basic helicopter - report1

MD 500 Series – The MD 520N® Helicopter

1. OPERATIONS/FUNCTIONS

An instrument panel located forward of the seat structure along the aircraft

centerline necessarily contains standard flight and engine instruments in addition to

warning and caution lights. This is referred to as the Dual Command Flight Controls used

for maneuvering the helicopter in taking off, landing, and in flight; also found on this

panel are devices used for navigation and communication, and flight status-monitoring

indicators.

Left-hand command is standard for the MD 520N Helicopter. The control

stick or yoke is used by the pilot by manipulation in order to achieve controlled

aerodynamic flight; it controls the helicopter such that the main rotor blades’ angle of

attack with respect to its relative circumferential path are adjusted for consequential

rolling or pitching maneuvers. The MD 520N has two vertical stabilizers that stabilize the

rotorcraft during forward motion in fight. The left vertical stabilizer is connected to the

pilot’s anti-torque (rudder) pedals. It operates similar to an airplane rudder. The stabilizer

moves through approx. 29 degrees of motion, and is moveable to provide sufficient

control power in an autorotation and to unload it in forward flight. A Yaw Stability

Augmentation System controls the right vertical stabilizer driven by a small electro-

mechanical actuator mounted within the horizontal stabilizer; this vertical stabilizer moves

through approx. 15 degrees of motion.

The NOTAR technology system innovatively uses an enclosed variable-pitch

composite blade fan which produces a low pressure, high volume of ambient air to

pressurize the composite tailboom. Air is expelled through a slot somewhat before the

middle of the tailboom, causing a boundary-layer control (with the downwash effect of

main rotor blades’ spinning) called the “Coanda Effect”. The tailboom therefore somewhat

becomes a wing, with a relative wind or flight path headed against the downwash of the

rotor system, producing up to 60% of the rotorcraft’s anti-torque. At the end of the

tailboom is a rotating direct jet thruster from where portion of the inputted ambient air

is also expelled out. In forward flight, the vertical stabilizers in conjunction with the direct-

jet thruster provide the required anti-torque and directional control.

Date : June 14, 2013

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Name : Dizon, John Kevin M. Report No. 01 : NOTAR Helicopter Controls

Instructor : Dr. Jay Jack R. Manzano

2. DESIGN

(A Schematic Diagram of the NOTAR System Design, Principle, and Operation)

(Simple Diagram of the Pilot to Roll/Pitch Maneuvers via the Control Stick)


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3. INSTALLATION

The MD 520N helicopter is a 5 place, turbine powered, rotary-wing aircraft

constructed primarily of aluminum alloy though its tailboom and thruster are made out

of graphite composite. Its airframe structure is egg-shaped and cleanly streamlined for

efficient aerodynamic flows. The fuselage body is a semi-monocoque design, divided into

the forward section which comprises of the pilot compartment and directly aft separated

by a bulkhead is a passenger or cargo compartment. The left seat in the pilot’s

compartment is the pilot’s seat. Just below the pilot/passenger floor panel is a

compartment space for the aircraft battery while it also provides a good small amount of

cargo storage or installation of avionics equipment.

The aft section includes the structure for the tailboom attachment, NOTAR

fan and engine compartment. The lower section features the center beam which provides

a housing for the two fuel cells. Cyclic, collective, and adjustable pedal controls are

provided at the left crew position. Adjustable friction devices, which may be varied to suit

the individual pilot, are incorporated in the cyclic, collective and throttle controls.

An optional Dual control system may be easily uninstalled to provide an

extra space for an extra passenger or for cargo.

4. MECHANISM

For the MD 520N helicopter, the main rotor is a fully articulated five-bladed

system, with anti-torque provided by the NOTAR system. While contemporary helicopters

use torsion tension straps in lieu of thrust bearing stacks to contain blade centrifugal

loading and allow feathering, the MDHS strap pack arrangement goes three steps further.

First, the strap configuration (while secured firmly to the hub) actually allows the

centrifugal load exerted by one blade to be countered by the force exerted by the

opposite two blades. Thus, very light centrifugal loads are sensed by the hub. Second,

the V-legs of the strap pack rotate as driving members to turn the blades. Finally the

straps are configured to allow feathering and flapping of the blades. The main rotor

blades are secured to the hub with quick release lever type pins. Power from the turbo-


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-shaft engine is transmitted through the main drive shaft to the main rotor

transmission, from the main transmission through a drive shaft to the aft transmission

and through a second drive shaft to the NOTAR. An overrunning (one-way) clutch,

placed between the engine and main rotor transmission permits free-wheeling of the

rotor system during autorotation. The overrunning clutch transmits power from the

engine to the main drive shaft. The clutch has no external controls and disengages

automatically during autorotation and engine shutdown. The main drive shaft connects

to the main rotor transmission input shaft. The engine oil cooler blower is belt driven off

the main drive shaft. The oil cooler blower draws cooling air from the air inlet fairing to

supply ambient air to the engine and transmission oil coolers and to the engine

compartment. The main rotor transmission is mounted on the basic airframe structure

above the passenger/cargo compartment. The transmission is lubricated by its own air

cooled lubrication system. The main rotor static mast is non-rotating and is rigidly

mounted to the mast support structure. The rotor hub is supported by the rotor mast.

4. ILLUSTRATIONS/FIGURES

MD 520N – 3 Views


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The Instrument Panel

An MD 520N Helicopter in flight


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Labeled Aft Section View showing the NOTAR System


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basic helicopter - report1

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