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|Danang City Tour by Helicopter 1day|
Highlight: Danang City Tour by Helicopter 1day
Danang City Tour by Helicopter 1day
- 08h00 : Pick up guests.
- 08h30 : Arrive Da Nang Airport. Take photos with the helicopter and pilots for souvenirs.Listen to tour guide to know Da Nang airport history and flying skills when joining a helicopter tour.
- 09h00 : Take off and circle to enjoy Da Nang city view from board: famous buildings, My Khe beach, Son Tra Penisular, Tien Sa International Port and Bà Nà Mountains with the Huge Linh Ung Budha Statue.
- 10h00 : Land at Da Nang Airport. Receive souvenirs and say goodbye.
- 10h15 : Transfer back to hotel. End program.
* SERVICES INCLUDED:
- Helicopter and the professional pilot crew
- Experienced and enthusiastic English speaking tour guide
- Transit vehicles
- One solf drink and wet tissue
- Airport entrance ticket
- One photo with helicopter and pilots as souvenir
- Travel insurance
* TOUR PRICE ( USD/ 1PAX):
A helicopter is an aircraft that can take off and land vertically. Also called a "rotary aircraft," it can hover and rotate in the air and can move sideways and backwards while aloft. It can change direction very quickly and can stop moving completely and begin hovering.
A helicopter flies by means of the thrust that is created by the rotation of the blades of a main rotor that is mounted on a shaft above the fuselage, or body, of the aircraft. As the blades rotate, an airflow is created over them, resulting in lift. This raises the helicopter. A pilot maneuvers the helicopter by changing the pitch, or angle, of the rotor blades as they move through the air.
An engine is used to create the force needed to lift the aircraft and its passengers and cargo. Reciprocating gasoline and gas turbine engines are the most common types used on helicopters.
All helicopters need a way to counteract the torque produced by the main rotor. If this were not done, the rotor would turn in one direction, and the fuselage would turn in the opposite direction. Usually, a small tail rotor is used to produce a sideways thrust that prevents the fuselage from rotating. By increasing or decreasing the thrust produced by the tail rotor, the pilot can steer the helicopter to the left or right. Another way to counteract thrust is with two main rotors that turn in opposite, or counter-rotating, directions. Each rotor cancels the torque produced by the other. No tail rotor is needed in this type of helicopter.
Components of a helicopter
The pilot controls the helicopter by using rudder pedals, which turn the helicopter to the right or left, a cyclic pitch stick that tilts that helicopter forward, backward, or sideways, and a collective pitch stick that allows the helicopter to climb and descend vertically.
A helicopter is an aircraft which is lifted and propelled by one or more large horizontal rotors (propellers). Helicopters are classified as rotary-wing aircraft to distinguish them from conventional fixed-wing aircraft. The word helicopter is derived from the Greek words helix (spiral) and pteron (wing). The engine-driven helicopter was invented by the Slovak inventor Jan Bahyl. The first stable, fully-controllable helicopter placed in production was invented by Igor Sikorsky.
Compared to conventional fixed-wing aircraft, helicopters are much more complex, more expensive to buy and operate, relatively slow, have poor range and restricted payload. The compensating advantage is maneuverability: helicopters can hover in place, reverse, and above all take off and land vertically. Subject only to refuelling facilities and load/altitude limitations, a helicopter can travel to any location, and land anywhere with a clearing a rotor disk and a half in diameter.
Helicopters have many uses, both military and civil, including troop transportation, infantry support, firefighting, shipboard operations (http://www.tropicaled.com/helicopter2.htm), business transportation, casualty evacuation (including MEDEVAC, and air/sea/mountain rescue), police and civilian surveillance, carrying goods (some helicopters can carry slung loads, accommodating awkwardly shaped items), or as a mount for still, film or television cameras
Since around 400 BC the Chinese had a flying top that was used as a children's toy. Incidentally, the Wright brothers were given this toy as kids and were very much fascinated by it. This toy eventually made its way to Europe via trade and it has been depicted in a 1463 painting. "Pao Phu Tau" was 4th century AD book in China that described some of the ideas in a rotary wing aircraft.
The first somewhat practical idea of a human carrying helicopter was first conceived by Leonardo da Vinci in the 15th century, but it was not until after the invention of the powered aeroplane in the 20th century that actual models were produced. Developers such as Jan Bahyl, OszkÃ¡r AsbÃ³th, Louis Breguet, Paul Cornu, Juan de la Cierva, Emile Berliner, Ogneslav Kostovic Stepanovic and Igor Sikorsky pioneered this type of aircraft. A flight of the first fully controllable helicopter was demonstrated by RaÃºl Pateras de Pescara 1916 in Buenos Aires, Argentina. The Bell 47 designed by Arthur Young was the first helicopter to be licensed (in March 1946) for use in the United States.
A conventional aircraft is able to fly because the forward motion of its angled wings forces air downwards, creating an opposite reaction called lift that forces the wings upwards. A helicopter uses exactly the same method, except that instead of moving the entire aircraft, only the wings themselves are moved. The helicopter's rotor can simply be regarded as rotating wings.
Turning the rotor generates lift but it also applies a reverse force to the vehicle, that would spin the helicopter in the opposite direction to the rotor. At low speeds, the most common way to counteract this torque is to have a smaller vertical propeller mounted at the rear of the aircraft called a tail rotor. This rotor creates thrust which is in the opposite direction from the torque generated by the main rotor. When the thrust from the tail rotor is sufficient to cancel out the torque fromt the main rotor, the helicopter will not rotate around the main rotor shaft.
If the tail rotor is shrouded (i.e., a fan embedded in the vertical tail) it is called a fenestron. A fenestron rotor uses a belt driven system to turn the fan and is less efficient, but less noisy than a traditional tail rotor. Other helicopters use a "Notar" design: they blow air through a long slot along the tail boom, utilizing the coanda effect to produce forces to counter the torque. Notar is an acronym meaning no tail rotor. Notars adjust thrust by opening and closing a sliding circular cover near the end of the tail boom.
Another alternative, which saves the weight of a tail boom and rotor but adds its own complexities, is to use two large horizontal rotors which turn in opposite directions. An example is the Boeing CH-47 Chinook or the Kamov Ka-50. All of these systems are designed for the same purpose: to produce a net rotational speed of zero.
The amount of power required to prevent a helicopter from spinning is significant. A tail rotor can use up to 30% of the engine's power, and this power does not help the helicopter produce lift or forward motion. To reduce this waste during cruise, the tailfin is angled to produce a sideways lift which helps counter the main rotor torque. At high speeds, it is common for the tailfin to counteract the entire torque, thus leaving more power available for forward flight. This is commonly known as slip-streaming and can occur while in a hover on windy days making hovering turns difficult.
Useful flight requires that an aircraft be controlled in all three dimensions (see flight dynamics). In a fixed-wing aircraft, this is easy: small movable surfaces are adjusted to change the aircraft's shape so that the air rushing past pushes it in the desired direction. In a helicopter, however, there often isn't enough airspeed for this method to be practical.
For rotation about the vertical axis (yaw) the anti-torque system is used. Varying the pitch of the tail rotor alters the sideways thrust produced. Dual-rotor helicopters have a differential between the two rotor transmissions that can be adjusted by an electric or hydraulic motor to transmit differential torque and thus turn the helicopter. Yaw controls are usually operated with anti-torque pedals, on the floor in the same place as a fixed-wing aircraft's rudder pedals.
For pitch (tilting forward and back) or roll (tilting sideways) the angle of attack of the main rotor blades is altered or cycled during the rotation creating a differential of lift at different points of the rotary wing. More lift at the rear of the rotary wing will cause the aircraft to pitch forward, a increase on the left will cause a roll to the right and so on.
Helicopters maneuver with three flight controls besides the pedals. The collective pitch control lever controls the collective pitch, or angle of attack, of the helicopter blades together, that is, equally throughout the 360 degree plane-of-rotation of the main rotor system. When the angle of attack is increased, the blade produces more lift. The collective control is usually a lever at the pilot's left side, near his leg. Increasing the collective and adding power with throttle causes a helicopter to rise.
The throttle controls the absolute power produced by the engine that is connected to the rotor by a transmission. The throttle control is a twist grip on the collective control. RPM control is critical to proper operation for several reasons. Helicopter rotors are designed to operate at a specific RPM. If the RPM is too low, rapid descent with power, known as settling with power could result. If the RPM is too high, damage to the main rotor hub from excessive forces could result. In general, RPM must be maintained within a tight tolerance, usually a few percent. In many piston-powered helicopters, the pilot must manage the engine and rotor RPM. The pilot manipulates the throttle to maintain rotor RPM and therefore regulates the effect of drag on the rotor system. Turbine engined helicopters, and some piston helicopters, use servo-feedback loop in their engine controls to maintain rotor RPM and relieves the pilot of routine responsibility for that task.
The cyclic changes the pitch of the blades cyclically, causing the lift to vary across the plane of the rotor disk. This is how the pilot causes the aircraft to tilt, and the helicopter to move. The cyclic is usually controlled by the stick in front of the pilot.
As a helicopter moves forward, the rotor blades on one side move at rotor tip speed plus the aircraft speed and is called the advancing blade. As the blade swings to the other side of the helicopter, it moves at rotor tip speed minus aircraft speed and is called the retreating blade. To compensate for the added lift on the advancing blade and the decreased lift on the retreating bladeâ€” lift being a function of an airfoil's angle of attack and its relative airspeed the angle of attack of the blades is regulated by the geometry of the rotor blade control system and mechanisms that allow the blades to flap up and down. This fact of advancing and retreating blades defines the speed limitations of the helicopter.
If the angle of attack of any wing, including rotor blades, is too high, the airflow above the wing separates causing instant loss of lift and increase in drag. This condition is called aerodynamic stall. On a helicopter, this can happen in any of three ways.
1 As helicopter speed increases, the advancing blades approach the speed of sound and generate shock waves that disrupt the airflow over the blade causing loss of lift.
2. As helicopter speeds increase, the retreating blade experiences lower relative airspeeds and the controls compensate with higher angle of attack. With a low enough relative airspeed and a high enough angle of attack, aerodynamic stall is inevitable. This is called retreating blade stall.
3. Any low rotor RPM flight condition accompanied by increasing collective pitch application will cause aerodynamic stall.
Helicopters are powered aircraft, but they can still fly without power by using the momentum in the rotors and using downward motion to force air through the rotors. The rotors act like a "windmill" and turn. This technique is known as autorotation, and will give the helicopter crew a few precious seconds to quickly find a landing spot if its engine fails.
Helicopters are always designed so that even if the engines fail, autorotation will power the tail rotor or torque differential. Helicopters retain all flight controls when unpowered.
A very peculiar feature of the cyclic is that the lift is made to occur 90 degrees of rotation before the direction of tilt. This is because when one tries to tilt a spinning object (like a rotor), it moves at right angles to the direction of the force. This is called "gyroscopic precession". So control forces on the rotor are rotated 90 degrees before the desired motion. For example, forward motion requires less lift at the front of the disk and more lift at the rear of the disk, so the pilot pushes the cyclic forward. The helicopter's control linkages rotate the pitching forces 90 degrees backwards against the rotor spin, to push on the sides of the rotor rather than its front and back.
It took inventors many years to recognize precession, and to learn how to arrange the cyclic's control system to overcome it
Limitations of rotary-wing flight
The single most obvious limitation of the helicopter is its slow speed. The current record is around 400km/h set by the Westland Lynx. There are several reasons why a helicopter cannot fly as fast as a fixed wing aircraft.
When the helicopter is at rest, the outer tips of the rotor travel at a speed determined by the length of the blade and the RPM. In a moving helicopter, however, the speed of the blades relative to the air depends on the speed of the helicopter, as well as on their rotational velocity. The airspeed of the forward-going rotor blade is much higher than that the helicopter itself. It is possible for this blade to exceed the speed of sound, and thus produce vastly increased drag and vibration. It is theoretically possible to have spiralling rotors, similar in principle to variable-pitch swept wings, which could exceed the speed of sound, but no presently known materials are light enough, strong enough, and flexible enough to construct them.
Most rotors are not rigid. Because the advancing blade has higher airspeed than the retreating blade, a perfectly rigid blade would generate more lift on that side and tip the aircraft over. In consequence, rotor blades are designed to "flap" - lift and twist in such a way that the advancing blade flaps up and develops a smaller angle of attack, thus producing less lift than a rigid blade would. Conversely, the retreating blade flaps down, develops a higher angle of attack, and generates more lift. At high speeds, the force on the rotors is such that they "flap" excessively and the retreating blade can reach too high an angle and stall. In some designs the hub is rigid. The blades are made from composites which can bend without breaking. Fully rigid rotors exist and create very responsive helicopters. In most such designs, the lift is varied cyclically and according to the speed of the helicopter. The adjustment is either by adjusting the angle of attack of the blades, or by engine-powered vacuum devices that suck air into the blades, adjusting the lift.
The Westland Belvedere twin rotor helicopter had a large cargo door and external hoist, and was used as personnel/paratroop transport, casualty evacuation, and for lifting large loads. The Belvedere had a production run of only 26 and went into RAF service in 1961.
Rotorhead design is a limiting factor on many helicopters. Low or negative-G situations encountered in a semi-rigid system will result in blade flapping down until it hits the tail boom or other airframe structure, followed by rotor separation and catastrophic terrain impact.
Helicopters are susceptible to potentially disastrous vortex ring effects. In these, the downward wind from the rotor causes a circular vortex to form around the rotor. If this ring is augmented by terrain, wind, rain, or sea spray, the helicopter can lose enough lift to have settling with power and hit the ground.
During the closing years of the 20th century designers began working on helicopter noise reduction. Urban communities have often expressed great dislike of noisy aircraft, and police and passenger helicopters can be unpopular. The redesigns followed the closure of some city heliports and government action to constrain flight paths in national parks and other places of natural beauty.
Helicopters vibrate. An unadjusted helicopter can easily vibrate so much that it will shake itself apart. To reduce vibration, all helicopters have rotor adjustments for height and pitch. Most also have vibration dampers for height and pitch. Some also use mechanical feedback systems to sense and counter vibration. Usually the feedback system uses a mass as a "stable reference" and a linkage from the mass operates a flap to adjust the rotor's angle of attack to counter the vibration. Adjustment is difficult in part because measurement of the vibration is hard. The most common adjustment measurement system is to use a stroboscopic flash lamp, and observe painted markings or coloured reflectors on the underside of the rotor blades. The traditional low-tech system is to mount coloured chalk on the rotor tips, and see how they mark a linen sheet.
Landing On a ship
A helo deck is a helicopter pad on the deck of a ship, usually located on the stern and always clear of obstacles that would prove hazardous to a helicopter landing. In the U.S. Navy it is commonly and properly referred to as the flight deck. Shipboard landing for some helicopters is assisted though use of a haul-down device that involves attachment of a cable to a probe on the bottom of the aircraft prior to landing. Tension is maintained on the cable as the helicopter descends which assists the pilot with accurate positioning of the aircraft on the deck; once on deck locking beams close on the probe, locking the aircraft to the flight deck. This device was pioneered by the Royal Canadian Navy and was called "Beartrap". The U.S. Navy implementation of this device, based on Beartrap, is called the "RAST" system (for Recovery Assist, Secure and Traverse) and is an integral part of the LAMPS MK III (SH-60B) weapons system.
Hazards of helicopter flight
As with any moving vehicle, operation outside of safe regimes could result in loss of control, structural damage, or fatality. For helicopters the hazards are particularly acute since they are flying at relatively low altitude, with little time to react to a sudden event. The following is a list of some of the potential hazards:
Retreating blade stall
Settling with power
Operating within the shaded area of the height-velocity diagram
Each of these conditions is potentially fatal and recovery might not be possible. For this reason, good pilotage demands operation within safe flight regimes and avoiding hazardous conditions at all costs.
Helicopter models and identification
n identifying conventional helicopters during flight it is helpful to know that when viewed from below, the rotor of a French, Russian, Soviet or Ukrainian designed helicopter rotates anti-clockwise, whilst that of a helicopter built in Italy, the UK or the USA rotates clockwise (see list of helicopter models).
Some companies, notably Schweizer in the USA, are developing remotely-controlled variants of light helicopters for use in future battlefields.
Hybrid types that combine features of helicopters and fixed wing designs include the experimental Fairey Rotodyne of the 1950s and the Bell Boeing Osprey, which is on order by the US Marine Corps and is the first mass produced tilt-rotor aircraft to enter service.
A helicopter should not be mistaken for an autogyro, which is a historical predecessor of the helicopter that gains lift from an unpowered rotor.
Some common nicknames for helicopters are "copter", "chopper", "whirlybird", "helo" (common U.S. Navy usage) or "paraffin budgie" (the latter term being mostly used in the UK offshore oil industry).
Helicopters : How They Work
Rotary Wing Terminology
Lets talk a moment about terminology. There are many terms associated with rotary wing flight. One must become familiar with the terminology of rotorcraft before they can expect to understand the mechanics of rotary wing flight. Let's look at a few definitions.
Main Rotor System
• Root: The inner end of the blade where the rotors connect to the blade grips.
• Blade Grips: Large attaching points where the rotor blade connects to the hub.
• Hub: Sits atop the mast, and connects the rotor blades to the control tubes.
• Mast: Rotating shaft from the transmission, which connects the rotor blades to the helicopter.
• Control Tubes: Push \ Pull tubes that change the pitch of the rotor blades.
• Pitch Change Horn: The armature that converts control tube movement to blade pitch.
• Pitch: Increased or decreased angle of the rotor blades to raise, lower, or change the direction of the rotors thrust force.
• Jesus Nut: Is the singular nut that holds the hub onto the mast. (If it fails, the next person you see will be Jesus).
Main Rotor Blade
• Leading Edge: The forward facing edge of the rotor blade.
• Trailing Edge: The back facing edge of the rotor blade.
• Chord: The distance from the Leading Edge to the Trailing Edge of the rotor blade.
• Swash Plate: Turns non-rotating control movements into rotating control movements.
• Collective: The up and down control. It puts a collective control input into the rotor system, meaning that it puts either "all up", or "all down" control inputs in at one time through the swash plate. It is operated by the stick on the left side of the seat, called the collective pitch control. It is operated by the pilots left hand.
• Cyclic: The left and right, forward and aft control. It puts in one control input into the rotor system at a time through the swash plate. It is also known as the "Stick". It comes out of the center of the floor of the cockpit, and sits between the pilots legs. It is operated by the pilots right hand.
• Pedals: These are not rudder pedals, although they are in the same place as rudder pedals on an airplane. A single rotor helicopter has no real rudder. It has instead, an anti-torque rotor (Also known as a tail rotor), which is responsible for directional control at a hover, and aircraft trim in forward flight. The pedals are operated by the pilots feet, just like airplane rudder pedals are. Tandem rotor helicopters also have these pedals, but they operate both main rotor systems for directional control at a hover.
Here are some of the component parts that make up a helicopter. While this is an example of one specific helicopter (UH-1C), not all helicopters will have all of the parts listed here. Some of this may be a bit more of the same old stuff we have just discussed, but it will show everything as it relates to everything else on the aircraft and the location of each component.
Anatomy of a Helicopter
• Rotor Blade: The rotary wing that provides lift for the helicopter.
• Stabilizer Bar: Dampens control inputs to make smoother changes to the rotor system.
• Swashplate: Transfers non-moving control inputs into the spinning rotor system.
• Cowling: The aerodynamic covering for the engine.
• Mast: Connects the transmission to the rotor system.
• Engine: Provides power to the rotor systems.
• Transmission: Takes power from the engine and drives both rotor systems.
• Greenhouse Window: A tinted window above each of the pilot seats.
• Fuselage: The body of the helicopter.
• Cabin Door: Allows access to the cabin and cockpit.
• Skids: Landing gear that usually have no wheels or brakes.
• Crosstube: The mounting tubes and connection for the skids.
• Motor Mount: A flexible way to attach the engine to the fuselage.
• Tailboom: Also known as an "empenage" is the tail of the helicopter.
• Synchronized Elevator: A movable wing that helps stabilize the helicopter in flight.
• Tailrotor: Provides anti-torque and in-flight trim for the helicopter.
• Tail Rotor Driveshaft: Provides power to the tailrotor from the transmission.
• 45 Degree Gearbox: Transfers power up the vertical fin to the 90 degree gearbox.
• 90 Degree Gearbox: Transfers power from the 45 degree gearbox to the tailrotor.
• Vertical Fin: Holds the tailrotor and provides lateral stabilization.
• Tail Skid: Protects the tailboom when landing.
This picture illustrates how the helicopter moves when using the appropriate controls. Up and Down movements are controlled by the "Collective". Side to Side and Forward and Back motions are controlled by the "Cyclic". Lateral control (Also called directional control or "Yaw") is achieved by using the "Foot Pedals".
While you are looking at the picture of the controls (Left side of this paragraph), I will explain how to do a normal takeoff. First, you must make sure the throttle is all the way open (For a turbine powered helicopter, advanced properly for a reciprocating engine powered helicopter). Once you have established the proper operating RPM, then you can pull up slowly on the collective. As you increase collective pitch, you need to push the left pedal (In American helicopters...right pedal for non-American models) to counteract the torque you generate by increasing pitch. (In reciprocating engined models, you will advance the throttle as you increase collective pitch). Keep pulling in pitch and depressing the pedal until the aircraft gets light on the skids. You may sense a turning motion to the left or right, if so, you may need more or less pedal to maintain heading. The cyclic will become sensitive and (depending on how the aircraft leaves the ground heels or toes of the skids last) as you continue to pull in pitch and depress the pedal, you will put in the appropriate cyclic input to level the aircraft as it leaves the ground. As the aircraft eases into the air, forward cyclic will be required to start the aircraft in a forward motion. As the aircraft advances forward, it will gain speed until about 15 knots and then the aircraft will shudder a little as you transition through ETL (Effective Translational Lift...See the unique forces page for a more in depth explanation of ETL). As you transition through ETL, the collective will need to be reduced, the pedal will need less pressure, and the cyclic will need to be forced forward to counteract the force against the front of the rotor system. Failure to push forward will result in an abrupt nose high attitude and a reduction in forward speed. After the shudder of ELT is experienced, you will see a marked gain in forward airspeed, a reduced need for pedal input and a reduced need for collective pitch as the rotor system becomes more efficient. The airspeed indicator will most likely jump from zero to 40 knots indicated airspeed and will smoothly advance as the aircraft goes faster. Now you have taken off and with a little release of foward cyclic pressure, the aircraft will establish a climb and continue to gain airspeed. At this point, the pedals are only used to trim the aircraft, and most maneuvers are accomplished by using a combination of the cyclic and collective controls. (That wasn't so hard...was it?)
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