Group Project Final

AVIA 1000 – Group Project ‘Boeing 737-800’

Group participants:

Ikram Benferchiche Aous Awida Peter ZulkJoshua Colton Jonny Bentley

Due Date: 21st January 2016

AVIA 1000 – Technical Skills and Applications

Module Leader: Cllr Clive Hudson

Group advisor: Dr Darron Dixon-Hardy

AVIA 1000. 2015/16. Boeing 737

Executive Summary: (198)The report contains an overview of the Boeing 737 and will be discussed in detail throughout, beginning with the history and generation of the aircraft, moving onto one specific version of the 737; the -800. The design configuration, design concept and main features that determine performance were discussed.

Ethical issues associated with the -800 are also reviewed. Problems such as how the 737 was effected by a faultily designed rudder, which lead to many fatal incidents, as well as how the aircraft affects noise pollution and the global climate.

Further along the report, certain aspects of the -800 are reviewed and discussed. These aspects were as followed:

Mass & Centre of gravity Engines Undercarriage Fuselage Wings Tail

Simulation of the Boeing 737-800 are also conducted on the Merlin simulator. Many aspects are altered in different methods and then simulated to produce results which are observed and analysed.

It was concluded that the dihedral angel of the wings is ideal at 6⁰ and cannot be altered to improve the aircraft. The wing sweep angel of 25.02⁰ is good enough for the operation of the aircraft, though if higher speeds are required then an increase in sweep should be considered.

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Table of Contents

Executive Summary:..................................................................................................................1

1. Introduction: (Group work)................................................................................................3

2. Overall Design of the Aircraft: (Group work)....................................................................4

3. Ethical issues associated with the aircraft: (Group work)..................................................7

4. Mass, Centre of Gravity, Construction and Materials: by Ikram Benferchiche.................9

5. Engines: by Aous Awida..................................................................................................13

6. Fuselage: Petar Bukureshtliev..........................................................................................16

7. Undercarriage: by Zulquarnain Ayub...............................................................................21

8. Wings: by Joshua Colton..................................................................................................25

9. Tail: by Jonny Bentley......................................................................................................30

10. Conclusion: (Group work).................................................................................................35

11. Acknoweldgments: (Group Work).....................................................................................36

12. References:.......................................................................................................................36

13. Appendix:...........................................................................................................................38

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1. Introduction: (276)

The objectives of the group project were to be introduced to the basic principles of aircraft design and to research the design features of the Boeing 737. There are six sections of the aircraft to study in detail and nine aspects (Mass, Centre of gravity, Construction, Materials, Engine, Fuselage, Undercarriage, Wings and Tail). Considerations were made on the effects of changing these aspects on the performance of the aircraft. The changes that were decided on for each aspect of the aircraft would be examined using the Merlin Engineering Flight Simulator. Small changes were made to see if the aircrafts performance would improve or not.

The aims of this project were to widen the knowledge on how commercial aircrafts operated. Completing this project would give an insight for future projects that can be given in the final year and what will be expected of students.

The design, construction and function of each aspect of the Boeing 737 were found through the research made during this project. By doing so, this has widened the knowledge on Aviation Technology and how each aspect interconnects with one another for the aircraft to function to the best of its ability. The use of the Merlin Engineering Flight Simulator gave an overview to flight simulation. It also gave insight on what is to be expected when using the simulator again in future if undertaking another project.

The figure below demonstrates the route map of the project. It represents all the task that were taken and it also illustrates the duration that has been set to each task to be completed.

Intro to the project

First meeting with supervisor

Complete the individual sections

Meeting with supervisor and Sim session

Group meeting (Ethics)

Analyse Sim Data

Group meeting (design and intro sections)

Group meeting (finish the project)

Practice presentation

finnal presentation

9/12 14/12 19/12 24/12 29/12 3/1 8/1 13/1 18/1

Figure 1: Gantt chart representing a Route Map for the Group Project.

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2. Overall Design of the Aircraft: (1597)

Design concept:

The design process is a long and variant journey; as the process continues, certain aspects will always be improved or removed, and/or new components may be implemented. To minimise every possibility of these altercations, a robust design concept must first be created. Therefore the design concept of the Boeing 737 was simple: the main purpose of this aircraft would be to conduct many short-haul flights all across the world and to carry as many passengers as possible while maintaining efficiency. The reason for the production of this aircraft was that Boeing wanted a superior short-haul jet to compete with the Caravelle, DC-9 and the BAC One-Eleven [1]. In November 1964, designers Joseph Sutter and Jack Steiner began work on the 737. The original specification in 1964 for the 737 was that the aircraft was to hold a capacity of about 60-85 passengers, an operating range of approximately 100 to 1000 miles while also having 35% load factor [1]. However, the final design conception discussions between Boeing and their launch customer Lufthansa, the capacity was increased to 100, however the range and load factor statistics remained the same.

One huge design concept that allowed the 737 to shine among its competitors was due to designer Joe Sutter who decided to mount the engines hard against the underside of the wing instead of having them mounting them away from the wing on struts [2]. These wing mounted engines produced many advantages, such as reduced interference drag, a better centre of gravity position, quieter cabin, increased cabin space in the rear, an easier access to engines for maintenance and meant that less pipework for fuel and bleeds was required.

In a general summarisation, the final wing-mounted engine design coupled with a new fuselage-mounted horizontal stabiliser had an overall weight saving of 700Kgs over previous designs as well as producing performance advantages.

History of the Boeing 737:

On 17th January 1967, the first 737-100 was introduced to the world inside the Thompson site with Lufthansa being the principle customer, and was known as “the square”, due to it being wide and long [2]. Later on, in 1988, United Airlines received the first delivery of the Boeing 737-200 [2], with a higher fuel capacity and more powerful engines [3].

1991 saw production of the models -300/-400/-500. Two years later, the orders of the 737 reached 3,100 and Boeing was developing the next generation model. Boeing 737-800 was then launched in 1994 and made its first flight in 1998 [2].

The main change between each generation of 737 is the size of the wing. Most notably between the Classics (-300, -400, -500) and the 'Next Generation' (-600, -700, -800, & -900). The wingspan increased from 28.88m to 34.32m. The gross area of the wings also increased from 105.40m2 to 124.58m2 [4]. This is marginally longer and larger than its main competitor the A320 which has a wing span of 34.09m and an area of 122.6m2 [5].

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AVIA 1000. 2015/16. Boeing 737

The Boeing 737 is also produced in cargo variants which offer a larger capacity for the transportation of goods than the passenger variants. The current variants in service are the 737-300SF, 400SF, 700C and 800BCF [6], though none of these offer as great a capacity as the larger aircraft such as the 747-8F.

The Boeing 737-100 originally began with the Pratt & Whitney JT8D-1 turbofan engine, however just before the order was confirmed the JT8D-7 was commonly used by the 727. The -7 was developed so that it could produce the same thrust of 14,000lb.st, however would be able to perform at higher ambient temperatures than the -1, and for this reason the JT8D-7 was chosen to be the standard power plant for the 737-100 and when approaching the end of the -200 production the JT8D-17R was able to produce 17,400lb.st of thrust [1].

The solitary power plant for all 737’s after the -200 is the CFM-56, this was an improvement of the previously used Pratt & Whitney JT8D-17R as it immediately produced 1,500 lb.st of thrust more. Issues were found when attaching the engine to the wings of the -300 as its size was a restriction in regards to ground clearance, this was resolved by flattening the nacelle bottom and intake lip as well as moving the engines forward and raising them so that they were level with the upper surface of the wing [1]. The engines were also tilted 5 degrees up allowing there to be not only ground clearance, however also a enabling the exhausts to be directed downwards reducing the effects of pylon overheating while also producing vectored thrust to assist take-off performance. The fir CFM56-3 demonstrated to be almost 20% more efficient than the JT8D. The structure of the turbine itself and the materials used to create it allowed for an 8% fuel reduction and a 15% maintenance cost reduction allowing for a superior engine performance [1].

Key Features of the Boeing 737-800:

The 800 (known as the 737-400X Stretch before its official launch as the 800 [7]) is one of the strongest selling of the 737 family due to it having a new fuselage length which made it a more comfortable plane than previous models.

The 737-800 is a particularly environmentally friendly aircraft with many significant features, for example:

The 800 has been improved with winglets; these help to reduce the aerodynamic drag and fuel consumption by 7% [2].

More thrust can be produced, while noise levels are below average [2]. It can fly faster, higher and further. This is due to the improvements that have been

made to it, which are: increasing the wing area by 25%, extending the fuel capacity by 30% and the aerodynamic efficiency by 22% [2].

The use of two fuel efficient and low noise CFM56-7 engines, which allow it to fly at a cruise speed of Mach 0.785 at ranges of over 3,000 nautical miles [2].

“Engine technology improvements, blended winglets and carbon brakes are among the enhancements that reduce maintenance and improve the environmental performance” [8].

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Figure 2: Schematics for the Boeing 737-800 showing dimensions in plan, side and forward view [9].

Figure 3: Graph shows how the advanced wing design helped to improve the efficiency of the 737-800 [8].

Airworthiness Codes:

The airworthiness codes contained in CS-25 apply to larger aircrafts. This is the category that the Boeing 737 falls under. An example of this is section 25.613: Materials. It groups materials in the aircraft into two main sections. The first section is where loads are applied through a single member within assembly, failure of which would result in loss of structural integrity. The other group is where this is not the case. Instead, the applied load safely distributes to other load carrying members [10].

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The airworthiness code states that the first group of materials must have a 99% probability of not failing and a 95% confidence about this. The second group must have a 95% probability of not failing and again, a 95% confidence about this.

There are also many codes in place for the power plant of large aircrafts like the 737 in Section E of the document. These range from obvious things like the power plants need to be able to create propulsion to things like needing to be able to be access the inside of the engine for necessary inspection and maintenance. The electrical components of the power plant must also have an electric connection to the rest of the aircraft [11]. A very important specification that must be met is each engine must be operable separately in at least one configuration. This is so that if the failure of one engine arises in flight, power can be cut from it and flight can be maintained [12].

These are only a few examples from tens of thousands but the point is that the designers of the 737 aircrafts had to follow these very specific guidelines along with thousands of others for every aspect of the design.

Simulator Performance:

In order to learn more about, and potentially improve, the design of the Boeing 737, a model of the aircraft was flown in a Merlin simulator whilst data about the flight was recorded. Certain parameters were changed to see how they affected flight performance so that the design choices of the aircraft could be better understood. The model was initially flown through a take-off and cruise in order to provide a standard set of data for comparison, then further test were conducted specific to each component to learn about their properties.

Overall, many aspects of the simulator model were accurate to the actual aircraft. For example, during the first test flight, the data collected gave the largest thrust value from the engines to be approximately 20534lbs, which lies between CFM’s published thrust range of 18,500lbs - 27,300lbs (CFM Aero Engines website). Furthermore, the basic dimensions such as wingspan, length and height that were entered into the simulator model matched those values published on the Boeing 737 technical website [1].

However, several problems were encountered whilst flying the aircraft as well as some discrepancies in the model’s construction. On take-off, it was discovered that the aircraft’s nose tended to dip down, causing the front wheel to oscillate in a caster effect and send the aircraft off the runway. This was attributed to uneven force distribution with too much weight being placed on the nose wheel, which is not a problem encountered on actual 737 aircraft. This inaccuracy between the model and the real aircraft projects itself as an inaccuracy in the results collected.

3. Ethical issues associated with the aircraft: (508)

Global Environmental Impact

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Millions of flights a year result in a large amount of carbon emissions, which takes its toll on the Earth in the form of Climate Change. Climate Change will affect everyone. The aviation industry is growing at a very fast rate and many parties need to make changes to create a sustainable effect on the environment. One of the most important parties is aircraft manufactures.

The Boeing Company has acknowledged that their fleet of aircrafts is going to grow at a very fast rate and that it is their responsibility to maintain and improve the environmental impact of their aircrafts. Boeing predicts a growth of traffic of 5% every year and for traffic to have doubled in 20 years [13].

Boeing have spent a considerable amount of time and money trying to reduce the environmental impact of its aircrafts. The original 737s were far less fuel efficient than the 737s of today. The 737 MAXs are 70% more fuel efficient than the 737 Originals [13]. Such a reduction in fuel consumption has led to less carbon emissions. This has reduced the possible effect of climate change that would have been present if these changes hadn’t been applied.

Local Environmental Impact

The turbofans engine equipped to the 737 are incredibly loud. This can cause discomfort and irritation to residence near airports around the world.

Boeing have also implement many innovations towards reducing the sound pollution of its aircrafts. Most of the new noise reducing technology implemented into the 737-800 was a joint venture between American Airlines and the FAA who funded the project. Most notably, this added a feature to the rear of the engine called the Variable Area Fan Nozzle (VAFN) [14]. This can be seen in Figure 1.

The VAFN is designed to improve fan efficiency during take-off, climb and descent. It does this by directed noise upwards away from homes [15].

Safety

The safety record of the 737 has been almost immaculate in the 50 years of its operation. There have been a total of 170 hull-lose accidents, resulting in the deaths of 4191 passengers and crew [16]While this is relatively low, those are 4191 deaths that could have been avoided or reduced with improved design of the aircraft.

A clear example of this is the 737 faulty rudder scandal of the 90s. Two major crashes in 1991 and 1994 have been faulted to malfunctioning rudders. Between these two crashes, 157 people died. There were also 4 other rudder related failures in the 90s that ended in safe

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Figure 4: Variable Area Fan Nozzle [15].

AVIA 1000. 2015/16. Boeing 737

landings [16]. The FAA ordered a full rudder control system upgrade to all 737s by 2002 which has appeared to fix the problem. These lives could have been saved if the rudder control system wasn’t built with this design flaw initially.

However, the Boeing Company has been striving to safer aircrafts. The original 737s had a hull loss rate of 1.75 per million departures verses 0.54 for the classic series and 0.27 for the Next Generation series [17].

4. Mass, Centre of Gravity, Construction and Materials: by Ikram Benferchiche (1144)

Mass:

The mass of the aircraft plays an important role in the performance of that aircraft, where minimising the mass as much as possible will lead to better fuel efficiency and performance. The Boeing 737 family has different masses depend on the model. The table below represents a typical operating empty weight and maximum take-off weight of the 737 family.

Table 1: A typical operating empty weight and maximum take-off weight for different models of the 737 Family [18].

Model 737-100 737-200 737-200 Advanced

737 Classic (-300/-400/-500)

737 Next Generation (-600/-700/-800/-900ER)

Operating empty weight (kg)

28,100 31,600 31,700 31,300 -33,600 36,400 -44,700

Maximum take-off weight (kg)

50,300 52,400 58,100 62,800 -68,000 65,500 -85,100

Centre of gravity (CG):

For an aircraft, the centre of gravity is the point of balance and its position is dependent on the weight and position of all the parts of the plane and also the load the aircraft is carrying [19].

For a neutral stability the centre of gravity should be in front of the centre of pressure (CP). If the CG moves forward of the CP, the aircraft’s nose will pitch down.

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AVIA 1000. 2015/16. Boeing 737

The manufacturer of the aircraft will place limits for the location of C of G on the ground and during the flight, this is due to making sure that the plane is correctly controllable and stable. The figure below illustrates an example of those limits and the position of both CG and CP.

Figure 5: The position of CG and CP on an aircraft and their limits [20].

Construction:

There are approximately 367,000 parts on a 737 Next Generation, not all part are built by Boeing, they are all from over the world for the purpose of saving time and money. For example: Fuselage, engine nacelles and pylons were built in Wichita (US); Ailerons were built in Malaysia, rudder from Belfast (Northern Ireland) and Inboard flaps from Japan [1].

Once the fuselage was joined with wings and the landing gear, it was moved down for the engine, interiors and avionics. Once all was done, Boeing made tests on the systems and the engine before making the flight to the Boeing field, where it was painted and all set to be delivered to the customers. .

The next generation models have 33% less parts that the classic model, this has reduced the time of production [21].

Materials:

[21] Listed the materials used for the Boeing 737, and also which part uses what material and the reason for that usage. It was found that the fuselage of the Boeing 737 is a semi-monocoque structure, the load is carried by the frames and stringers and partly by the skin. The fuselage is made from aluminium alloys, however the following materials are used for different parts.

Fibreglass: tail cone, centre and outboard flap track fairings.

Kevlar: Engine fan cowls, inboard track fairing and nose gear doors.

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Graphite/Epoxy: rudder, elevator, ailerons, spoilers, thrust reverser cowls and dorsal of vertical stab.

Giving that the main material used is aluminium alloys, there are different types used for different area. This is depending on what the characteristics and properties required for the part. Mainly, the alloys are of aluminium and zinc, magnesium or cooper. Below are some of the alloys and what parts they are used for.

Aluminium alloy 2024: it is used for fuselage skin, slats and flaps. This alloys is used for these parts as they are loaded in tension and by using that alloy the parts will have good fatigue performance, high fracture toughness and slow propagation rate.

Aluminium alloy 7075: which is used for frames, stringers and wing ribs to give them high mechanical properties and make them resistant to stress corrosion cracking.

Aluminium alloy 7175: it is used for landing gear beam to make it very tough and give it a very high tensile strength too.

Aluminium alloy 7055: that alloy is used for wing lower skin, which lead to it being a good superior stress corrosion.

Simulator data analysis:

The Merlin flight simulator was used to fly Boeing 737-800 in its actual conditions and then experiments were done by changing some of the figures to see what impact would that have on the aircraft performance and also maybe to try to improve the Merlin model.

The following experiments were carried in that section:

1. Normal take-off: take-off has been experienced where all technical figures on the simulator were kept constant (they meet the standard Boeing 737-800 figures). Full fuel and payload were used. Takeo-off wasn’t great due to slipping either to the right or to the left and that was due to some problems to the model itself.

2. Take-off with 50% of fuel and payload: once the fuel and payload levels were put down from full to 50%, the plane was able to take however the ground speed was different from the normal take-off mentioned above. Less fuel means that the aircraft will be lighter which therefore will lead to change in the position of centre of gravity.

3. Take-off with 10% of fuel and payload: with a very low level of fuel and payload, the aircraft tended to take-off in a short time and also the distance of take-off was less compared with the previous two.

The figure below illustrates the difference in terms of fuel percentage per unit time between the above three take-off’s with different initial fuel/payload state.

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0 5 10 15 20 25 30 35 40 45 500

20

40

60

80

100

120

f(x) = − 0.0163614163614164 x + 10.0536027676028

f(x) = − 0.0120168855534709 x + 50.0969494371482

f(x) = − 0.0162790697674418 x + 100.068344608879

Take-off with full fuel and payloadLinear (Take-off with full fuel and payload)Take-off with 50% fuel and payloadLinear (Take-off with 50% fuel and payload)Take-off with 10% fuel and payload

Time (s)

Fuel

Sta

te %

Figure 6: Rate of burned fuel per second.

4. Take-off / moving CG backwards by 0.5 m: when moving the centre of gravity toward the position of the landing gear, the nose of the aircraft pitched up. This means that the aircraft will have a higher cruising speed as the stabilizer deflection will increase in order to balance the aircraft.

5. Take-off / moving CG forwards by 0.5 m: moving the centre of gravity far away from the undercarriage involved pitching the nose down. As the CG moves forwards, stalling will occur at a higher speed as the angle of attack will be reached at a higher speed and this is because there are more loading on the wing. The forces needed to be applied on the elevator tends to be higher too, this is due to the need of increasing stabiliser deflection in order to balance the plane.

6. Take-off / moving CG backwards by 1 m: the aircraft became less stable when the CG moved backward as the angle of attack increased.

Conclusion from the simulator data: Changing the mass of the aircraft before take-off by decreasing the level of fuel and payload resulted in a change in the rate of burn of fuel per seconds. Where less fuel was burned each second. This also has an effect on the distance travelled before taking off, where less distance occurred at a lower fuel level.

The centre of the gravity position influences the angle of attack of the wing, the force on the tail and the degree of the stabilizer’s deflection needed to keep the aircraft in equilibrium.

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Forward CG results in a more stable aircraft that has faster Stall speed (higher Indicated Airspeed) but a lower cruising speed. Backwards CG makes the aircraft less stable, have a smaller Indicated Airspeed and the cruising speed will be higher.

5. Engines: (1191)

Generation of the 737 engine

The Boeing 737 is part of a long generation family, starting from the 737-100 and advancing all the way to the 737 – 900. Throughout this aircraft, like any other commercial aircraft, consists of many complex and imperative components ranging from the landing gear all the way to the yoke in the cockpit, however one very vital component to the operation of an aircraft is the engines. The engines provide certain pounds of thrust using a turbofan engine which is one example of a gas turbine engine. Throughout the advancement of the 737 generation, the maximum pounds of static thrust produced by these turbofan engines have increased substantially as seen [22]. The original engine used for both the -100 and -200 were in fact the Pratt & Whitney JT8D-7 which provided around a maximum of 14,000 lb.st. (Pounds of static thrust), however this was then improved throughout the aircraft series until the -200 advanced could produce 17,400 lb.st resulting in the JT8D-17R.

Figure 7: JT8D Cutaway [22].

After the generation of the -200 the sole power plant for all of the 737’s is the CFM-56. The core of this particular engine is produced by General Electric with SNECMA producing the fan, IP compressor, LP turbine, thrust reverses and all external accessories. A key issue with this particular engine was that it was such a high bypass, meaning that it was physically large which resulted in very little ground clearance, however this was overcome by mounting fittings on the lower sides to flatten the bottom nacelle and intake lip. The CFM56 consisted of different features to the JT8D as the engines were raised and moved forward so that it was level with the upper surface of the wing and was also slanted 5 degrees up allowing for a better ground clearance as well as directing the exhaust downwards which not only reduced some of the effects of the pylon overheating, however it also gave some vectored thrust which assisted take-off performance, this along with many other aspects proved that the CFM56 was almost 20% more efficient than the JT8D [22]. The most recent and up to date series of this engine, the CFM56-7B, consists of a 61 inch diameter solid titanium wide-chord

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fan with a new LP turbine turbomachinery, a new single material in the HP turbine, all of which produced an 8% fuel reduction, and a 15% maintenance cost reduction.

There are significant improvements to the engine between the JT8D and the CFM56, one of them being the noise levels produced. The original JT8D-9 engines used for the -100/-200, produced around 75 decibels in noise, enough to disrupt passengers from normally conversing with a noise contour that extended 12 miles, however since the introduction of the 737-700’s CFM56-7B in 1997 the 75-decibel noise contour is reduced to 3.5 miles long.

Figure 8: CFM56-7B Jet Engine used in the (737-600/-700/-800/-900/-900ER) [23].

Data Collected

A lab practical was conducted on the Merlin simulator, where a series of tests were completed. The Merlin simulator allows designs of certain types and hybrids to be simulated. These types of designs can be:

Single and Multi Engined Piston and Turbo Prop Aircraft Single and Multi Engined Jet and Turbo Fan Aircraft Gliders Fixed Wing V/STOL Rotary Wing Aircraft with up to four rotors – and Auto Gyros

These are a list of many more designs that can be simulated on the Merlin. A model of the Boeing 737 was introduced into the database of the merlin, allowing for a range of tests and data to be collected. Some of these tests included the change and manipulation of the CFM-56 engines on the 737.

The model of the Boeing 737-800 did contain an issue that did cause an impact to the simulation experiments. The undercarriage of the aircraft, specifically the front nose gear, failed when approaching 100 KIAS (Indicated air speed). The nose itself would collapse into the ground, lowering the nose which subsequently caused the aircraft to yaw greatly to the

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right or left. This affected the way experiments were conducted as the pilot was forced to counteract the failure by pulling back on the yoke without lifting before take-off speed. Due to this reason, the results of each experiment were not as valid as intended because of the effect of the nose failure.

Figure 9: Graph showing time against the indicated air speed during take-off. Aircraft reaches take of speed at 26 seconds, 10 seconds faster than default aircraft.

The first aspect of the engine that was to be altered was the angle at which the exhausts exits. The first experiment was running a normal take-off, however the angle pitch of both CFM-56 engines was set to 5 degrees above its default pitch. The effect of this was fairly minimal with the only change in the indicated airspeed, when compared to an alike take-off with the default angle of the Boeing 737 engines. The altitude pitch rate was smaller in comparison to the default take-off, however this was due to the nose failure as the values were below ground level meaning that the front nose gear did in fact lower into the ground requiring the pilot to counteract the issue until take-off speed was reached, where the altitude pitch rate increased by a larger amount than that of the default take-off. This is the result of the engine pitch changing to an angle of 5 degrees. Another aspect of the data results that was observed was that the aircraft reached take-off speed of about 150 KIAS, at a faster rate than that of the default take-off.

The same experiment was repeated however, the pitch this time was a larger angle of 10 degrees instead. When factoring in the effect of the undercarriage, the data received was slightly larger with the nose lowering into the ground even more, thus subsequently meant that the pilot was forced to counteract this issue even more than the previous experiment, however the pitch rate was a slightly larger value with the pilot rotating at the same speed then previously. The pilot added a comment of that the change of the angle to 10 degrees was in fact a smoother take-off than that of both the angle of 5 degrees and the default take-off.

The next experiment was to move the position of the engine further forward on the wing, moving from -11.65 m to -8 m. This produced results that were fairly similar to the previous experiments in the sense as the nose failure still occurred, however the altitude pitch did not differ from the previous experiments, although the indicated speed did increase for take-off speed.

One more experiment was conducted with the position of the engine, however it was moved further forward to -4 m along the wing. The results were again quite similar to the previous

15

020406080

100120140160180200

Time IAS Time (s)

IAS

(kn)

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experiment with the altitude pitch rate still having a similar value, however the increase in take-off speed was still consistent with the previous experiments.

Table 2: Table showing data comparison of the Indicated Air Speed and the Body Axis Pitch Rate during take-off

Overall the experiments conducted on the Merlin simulator produced results did show certain improvements to the performance of the aircraft, as take-off speed was reached at a quicker rate. Not only this, however the pitch rate was also improved when the angle of the engine was increased, however the result was invalid due to the major issue of the undercarriage on the implanted model on the simulator.

6. Fuselage: (1186)

General knowledge

There are two main types for fuselage construction in use:

Truss or framework type mainly used in light non-pressurized aircrafts. Monocoque or more widely used Semi-Monocoque which is in use for

construction of any other aircrafts. This type of use generally referred to stressed skin.

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The fuselage is the main and the biggest structure of the aircraft which is designed to carries the aircraft payload i.e. the passengers or the freight as well as the flight crew. In addition it offers an effective position to the flight crew for the aircraft operation, enough space for controls, accessories and other equipment [24]. It spreads loads to and from main planes (wings), tail planes, fin, and landing gear and in certain configuration, the power plant.

Pressurized Aircrafts

Structure must be capable of withstanding the axial and hoop stresses implemented by pressurization forces.

Axial stress

Axial or also longitudinal stresses are formed in the fuselage of the aircraft when pressurized and tend to elongate the fuselage.

Hoop stress

Hoop or radial stresses are produced in addition to the axial stress and tend to expand the fuselage cross section area. The internal pressure produced by these stresses can be as high as 65,5 KN/m2 (9.5psi).

SEMI-MONOCOQUE CONSTRUCTION

With the increase of the aircraft size and the loads become greater the traditional monocoque structure is not suitable. In this way additional members known as stringers and longerons (Figure 11) are added to run lengthwise along the fuselage and joining different sections together. The light alloy skin is then attached to the frames and stringers by riveting or adhesive bonding [25]. The purpose of the stringers is to stiffen the skin and assist to sheet materials to spread the loads equally along the entire length.

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AVIA 1000. 2015/16. Boeing 737

BOEING 737-800 Fuselage:

The Boeing 737-X program was launched on 29 June 1993. The new program substituted the previous series. The 737-300X became the new 737-700 and the 737-400X became the new 737-800 (Figure 10). 737-800 was built significantly longer than its ancestor 737-400 at fuselage length of 39.4m and seats up to 189. The fuselage diameter is 3,76m and max cabin width is 3,53m. The maximum take-off weight of 737-800 version is 78,960kg. The maximum structural payload which the aircraft can support is 21,319kg. The max cargo volume which can be suited in the lower deck is 44.1 cubic meters [28]. The fuselage has semi-monocoque structure. The loads are carried partly by frames and stringers and partly by the skin. In Boeing 737-800 fuselage design, the designer reinforce where there are going to be apertures for windows, doors as well as hatches. Primarily the purpose of this reinforcing in form of a frame around the aperture, is to absorb the exerted loads that would have been carried by the skin that has been cut away. The fuselage frames are stiffened together in order

18

Figure 10: Boeing 737-800 Fuselage [26]. Figure 11: Semi-Monocoque structure [27].

AVIA 1000. 2015/16. Boeing 737

to transfer and share loads and act to prevent cracks and propagation. The manufacture uses various different aluminum alloys except for the following sections. Fiberglass is used for radome, tail cone as well as center and outboard flap track fairings. Kevlar is used for engine fan cowls, inboard track fairing and nose gear doors [21]. Epoxy and graphite can be found in the rudder, elevators, ailerons, spoilers as well as thrust reverse cows and dorsal of vertical stab. The alloys used for fuselage constructer are mainly of aluminum and zinc, magnesium or copper. The different alloys are mixed with different ingredients to give different properties for specific purpose. Fuselage, skin, flaps and stabilizer area primarily loaded in tension are made by aluminum alloy 2024 which gives good fatigue performance, higher fracture toughness and slow propagation rate. Boeing 737-800 has a composite airframe. Composite materials do not corrode, do not fatigue, they are more reliable and are easier to maintain. Originally the designed life of the airframe of Boeing 737-800 was set at 20 years, 75,000 cycles or 51,000 hours. In the aft part of the fuselage horizontal and vertical stabilizer are attached to it. The radome (Radar DOME) is an aerodynamic fairing which is located in the front part of the fuselage and houses the weather radar and ILS localizer and glideslope antennas. Unlike the rest of the fuselage the radome is made by fiberglass to allow the RF signals through. There are many drain holes located on fuselage, wings and empennage. The primarily purpose of these drainage system is to prevent fluids such as leaking waste water, condensation or any other fluid collecting in the fuselage which may become corrosion or fire hazard. Drain holes in pressurized areas of the fuselage have a valve behind them which seals during flight and re-opens on the ground.

FLIGHT SIMULATOR TEST SESSION

Series of experimental sessions were conducted in order to investigate the role of fuselage in relation to aircraft performance. The fuselage width was increased with 0.50m. The aircraft was tested during take-off so to be examined how the aircraft changed its take-off length and time required to lift off the ground. In addition the Boeing was tested inflight to see how the load factor increases with fuselage enlargement and increased weight. As a result the overall drag of the aircraft increased dramatically. That includes parasite, induced and compressibility. Based on that, the critical Mach number reduced by 0.05 and increased the overall. It was observed an increase in take-off distance and thrust configuration with 15%. Consequently the fuel consumption raised with 12% per passenger. The increase in mass requires a higher lift force to be produced by the wings. Mass increase resulted in aircraft performance. The initial take-off time was 34.1 sec. After applied changes the time increased with 3 sec. In addition, during inflight the aircraft was exposed to a lot higher load factor compared to take-off. The load factor inflight during session reached the max value of 10g compared to take-off where the max value was approximately 2g. Change in vertical climb rate was observed as well. The normal climb rate of Boeing 737-800 till reaching the cruise level is 1800 ft./m. After changes implementing the climb rate was reduced to 1400 ft./m. Adding extra sections (‘plugs’) in front of the wings resulted in a CG change towards the forward limit which caused:

An increase in in lateral and longitudinal stability An increase in the take-off distance required

19

AVIA 1000. 2015/16. Boeing 737

An increase in the thrust setting A decrease in the controllability of the aircraft

Adding extra sections (‘plugs’) behind the wings resulted in a CG change towards the aft limit which caused

A decrease in lateral and longitudinal stability A decrease in the take-off distance required A decrease in thrust setting An increase in aircraft controllability

3.76 3.88 4 4.260

0.005

0.01

0.015

0.02

0.025

0.03

0.035

Fuselage width (m)

Drag

coe

ffici

ent

Figure 12: Fuselage width vs. Drag coefficient

In conclusion, it can be said that drag increase proportionately with the increase the fuselage width. With the fuselage enlargement and adding new extra section, the center of gravity is driven to change by the new section configuration. With the increased take-off weight and drag coefficient the aircraft is required to use more thrust and pays with more fuel which makes it less fuel efficient.

7. Undercarriage: (1046)The undercarriage also known as the landing gear. The undercarriage is used for the following procedures; holding dead weight when at a standstill, taxiing, take-offs and

20

AVIA 1000. 2015/16. Boeing 737

landings. When the aircraft is landing the landing forces can reach up to several times the mass of the aircraft itself.

Modern day aircrafts have the tricycle gear undercarriage where the smaller wheel is placed at the nose (this is called the nose wheel) of the aircraft and the main gears are placed near the centre of gravity these are made up of two or more wheels [29]. On all the versions of the 737’s (Original, Classics, NGs and Max) they all have the tricycle gear undercarriage. None of the 737’s has had a full main gear door. So in its place the outer wall of the tyres meets with aerodynamic seals in the wheel well so that a smoother surface is created alongside the undercarriage of the aircraft, as shown in figure. Originally on the first few 737’s inflatable seals that were inflated by bleed air when the gears were either up or down and deflated during transit. This was soon dropped as it was too complex and with the modern fixed rubber seals a similar drag and noise advantage was achieved [30].

Figure 13: Storage column for landing gear during flight [30].

The breaks of the 737 are made from a steel alloy called Cerametalix(R) with two different forms made by Honeywell or Goodrich. The 737 NG has had a carbon break choice, these breaks from Goodrich or Messier-Bugatti both weigh 300kg lighter than steel and last double the expectancy of the steel alloy breaks [30].

Figure 14: Brakes of the 737 [30].

The brake pressure gauge should normally show 3000psi. The autobrakes and the normal

21

AVIA 1000. 2015/16. Boeing 737

break system are powered by hydraulic system B. If the break pressure drops below 1500psi, hydraulic system a will automatically provide alternate brakes that are manual only and the break pressure will return to 3000psi [30].

Weight distribution between the main gears and the nose wheel are vital for manoeuvrability and steadiness while on the ground. If the weight distribution is off on the gears for instance if a considerable amount of weight is on the nose wheel of the aircraft, when building up speed on the for take-off the aircraft can lose control and swerve off the runway and crash. And if too much weight is the main gears of the aircraft, the aircraft can topple back when speed is built up for take-off.

On large commercial aircrafts multiple wheeled trucks are used to reduce wheel load on the runways. Retractable landing gear retract into the fuselage or the wing sections while the air craft is in flight. Once the landing gear have been retracted and stowed into the wheel wells, the gears are out of the way of the slipstream and no parasite drag is created. The majority of retractable landing gear have close fitting panels, they fair with skin of the aircraft when the gears have completely retracted. (U3) For supporting the 737 while it is taxied, the force of the impact while landing is controlled by the landing gear. There are two ways this is done: the first is the shock energy is that is absorbed is converted into heat heat energy and the second, the shock energy on touchdown is changed and shifted through the airframe at an altered rate and time than the single strong pulse of impact. (U3

Undercarriage Data

The Merlin Engineering Flight Simulator was used to alter a few small changes. While on the simulator we chose the 737 - 800 model, the 737 would reach a ground speed of up to 145 knots before take-off within the space of 40seconds.

The Boeing 737 - 800 is supported by six wheels. A few experiments regarding the landing gear were done. The reason these experiments were done was to see how the performance of Boeing 737 – 800 was affected by where the position of the landing gear is. The data from the experiment of the Merlin Engineering Flight Simulator was collected and it was compared so that a difference can be seen the Boeing 737 – 800’s performance.

When the changes were made on the simulator, where the centre of gravity was at -5 and the centre of pressure was at -1 the pilot of the pilot said it was a lot harder for the pilot on the simulator said he was finding it difficult to control the aircraft and it was a lot harder to take off. This meaning the controls were a lot stiffer and more force was required to control the aircraft. The Euler pitch attitude started off at a minus degree number but as speed was gradually built up the pitch was more was not controllable and the nose wheel would start

22

AVIA 1000. 2015/16. Boeing 737

digging down into the ground. As shown in table 3 and figure 15.

Table 3: Mach number and Euler pitch attitude when centre of gravity is -5 and centre pressure is -1

Mach number Euler pitch attitude 0.8306 -16.680.8293 13.080.7764 29.750.7483 -26.570.7092 -26.30.7225 -19.360.7289 12.740.6904 22.640.6859 -14.710.6881 5.830.6872 6.1

1 2 3 4 5 6 7 8 9 10 11

-30

-20

-10

0

10

20

30

40

mach number euler pitch

Euler pitch

Mac

h nu

mbe

r

Figure 15: Mach number vs Euler pitch attitude

When the centre of pressure was at minus 1 while during the take of sequence part of the experiment the and as shown on table 4 and figure 16, the correlation in Mach number and the Euler pitch attitude is the higher the Mach number the higher the Euler pitch attitude.

23

AVIA 1000. 2015/16. Boeing 737

Table 4: Mach number and Euler pitch attitude when CP x coordinate was -1

1 2 3 4 5 60

5

10

15

20

25

mach number euler

Euler pitch

Mac

h nu

mbe

r


When the centre of pressure was at minus 1 while during the mid-flight sequence part of the experiment the and as shown on table 5 and figure 17, the correlation in Mach number and the Euler pitch attitude is the higher the Mach number the higher the Euler pitch attitude.

Table 5: Data of the Mach number and the Euler pitch data

Mach number Euler pitch attitude 0.08484 -3.420.8761 -1.550.9046 -1.440.9322 1.81

24

Mach number Euler pitch attitude 0.0078 5.020.0703 4.880.128 4.40.1745 4.060.2107 2.950.2101 21.4

AVIA 1000. 2015/16. Boeing 737

1 2 3 4

-4

-3

-2

-1

0

1

2

3

mach number euler

Euler pitch

Mac

h nu

mbe

r


8. Wings: (1153)

Swept Wings

Like many airline planes, the wings are swept back with a slight dihedral angel. Swept wings are defined as when the angle between the leading edge of the wings and the centreline of the fuselage meet at an acute angel (>90) [31].

A key feature of swept back wings is its aerodynamic affects near the speed of sound, the transonic region of speed. The maximum cruising speed of a 737 is 472 knots. This is slightly faster than the average turbofan-powered narrow-body commercial passenger plane [32]. The speed of sound travels at around 574 knots at the cruising altitude of a 737 [33]. This is about Mach 0.82 which is just entering the transonic region. If the aircraft was to make an emergency rapid descent, the speed will be much greater.

On non-swept wings, above around 400 knots, the drag of an aircraft starts to act in a less typical manor, especially around the wings. As the speed increases further, shock waves form which drastically increase drag. This affect can be observed at the ‘critical Mack number’. Achieving speeds past the critical Mack number can be quite challenging due to the incredibly steep increase of drag per unit of speed past this value [35].

Swept back wings affect the fluid compressibility which in turn delays the speed at which shock waves and accompanying aerodynamic drag form. This allows planes with swept back

25

Figure 18: Boeing 737-700 Profile Diagram [34].

AVIA 1000. 2015/16. Boeing 737

wings to cruise at faster speeds than airplanes without such wings. The wings of the Boeing 737 are swept at an angle of 25.02 [4]. This angle can be altered of the aircraft can be modified in the Merlin Flight Simulator to see if the cruising speed is really affected and by how much.

Dihedral Wings

Wing dihedral describes the angle between an aircraft’s wings and the horizontal. Dihedral wings describe wings that are angled upwards and anhedral wings are wings that point down towards the ground.

There are three planes of axis for fixed wing planes (lateral, longitudinal and normal). They are each controlled by a specific control surface (elevator, ailerons and rudder respectively). Equilibrium attitude is achieved in the lateral and normal axis after elevator and/or rudder inputs are neutralized. This is due to the horizontal and vertical stabilizers. No such mechanism is present for longitudinal stability. This leads to adverse yaw in rolls, an undesired affect [36].

By angling the wings up, the lower wing of a roll will have a greater angle of attack than the higher wing. This means that the lower wing will generate a greater lift than the higher wing. This acts as a restoring force to return the plane to straight and level flight when control inputs are neutralized. This also means that the lower wing will be creating more drag than the higher wing. This will counter the effect of the adverse yaw [36].

Too great of an angle can be detrimental. If an aircraft is too laterally stable, it will be directionally unstable and prone to Dutch rolls. This is when the direction of turning is always out of phase with the rolling motion.

The Boeing 737 has dihedral wings with 6 to the horizontal [4]. This angle has been specifically designed to balance the advantages and disadvantages of dihedral illustrated prior. The Merlin Flight Simulator can be used to test the effect on flight performance and roll stabilisation when the dihedral angel is changed.

Wing Sweep Data

Our model of the 737-800 was loaded in flight traveling at an indicated air speed of 325 knots (Mach 0.832) at 30,000ft. The aircraft was flown straight and level for 40 seconds.

This was repeated with different angles of swept wings. The angles included 15, 20, 30 and 35. Figure 19 illustrates the speed against time for the whole course of the experiment.

26

AVIA 1000. 2015/16. Boeing 737

5 10 15 20 25 30 35 400.84

0.86

0.88

0.9

0.92

0.94

0.96

0.98

115 20 Series6 30 35

Time (s)

Mac

h Nu

mbe

r

Figure 19: Mach number Against Time, 5s-40s

A pattern is hard to draw from this data. The data is clearer if it is split up into the start of the experiment and the end of the experiment. Figure 20 displays the start of the experiment and Figure 4 displays the end of the experiment.

5 6 7 8 9 10 11 12 13 14 150.84

0.85

0.86

0.87

0.88

0.89

0.9 15 20 Series6 30 35

Time (s)

Mac

h Nu

mbe

r


27

AVIA 1000. 2015/16. Boeing 737

The 35 sweep aircrafts is traveling a lot faster than the other aircrafts in the early stage of flight. The 30 and 20 aircrafts are traveling at roughly the same speed and the 15 aircraft is traveling slightly slower.

30 31 32 33 34 35 36 37 38 39 400.96

0.965

0.97

0.975

0.98

0.985

0.99

0.995

1

1.005

1.01

15 20 Series6 30 35

Time (s)

Mac

h Nu

mbe

r


Figure 21 shows that at the end of the experiment, the speeds of the altered aircraft were quite evenly separated. The speed is proportional to the angel of sweep of the wings. The 35 sweep aircraft being the fastest, then 30, 20 and finally 15 being the slowest. All aircrafts entered the supersonic region after 38 seconds.

Wing Dihedral Data

The first wing dihedral experiment was repeated four times, once for each dihedral angel. The flight was set up identically to the predecessor experiment. Maximum right rudder was then applied and released.

The dihedral angels recorded were the standard 6, 12, 0 and then an anhedral angel of 6. Observations were made about the lateral stability. The first observation that was made in the sim was that the 6 and 12 aircrafts rolled left while the 0 and -6 aircrafts rolled right. This is opposite to the direction of applied rudder. Figure 22 illustrates the effect of rudder inputs on the roll attitude. It is undesirable for an aircraft to roll away from the yawed direction.

28

AVIA 1000. 2015/16. Boeing 737

-10 0 10 20 30 40 50 60 70

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

-6 6

Roll Attitude/

Peda

l Pos

ition

Figure 22: Roll Attitude against Pedal Position

The anhedral aircraft rolled to a much greater attitude than the dihedral aircraft.

The next observation made was from the recorded data. This was the scalar body axis roll acceleration recorded the second after the rudder inputs were released. These results can be observed in table 1.

Table 6: Roll Acceleration of Aircrafts

Dihedral Angel/ Scalar Body Axis Roll Acceleration/ms-2 -6 32.410 6.556 14.7712 43.68

The standard angel of 6 had a roll acceleration of 14.77ms-2. Double the angel to 12 almost triples the roll acceleration. Removing dihedral from the wings reduces the roll acceleration by over a half. Interestingly, by applying the exact same angel of anhedral, the roll acceleration doubled though the acceleration was in the opposite direction.

Another experiment was done in which each aircraft was loaded at rest on a runway. The test pilot then tried to take off. The 6 aircraft could take off with minimal issue. The 12 aircraft fell victim of Dutch rolls and was un-flyable. The 0 aircraft couldn’t rotate before running off the end of the runway. The -6 aircraft was far too unstable to pilot.

Wing Conclusion

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AVIA 1000. 2015/16. Boeing 737

The angle of the sweep of the wings and dihedral are critical properties in the performance of the aircraft. The sweep of the wings is essential to reach higher speeds in flight. I believe that the current angel of 25 allows adequate speeds but if higher speeds are needed, a greater sweep could be used. I believe that the current dihedral angel of 6 is the most ideal angel as it delivers a great lateral stability without hindering flight performance.

9. Tail: (1099)

Variations:

The tail of an aircraft is a component of great significance, as it controls the aircraft’s movement about 2 of its 3 directional axes. The tail consists of elevators, which pitch the aircraft about the lateral axis, the rudder, which yaws the aircraft about the normal axis, and vertical and horizontal stabilisers to help maintain the desired attitude in flight. However, the configuration of these individual sections can vary between aircraft, offering different advantages for aircraft with different purposes.

The most common type of tail has a horizontal stabiliser and elevators positioned in line with the fuselage and a vertical stabiliser with an attached rudder rising from the centre of the horizontal stabiliser, commonly referred to as a conventional tail. The Boeing 737 uses this type of tail, as seen in figure 23, with a failsafe control system where, if the hydraulics should fail, the aircraft can fly using servo tabs [37][38].

Some aircraft, such as the Avro RJ-85, use a T-tail, which is similar to the conventional tail, but the horizontal stabiliser is positioned at the top of the vertical stabiliser rather than at the base (Figure 24). This configuration is most commonly found on high-wing aircraft, where the conventionally placed horizontal stabiliser would be caught in the turbulent downwash of

30

Figure 23: Conventional tail of a Boeing 737-300 [40].

AVIA 1000. 2015/16. Boeing 737

the wings. By raising the stabiliser, it is removed from this turbulent airflow, thus maintaining control. However, in the event of a stall at high angles of attack, the wings produce a turbulent wash due to a larger surface area being presented to the relative airflow. The horizontal stabiliser is caught in this wash, rendering the elevators useless and making it almost impossible to recover from the stall [40]. Safety systems such as stick shake are used to prevent stalls from occurring [41], but these raise the cost of the aircraft, making the high-wing T-tail option undesirable unless absolutely necessary.

As a compromise between a conventional tail and a T-tail, the cruciform tail was developed, as seen on the Sud Aviation Caravelle. In this configuration, the horizontal stabiliser is placed partway up the vertical fin to remove it from turbulent airflow (Figure 25). This type of positioning is often found on aircraft with aft mounted engines where, in conventional configuration, the horizontal stabiliser would be in the engines’ wake. The design presented difficulties however as the intersection with the fin produced undesirable drag [43].

31

Figure 24: T-tail configuration of an Avro RJ-85 [42].

AVIA 1000. 2015/16. Boeing 737

The V-tail has no horizontal or vertical stabilisers, but instead has two stabilisers arranged in a V shape on the tail, used on earlier versions of the Beech Bonanza. These stabilise the aircraft in much the same way as vertical and horizontal stabilisers, but, due to the fact that they are placed at an angle, their control surfaces can act as both a rudder and elevator. The V-tail uses fewer lifting surfaces than other forms of tail, so it therefore has a lower surface area, and thus produces less drag. A lower amount of material used also means that it is lighter than other tail configurations [45].

Figure 26: V-tail of a Beech V35A Bonanza [46].

Twin rudder tails have a vertical stabiliser on each end of the horizontal. This can be connected to either a single tail, as seen on the Antonov An-225, or can bridge across two tails in a twin boom configuration, such as in the F-82 Twin Mustang. Having two rudders offers a larger control surface area, meaning that the aircraft has more effective yaw control. Furthermore, the vertical stabilisers act in a similar way to tip tanks, reducing induced drag generated by the horizontal stabiliser [47].

32

Figure 25: Cruciform tail of a Sud SE-210 Caravelle [44].

AVIA 1000. 2015/16. Boeing 737

Additional components also feature on the tails of aircraft, such as trim tabs, allowing pilots to adjust the aerodynamic properties of control surfaces and relieve pressure from the control column [49]. The tail of the 737 also houses the cooling system for the aircraft’s auxiliary power unit, identifiable by the exhaust and inlet ducts on the tip of the tail [37][38].

Flight Simulator Data:

In order to learn more about the role of the tail and how its orientation affects the flight performance of the aircraft, several experiments were conducted, two of which will be discussed here.

Whilst testing the aircraft model, it was observed that it had a tendency to pitch forward onto the nose wheel during take-off, sending it off the runway. To try to correct this, the coefficient of lift of the tailplane was changed to see if it could create a balancing moment and take weight off the nose wheel. The coefficient was initially set to 0.5 and the model was flown through a take-off. This was repeated for a coefficient of 1.0. The data for this test is shown in figure 28, showing time versus lateral stick input from the pilot. The data shows that the pilot had to pull back on the controls less with higher coefficients of lift, showing that it did indeed create a balancing moment. This moment can also be seen to allow the aircraft to take off in a shorter space of time, a feature which could be useful in the future design of aircraft.

33

Figure 27: Twin rudder tail of an Antonov An-225 [48].

AVIA 1000. 2015/16. Boeing 737

0 5 10 15 20 25 30 35 40 45 50

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

CoL 0.3 (Original)CoL 0.5CoL 1.0

Time (s)

Long

itudi

nal S

tick

Positi

on (+

/-1)

Figure 28: Graph of stick position versus time during take-off with regards to changes in the coefficient of lift of the tailplane.

A second test explored the effects of changing the setting angle of the tailplane, the data for which can be seen in figure 29, measured with the same parameters as the previous experiment. First, the tailplane angle was changed from its original position to 3°. The pilot reported that they could not detect a great difference, so the setting was changed to 10°, to which the pilot said that the aircraft was much more difficult to handle and to lift off. Finally, the setting angle was changed to -10° as it was thought that positive setting angles were giving a turning moment in the wrong direction. The pilot reported that the new angle stopped the aircraft nose from dipping on take-off, and that take-off was much easier to accomplish. These reports are supported by the data which show that a -10° setting angle required less stick input to get the aircraft airborne.

34

AVIA 1000. 2015/16. Boeing 737

0 5 10 15 20 25 30 35 40 45 50

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

Setting Angle -3 Degrees (Original)Setting Angle 3 DegreesSetting Angle 10 DegreesSetting Angle -10 Degrees

Time (s)

Long

itudi

nal S

tick

Positi

on (+

/-1)

Figure 29: Graph of stick position versus time during take-off with regards to changes in tailplane setting angle.

Though this experiment into the simulator model construction went part-way to solving the model’s issues, it was not a perfect solution to the problems encountered as aircraft typically only have a 1˚/2˚ tailplane setting angle [50], but the test had to go as far as -10° before the model showed signs of improvement. Furthermore, in cruising flight at altitude, the simulator displayed that approximately 420% nose up trim was required to keep the aircraft in level flight, so it can be deduced that the problems encountered were not likely to lie in the tailplane.

10. Conclusion: (251)

As an overall, the overview of the project is that substantial information was obtained on the Boeing 737 generation, specifically the -800. The information gathered was through researching specific aspects of the aircraft in detail. It was concluded that the 737-800 is an improved aircraft which is environmentally friendly and it has a reduction in fuel consumption by 8% due to the use of CFM-56 engine. By altering and simulating certain experiments on the Merlin Engineering Flight simulator, it was concluded that some changes had an effect on the performance of the aircraft, for example: the fuselage diameter was increased as well as elongating the fuselage by adding two extra sections in front and behind the wing. It was noticed that the drag coefficient as well as weight increased which resulted in higher thrust setting and fuel consumption. Furthermore, moving the centre of gravity backwards by 5 m and moving the centre of pressure forwards by 1 m resulted in an unstable aircraft where it was hardly controllable. This led to evidence such as there are limits on where the position of both CG and CP could be at. When regarding wings, it was concluded that the sweep of

35

AVIA 1000. 2015/16. Boeing 737

the wings and the dihedral are critical in terms of the performance of the aircraft, however if higher speed is needed, an increased sweep would be the solution for that. Finally, it was conclude that there might be fault in the construction data due to some of the data obtained being unreliable.

11. Acknowledgments: (131)

Working as a group was a good way to get the project done correctly and properly. This is because there was an opportunity to have discussions between the group members. Furthermore, members had either similar or different opinions about the aircraft’s aspects made the group produces better quality work. The formal meetings the group had are provided in the appendix section.

Each member of the group has contributed by doing at least one section, however the group sections were not done by all members. The following are the sections that have been done by more than one person and who contribute in them.

Introduction: Zulk and Ikram Executive summary: Aous Design: Aous, Jonny, Ikram and Joshua Ethics: Joshua and Jonny Conclusion: Peter Acknowledgments: Ikram, Joshua

12. References:

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(2) Baciu, J. Top Speed’s website. 1998-2010 Boeing 737-800. 2010 [12/1/16] Available from: http://goo.gl/vJHquR

(3) Redding, R. Yenne, B. 1997. Boeing: Planemaker to the World. California: Thunder Bay Press

(4) Brady, C. The 737 Technical Site. [Online]. 1999. [22/12/15]. Available from: http://goo.gl/XHzney

(5) Frawley, G. The International Directory of Civil Aircraft. Australia: Aerospace Publications, 2003.

(6) Boeing’s website. Boeing Freighter Family: Leading the Air Cargo Industry. [Online]. 2015 [20/1/16] Available from: http://goo.gl/zFMS3H

(7) Airliners website. The Boeing 737-800/900. 2015. [12/1/16]. Available from: http://goo.gl/YnDBBZ

(8) Boeing’s website. Next Generation 737. [Online]. 2015. [12/1/16] Available from: http://goo.gl/zlW909

(9) Boeing Commercial Airplanes. 737 Airplane Characteristics for Airport Planning. [Online]. 2013. [25/11/25]. Available from: http://goo.gl/7yxO7z

(10) European Aviation Safety Agency. Certification Specifications and Acceptable Means of Compliance for Large Aeroplanes. [Online]. (25.901). Available from: http://goo.gl/G5b8GE

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(13) Kowal, J. Boeing Commercial Airplanes and the Environment. [Online]. 2015. [12/1/16]. Available from: http://goo.gl/mT8SaO

(14) Boeing tests noise-reduction, fuel-efficiency technology on 737-800. King 5. [Online]. September 18th, 2012. [12/1/16]. Available from: http://goo.gl/YSXabF

(15) Aviation Week Network. Mystery 737 Winglet Test. [Online]. 2012. [12/1/16]. Available from: http://goo.gl/ejU84P

(16) Aviation Safety Network. Boeing 737 Statistics. [Online]. 2016. [12/1/16]. Available from: http://goo.gl/fztCZn

(17) Boeing Commercial Aeroplanes. Statistical Summary of Commercial Jet Airplane Accidents. [Online]. Seattle: Aviation Safety. [2/1/16]. Available from: http://goo.gl/b8y10Y

(18) Boeing Commercial Airplanes. 737 Airplane characteristics for airport planning. [Online]. July 2007. [7/1/16]. Available from: http://goo.gl/aI3ZfS

(19) Pooleys. The Aeroplane-Techinical. Vol4. 2014. Air pilot publishing LTD. England.

(20) Weight and balance. Centre of gravity limitations. [Online]. [Accessed on 13th January 2016]. Available from: http://goo.gl/XZDy6L

(21) Brady, C. The Boeing 737 Technical Guide. [Online]. (Pocket Budget version). Tech pilot service LTD. 2015 [8/1/16]. Available from: https://goo.gl/HEZDmJ

(22) Brady, C. The 737 Technical Site, Powerplant. [Online]. 1999. [3/1/15]. Available from: http://goo.gl/Tpg23k

(23) CFM. Turbofan engine. [Online]. 2012. [4/1/16]. Available from: http://goo.gl/1TD4Es

(24) JAA Jeppesen: Airframes and systems, Oxford: Oxford Aviation, 2007(25) Oxford aviation training: Aircraft general knowledge, Airframes and systems.

Oxford: Oxford Academy, 2004(26) Boeing 737-800 fuselage [online] [17/1/16] Available from:

http://goo.gl/7mPYpF (27) Semi-monocoque structure [online] [17/1/16] Available from:

http://goo.gl/J40UfR (28) J.P. Fielding: Introduction to Aircraft Design CUP, Cambridge: Cambridge

University Press, 1999.(29) Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 524.

Aviation Supplies & Academics, 1997(30) Brady, C. The 737 Technical Site, Landing Gear. [Online]. 1999.

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Oxford: Oxford University Press, 2013(32) axlegeeks. Boeing 737-800 Detail. [Online]. 2014. [25/12/15]. Available

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(33) Fight Planes. Speed of Sound at Different Altitudes. [Online]. 2002. Available from: http://goo.gl/b6ojIz

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(36) Kuhlman, B and Kuhlman, B. Swept Wings and Effective Dihedral. RC Soaring Digest. March 2000, 3-5. Available online: http://goo.gl/4L63Uh

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13. Appendix:

Wing Appendix

Table 1: -6 Dihedral Data

Euler Roll Attitude/ Body Axis Roll Rate/ms-1

Body Axis Roll Acceleration/ms-2

Pedal Position

0 0 0.09 -0.01-0.01 0.31 1.02 -0.34-9.48 -26.51 -42.23 -0.75

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AVIA 1000. 2015/16. Boeing 737

-45.96 -39.22 -2.9 -0.75-88.8 -42.55 3.06 -0.3

-118.39 -8.25 32.41 -0.01

Table 2: 0 Dihedral Data



Pedal Position

0 0.02 1.12 0-0.07 0.25 3.19 -0.28-1.62 -4.66 -13.47 -0.76

-10.02 -8.53 0.67 -0.76-19.27 -10.08 -1.21 -0.47-26.91 -3.93 6.55 -0.02-28.55 -0.53 1.1 -0.01-28.82 -0.2 0.3 -0.01




Pedal Position

0 -0.16 -15.7 0-1.54 -0.89 2.3 -0.120.16 8.41 17.14 -0.72

15.43 21.53 4.68 -0.7637.86 21.8 -6.68 -0.3654.64 6.32 -14.77 057.11 0.91 -1.66 -0.0157.22 -0.15 0.16 -0.0156.95 -0.23 -0.09 -0.0156.57 -0.2 -0.05 -0.01




Pedal Position

0 0 0 00 0 0.02 -0.03

3.43 16.17 42.65 -0.739.84 51.4 9.48 -0.7695.41 53.43 -4.67 -0.47

136.96 20.61 -43.68 -0.01144.87 2.97 -3.53 0

39

AVIA 1000. 2015/16. Boeing 737

Group Meeting One 11/1/16

Discussed how much we’ve done Discussed if we want to focus on a specific 737 Going to move some content from other sections to history Who will fly in the sim?

o Each fly their own section o (Joshua ended up flying all sections)

Whoever we need to book a second sim sessiono Will see how the first session goes

Confirm meeting in Laid Law tomorrowo Disused further room bookingo AM or PM slots

Need to ask Darron about power point contents Who speaks in presentation

o Zulk & Jonny who rather not to present Weekend meeting Numeric results from sim? Maybe decide what 737 to focus on from what is available on the sim To what degree we can change variables on the sim

Time: 21 minutes 24 seconds

Group Meeting 2: 12/1/16

Early start in the Laid Law Library Need a special program to open the data recording from the sim

o Possibly Autocad 2016 o (turned out to be a special method with Excel

Eassa document on the 737 found Google drive with useful documents created Ikram to gather resources for Aircraft Design Josh to start ethics Jonny to gather information of safety failure

Time: 4 hours 30 minutes


Started researching about the design of the aircraft. Discussed the progress of the individual sections. Finished off the introduction and decided to add the Gantt chart to it. Plan for the next meeting.

Time: 2 hours

40

AVIA 1000. 2015/16. Boeing 737


Ikram has gone to book a lecture theatre to practice presentation tomorrow We will first work on our individual data sections Jonny writes labels for data spreadsheet Ikram creates Gantt chart Peter leaves for conflicting meeting and returns later Another group joins us Jonny leaves to improve own section further as crucial website is blocked on the wifi Josh finishes individual section Various sections completed including acknowledgments and abstract Lecture theatre for tomorrow successfully booked Started working on presentation

Time: 8 hours, 30 minutes


Made a list of topics to ask Darron in meeting later in the day Meeting with Darron:

o Power point is too dense with information o Increase amount of slides to 9-11o Most of marks aren’t from speaking

Aous, Josh and Jonny all add content to design We go to lecture theatre to add to presentation slides, rehearse and time our

presentation Spend 20 minutes improving ourselves and presentation before rehearsing again We start piecing together the separate sections and standardise the formatting We all split up proof reading and make changes Ikram standardises figure numbers All that’s left up is brushing up and standardising references

Time: 9 hours and 30 minutes

41

Documents

Group Project Final