Aerospace Engineering Interview Preparation Guide

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What do you understand by Aerodynamics/performance analysis?
What will be the responsibility of the spacecraft operations, dynamics, and controls?
What would you do if your Captain were not following the instructions properly?
When can one deviate from any flight rules and regulations?
Without Air Traffic Control, what is the minimum descent rate you can descend the plane?
You are about to take off the plane in few seconds and a catastrophic engine fails, and your captain tells you not to take off and just stay in the center line. What would you do?
How would you handle the extreme pressure during emergency if you know that plane is not safe and it might crash anytime?
What operational benefits do hydraulic actuator/rate controls have over gas charged units?
How do I decide which is the best technology to solve my vibration isolation problem?
What is isolation efficiency?

When a pilot is assigned a speed, how much can one deviate from that speed?
Without Air Traffic Control, what is the minimum descent rate you can descend the plane?
How would you handle the extreme pressure during emergency situation if you know that plane is not safe and it might crash anytime?
How important is to get the passengers switch off the mobile phones and laptops during land off? What could be the consequences?
How many types of emergency landings are there and explain?
What are the three tactical elements of electronic warfare?
What are the main areas in Aviation?
What is the requirement to become a Professional Engineer (PE) in the field of Aerospace?
Explain the differences between Aeronautical Engineering and astronautical engineering?
Does the knowledge of mathematics of Science is required to get into aerospace engineering?

What is the requirement to become a Professional Engineer (PE) in the field of Aerospace?
What made you choose aerospace engineer line as your career?
Explain the day to day responsibilities of Aerospace engineering?
Explain the differences between Aeronautical Engineering and astronautically engineering?
What do you understand by Aerodynamics/performance analysis?
What will be the responsibility of the spacecraft operations, dynamics and controls?
What is the testing done in aerospace engineering?
How would you handle if your co-worker is not co-operating with you?
What would you do if your Captain is not following the instructions properly?
When can one deviate from any flight rules and regulations?

Why the stall of the swept wing tends to occur at the tips first?
Why the fuselage of the pressurized aircraft is made of circular cross section?
Can we put engines on the end of a wing? If not, then why?
What is ram jet?
Why refrigeration is done inside aircraft, and why aircraft body is made of aluminum's?
Does not simplification of complex honeycomb designed for thermal protection system of are usable launch vehicles jeopardize the accuracy of results?
Are thermal protection systems of space craft's commonly composed of one panel or a collection of smaller tiles?
What is the highest temperature the space shuttle under surface experiences during its mission?
Explain how you overcame a major obstacle?
What are the main areas in Aviation?

Why the fuselage of the pressurized aircraft is made of circular cross section?
Can we put engines on the end of a wing? If not, then why?
What is ram jet?
Why you would like to join the aviation industry?
Doesn't simplification of complex honeycomb designed for thermal protection system of are usable launch vehicle jeopardize the accuracy of results?
Why insulating tiles on reusable launch vehicles must be isolated from one another?
Are thermal protection systems of space craft's commonly composed of one panel or a collection of smaller tiles?
Why are all shear loads and twisting moments set to zero for the preliminary design phase of TPS?
How difficult is to mould and shape graphite epoxies compared with alloys or ceramic that may be used for thermal protective applications?
What is the highest temperature the space shuttle undersurface experiences during its mission?

Category C personnel are responsible for maintaining the management role of controlling the progress of the base maintenance inspections and seeing the work that is getting performed. These handle the category B and category A staff and monitor their work. They are responsible for ensuring the good work that will be carried out by providing the certification of maintenance. Category C personnel upon the completion of the maintenance job done by the base maintenance staff provides the certificate to allow the servicing of the aircraft to proceed. This way the people working in the staff become eligible to perform and provide services for flight.

The difference that exists between the two is that line maintenance certifying staff has the responsibility to inspect, rectify and perform the related or associated maintenance activities on the aircraft on the airfield. Whereas, the base maintenance certifying staff, perform the maintenance activities away from the live aircraft areas.

The maintenance that is being performed by the line maintenance staff is restricted to use limited tools, and equipments that are present on the site to perform the first line diagnostic maintenance. Whereas, Base maintenance certifying staff is associated with the line maintenance staff as it requires inspecting and performing complex modification in the aircraft carriers.

The main source of power is the hydraulic motor that is provided by the scheduled service and involves operations that allow technicians to solve complex system problems. This setup required certifying the technician to operate all the system the same way as it is been done with one system. The hydraulic motor needs to be operated the same way and maintained in a proper way. The alignment need to in synchronization with the aircraft auxiliary power unity (APU) before anything is done with the aircraft positioning. A standard need to, be followed to maintain the aircrafts and its parts equipped and working.

Category B consists of two sectors in the field of maintenance and they are divided in B1 and B2 with certain roles. The operations performed by Category B technicians are as follows:

► Activities related to scheduled on field inspections for aircraft maintenance.
► Activities of complex rectification
► Fault diagnosis on aircraft systems and their equipment's.
► Modification and performing special instruction to monitor and manage the system
► Repairing of air-frame and other aircraft's
► Activities performed like removal of aircraft components and fitting the required parts.
► Use of BITE (built-in test equipment) and diagnostic equipment's to perform repair tasks.
► Supervising and certifying the work of other technicians involved in it.

There are two major sectors involved in aircraft maintenance and these are handled by certifying technician in the field of support and maintenance. These are divided into two sectors as:

► Category B1 (mechanical): these are the maintenance technicians that have good knowledge regarding the working of air-frame, engine, electrical power systems and equipment. It also requires additional knowledge of aircraft structures and materials.
► Category B2 (avionic): this deals with the integrated knowledge of aircraft equipment's, electrical, instrument and radar related systems. They undergo proper training to handle the aircraft equipment's and gain practical experience to deal with day to day activities.

There are four types of flows that consist of different speeds and can be identified using Mach number:

► Subsonic flow where M<1 everywhere, this is a field that is defined as subsonic if it matches the Mach number that is less than 1 at every point. These are displayed by smooth streamlines that consists of no discontinuity in slope. The flow velocity is everywhere less than the speed of sound and the disturbances are all around the flow field.
► Transonic flow, where mixed regions exist and M<1 or M>1, this is a flow field that defines that the M8 is increased just above the unity and it is formed in front of the body. These are the mixed subsonic and supersonic flows that are influenced by both the flows.
► Supersonic flow where M>1 everywhere, this type is defined when Mach number is greater than 1 at every point. They are represented by the presence of shock waves across which the flow properties and streamlines changes discontinuously.
► Hypersonic flow where the speed is greater than supersonic, this is defined when the shock waves moves closer to the body surface and the strength of the shockwave increases leading to higher temperatures between the shock and body surface.

► Incompressible flows are the flows that have a constant density (?). Whereas, the compressible flows are those that consists of variable densities.
► The flows that exist are compressible in nature. Whereas, incompressible flows, doesn't exist in nature or are very rare.
► Incompressible flows are used to model aerodynamic problems without loosing any detrimental accuracy i.e. most problems that exist in hydrodynamics considers the density (?) = constant. Whereas, compressible flow is hardly used as a mathematical model to, represent the hydrodynamics.
► High speed flows are and must be treated as compressible, whereas incompressible flows are not considered for high speed flows.

Lift augmentation devices provides flaps that are moving wing sections that increase wing camber and provide an angel of attack. Flaps have their own use like if an aircraft takes off and land in a short distance then the wings of it should produce sufficient lift at lower speed. Flaps provide a way to slow down the aircraft. There two categories and they are as follows:
► Trailing edge flaps includes different flaps like
► Plain flap that is used to retract the complete section of trailing edge and it is used in downward.
► Split flap gets formed by the hinged lower part of trailing edge and the lowered top surface remains unchanged and it eliminates the airflow that occurs over the top of the surface of the plain flap.
► Leading edge flaps: is used to augment the low speed lift that is swept on the wing aircraft. They help in increase the camber and allow the coupling to operate together with the trailing edge flaps.

The elements required to display oscillatory motion are as follows:
Period: this is related to the time and it signifies the time that elapses in between the motion that will repeat itself after some time again. Oscillatory motions allow themselves to be repeated after equal intervals of time and this is called as periodic.
► Cycle: it represents the completion of one period and it also signifies the motion that is completed in one period.
► Frequency: defines the number of cycles completed in unit time.
► Amplitude: defines the distance from one point to another or from highest to lowest point of the motion from the central position.

Sperry's rule of precession describes about the direction in which the precession takes place. This precession is dependent on the direction of rotation for the mass and the axis of the torque that is applied on the material. It provides a guide to the direction of precession that allows easy finding of the direction of the applied torque. This also helps in finding out the direction of the rotation of gyro-wheel. If the torque is applied and is perpendicular to the spin axis then it can be transferred as a force.

Gyro-dynamics deals with gyroscopic motion that is used for creating aircraft application as it allows inertia and momentum of the body. These laws consist of the two properties of rigidity and precession to provide the visible effects gyro-dynamics. These are as follows:

► If a rotating body is mounted and it is free to move about any axis that passes through the center of mass, then the spin axis that is used will remain fixed in inertial space without displacing any of the frame.
► If a constant torque is applied to any direction such as about an axis, or perpendicular to the axis, then the spin axis will move about an axis that is mutually perpendicular to both the spin and the torque axis.

Gyroscopic motion is considered as an important study for aircraft application for the inertia and momentum of the body that is used in circular motion. The momentum is the product of the mass of a body and its velocity. This is a measure of the quantity of motion of a body. Inertia is the force that doesn't allow any change to happen in momentum. Gyroscope is the rotating mass that can be moved freely at right angles to its plane of rotation. This utilizes the gyro rotor or gyroscopic inertia to provide the motion unless it is compelled by an external force to change the state. This uses property of rigidity as gyroscope acts as a reference point in space.

Propulsive thrust is used in aircraft system, when an aircraft is traveling through air in straight or level flight then the engine produces a thrust that is equal to the air resistance or the drag force on the aircraft. If the engine thrust exceeds the drag then the aircraft will accelerate and if drag exceeds the engine thrusts then the aircraft system will slow down.
The thrust force that is used for aircraft propulsion should always come from air or gas pressure. The forces that are external always act on the engine or propeller. This propeller can be driven either by a piston or a gas turbine engine. If there is a use of jet engine then the high velocity exhaust gas is produced.

Torsion is used to drive shafts for aircraft engine driven pumps and motors. They are also involved in having a force behind propeller shafts, pulley assemblies and rive couplings for machinery. The shear stress is setup within the shafts and it results from the torsional loads. The size and the nature of torsional loads and stresses need to be known while making the design or else premature failure can occur. The shafts are used as a component to transmit torsional loads and twisting moments or torque. They can be a cross section or a circular component as it is more suitable to transmit the torque for pumps and motors to supply the power to the aircraft system.

Load extension graphs are used to show the result of mechanical test done on the material to know their certain properties for example finding out the heat treatment of a material. These graphs shows certain phases of a material when it is being tested for destruction of the properties like elastic range, limit of proportionality, etc. The material needs to obey Hooke's law. The elastic limit needs to be at or very near to the limit of proportionality. If the limit is passed the material ceases to be proportional to the load. If the stress increases on the material then the waist reduces as the stress = force/area. This graph represents a curve that shows different stages like elastic stage, and plastic stage.

The properties of the mechanics are as follows:
► Strength: this is the applied force on a material that can withstand prior to fracture. It is measured by the proof or yield stress of a material that is under action.
► Working stress: this is the stress that is being imposed on a material as a result of the load that is being subjected on the material. The loads that are given must be in the elastic range.
► Proof stress: defines the tensile stress
► Ultimate tensile stress (UTS): defines of a material that is given by a relationship or its maximum load.
► Specific strength: defines the light and strong of a material that is used in aircraft making. This is done to maximize the payload and meeting all the safety requirements.
► Malleability: defines the ability to be rolled into sheets or get a shape under pressure. This includes examples of gold, copper and lead.
► Elasticity: defines the ability of a material to return to its original shape when an external force is removed from the material.

► Viscous flow is the flow in which the molecule moves in random fashion and transfers their mass, momentum and energy from one place to another in fluid. Whereas, an inviscid flow is the flow in which there is no involvement of friction, thermal conduction or diffusion while the molecules are moving.
► Inviscid flow consists of the limited influence of friction, thermal conduction and diffusion that is limited to thin region that is limited to the body surface. Whereas, the viscous flows involve the flows that dominates the aerodynamics of the blunt bodies like cylinder. In this the flow expands around front face of cylinder and it separates from the rear surface of it.

The flow that is moving over the body i.e. in a circular cylinder of diameter d is the continuum flow, whereas the flow that consists of individual molecules moving in random motion is the free molecule flow.
► The mean free path (?) defines the mean distance between the collisions of the molecule and if this path (?) is smaller than the scale of the body measured (d) then the flow of the body is considered as continuum flow.
► The path (?) that is of same order as the body scale then the gas molecules then the body surface will have an impact of the molecules and this is known as free molecular flow.

To measure the dynamicity of the two flows consider two different flow fields over two different bodies. This way the conditions that get generated are as follows:

► The streamlined pattern shouldn't be geometrically similar.
► The distribution of the volume over change in volume (V/V8), pressure over change in pressure (p/p8), and time over change in time (T/T8). These changes take place throughout the flow of the field and they remain the same against the common non-dimensional coordinates
► The force coefficient remains the same.
► There is a similarity in both the flows like the solid boundaries are geometrically similar for both flows.

There are two sources that are involved in the case of aerodynamics forces and moments that are on the body. These forces are as follows:

► Pressure distribution: this is the distribution that is over the body surface
► Shear stress distribution: this is the distribution that is over the body surface
These sources are for the body shapes and it doesn't matter how complex they are. The mechanism that is being used to communicate with the bodies that is moving through a fluid. Both the pressure (p) and shear stress (?) having the dimension force per unit area. This helps the movement of the body through the fluid.