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We see here what is called is oil canning.
Here is the area where the engine is located.
The size of this engine is similar to the one used on the APU units of big planes.
The manufacturer of the engine is Allison, Rolls Royce.
There is a compressor module, accesory gear box, the tubine and the combustion chamber.
The cycle begins where the red covers are seen.
The air goes through the compressor, then the combustion chamber,
the air gasses turn around and then they are expelled.
There are two turbines, and N1 moves N2.
From N2 there is an axle that goes to the transmission.
The speed is reduced and the main rotor moved.
The other axle goes rearwards to move the tail rotor.
The panelling and rotor blades are made of composite material.
To avoid rotation caused by crossed winds, the step of the tail rotor blades is controlled
by displacing the blades. At takeoff, they need to be moved to compensate
the initial rotation caused by the main rotor.
We need to compensate the force of rotation that results from the impulse of the main
rotor.
The main rotor twists counter-clockwise, so the fuselage tends to rotate clockwise.
To avoid that rotation of the fuselage, the tail rotor creates a torque force.
Big helicopters have big tail rotors.
The blades of this tail rotor are made of metal.
They need metal to metal glue to be attached toghether.
These fairings cover the transmission that gives propulsion to the tail rotor.
The spin is reversed and the speed lowered.
The engine has a spin of 6000 RPMs and here its reduced to 2000 RPMs,
The same applies to the power sent to the main rotor. There is a transmission
reducing the speed in two stages, so the main rotor spins at aprox. 300RPMs.
Lets go see the bearings on the front.
It has a pitch articulation, step change and the blades also rotate horizontally around
themselves.
This main rotor is a semi-rigid configuration. There are rigid, semi-rigid and totally flexible.
The blade has two bearings, one vertical and one horizontal.
They also use lead weights inside the bolts.
The tail blades are red, while the main rotor´s are blue.
The white bands help to adjust the trace visually. When they are balanced,
we only see one trace. This helps to avoid excessive vertical vibration.
The main blades have reinforcements to help resist abrasion on the leading edge.
If blade repair has to be made, one blade costs aproximately US $30,000.
They need constant cleaning and polishing for maintenance.
This helicopter shouldn´t fly throw hail or volcanic dust.
Also if the dust enters to the engine, the compressor has to be washed.
Lets see the airframe structure. It can carry two pilots and three passengers.
The fuel tank is located below. The fuel is loaded from the other side.
This is the fuel register. Care should be taken here.
These are the panels. The main airframe is composed of several frames attached
to the transversal tubes of the landing gear. They have bolts for attaching wheels.
The center of gravity is aligned a few inches behind the mast.
All the control tubing passes below the floor, then rises up and goes to the hydraulic actuators,
those rods at the center of the mast. They change the step of the blades.
These are like the wings of an airplane, but in this case the step need to be controlled.
As the step is changed, the ascent begins, which is done with the collective lever, up
and down.
Below to the rods is located an oscilating which also moves when the cyclic is moved.
The pilot controlling causes the main rotor to pitch forwards or backwards and left or
right,
thus moving the aircraft in the same directions. It requires lots of expertise to maintain
a stationary flight with the aircraft.
This aircraft is not pressurized. It carries light weight doors and low number of rivets.
The core material is aluminum on this panels.
This main square is closed with a main beam above.
The transmission is attached with two brackets, four bolts on each bracket.
Sixteen in total supporting the airframe.
Up there is located a nut holding the main rotor with the mast. It requires a specialized
torquing considerably big.
This part of the assembly is critical for the safe flight of the helicopter.
If torquing is not done properly, the rotor can separate from the fuselage during flight
maneuvers.
The actuators have an hydraulic pump impulsated by the transmission.
If the engine shuts down suddenly, the rotor can keep spinning thanks to a clutch
that goes from the engine to the transmission.
The rotor keeps spinning like when no pedal is done on a rolling bike.
The hydraulic pump still generates pressure after the engine has shut down.
If the engine shuts down, pilots can use autorrotation to land the aircraft safely.
Its a maneuver to keep the rotor spinning because if the spinning stops,
the helicopter drops down very quickly.
After 60 knots of speed, the rudder pedals can be aligned toghether again.
The vertical stabilizer on the tail serves as a lateral compensation at those speeds.
It is inclined to the right by about 7 degrees and functions like a wing.
The horizontal stabilizer is like a wing upside down. Look how it is inverted.
When the tail pitches upwards, the horizontal stabilizer holds the tail downwards.