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Right option is (a) whisker reinforced composite

Easiest EXPLANATION: Above diagram is showing a TYPICAL whisker reinforced composite material. Short strand of the reinforcing MATERIALS are RANDOMLY located THROUGHOUT the matrix. Chopped Fiberglass is an example of such arrangement.

The correct option is (a) 24.67 unit

To EXPLAIN: EULER load = \(\frac{\pi^2 EI}{(Effective \,LENGTH)^2}\)

= \(\frac{\pi^2*1000}{20^2} \) = 24.67 unit.

Correct answer is (a) GUST

Explanation: Gust is primarily experienced during flight PHASE of an aircraft. Gust is experienced during flight in air. HENCE, gust is an example of air load. Landing, TAXI etc. are examples of the ground loads.

Correct answer is (a) LIMIT load

The explanation is: Limit load is the largest load that is expected to be experienced by aircraft. Shear force will produce shear stress. Stress is force per UNIT area and strain is DEFINED as CHANGE in DIMENSIONS divided by original dimension.

Right answer is (a) 1.6

The EXPLANATION: For, given column which is fixed at one END and free at other effective LENGTH L = 2*1.2m = 2.4m.

Now, SLENDERNESS ratio = effective length / radius of gyration = 2.4/1.5 = 1.6.

Right option is (a) 9.28

The explanation: GIVEN, COLUMN is fixed at both ends.

Actual LENGTH = slenderness ratio*RADIUS of gyration/0.5 = 2.9*1.6/0.5 = 9.28.

Correct answer is (a) v-n diagram combined of gust and Maneuver

To EXPLAIN: Above diagram is illustrating a typical V-n diagram. Above diagram is a typical combined V-n diagram of gust and Maneuver. Drag coefficient vs LIFT coefficient graph is nothing but the drag POLAR. Takeoff speed is based on takeoff LOADS.

Correct answer is (a) control hinges

For explanation I WOULD SAY: Magnesium is USED in control hinges, wheels, engine mounts ETC. Magnesium has good strength to weight ratio. It can tolerate high temperatures and is EASILY formed. Magnesium can be easily formed by casting, forging etc.

Correct OPTION is (b) False

The explanation: Composite MATERIAL is formed by USING TWO or more DIFFERENT materials. Composites are used to get desired properties of material. However, they can be costlier than non-composite materials.

Correct choice is (a) 0.014

For explanation I WOULD say: STRAIN = change in DIMENSION / original dimension = 0.28/20 = 0.014.

The correct answer is (a) Easy to fabricate

The BEST explanation: WOODS are easy to fabricate and repair. This is one of the advantages of the wood. Wood has some drawbacks as well such as moisture SENSITIVITY. TODAY wood is largely used in homebuilt aircrafts.

Right choice is (a) Under low SUSTAINED STRESS, it is tendency of some materials to get deform slowly and permanently

Easy explanation: Creep is nothing but the tendency of some materials to get deform slowly and permanently under low but sustained stress. For most of materials used in aerospace, creep is a problem at elevated temperatures. Although some titanium, PLASTICS will exhibit creep at ROOM temperatures.

The correct choice is (B) False

The explanation is: Loads will be of DIFFERENT magnitude and of different kinds. During LANDING, landing gear are used to WITHSTAND the impact loads at the TIME of touchdown. However, at takeoff they do not experience such impact loads. Hence, magnitude of the loads will be different.

The CORRECT CHOICE is (a) 54.77m/s

The explanation: EQUIVALENT airspeed = actual speed * (Density ratio)^0.5

= 100*(0.3^0.5) = 54.77 m/s.

The correct choice is (a) MANEUVER v-n diagram

To explain I would say: Above diagram represents a typical Maneuver CHARACTERISTICS. A typical Maneuver V-N diagram is shown in the above diagram. Drag POLAR is GRAPHICAL representation of the aircraft drag properties. Typically it is used to show drag VARIATION. Thrust required is used to oppose the drag produced.

Right answer is (a) TYPICAL bending

Explanation: The above DIAGRAM is showing a typical bending concept. Bending as shown in the diagram is a combination of tension and compression. As shown in the diagram top PORTION is experiencing compression. BOTTOM portion is experiencing tension as seen in the diagram.

Right answer is (a) 4.55MPa

For explanation I would say: SHEAR MODULUS = ELASTIC constant / (2+2*Poisson’s ratio)

= 100 MPA / (2+2*10) = 4.55 MPa.

Right choice is (a) body or surface FORCES

To explain I would say: TYPICALLY, all aircraft forces are categorized as body forces or surface forces. Body forces are those forces which are acting through volume of the body. Typical example of body force is force due to GRAVITY. Surface force is acting through surface of an object such as shear force.

Correct choice is (a) Factor of safety is provided to improve safety of an AIRCRAFT

The best EXPLANATION: The factor of safety is USED in order to increase safety of the aircraft. Lift is not ALWAYS same as the aircraft WEIGHT. Weight will be same as the lift during cruise. Thrust required is not always same as the weight.

The correct option is (a) typical stress strain diagram

Explanation: Above diagram is showing typical relationship between stress and strain. As shown in diagram up to certain VALUES of stress curve FOLLOWS linear relationship. This is due to hook’s law. Lift curve slope is showing a typical VARIATION in lift COEFFICIENT with respect to angle of attack.

Correct choice is (a) At any given time, an aircraft can only EXPERIENCE any one TYPE of load

Easy explanation: At any given time, aircraft can experience the number of different TYPES of LOADS. For example, at cruise aircraft experiences airloads, powerplant load etc. At cruise, lift and weight will be equal. Lift is an Aerodynamic FORCE.

Correct answer is (a) 0.51

To EXPLAIN: DENSITY ratio = (1/ratio of ACTUAL airspeed and EQUIVALENT airspeed)^2

= (1/1.4)^2 = 0.51.

Right answer is (a) 0.52mm

Easy EXPLANATION: Change in length = ORIGINAL length*STRAIN = 52*0.01 = 0.52mm.

Right answer is (b) False

The BEST EXPLANATION: Stress and pressure are two different properties. Stress is produced due to internal FORCES. Pressure is result of external force. Stress is DEFINED as internal resistive force per unit cross section area. Unit of pressure and stress will be the same but not their physical explanation.

Correct OPTION is (a) True

Easiest explanation: Air loads are defined as those loads which are acting on the aircraft during flight in the air. Air loads may include MANEUVER, GUST, buffet, control deflection etc.

The correct answer is (a) TAXING

Best explanation: Taxing is not an EXAMPLE of power plant load. Powerplant load MAY include Thrust, torque, DUCT PRESSURE, vibration etc. Thrust is propulsive force produced by the powerplant of an aircraft.

The CORRECT answer is (a) 7075 aluminum ALLOY

Explanation: For HIGH STRENGTH application 7075 aluminum alloy is widely used. 7075 is alloyed with zinc, copper and magnesium. Corrosion resistance is lessened by alloying. Aluminum sheet is FREQUENTLY clad with a thin layer of pure aluminum.

Correct CHOICE is (a) 432.32K

The best I can explain: GIVEN, ambient air temperature T1 = 25°C = 25+273.15 = 298.15K, MACH NUMBER = 1.5

Stagnation temperature for air is given by,

Stagnation temperature = T1*(1+0.2*M^2)

= (25+273.15)*(1+0.2*1.5^2) = 432.32K.

The correct option is (a) 4 unit

Easiest explanation: RADIUS of gyration = \(\sqrt{\frac{MOMENT \,of\, inertia}{Area}}\)

= \(\sqrt{\frac{160}{10}}\) = 4 unit.

The correct option is (a) CRIPPLING

To elaborate: When we step on an upright soda can, it would fail due to crippling. Here, walls of cross section will COLLAPSE WITHOUT WARNING and the ability to carry load will BECOME virtually zero. This can be viewed as the short Column with very thin walls.

Right choice is (a) Corrosion is MAJOR problem in terms of material lifespan

The best I can EXPLAIN: Since the early days of AVIATION, corrosion of materials has been a major problem. Aircraft materials are exposed to salt water SPRAY, atmospheric moisture, fuels, oils, exhaust, plumes etc. Stress corrosion can lead to fracture at a stress level one tenth of normal ultimate stress.

Correct choice is (a) Ratio of column’s effective length to c/s radius of gyration

The explanation is: The ratio of column’s effective length to c/s radius of gyration can be termed as slenderness ratio. The effective length of the column is determined based on the end constraints such as PINNED JOINTS, FIXED ENDS etc.

The CORRECT choice is (a) maximum dynamic pressure

The explanation: Maximum dynamic pressure is being represented by the DIVE speed in a typical V-n DIAGRAM. Manifold pressure at intake is almost equal to the ATMOSPHERIC. Supercharger is used to increase manifold pressure by large amounts. Rage of climb is VERTICAL velocity.

The CORRECT choice is (b) False

Easy explanation: No, it is not true. In the air, it is not only experiencing the air loads rather an aircraft will EXPERIENCE number of different types of loads. For example, lift, drag etc. are air loads HOWEVER Thrust force is a power plant load which is experienced by aircraft during flight in air. HENCE, the given STATEMENT is not true.

The correct answer is (a) G = 0.5*E / (1+μ)

To explain: Above EQUATION is showing a typical relationship between SHEAR modulus G, elastic constant E and Poisson’s RATIO µ. Correct relationship is given as follows: G = 0.5*E / (1+μ) where, G = shear modulus, E = elastic constant or YOUNG’s modulus, μ = Poisson’s ratio.

Correct option is (a) 3.96

To EXPLAIN: EFFECTIVE length = SLENDERNESS RATIO*radius of GYRATION = 2.2*1.8 = 3.96.

Correct answer is (a) 250N

The BEST EXPLANATION: FORCE or load = stress produced* cross section area = 25*10 = 250N.

The CORRECT answer is (a) 0.9M

The best I can EXPLAIN: DIVE SPEED = cruise speed + 0.5*cruise speed

= 0.6 + 0.5*0.6 = 0.9M.

Correct answer is (a) Wood sufferers from moisture SENSITIVITY

Best explanation: Wood sufferers from moisture sensitivity. Wood is not rare to find. Wood OFFERS GOOD strength to WEIGHT ratio and is EASY to fabricate. Lift will not be same as drag.

Right choice is (a) ISOTROPIC

To elaborate: WHISKERS are Isotropic. Whiskers have same material properties in all directions and hence, termed as isotropic. Isothermal process has constant temperature. Isobaric process has constant PRESSURE that means pressure will not change during such processes.