1 evolution and type of structures

04/07/2304/07/23 Author: Harry L. WhiteheadAuthor: Harry L. Whitehead 11

AVAF 209 Aircraft Structures IIAVAF 209 Aircraft Structures II

I. Evolution of Aircraft StructuresI. Evolution of Aircraft Structures

II. Types of Aircraft Structures:II. Types of Aircraft Structures:A.A. That Produce LiftThat Produce Lift

B.B. That Produce ControlThat Produce Control

C.C. That Modify LiftThat Modify Lift

D.D. That Aid ControlThat Aid Control

E.E. That Hold PeopleThat Hold People

F.F. That Support the Aircraft on the GroundThat Support the Aircraft on the Ground

G.G. That Hold the PowerplantThat Hold the Powerplant

H.H. RotorcraftRotorcraft

•Wright brothers

Wilbur

Orville

•Gustave Whitehead

•Structure of early machines:•Wings of bent wooden ribs covered with fabric

•Body of open frameworks of wood strips lashed together with wire

•Landing gear were skids

•Control surfaces •small wings •“Wing Warping”

•Structure of early machines:

•Up to World War I:•drag problem

•World War I:•Biplane •open cockpits • radial engines

•metal tube truss construction•Welded thin-walled metal tube • covered with fabric• lighter weight and stronger

•World War I:

•1920s and 30s: •Stressed-Skin construction

•Aluminum skin•1920s and 30s:

I. Evolution of Aircraft StructuresI. Evolution of Aircraft StructuresII. Types of Aircraft Structures:II. Types of Aircraft Structures:

A.A. That Produce LiftThat Produce LiftB.B. That Produce ControlThat Produce ControlC.C. That Modify LiftThat Modify LiftD.D. That Aid ControlThat Aid ControlE.E. That Hold PeopleThat Hold PeopleF.F. That Support the Aircraft That Support the Aircraft

(Ground)(Ground)G.G. That Hold the PowerplantThat Hold the PowerplantH.H. RotorcraftRotorcraft

•Aluminum structure •MONOCOQUE construction

•1920s and 30s:

•Since 1930s: •SEMI-MONOCOQUE construction

•High altitude flight

•Since 1930s:

Author: Harry L. WhiteheadAuthor: Harry L. Whitehead 1515

•Early 1950s:

Part 91: General Part 91: General Operating and Flight Operating and Flight RulesRules

Special Inspections:Special Inspections:

Part 91GeneralRequired EquipmentMaintenance RequirementsInspectionsSpecial InspectionsMaintenance Records

•Altimeter & Static System, Transponder, ELT, Hard/Overweight Landing, Severe Turbulence, Aging Aircraft

•For certain older Large Aircraft the Pressure Vessel must be specially inspected after so many Pressurization Cycles•Also, after Dec. 16, 2008 all turbine-powered transport category aircraft must have their fuel tank systems specially inspected and maintained

•“Aging Aircraft” – 91.410

•Aloha Airlines “Patio Seating”•Boeing 737-297•April 28, 1988

Structures That Produce Lift:

AIRFOIL•LEADING EDGE

•TRAILING EDGE

•ASYMMETRICAL

• SYMMETRICAL

Lift Theories: Bernoulli’s Principle

To create Lift, an AIRFOIL must be moved through the air at an ANGLE OF ATTACK

Lift Theories: Newton’s Laws

Downwash Angle

GreaterDownwash Angle

Too MuchDownwash Angle

STALL!

= Too LittleDownwash Angle

STALL!

•CENTER OF GRAVITY

•CENTER OF LIFT

•NOSE-HEAVY AIRCRAFT

•CANTILEVER (NO EXTERNAL STRUTS)

•WINGLETS

•3 AXES:

•LATERAL AXIS

•PITCH

Structures That Produce Control:

To successfully fly, there needs to be some way to control the maneuvering of the aircraft

•3 AXES:

•LONGITUDINAL

•ROLL (BANK)

•3 AXES:

•VERTICAL

•YAW

•PRIMARY CONTROLS:

•ELEVATOR

•AILERONS

•RUDDER

•PITCH:

•ELEVATOR

•HORIZONTALSTABILIZER

•EMPENNAGE

•TAIL LOAD

•PITCH:

•WHEEL OR

STICK PULLED

•TAIL LOAD

INCREASED

•NOSE UP

•PITCH:

•STABILATOR

•ROLL:

•ROLL: AILERONS

LEFT BANK

•ROLL: AILERONS

•ADVERSE YAW

•ROLL: AILERONS

•ADVERSE YAW

•ROLL: AILERONS

•ADVERSE YAW – 4 WAYS TO COMBAT IT:

•1. PILOT RUDDER ACTION ONLY

•ROLL: AILERONS

•ADVERSE YAW – 2. DIFFERENTIAL TRAVEL

•ROLL: AILERONS

•ADVERSE YAW – 3. FRISE (freeze) TYPE AILERON

•ROLL: AILERONS

•ADVERSE YAW –

4. RUDDER-AILERON

INTERCONNECT

SPRINGS

•ROLL: SPOILERS

•YAW:

•RUDDER

•VERTICALSTABILIZER

•YAW: RUDDER

•PEDALS IN

COCKPIT

•YAW: RUDDERVATORS

•YAW:

•RUDDERVATORS

Elevator Action

Rudder Action

•AUXILIARY LIFT DEVICES (HIGH LIFT DEVICES):

Structures That Modify Lift:To shorten the Landing and Takeoff rolls and to allow

more weight to be carried:

•TO DECREASE STALLSPEED•TO ALLOW HIGHER ANGLES OF ATTACK•TO CONTROL THE BOUNDARY LAYER

•TO DECREASE STALLSPEED•FLAPS

•TRAILING EDGE•LEADING EDGE

•TRAILING EDGE FLAPS

•PLAIN FLAP

•SPLIT FLAP

•SLOTTED FLAP

•FOWLER FLAP

•TRIPLESLOTTEDFOWLERFLAP

•LEADING EDGE FLAPS

•DROOPED

•KRUEGER

•TO ALLOW HIGHER ANGLES OF ATTACK•SLOTS•SLATS

•TO DECREASESTALL SPEED•TO ALLOWHIGHER ANGLESOF ATTACK

•TO CONTROL THE BOUNDARY LAYER•UPPER SURFACE SUCTION•FLAP AUGMENTATION

SUCTION

•STALL CONTROL DEVICES:

•WANT WINGROOT TO STALL FIRST

•STALL STRIP OR TWISTED WING

•SHOCK INDUCEDSEPARATION

@ Critical Mach Number

•VORTEXGENERATORS

•TIP VORTICES

•SECONDARY CONTROLS OR TABS:

Structures That Aid Control:To allow the aircraft to be flown “Hands-off” and to aid the pilot in moving the controls:

•FIXED TRIM TAB

•ADJUSTABLE TRIM TAB

•SERVO TAB

•ANTI-SERVO TAB

•SPRING TAB

•OTHER AIDS:

•RUDDER OVERHANG OR BALANCE SURFACE

•OTHER AIDS:

•AERODYNAMIC BALANCE PANEL

Structures That Hold People:To protect the crew and passengers,

withstand the stresses created in flight and landing, and mount all other major

components

•Truss•Pratt

•Longerons•Struts•Wire Stays

Structures That Hold People:To protect the crew and passengers,

withstand the stresses created in flight and landing, and mount all other major

components

•Truss•Warren

•MetalTubing

•Conventional Landing Gear:

•Tail Wheel

•2 Main Wheels

•“Tail Dragger”

Structures That Support the Aircraft on the Ground:

To absorb the landing stresses and allow movement on the ground:

•Conventional Landing Gear:

•Ground Loop

•Visibility on Ground

•Tricycle Landing Gear:

•Nose Wheel

•2 Main Wheels

•Drag Problems:

•Fixed Gear

•Drag Problems:

•Fixed Gear

•Wheel Fairings

•“Wheel Pants”

•Streamlines

•Drag Problems:

•Retractable

•Other Types of Landing Gear:

•Floats

•With wheels =

Amphibian

•Other Types of Landing Gear:

•Seaplane

•With wheels =

Amphibian

•Reciprocating (Piston) Engines:•The engine is attached inside the cowling to an ENGINE MOUNT which may be:

•Semimonocoque

•Welded tubular

That Hold the Powerplant:To hold the Powerplants in position,absorb the vibration, and cool and streamline them:

•Reciprocating (Piston) Engines:•The engine is attached inside the cowling to an ENGINE MOUNT which may be

•Semimonocoque

•Welded tubular

•“Rails” or “Cradle”

•Reciprocating (Piston) Engines:

•On all, the engine is attached to the mount by RUBBER SHOCK MOUNTS

•Known generically as “Lord Mounts”

•Isolate engine vibrations from the fuselage

•Turbine (Jet) Engines:•Turbine engines are mounted in PODS or NACELLES under the wings or on the side of the rear fuselage or inside the fuselage

•The pods are attached with PYLONS

•Turbine (Jet) Engines:

Rotorcraft:

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