Table 1.1 Selection and justification of aircraft layout

Power-plant Data
Type	Turbofan	Turbofan	Turbofan	Turbofan	Turbofan	Turbofan
number of engines	TWO	THREE	THREE	TWO	TWO	FOUR
P_O (N_O), N		533.7
m_EN,kg
C_p0, g/daN.h
C_pH, g/daN.h

Flight mass data

B 767-200

MD-DC10

L-1011-1

A 320

A 300-B4

IL-86

m_{0 max}, kg

m_0, kg

m_L, kg

m_EM,kg

m_EQ,kg

m_K,kg

m_C,kg

n_pass

m_f,kg

Dimensional Data
S,m²	283.3	367.7		122.6		320.
L,m	47.57	50.4	47.34	34.09	44.84	48.06.
χ
λ	7.99	6.91	7.003	9.48	7.73	7.22
C(C _TR )
η		3.125	3.87	3.067	2.53	3.02
L_F,m
D_F,m
λ _F
∑ S_m,m²
S_EL,m²
S_HS,m²
S_VS,m²
p₀, N/m²	4942.55	5198.37	5971.86	6154.98	6219.23
t₀,	0.317	0.279	0.294	0.318	0.281	0.250
γ_EN, kg/daN
K_C
k_m
S_F
S_HS, m²

The calculations in the zero approximation are based on the use of the statistical data for parameters and characteristics of already constructed airplanes of a similar class.

In this case calculations consist of such stages:

· Gathering and processing statistical data (flight, mass, geometrical characteristics) and power-plant parameters of airplane’s-analogues;

· Addition of set TTR;

· Choice and substantiation of the airplane aerodynamic configuration;

· Determination of take-off mass for the projected airplane;

· Determination of the engine parameters;

· Determination of the basic geometrical sizes for airplane units;

· Performance of drawings of general views for the airplane and its units;

· Determination of load-carrying structures for the basic airplane units.

Ø Table 1.2: Parameters of the projected airplane.

λ	χ	η	C̅	̅b_fl	δ_FL	̅S_AL	λ_F	D_F, m	̅S_HS
7.8		2.6	0.09					5.8	0.24

̅S_VS	λ_HS	λ_VS	χ_HS	χ_VS	C̅_HS	C̅_VS	η_HS	η_VS
0.16	2.1	1.4			0.04	0.04	2.4	2.6

They are:

§ Wing: aspect ratio λ, sweep angle χ, taper ratio η, airfoil thickness ratio C̅, flap chord ratio ̅b_fl = b_fl/b, flap angles (take-off and landing positions) δ_FL, ailerons relative area ̅ S_AL = S_AL/S.

§ Fuselage: aspect ratio λ_F, diameter D_F.

§ Tail unit: the relative area of horizontal surface ̅ S_HS, the relative area of vertical surface ̅S_VS, aspect ratio of horizontal surface λ_HS, aspect ratio of vertical surface λ_VS, sweep angle of horizontal surface χ_HS, sweep angle of vertical surface χ_VS, airfoil thickness ratio of horizontal surface C̅_HS, airfoil thickness ratio vertical surface C̅_VS, taper ratio of horizontal surface η_HS, taper ratio of vertical surface η_VS.

This stage of activity provides:

· A choice of the form and a relative position of wing, fuselage and tail-unit.

· Type and number of engines.

· Engine’s arrangement for the projected airplane.

· Type of landing gear.

· Determination of some geometrical parameters of wing, fuselage and tail-unit, by the results of processing the collection statistical data of given airplane.

Selection of Structural Components Design

The main structural components which we have to be chosen for outcrop are as follows:

1. Fuselage.

2. Wings.

3. Horizontal Stabilizer.

4. Vertical Stabilizer.

5. Landing gear.

6. Engines.

We have to provide a detailed study about all these structures and have to choose what kind of individual structural components are suitable and ideal for our projected aircraft.

Fuselage

The fuselage of an airplane unites the plane’s basic units; the wing, tail units, the landing gear. The crew and the useful loadings, various devices and systems are placed inside the fuselage. The exterior form or cross-sectional form of the fuselage is determined by its purpose, range of Mach number, arrangement of the engines and other factors.

The cross-section of the projected aircraft is chosen to be round shaped.

Advantages

1. The chosen round shaped fuselage structure is considered best for aerodynamical characteristics.

2. The projected airplane is given the semi-monocoque structure fuselage which provides a framework of vertical and longitudinal members covered with a structural skin that carries a large percentage of the stresses imposed upon the structure.

3. Mass of the projected fuselage is reduced in comparison to other shapes, due to the use a round shape.

4. Moreover our fuselage structure or shape is also expedient for pressurized compartments, thus it can perceive such loading well.

Diadvantage

1. The only disadvantage of round shaped fuselage is its complexity of manufacturing.

The wing

The wing of an aircraft is the chief lift generator. So this structure is the most complex and important for an aircraft to take flight. In our arrangement we have chosen to use swept with low-wing configuration with a dihederal angle.

Ø The advantages and disadvantages of such configuration are as follows:

1. Low-wing configuration produces considerable increment of lift within take-off and landing modes due to screening effect of ground.

2. Due to smaller height of landing gear struts there is reduction in their mass and it simplifies its storage.

3. Our wing has swept wing which is good for reduction of drag.

4. Dihedral wing augments stability of an aircraft.

5. There is a possibility of increasing the high-lift devices area.

6. Safety increases of crew and passengers during emergency landing as the touchdown occurs on a wing, which protects fuselage.

Ø Disadvantages of such configuration are as follows:

1. Deterioration of downward view

2. Possibility of foreign object getting into engine air-intakes during movement along the runway.

3. Possibility of engine touching the runway during bank landing, because they are arranged under the wing.

Horizontal stabilizer

The horizontal stabilizer is used to provide longitudinal pitch stability to the aircraft. It is generally attached to the tail part of the fuselage. It may be located above or below the vertical stabilizer or in some cases on the midpoint of the vertical stabilizer.

In our case we have chosen the conventional type of Horizontal stabilizer configuration.

The advantages of horizontal stabilizer of our airplane are as follows:

1. Our conventional creates fewer loads in comparison to T-shaped tail-unit.

2. Placing horizontal stabilizer in the back of the wing increase the stability of the airplane.

3. It offers anti-lift during take-off.

The disadvantages of the conventional type horizontal stabilizer are as follows:

1. These types of horizontal stabilizers are less effective because the airflow from the engine passes though them.

2. The anti-lift feature obviously decreases lift of the airplane.

Vertical stabilizer

The vertical stabilizer is the airfoil section forward of the rudder, it is used to provide longitudinal (yaw) stability for the aircraft. This unit is commonly called the fin. The construction of the vertical stabilizer is very much like that of the horizontal stabilizer. It may be constructed as an integral part of the fuselage.

The rear structural member of the fin is provided with hinges for the support of the rudder. In our projected aircraft a dorsal fin is installed immediately forward of the vertical stabilizer. The function of the dorsal fin is to improve the yaw stability of the aircraft and to provide a streamline fairing between the vertical stabilizer and the fuselage.

The advantages of this type of vertical stabilizer are as follows:

1. Aspect ratio of vertical surface is less than horizontal surface which reduces bending moment and torque.

2. Low structural weight.

The disadvantages of this type of vertical stabilizer are as follows:

1. This type of vertical stabilizer provides higher induced drag and lower lift slope in comparison with T-tail.

Landing gear

The landing gear of an aircraft is the main load carrying body of the airplane when it is landed or grounded. It provides the necessary support to the airplane during landing and take-off. Other than these, landing gear also serves a number of very important purposes like dampening the aircraft when it is being taxied or towed, it cushions the landing impact. The landing of an aircraft often involves stresses far in excess of what may be considered normal; therefore the landing gear must be constructed and maintained in a manner that provides the strength and reliability to withstand and survive all landing predicaments.

The landing gear of an aircraft consists of main and auxiliary units, either of which may be fixed or not. The main landing gear provides the main support of the airplane on land. It may include a combination of wheels, floats, skies, shock-absorbing equipment, cowling, fairing and structural members needed for attachment to the preliminary structure of the airplane. The auxiliary landing gear consists of tail or nose landing-wheel installations, skids, outboard pontoons etc.

The landing gear of our estimated aircraft is tricycle or conventional. The majority of the aircraft has this type of landing gear. And obviously it is also of the retractable type.

The advantages of such landing gear are as follows:

1. Tricycle landing gear is characterized by a nose wheel assembly and two main gear assemblies, one on each side of the aircraft. This arrangement places the aircraft fuselage in a level altitude when the aircraft is on the ground. In this altitude the pilot offers a good forward view and the cabin area is also leveled.

2. This configuration also makes the aircraft stable during ground operations and easy to control.

3. Retractable landing gear reduces the aerodymical drag during flight.

The disadvantages of this type of landing gear are as follows:

1. Retractable landing gear is heavier than non-retractable ones.

The engine

The selection of the engine for each aircraft depends mainly on the individual performance of each aircrafts. Mainly on how much thrust or power we need for the aircraft to have a safe journey and for all extra performances. We selected turbofan engines to be used in our proposed aircraft and the number of engines to be used is two. We chose Rolls Royce’ turbofan engine named “RB211-524G/H”.

Engines positioning on the aircraft is also very important as choosing an engine for the aircraft. Positioning of engine is depending on the positioning of other structural elements of the aircraft. In our project the engines are positioned under the wing.

The main advantages of our engines are as follows:

1. Servicing is more convenient.

2. Power layout of the wing is simplified.

3. Turbofan produces less sound and is more efficient jet engine.

The main disadvantages of our proposed engines are as follows:

1. Placing the engines under the wing increases the loading on the wing thus it requires for stronger joining of wing.