SEMINAR ONLANDING GEAR

PRESENTED BYABHIJITH.VPREGNO:13021896

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Contents1. Introduction2. Purpose of landing gear3. Types of landing gear arrangement4. Design considerations5. Construction6. Aircraft breaks7. Development of landing gears8. Antiskid systems

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INTRODUCTION Aircraft landing gear supports the entire weight

of an aircraft during landing and ground operations.

They are attached to primary structural members of the aircraft.

For snow it will be skis type For water it may of pontoon type For ground and water An amphibious aircraft

with retractable wheels

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Purpose of Landing Gear To provides structural support to the aircraft

for ground operation To provides maneuverability for ground

operation To provides a mean to absorb unusually

loads incurred during landing and ground operation

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TYPES OF LANDING GEAR ARRANGEMENT

A. Tail wheel type (Conventional)B. Tandem loading gear (longitudinally Aligned) C. Tricycle type landing gear

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Retraction Type –. As speed of aircraft increases the drag caused by the landing gear becomes Greater and a means to retract the gear to eliminate parasite drag is required.

Shock Absorbing-The shock energy is altered and transferred throughout the airframe at a different rate and time than the single strong pulse of impact.

Non Shock Absorbing- The shock is absorbed by converting the energy into heat energy.

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Design considerations Maximum strength Minimum weight High reliability Overall aircraft integration Low cost Airfield compatibility Landing Gear should locate near the center

gravity (CG) of the plane CG location are depended on aircraft

configuration, loading, fuel state

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CONSTRUCTION

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Wheel alignment on an aircrafta) Parallel to the longitudinal axis

(aligned) b) Converge on the longitudinal axis

(tow-in)c) Veer away from the longitudinal

axis (tow-out)

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To decrease drag in flight some undercarriages retract into the wings and/or fuselage with wheels flush against the surface or concealed behind doors; this is called retractable gear.

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Air Craft Brakes The brakes slow the aircraft and stop it in a reasonable amount of time. They hold the aircraft stationary during engine run-up and, in many cases, steer the aircraft during taxi.

On most aircraft, each of the main wheels is equipped with a brake unit.

The nose wheel may have or may not have a brake. In the typical brake system, mechanical and/or hydraulic linkages to the rudder pedals allow the pilot to control the brakes.

Brakes principle is the conversion of kinetic energy of motion into heat energy through the creation of friction.

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on some independent braking systems.

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Types of Brakes1. Single Disc Brakes or Floating Disc Brakes2. Dual Disc Brake3. Segment Rotor Disc

Brakes4. Carbon Disc Brakes5. Expander Tube Disc

brakes6. Boosted brakes 7. Power Brakes

A cross-sectional view of a Goodyear single-disc brake calliper illustrates the adjusting pin assembly that doubles as a wear indicator.

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Materials

- Ultra-High Tensile Steels are already being integrated into the A400M and the B-787 landing gear, replacing the low-alloy steels.

- Research into organic matrix composites and metal matrix composites using titanium are promising, though still very expensive.

Corrosion- Many modern aircraft have cadmium in the

landing gear to prevent corrosion and chrome plating to reduce friction wear.

- Advancements in stainless steels and titanium will replace the cadmium in landing gear.

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ANTISKID SYSTEM Antiskid system is a feature found in high

performance aircraft braking system. It is important because if a wheel goes into skid, its braking value is greatly reduced.

The skid control system performs four functions: i) normal skid control, ii) locked wheel skid control, iii) touchdown protection and iv) fail-safe protection.

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Normal Skid Control

It comes into play when wheel rotation slows down but has not come to a stop. When this slowing down happens, the wheel sliding action has just begun and not reached a full scale

slide. In this situation the skid control valve removes

some of the hydraulic pressure to the wheel, which permits the wheel to rotate a little faster and stop its sliding.

The skid detection and control of each wheel is completely independent of the others.

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QUESTIONS ?

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