the Learjet 23 in the early 1960s. They provide access to small airports and the speed to be an effective air travel tool. Number of Passengers: 3 10 Sample Aircraft: Learjet 40, Cessna Citation CJ1, Dassault Falcon 10, Beechcraft Premier I VIP business jets / Heavy airliners With a variety of potential configurations, jets in this category have the capacity for dining rooms, bedrooms and offices. Number of Passengers: 18-40/

29 These heavy airliners are an ideal choice for larger groups, corporate meetings and special events. Sample Aircraft: Boeing BBJ, Airbus AGJ, Embraer Lineage Need for Business Jets The following list details some of the primary reasons companies utilize business aviation as a solution to some of their transportation challenges: Accessing communities with little or no airline service Business aviation serves ten times the number of communities (more than 5,000 airports) served by commercial airlines (about 500 airports). This means business aviation can allow companies to locate plants or facilities in small towns or rural communities with little or no commercial airline service. With nearly 100 communities having lost airline service, this is important. Reaching multiple destinations quickly and efficiently. Companies that need to reach multiple destinations in a single day may elect to use business aviation because that type of mission could be hard or impossible to complete with other modes of transportation. 16

30 Supporting the travel needs of many types of company employees. An NBAA survey revealed that 72 percent of passengers aboard business airplanes are non-executive employees. Companies often send teams of employees to a given destination because it is the most cost-effective means of transport. Moving equipment. When companies need to immediately move sensitive or critical equipment, business aviation is often the best solution. Ensuring flexibility. Businesses don t always know in advance where or when opportunities will present themselves. In today s business environment, companies need to be nimble enough to move quickly. Business aviation provides flexibility for companies that need to ensure employees can respond to changing demands and circumstances Increasing employee productivity and providing security. Business aviation is a productivity tool when traveling aboard business aircraft, employees can meet, plan and work en route. Business aviation also allows employees to discuss proprietary information in a secure environment without fear of eavesdropping, industrial espionage or physical threat. 17

31 Keeping in contact. Many aircraft have technologies that allow employees to remain in communication throughout the duration of their flight. This can be critical for companies managing a rapidly changing situation. Providing a return to shareholders. Studies have found that businesses which use business aviation as a solution to some of their transportation challenges return more to shareholders than companies in the same industry that do not utilize business aviation. Schedule Predictability. More than 3 percent of all commercial airline flights are cancelled. Nearly one quarter are delayed. Today, because of record load factors on commercial airlines, if your flight is cancelled or a delay causes you to miss your connection, the odds of you getting on the next flight are significantly reduced. When the future of a company and its employees is dependent upon you arriving on time, business aviation is an important tool. 18

32 3. COMMON COMPARATIVE STUDY Parameters Lancair IV Boeing 777 Antonov An-70 Gulfstream G550 F-16 Dimensions Length 7.62 m 63.7 m 40.7 m m m Height 2.44 m m m 7.87 m 4.88 m Wing span 9.93 m m m m 9.96 m Aspect ratio Wing area 9.1 m m m m m 2 Specifications Empty weight 907 kg kg kg kg 8570 kg MTOW 1610 kg kg kg kg kg Fuel weight 703 kg kg kg kg 7797 kg Performance Max. speed 595 kph 950 kph 780 kph 1086kph 2120 kph Range 2494 km 9700 km 6600 km km 4220 km Max. (R/C) 13.2 m/s m/s 24.9 m/s 21 m/s 254 m/s Max. (W/S) 176.9kg/m kg/m kg/m kg/m kg/m 2 Service ceiling 8840 m m m m m Takeoff run 457 m 2440 m 1800 m 1801 m - 19

33 4. COMPARATIVE DATA SHEET (BUSINESS JETS) Parameters Airbus A340 Boeing B777 Embraer Lineage Prestige VIP 1000 Type Long range Wide body Long range corporate jet business jet business jet Dimensions Length m m m Height m m m Wing span 60.3 m 60.9 m m Aspect ratio Wing area m m m 2 Wing Sweep angle Root chord 10.6 m 9.57 m 4.76 m Tip chord 2.6 m 2.29 m 1.22 m Mean chord 7.26 m 7.01 m 3.22 m Flaps Single slotted Double slotted Double slotted Taper ratio Wing loading m m m 2 20

34 Weights Payload kg kg kg Empty weight kg kg kg MTOW kg kg kg Fuel weight kg kg kg Powerplant Name CFM56-5C3 GE90-115B GE CF34-10E Thrust rating 145 kn (x4) 514 kn (x2) 82.3 kn (x2) SFC Dry weight 3990 kg 8283 kg 1700 kg Performance Max speed 914 kph 927 kph 890 kph Cruise speed 880 kph 895 kph 847 kph Max R/C 23 m/s m/s m/s Service ceiling m m m Range km km 8334 km Takeoff run 3125 m 3045 m 1852 m 21

35 5. COMPARATIVE GRAPHS 1. Cruise Speed vs. Range 22

36 2. Cruise speed vs. Altitude 23

37 3. Cruise Speed vs. Wing Loading 24

38 4. Cruise Speed vs. Gross Weight 25

39 5. Cruise Speed vs. Aspect Ratio 26

40 6. Range vs. Aspect ratio 27

41 7. Wing loading vs. Aspect ratio 28

42 8. Wing Loading vs. Takeoff run 29

43 9. Wing Loading vs. R/C max 30

44 10. Aspect ratio vs. R/C max 31

45 6. WEIGHT ESTIMATION MISSION PROFILE Gross weight W 0 = W crew + W payload + W fuel + W empty W crew = 800 kg ( 2 pilots + 6 cabin crew) W payload = 4000 kg (40 passengers max) Gross weight W 0 = W crew + W payload [1 (W f W 0 ) (W e W 0 )] 32

46 Estimation of empty weight fraction (W e W 0 ) W e W 0 = A W 0 c = x W Estimation of fuel fraction (W f W 0 ) W f W 0 = K tf x (1 -W n W 0 ) W n W 0 = W 1 W 0 x W 2 W 1 x. x W n-1 w n-2 x W n W n-1 Fuel fraction for warm up, taxing and take-off (W 1 W 0 ) = 0.98 Fuel fraction for climb (W 2 W 1 ) = 0.98 Fuel fraction for cruise (W 3 W 2 ) From Breguet range equation: W 3 W 2 = exp { -R x TSFC / (3.6 x V x L/D) } To calculate L/D (L/D) max = 1/ (4 Cd 0 k) Cd 0 = R w T f S -0.1 {1- (C lf /R w )} [1-0.2M {M (cos 1/4 ) 1/2 / A f - t / c} 20 ] We have, M=

47 AR= 9.45 t / c = 0.14 Taper ratio, = 0.25 Sweep angle, 1/4 = 25 0 N e = 0 (no. of engines located on top of the wings) C lf = 0 (assuming no laminar flow over the wing in cruise) R w = S wet /S = 5.5 T f = 1.1 (a factor which is unity for streamlined shape) A f = 0.93 (airfoil factor) = (wing thickness ratio correction factor) f ( ) = Substituting, Cd 0 = [0.8868] Cd 0 = To calculate K K = 1/πAR { M 6 [((1+ { f( )A(10 t / c) 0.33 })/ (cos 1/4 ) 2 ) +{0.1 (3N e + 1)/ (4+ AR) 0.8 }] K = {1.029 [ ]} 34

48 K = (L/D) max = 1 / (4Cd 0 k) (L/D) max = (L/D) cruise =86.6 % (L/D) max (L/D) cruise = W 3 W 2 = exp { -R x TSFC / (3.6 x V x L/D) } W 3 /W 2 = = exp { x 0.51 / (3.6 x x 16.07) Fuel fraction for loiter (W 4 /W 3 ) W 4 /W 3 = exp { - E x TSFC / (L/D)} W 4 /W 3 = = exp { x 0.41 / } Fuel fraction for descent, landing and taxing (W 5 /W 4 ) =

49 W 5 /W 0 = W 1 W 0 x W 2 W 1 x W 3 /W 2 x W 4 /W 3 x W 5 /w 4 = 0.98 x 0.98 x x x 0.98 W 5 /W 0 = W f W 0 = K tf x (1 -W n W 0 ) W f /W 0 = 1.06 x 1 (0.617) W f /W 0 = Gross Weight, W 0 = W crew + W payload [1 (W f W 0 ) (W e W 0 )] W 0 = 4800 / [ (W 0 ) ] W 0 Guessed (kg) W e /W 0 W 0 Calculated (kg)

50 The estimated Gross weight (W 0 ) is kg W f = x = kg is the maximum fuel weight onboard. Maximum fuel capacity, V f = W f / fuel = / 0.809; fuel = kg/l, (value obtained from Jane s All the World Aircraft) V f = L (in wings belly tanks) 40% Empty weight Paylod Fuel weight 54% 6% Weight Distribution Chart 37

51 7. WING LOADING THRUST LOADING (T/W) C T/W 0 = AM max = (0.82) (T/W) takeoff = (T/W) cruise = 1/(L/D) cruise (T/W) cruise = WING LOADING (W/S) Stall: V stall = V approach / 1.3 = 72.5 / 1.3 V stall = m/s C Lmax = C L =0 cos 1/4 = 3.4 cos 25 0 =

52 W/S = ( V stall 2 C Lmax )/2 = (1.225 x x 3.08) / 2 W/S = kg/m 2 (at sea level) Landing: Ground roll distance, S = 80 (W/S) / ( C Lmax ) (W/S) = S ( C Lmax )/ 80 = 662 x 0.82 x 3.08 / 80 (W/S) landing = 21 kg/m 2 Cruise: Skin friction coefficient, C fe = (subsonic) Assuming S wet /S = 5.5 Parasite drag C Do = C fe (Swet / Sref) C Do = Oswald efficiency factor, 1/e = 1/e wing + 1/e fuselage

53 e wing = 0.84 for an unswept wing of A = 9.45 and λ = 0.25 e wing for a swept wing is, e wing = e wing =0 cos ( -5) = 0.84 cos (25-5) = /e fuselage = 0.1 1/e = Therefore, e = At 10 km altitude, V= , = 0.41 kg/m 2 q 0 = l V 2 / 2 = kg/m 2 (W/S) optimum cruise = q 0 (πearc D0 /3) 0.5 = ( 0.432) (W/S) optimum cruise = kg/m 2 (W/S) takeoff = (W/S) opt cruise x (W 1 /W 0 ) -1 x (W 2 /W 1 ) -1 = x x (W/S) takeoff = 527 kg/m 2 40

54 W/S takeoff cruise landing stall Wing loading 41

55 8. AIRFOIL SELECTION AIRFOIL GEOMETRY An airfoil is a surface designed to obtain a desirable reaction from the air through which it moves. Chord line: Straight line connecting leading edge and trailing edge. Thickness: Measured perpendicular to chord line as a % of it. Camber: Curvature of section perpendicular distance of section mid-points from chord line as a % of it. ANGLE OF ATTACK ( ) 42

56 Angle of attack ( ) is the angle between the free stream and the chord line. Aerofoil Selection is based on the factors of Geometry & definitions, design/selection, families/types, design lift coefficient, thickness/chord ratio, lift curve slope, characteristic curves. The following are airfoil categories: Early on, airfoil selection was based on trial & error. NACA 4 digit was introduced during the 1930 s. NACA 5-digit is aimed at pushing position of max camber forwards for increased Cl max. NACA 6-digit is designed for lower drag by increasing region of laminar flow. The modern airfoil is mainly based upon need for improved aerodynamic characteristics at speeds just below speed of sound. NACA 4 Digit: 1st digit: maximum camber (as % of chord). 2nd digit (x10): location of maximum camber (as % of chord from leading edge (LE)). 43

57 3rd & 4th digits: maximum section thickness (as % of chord). NACA 5 Digit: 1st digit (x0.15): design lift coefficient. 2nd & 3rd digits (x0.5): location of maximum camber (as % of chord from LE). 4th & 5th digits: maximum section thickness (as % of chord). NACA 6 Digit: 1st digit: identifies series type. 2nd digit (x10): location of minimum pressure (as % of chord from leading edge (LE)). 3rd digit: indicates acceptable range of CL above/below design value for satisfactory low drag performance (as tenths of CL). 4th digit (x0.1): design CL. 5th & 6th digits: maximum section thickness (%c) It becomes necessary to use high speed airfoils, i.e., the 6x series, which have been designed to suit high subsonic cruise Mach numbers. 44

58 NACA 63A-514 (Root airfoil) Max thickness 14% Max camber 3.2% 45

59 NACA (Midspan airfoil) Max thickness 12.5% Max camber 2.2% 46

60 NACA (Tip airfoil) Max thickness 10% Max camber 1.1% (JavaFoil airfoil generator) 47

61 MAXIMUM THICKNESS (T/C) Maximum thickness of the airfoil desired to produce max Cl is 14% With a wing sweep angle of 25 0, the max lift coefficient can be obtained from Cl max = Cl =0 cos 1/4 = 3.4 cos 25 0 = 3.08 (at 40 0 flap settings) Cl cruise = 2W/ ( V 2 S) = 2 x 598 x 9.81 / 0.41 x ) = Cl req,takeoff = 1.5 (at 12 0 angle of attack).. (From the plots above) 48

62 . Wing area, S = / = 142 m 2 Wing span, b = (9.45 x 142) = m Root chord, c R = 2 x 142 / [36.63 x ( )]. ( = 0.25) = 6.2 m Tip chord, c T = 0.25 x 6.2 = 1.55 m Mean aerodynamic chord (m ac ) = (2/3) [( )/(1+ )] c = 4.34 m 49

63 LE = c/4 + [(1- ) / AR (1+ )] = / (9.45 x 1.25) = M eff = M cos LE = 0.79 cos = Wing sweep reduces effective Mach number over the wing. = (1-M 2 eff) =

64 Dihedral ( ) is the angle of the wing with respect to the horizontal plane when seen in the front view. Dihedral of the wing affects the lateral stability of the airplane. A value of Γ = 5 0 is chosen. Wing sweep effect on dc L /d dc L /d = 2.π.AR / [2+ {4+(AR. ) 2. (1+tan 2 t/c / 2 )}] = 2 x π x 9.45 / [2+ {4+(9.45 x 0.7) 2 x (1+tan 2 25 / )}] = / =

65 WINGLETS Blended winglets are used in this heavy business jet. A blended winglet is attached to the wing with smooth curve instead of a sharp angle and is intended to reduce interference drag at the wing/winglet junction. These winglets which stand 2.5m tall each offers 5 to 7% reduction in cruise drag (induced drag) and increase in wing area and aspect ratio without geometrically increasing the wing span which results in 8 to 10% increase in range. 52

66 WING PARAMETERS: Design Parameters Values Wing loading (W/S) 598 kg/m 2 Wing area (S) 142 m 2 Aspect ratio (AR) 9.45 Wing span (b) m Taper ratio ( ) 0.25 Root chord (c R ) Tip chord (c T ) Mean chord (c m ) 6.2 m 1.55 m 4.34 m Design C L Sweepback angle ( ) 25 0 Dihedral angle ( )

67 9. DRAG ESTIMATION The drag polar is expressed as 2 C D = C D0 + KC L Where K = 1 / πae e = Oswald efficiency factor Parasite drag C Do = C fe (S wet / S ref ) Where, Cfe = equivalent skin friction drag coefficient ; S wet = Wetted area of the airplane. S wet /S ref = 5.5 The estimation of K is carried out next and then the value of C D0 is deduced using the earlier calculation that (L/D) max = ESTIMATION OF K: Oswald efficiency factor, 1/e = 1/e wing + 1/e fuselage e wing = 0.84 for an unswept wing of A = 9.45 and λ = 0.25 e wing for a swept wing is, 54

68 e wing = e wing =0 cos ( -5) = 0.84 cos (25-5) = /e fuselage = 0.1 1/e = Therefore, e = K = 1 / πae = 1 / π x 9.45 x = (L/D) max = 1 / 2 (C D0 K) C D0 = 1 / 4K (L/D) 2 max = 1 / 4 x x = C fe = / 5.5 = The drag polar is: C D = C L 2 Drag, D = (1/2) V 2 SC D 55

69 Takeoff: = kg/m 3 V = 1.15 V stall = 1.15 (55.77) = m/s S = 142 m 2 Drag, D = 0.5 x x x 142 x ( x ) D takeoff = kn Landing: = kg/m 3 V = 1.3 V stall = 72.5 m/s Drag, D = 0.5 x x x 142 x ( x ) D Landing = kn Cruise: = (at 10 km altitude) 56

70 V = m/s S = 142 m 2 Drag, D = 0.5 x 0.41 x x 142 x ( x ) D cruise = kn also, (T/W) cruise = 1 / (L/D) cruise T/W = T = x (84907 x 9.81 ) T cruise = kn In straight and level flight, D ~ T Here, D cruise and T cruise calculated are almost equal. 57

71 10. POWERPLANT SELECTION COMPARISON OF TURBOFAN ENGINES: Engine Length Diameter Thrust Weight Bypass Pressure Sfc (m) (m) (kn) (kg) T/W ratio ratio (hr -1 ) CFM56-7B :1 32.8: PW :1 28.2: CFM leap A :1 40: :1 - PW1000G :1 38: ENGINE SELECTION: The thrust loading based on sea level static thrust is: T/W = (from thrust loading calculation) Thus, the thrust required is, T req = x x 9.81 = kn 58

72 It is observed that the maximum thrust requirements occurs from V max consideration i.e. T max = kn. As a twin engine configuration has been adopted, the above requirement implies a thrust per engine of kn. The above comparison of high bypass turbofan engines shows the competition between CFM LEAP-1C and PW1000-G in various parameters. Unlike fighter aircraft, business jets or any airliner in that case looks for an important parameter which is lowest specific fuel consumption. Though LEAP-1C gives a pressure ratio higher than PW1000-G, it contains more number of stages which adds weight to the aircraft. On the other hand, PW1000G has a lowest TSFC of 0.39/hr. PW1000-G will be designed with a variable inlet duct and a Gearing system (Geared turbofan), that will allow changes in bypass ratio by controlling the rpm of the fan, whenever required as per the flight phase. In addition to the geared turbofan, the current design includes a variable-area nozzle, which offers reduction in noise. It also offers 15% reduction in CO 2 emission and 55% reduced NO x margin in accordance with CAEP/6. Taking these advantages in consideration, PW1000-G is selected. Selected Engine series of PW1000G family: PW1124G PW1127G PW1133G 59

73 DETAILS OF THE SELECTED ENGINE: PRATT & WHITNEY PW1000G The Pratt & Whitney PW1000G is a high-bypass geared turbofan engine family, currently selected as the exclusive engine for the Bombardier CSeries, Mitsubishi Regional Jet (MRJ), Embraer's second generation E-Jets, and as an ultra efficient option for the Airbus A320neo. 60

74 FAN: A large, light-weight fan moves well over 90% of air around the core, delivering a very quiet engine with very low fuel burn. COMPRESSORS AND TURBINES: A compact, high-speed low-pressure system accomplishes the same work in fewer stages. That means fewer airfoils, fewer life-limited parts, and ultimately lower maintenance costs. CORE: The supercharged low-pressure system allows the advanced PurePower engine core optimized for high-cycle durability to run cooler than the closest competition, with fewer stages, and without expensive materials. That means longer time on wing and lower maintenance costs 61

75 PW1000G COMPONENTS: COMPRESSOR: Axial flow, 1-stage geared fan, 3-stage LP, 8-stage HP COMBUSTORS: Annular combustion chamber TURBINE: Axial, 2-stage HP, 3-stage LP 62

76 GEARED TURBOFAN: In a conventional turbofan engine, a single shaft (the "low-pressure" or LP shaft) connects the fan, the low-pressure compressor and the low-pressure turbine. A second concentric shaft connects the high-pressure compressor and high-pressure turbine. In this configuration, the maximum tip speed for the fan limits the rotational speed for the LP shaft and thus the LP compressor and turbine. At high bypass ratios (and thus high radius ratios) the tip speeds of the LP turbine and LP compressor must be relatively low, which means extra compressor and turbine stages are required to keep the average stage loadings and, therefore, overall component efficiencies to an acceptable level. In a geared turbofan, a reduction gearbox between the fan and the LP shaft allows the latter to run at a higher rotational speed thus enabling fewer stages to be used in both the LP turbine and the HP compressor, increasing efficiency and reducing weight. Also the weight saved on turbine and compressor stages is offset to some extent by the mass of the gearbox. The Pure Power engine allows for a more efficient arrangement: a big, slow fan shoving air into a small, fast turbine. The result is a shorter, lighter engine that can produce the same amount of power as a larger conventional turbofan, while burning 15 percent less fuel and emitting 15 percent less carbon dioxide. 63

77 11. LANDING GEAR DESIGN The landing gear supports the aircraft when it is not flying, allowing it to take off, land and usually to taxi without damage. Landing gear placement is essential for ground stability and controllability. A good landing gear position must provide superior handling characteristics and must not allow overbalancing during takeoff or landing. Landing gear arrangement: Landing gears normally come in two types: conventional or "taildragger" landing gear, where there are two main wheels towards the front of the aircraft and a single, much smaller, wheel or skid at the rear; or tricycle landing gear, where there are two main wheels (or wheel assemblies) under the wings and a third smaller wheel in the nose. To decrease drag in flight some undercarriages retract into the wings and/or fuselage with wheels flush against the surface or concealed behind doors; this is called retractable gear. With a tricycle landing gear, the c.g is ahead of the main wheels, so the aircraft is stable on the ground. It improves forward visibility on the ground and permits a flat cabin floor for passengers and cargo loading. Thus retractable tricycle landing gear system is selected. 64

78 Tyre sizing: The wheel is the circular metal object upon which the rubber tyre is mounted. The brake inside the wheel slows the aircraft by increasing the rolling friction. However, the term wheel is frequently used to mean the entire wheel/brake/tyre assembly. The tyres are sized to carry the weight of the weight of the aircraft. Typically the main tyres carry about 90% of the total aircraft weight. Nose tyres carry only about 10% of the static load but experience higher dynamic loads during landing. 65

79 The nose gear is of double bogey type with two wheels. The main gear consists of two sets of wheels (wing retracted) each of multi bogey type with 4 wheels each. Nose gear: Load on nose gear = 0.1W 0 = kg Load per tyre, L t = kg = lb Wheel diameter = 2.69L t..(from Raymer) = 21.9 in = 0.56 m Wheel width = 1.17L t (from Raymer) = 7.11 in = 0.18 m Tyre size, 27 x 7.75 Tyre diameter, d = 27 in = m Tyre width, w = 7.75 in = m Rolling radius, R r = 11.5 in = 0.3 m Pavement contact area, A p = 2.3 x (wd) x (0.5d R r ) = in 2 Tyre pressure = / = psi 66

80 Main gear: Load on main gear = 0.9 W 0 = kg Load per tyre, L t = kg = lb Wheel diameter = 2.69L t..(from Raymer) = in = 0.81 m Wheel width = 1.17L t (from Raymer) = 9.83 in = 0.25 m Selecting Goodrich tyre of size 40x14.5 Tyre diameter d = 40 in = 1 m Tyre width, w = 14.5 in = 0.37 m Rolling radius, R r = 16.3 in = m Pavement contact area, A p = 2.3 x (wd) x (0.5d R r ) = 205 in 2 Tyre pressure = / 205 = 205 psi Wheel base = m Wheel track = 5.71 m (incl. shock struts) 67

81 12. PERFORMANCE CHARACTERISTICS TAKEOFF PERFORMANCE: Distance from rest to clearance of obstacle in flight path and usually considered in two parts: - Ground roll - rest to lift-off (S LO ) - Airborne distance lift off to specified height of 50ft The aircraft will accelerate up to lift-off speed (V LO = about 1.2 x V stall ) when it will then be rotated. Ground roll take-off distance is given by S LO = 1.21W / g SC Lmax (T/W).. (from Aircraft Performance & Design by John. D Anderson) = 1.21 x 84907x9.81 / (9.81 x x 142 x1.5 x 0.248) S LO = m (C Lmax for takeoff = 1.5, from airfoil selection) CLIMBING: Consider aircraft in a steady unaccelerated climb with vertical climb speed of V c L=W cosγ C T=D+W sinγ C 68

82 V C = (T - D)V stall / W R/C max = V C = (2x ) x / (84907 x 9.81) R/C max = 24.7 m/s LEVEL TURN: In the case of a commercial transport aircraft, it is capable of performing only a constant altitude banked turn and not any vertical pull-up or pull-down manoeuvres. In steady condition: T = D Force balance gives: W = Lcos F r = mv 2 / r = Lsin tan = V 2 / Rg So for given speed and turn radius there is only one correct bank angle for a coordinate (no sideslip) turn. 69

83 In the turn, n = L/W = sec > 1 and is therefore determined by bank angle. Turn radius (R) and turn rate ( ) are good indicators of aircraft manoeuvrability. V 2 / (Rg) = tan = (sec 2-1) = (n 2-1) R = V 2 / (g (n2-1)) And = V/R = (g (n 2-1)) / V W = Lcos Let = 60 0 n = L/W = 2 R = V 2 / (g (n 2-1)) = / (9.81 x (2 2 1)) R = m = V/R = / = rad/s 70

84 GLIDING: The thrust can be assumed to be zero while the aircraft is gliding. = tan -1 [1/ (L/D)] = tan -1 [ 1 / 18.57] = is the glide angle. LANDING PERFORMANCE: APPROACH & LANDING: - Airborne approach at constant glide angle (around 3 0 ) and at constant speed. - Flare - transitional maneuver with airspeed reduced from about 1.3 Vstall down to touch-down speed. - Ground roll - from touch-down to rest. 71

85 Ground roll distance (S TD ): S TD = 1.69 W 2 / gρsclmax [D + r (W-L)] r is higher than for take-off since brakes are applied - use r = 0.4 for paved surface. S TD = 1.69 x (84907 x 9.81) 2 / (9.81 x x 142 x 3.08 x [ ( x )] Landing distance is S TD = 795 m Performance Parameters Values Units Takeoff distance m (R/C) max 24.7 m/s Turn radius m Turn rate rad/s Glide angle 3.08 deg Landing distance 795 m 72

86 13. CENTRE OF GRAVITY ESTIMATION The weight of an airplane changes in the flight due to consumption of fuel and dropping off / release of armament or supplies. Further, the payload and the amount of fuel carried by the airplane may vary from flight to flight. These factors lead to change in the location of the centre of gravity (c.g.) of the airplane. The shift in the c.g location affects the stability and controllability of the airplane. The weight of entire airplane can be sub divided into empty weight and useful load. The empty weight can be further subdivided into: (i) structures group (ii) propulsion group and (iii) equipment group. The structures group consists of the following components: - wing - horizontal tail /canard - vertical tail - fuselage - landing gear - main and nose/tail wheel - nacelle, engine pod and air intake 73

87 The propulsion group consists of the following components: - engine as installed - reduction gear - propeller for piston and turboprop engines - cooling provisions - engine controls - fuel system and tanks The equipment group consists of the following items: - flight controls - auxiliary power unit (APU) - instruments - hydraulic, pneumatic, electrical, armament, air conditioning, anti-icing - avionics - furnishings in passenger airplanes The useful load consists of: (i) Crew (ii) Fuel - usable and trapped (iii) Oil (iv) Payload - passengers, cargo and baggage in transport airplane; ammunition, expendable weapons and other items in military airplanes. 74

88 Approximate group weights method: (Reference: Aircraft design: A Conceptual Approach by Daniel P. Raymer) The aim of estimating the weights of individual components and their c.g. is to obtain the location of the c.g. of the airplane. Then, the shift in the airplane c.g. is examined under various conditions. At this stage of preliminary design, the weights of individual components are estimated using simpler method like using the table above. The gross weight of the airplane estimated is kg The weights and c.g. locations of various components are estimated below: 75