Questions Wing Fuselage

8/6/2019 Questions Wing Fuselage

1/18

Part A - AIRCRAFT WING

1) What are the main functionalities of a wing ?

The main functionality of the wing is to provide the necessary lift to the

aircraft with the help of flaps and slats which are the controlling surfaces.

To withstand the bending moment which are greatest during flight and

upon landing.

2) How are wings classified ?

There are several types of wing structures for modern high speed

airplanes.

Thick box beam structure ( usually built up with two or three spars for

high aspect ratio of wings as

shown in the figure a.

Multi spar box structure with

for lower aspect ratio of

wings with thin wing airfoil

as shown in the figure b.

Delta wing box as shown in

figure c.

Fi ure a

Figure b


2/18

3) What are the main components of a wing ?

The main components of a wing are shown in the below diagram.

Figure c


3/18

4) Design the wing with lightening strike considerations ?

Airplanes flying in and around thunderstorms are often subjected to direct

lightening strikes and also to lightening discharges that produce carona and

streamer formations.

Three zones may be identified for the understanding purpose.

Zone 1 : Surfaces of the aircraft for which there is a high probability of

direct stroke attachment.

All surfaces of the wing tips located approximately within 18 inches of the

tip ( measured parallel to the lateral axis of the aircraft )


4/18

Forward projections such as engine nacelles, external fuel tanks and

propeller disks.

Any other projecting part that might constitute a point of direct stroke

attachment.

Zone 2 : Surfaces for which there is a probability of strikes being swept

rewarded from a zone 1 point of direct strike attachment such as ( engine

nacelles, propellers.. etc ). Zone 2 extends approximately 18 inches laterally to

each side of fore and aft lines passing through the zone 1 forward projections of

stroke attachment.

Zone 3: Surfaces for which there is a low probability of wither direct or swept

strokes. Ignition sources in these areas would exist only in the event of

streamering. This zone includes all surfaces of the aircraft not coming under

definitions of zone 1 and 2.

Please see the below picture representing the different zones.


5/18


6/18


7/18

5) What are the design factors considered for a wing ?


8/18


9/18

6) What are the general rules for spar design ?


10/18


11/18


12/18


13/18


14/18


15/18

Part B Fuselage

1. Why the Fuselage of a pressurized airplane built into the circular shape?

Because fuselage is an aerofoil, it has a low pressure area over theupper surface and higher pressure at the lower surface. when the fluid flowthrough an aerofoil this creates a variance in temperature and pressure insidethe fuselage. So to minimize this effect inside the fuselage, it is made of circularcross section

Circular cross section can resist Hoop's stress effectively as compared to

other cross section.

Distribution of air is uniform.

Increases area of the fuselage.

2. What is Panel Instability?

The internal frames in a semi monocoque structure, such as fuselage,

divide the longitudinal stringers and their attached skin into lengths called

panels. If these frames are sufficiently rigid, a monocoque structure if subjected

to bending will fail on compression side. The longitudinal stringers acts ascolumns with an effective length equal to that of the frame spacing which is the

panel length. Initial failure thus occur in a single panel and is referred to as


16/18

Panel Instability.

3. Summary of fuselage loads

Ultimate design conditions:

Flight loads

Flight loads + Cabin pressure

Cabin pressure only

Landing and ground loads

Fatigue design conditions:


17/18

Fatigue loads based on the flight profile developed by themanufacturer to encompass

anticipated airplane usage

Fatigue objective- design flight hours of service life without

modification of primary

structure

Special area conditions:

Depressurization of one compartment

Bird strike

Hail strike

Cargo and passenger loads on floors

Crash loads (emergency landings)

4. what are the materials considered for the design of fuselage ?

Aluminum alloy

Graphite epoxy composite material

copper-aluminum alloy

Steel

Glass/epoxy Kevlar/epoxy

5. What are the requirements to consider to design the fuselage ?

Size of the Aircraft for the required application

Producibility

Structural efficiency Weight

Effect on fuselage for the outside diameter of the shelldetermined

Noise attenuation

Structural arrangement

Corrosion resistance


18/18

Stability

Aerodynamic shape for the maneuverability

6. What are the other aircraft systems interface with Fuselage ?

Wings Cockpit

Fairings

Empennage

Landing gears

Electrical systems

Hydraulic and Pneumatic system

7. How do you determine the primary structure spacing on the shell

L = MD2 /16000*EI

This is the theoretical formula to calculate the spacing between theframes/bulkheads

M = Bending moment of fuselage

D = Diameter of the stiffened fuselage

E = Modulus of Elasticity

I = Moment of Inertia of fuselage

Documents

Questions Wing Fuselage