Group Two Materials' Presentation

8/3/2019 Group Two Materials' Presentation

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BRIEF HISTORY OF HELICOPTERS

The idea of a helicopter is bionic in origin,

i.e. it was derived from an attempt to adapt anatural phenomena-in this case, the whirling,bifurcated fruit of the maple tree-to a

mechanical design. Leonardo Da Vinci sketched a flying

machine that may have been based on thewhirlgig during the 15th century.

In the early 19th century, Sir George Cayleydrew a twin-rotor aircraft.

In the early 20th century, Paul Cornu

managed to lift himself off the ground for a


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For a long time no one could devise anengine that could generate enough verticalthrust to lift both the helicopter and anysignificant load off the ground.

The first helicopter was built by Igor Sikorskyin 1909 but neither the prototype not itssuccessor in 1910 succeeded.

During World War I, Theodore von Karmanconstructed a helicopter that was able hoverfor extended periods.

Years later, Juan de la Cierva developed amachine called an autogirowhich became

popular in the 1920s and 30s. The helicopter was eventually perfected by

Igor Sikorsky with advances in aerodynamictheory and building materials. It was used

extensively during World War II.


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A TYPICAL HELICOPTER

A typical helicopter has four(4)

compartments; The rotor blades

The fuselage

The tail plane The landing gear

A helicopters power comes from either a

piston engine or a gas turbine (recently,the latter has predominated), whichmoves the rotor shaft causing the rotor to

turn. The rotor achieves lift by pushing the


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MATERIALS USED IN THE

PRODUCTION OF A HELICOPTER

In general, the airframe i.e. fundamentalstructure of a helicopter can be made ofeither metal or organic compositematerials or a combination of the two.

Higher performance requirements willrequire higher strength-to-weight ratiooften epoxy reinforced with glass, aramid(a strong flexible nylon fiber) or carbonfibre.

Tubular and sheet metal substructuresare usually made of aluminum, though

stainless steel or titanium is sometimes


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HELICOPTER ROTOR BLADES

They are usually made of fibre-reinforcedplastics (FRPs) which may be adhesivelybonded with an external sheet metal layer toprotect the edges. The composite can beglass or carbon FRPs

The matrix has the following characteristics; They allow external stresses to be conveyed

and distributed to them.

They are ductile and relatively soft.

With high plasticity, they prevent crackpropagation between fibres.

They are light and readily available at low

cost.


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THE FUSELAGECanopies, windscreens and passengercompartment windows are generally made of

polycarbonate sheet. They are made by layingthe sheet over a mould, heating it and forming itwith air pressure in a process called free-blowingin which no tool ever touches the part. Other

materials used are polystyrene, fibreglass andcarbon fibre.

These materials have the followingcharacteristics;

Polystyrene is very inexpensive and serve as verygood protective shells for little helicopters.

Polycarbonate is light and inexpensive but coldweather makes them very brittle.

Fibreglass is heavier and more expensive butstron er.


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THE TAIL PLANE

This carries the anti-torque rotor or tail rotor;which is a smaller rotor mounted so that it

rotates vertical or near-vertically in order tocounter the torque effect created by the mainrotor. They are majorly made from carbonfibre and glass fibre but for smallerhelicopters, aluminium and plastics are used.

The characteristics of the materials are;

They are strong and light.

They handle heat and cold properly. They absorb vibration.

Carbon fibre can be moulded to be superstiff in one direction and flexible in anotherdirection.


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THE LANDING GEAR

This is an area of helicopter design that

continues to elude the compositescommunity. This is due to the fact thatstructural elements with concentratedloads and conservative design practice

has traditionally dictated metals for itsuse.

But this may change if the on-going

research to design and fabricatelightweight and durable composite landinggears is successful.


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THE LANDING GEAR


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THE FUTURE HOTELICOPTERS


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THE FUTURE: HOTELICOPTERS

The hotelicopter is modelled on an old soviet Mil

V-12 helicopter and features 18 luxuriously-appointed soundproof rooms complete withqueen sized beds, wireless internet and roomservice as expected from a 5-star hotel.

Group Two Materials' Presentation

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