Airframe Design

Question 1

Aircraft loads are mainly?

Answer 1

manoeuvre, pressurisation and inertia loads.

Question 2

What are the type of Proof & Qualification Tests? (5)

Answer 2

Static
Fatigue
Fail-Safe
Flight Test
Weight & Balance Test

Question 3

Margins of Safety Equation

Answer 3

(UTS of Material [Failure Load]/Limit Load [Design Load] x 1.5)- 1 > 0, where UTS is the Ultimate Tensile Strength.

Question 4

Airframe Design Philosophies include the following? (3)

Answer 4

Safe-Life
Finite life; significant damage will not develop during the permitted service life of the aircraft
LIMITATION: Uneconomical because useful life may be wasted if A/C is prematurely withdrawn from service

Fail-Safe
After the failure of a part, remaining structures will still possess sufficient strength and stiffness; design redundancies; loads re-distributed among adjacent structures

Damage-Tolerant
Assumes primary structures have inherent manufacturing flaws
MIL-A-83444 (Airplane Damage Tolerance Requirements) - Dimensions of assumed cracks range from 0.1mm to 1.5mm
Cracks assumed located at fastener holes and other critical areas, and not detectable initially

Question 5

The main difference between a monocoque [single shell] fuselage and a semi-monocoque fuselage is?

Answer 5

The use of longitudinal members to reinforce the skin in the semi-monocoque fuselage, allowing the skin to the thinner.

Question 6

What the structural members? (4)

Answer 6

Bulkheads & Frames - Transverse structural members located at intervals to carry concentrated loads and provide shape/contour for the fuselage skin
Longerons - Longitudinal members taking concentrated loads due to fuselage bending
Fairings - Tertiary structures for aerodynamics
Spars - Principal structural members of the wing, used to transmit main bending and shear loads along the wing

Question 7

What are the Primary Flight Control Surfaces? (3)

Answer 7

Ailerons - Roll
Elevators - Pitch
Rudder - Yaw

Secondary FCS - Trim Tabs, Balance Tabs, Servo Tabs, Flaps, Spoilers, Leading Edge Devices

Question 8

Primary Structures are? Tertiary Structures are for?

Answer 8

Primary Structures are the main load-bearing members. Tertiary Structures are for aerodynamic load requirements.

Question 9

Titanium 6AL-4V

Answer 9

6% Al
4% Vanadium
Balance Titanium