PoF (inc formulas)

Question 1

What is the formula for ‘‘Kinetic Energy’’ ?

Answer 1

ke= 1/2 x m x v^2 (ke=kinetic energy in Joules, M = Mass in Kg, V = Velocity^2 in m/s)

Question 2

What is the “Force’’ formula (Newton’s second law of motion) ?

Answer 2

F = M x A (Force = Newtons, M = Mass in Kg, A = acceleration in m/s^2)

Question 3

What is the formula for “Power” ?

Answer 3

Power = Work Done / Time (Power = Watts, Work Done = Joules, Time = Seconds

Question 4

What is the ‘‘Acceleration/Velocity’’ formula ?

Answer 4

Vf - Vi / t = a (Vf = Velocity final, Vi = Velocity initial, t = time in m/s, a = acceleration in m/s^2)

Question 5

What is the formula for ‘‘Weight”

Answer 5

W = M x G (W = Weight in Newtons, M = Mass in Kg, G = Gravity, Usually 9.81 sometimes rounded to 10

Question 6

What is the definition of “tension” (AKA traction) ?

Answer 6

Tensile loads are a the stretching of a material.

Question 7

What is a “tensile load” ?

Answer 7

Tensile Load is the ability of a material to withstand a pulling force.

Question 8

What is the definition of “compression” ?

Answer 8

The opposite of a tensile load, the squashing of a material.

Question 9

What is “Shear” ?

Answer 9

Shear is a force which tends to slide one face of the material over an adjacent face.

Question 10

What is used to resist tension ?

Answer 10

Ties are used to resist tensile loads.

Question 11

What is used to resist compression?

Answer 11

Struts are used to resist compressive loads.

Question 12

What is used to resist shear?

Answer 12

Rivets can be used to resist shear forces.

Question 13

What is torsion?

Answer 13

Twisting. Torsion or twisting forces produce tension on the outer edge, compression in the centre and shear across the structure.

Question 14

What is stress and it’s associated units?

Answer 14

Stress is the internal force per unit are inside a structural part as a result of external loads and therefore a tensile load or force will set up a tensile stress, compression loads will set up compressive stress.

Stress is defined as the force per unit area and is measured in units of N/mm^2 or MN/m^2

Question 15

What is buckling?

Answer 15

Buckling normally occurs to thin sheet materials when they are subjected to end loads and to ties if subjected to compressive force.

Question 16

What is a dynamic load?

Answer 16

Dynamic loads are those that tent to build up quickly due to changes in flight conditions. Theses loads are produced when an aircraft is manoeuvered nd may induce additional loads on other parts of the aircraft. They can often be severe.

Question 17

What is a static load ?

Answer 17

Static loads are generally constant and build slowly. An aircraft on the ground will experience static loads. The weight of the aircraft will produce an opposing force coming up from the landing gear which will have to be carried by the wing structure.

Question 18

What is design load limit (DLL)

Answer 18

This is the maximum load that the designer would expect the frame or component of experience in service.

Question 19

What does DLL stand for?

Answer 19

Design Limit Load.

Question 20

What is the common Design Limit Load (DLL) for transport aircraft?

Answer 20

+2.5g and -1.0g

Question 21

What is the common Design Limit Load (DLL) for utility aircraft?

Answer 21

+3.4 to 3.8

Question 22

What is the common Design Limit Load (DLL) for aerobatic aircraft?

Answer 22

+6g

Question 23

What is Design Ultimate Load

Answer 23

The DUL is the DLL x Safety factor. Safety factor specified in design requirements is 1.5. The structure must withstand DUL without collapse.

Question 24

What is the Safety Factor?

Answer 24

The safety factor is the ratio of the ultimate load to the limit load.

Question 25

What is the Safety Factor Formula?

Answer 25

Safety Factor (SF) = DUL / DLL

Question 26

What is safe life?

Answer 26

Safe is defined as the minimum of life during which it is known that no catastrophic damage should occur.

Question 27

What is fatigue?

Answer 27

Fatigue happens as a structure is subject to cyclic loads, eventually the part will fail with enough cycles.

Question 28

What is a fail safe or damage tolerant structure?

Answer 28

An example of a damage tolerant structure is when extra members are used to provide alternative load paths providing redundancy. The extra structural members are capable of taking the by themselves.

Question 29

What are station numbers?

Answer 29

Station numbers refer to numbered points along a diagram of the aircraft so as to allow for easy location of an area, parts or objects. note: the zero datum point is the starting point of the map.

Question 30

What is axial stress?

Answer 30

Axial or longitudinal stresses are set up in the fuselage of aircraft when pressurized and tent to *elongate the fuselage*

Question 31

What is hoop stress?

Answer 31

Hoop or radial stresses are set up in addition to axial stress and *expand fuselage cross-section area.*

Question 32

What is the *EASA* definition of a fuselage?

Answer 32

The fuselage is main structure whole body of the aircraft which carries the aircraft payload i.e the passengers, and/or freight as well as the flight crew and cabin crew and cabin staff in safe, comfortable conditions.

Question 33

How are flight deck windows constructed?

Answer 33

They are constructed from toughened glass panels attached to each side of a clear *vinyl* interlayer. And electrically conducting coating applied to the inside of the outer glass panel is used to heat the window. This prevents ice from forming and helps make the window more resilient and able to withstand bird strikes. *The heating of the window helps it to be less brittle and able retain some flexibility*.