9.15 Take a bus to the National Park.
9.30 5 hour hike through the moutain rainforests and valleys to Frog Lake. Along the way you have a chance to see native cats, squirrels, spotted dear, snakes, thousands of butterflies, and if you’re lucky, a Cat Ba Langur.
13.30 Arrive at remote Viet Hai village and meet the friendly local people who live within the National Park.
14.00 Lunch at a local house with home cooked food.
15.00 Walk fromt he village to the harbour and visit Lan Ha Bay and the floating fishing village. Optional swim at a secluded beach.
16.00 Return to Cat Ba Town for Helicopter back to Hanoi.
The helicopter is type of aircraft in which lift is obtained by means of one or more power-driven horizontal propellers called rotors. When the rotor of a helicopter turns it produces reaction torque which tends to make the craft spin also. On most helicopters a small rotor near the tail compensates for this torque. On twin-rotor craft the rotors spin in opposite directions, so their reactions cancel each other. The helicopter is propelled in a given direction by inclining the axis of the main rotor in that direction. The helicopter’s speed is limited by the fact that if the blades rotate too fast they will produce compressibility effects on the blade moving forward and stall effects on the rearward moving blade, at the same time.
Although the helicopter was only recently fully developed, its concept can date back to the late 1400’s. Since then, helicopters have been put into use by society in many ways. One can find helicopters in both civil and military areas. The early helicopters were mainly developed for military use, but later became certified for civilian use. Since then helicopters have evolved greatly, specifically with the design. Because a helicopter can perform more actions than a fixed-wing aircraft can, it is more complicated to fly. The helicopter must compensate for a variety of forces, like the spinning force induced by the main rotors. The
Who build the Helicopter?
Although fixed-wing aircraft receive all the attention by most historians, helicopter flight was the first flight envisioned by man. In fact, the ancient Chinese were playing with a hand-spun toy that rose upward when revolved rapidly and as early as the mid 1500’s, the great Italian inventor Leonardo Da Vinci had used his fertile mind to make drawings of a machine that we now know as the helicopter.
His design, like many others to follow, would work theoretically but would have been impractical in full-sized form.
Many extraordinary models were developed by an ever increasing number of great thinkers, but all the pioneers were missing two essentials: a true understanding of the nature of lift and an adequate engine.
The great breakthrough came at the end of the nineteenth century. The invention of the internal combustion engine made it possible for the pioneers to develop full-sized models with an adequate power source. It was then they found the first of many great problems: torque, the effect produced by the rotor to force the fuselage to rotate in the opposite direction as the engine.
The beginning of the 20th century saw the pioneers experimenting and resolving many of the problems that appeared with each advancement. The old saying,”One step forward and two steps back,” was the order of the day for the early pioneers. Dissymmetry of lift, the action that tended to cause the early helicopters to flip over, confounded the early pioneers until the invention of the swashplate. The swashplate, with cyclic pitch control allowed the rotor blade angles to be altered so that lift would be equal on each side of the central shaft.
However, there were many problems that had not been worked out on any one individual helicopter. Then on November 13, 1907, the French pioneer Paul Cornu lifted a twin- rotored helicopter into the air entirely without assistance from the ground for a few seconds.
After that, several models were produced by many designs but there were no more great advances until another French pioneer, Etienne Oehmichen, became the first to fly a helicopter a kilometer in a closed circuit in 1924. It was a historic flight taking 7 minutes and 40 seconds.
Advances began to come fast and furious. One of the more important advances in the development of vertical flight was made by the Spaniard Juan de la Cierva. His design, called the autogyro, was not a true helicopter but his contribution was very important.
By 1936, many of the problems had solutions and with the introduction of the German Focke-Wulf Fw 61, the first practical helicopter was a reality.
Vertical flight was not a dream anymore.
How Helicopters Fly ?
They have existed for only 70 years, yet they are without question one of the most versatile and vital vehicles in the world. They transport world leaders and the critically wounded; they fight forest fires and rescue people trapped in burning buildings; they can deliver huge payloads to areas that no other vehicle can reach.
In the last 40 years, helicopters increased their speed from 150 Km/h to 400 and their lifting capacity (payload) from 100 Kgs to 40.000
They were used extensively for the first time in the Korean war and today, they are used in all type of rolls. Some of them are :
• Search and Rescue
• Fire suppression
• Mail Service
• Arial photography
• Traffic ‘s Control
• Fertliser spreading
• Cattle ‘s Control
• Fence mending
• Militaries : Assault, Gunships, Antisubmarine, Electronic Warfare, etc
Where did the name and word Helicopter come from ?
On 24th September 1863, Viscount Gustave de Ponton d’AmÃ©court used the word in a monograph entitled “La ConqÃ»ete de l’air par l’hÃ©lice. ExposÃ© d’un nouveau systÃ¨me d’aviation”, published in Paris. In this 40-page document he put together the Greek words helico and pteron, meaning “spiral” and “wing”, to make the word hÃ©licoptÃ¨re. (Thanks Chris Jones)
How long can a helicopter stay in the air without moving around ? For example, if it where hovering over my house could it stay till it ran out of gas?
Yes, it can hover in one place until the fuel runs out or the pilot gets exhausted which ever occurs first. It takes more work to hover than in any other mode of flight, unless of course, the aircraft is equipped with hover hold. But trust me, you do not want a helicopter to hover over your house long.
What happens when the engine fails ? [Autorotation]
Well, in a multi-engine helicopter, the remaining engine will still be able to power the rotors and therefore normal flight will be able to be maintained.
“What happens if I lose my only engine or god-forbid, I lose all my engines?”
The simple answer to this question is that the helicopter will enter autorotation.
What is autorotation?
Autorotation is a condition where the main rotor is allowed to spin faster than the engine driving it. How is that achieved? It is actually quite simple.
All helicopters are fitted with a free wheeling unit between the engine and the main rotor, usually in the transmission. This free wheeling unit can come in different forms but one of the most popular is the sprag clutch. The free wheeling unit will allow the engine to drive the rotors but not allow the rotors to turn the engine. When the engine/s fail the main rotor will still have a considerable amount of inertia and will still want to turn under its own force and through the aerodynamic force of the air through which it is flying. The free wheeling unit is designed in such a way to allow the main rotor to now rotate of its own free will regardless of engine speed. This principle is the same reason that if you are in your car and you push your clutch in, or put it into neutral while the car is still moving, the car will coast along under it’s own force. This occurs regardless of what you do to the accelerator pedal.
Controlled Descent ?
The next question you are probably asking yourself is: “Does the pilot retain control of the helicopter?” The answer is yes. The pilot will still have complete control of his descent and his flight controls. The majority of helicopters are designed with a hydraulic pump mounted on the main transmission. As the rotor will still be turning the transmission, the pilot will still have hydraulically assisted flight controls. The pilot will be able to control his descent speed and main rotor RPM with his collective control stick. He will be able to control his main rotor RPM by increasing the collective pitch, which will increase drag on the rotor blades and thereby slow the main rotor. If he needs to increase his rotor RPM, he can decrease his collective pitch therefore decreasing drag.
The pilot will usually be able to find a suitable area for a safe landing by normal manipulation of his cyclic control stick and his directional, or tail rotor pedals.
Larger helicopters will usually have a generator mounted on the transmission that will still provide electrical power for flight and communication systems.
What happens to Torque Effect ?
Torque effect is the aircraft’s tendency to rotate in the opposite direction to the main rotor due to Newton’s third law “Every action has an equal and opposite reaction”. This is the reason why we need a tail rotor or some other form of anti-torque control. The question at hand is what happens to torque effect during autorotation? Well torque effect is directly proportional to the amount of force driving the main rotor, so when when the engine fails the amount of force driving the main rotor instantaneously decreases and therefore the torque effect decreases. This being the case the fuselage of the helicopter will tend to rotate due to the sudden lack of torque effect. The pilot will therefore have to immediately manipulate his directional pedals to overcome this problem and retain control of his aircraft.
So in conclusion if your helicopter’s engine/s should fail it is not just possible, but quite easy for the pilot to retain control and land safely and gently. This is the reason I believe that helicopters are far safer and more fun to fly in than fixed wing aircraft. A fixed wing aircraft will always need forward speed to safely land, with or without an engine operating. A helicopter can be made to land with zero forward speed whether the engine is operating or not.
Helicopter Vietnam offer a customized transportation experience for individuals who choose to use helicopter. Both individuals and corporations can greatly benefit from the use of air charter companies. With benefits that include convenience, comfort, and time saving, using an air charter company can be a good decision.
Helicopter Vietnam can also customize the in flight experience with Helicopter rides and specialized entertainment. The cost of helicopter charter can be quite competitive, and the experience very pleasant and enriching. The Helicopter Vietnam take the lead in providing flight packages, charter flight to through out Vietnam including:
Hanoi, Halong, Catbi, DonSon, Catba island, MongCai, LangSon, Caobang province, Laocai, Sapa, Dienbienphu, Hoabinh, Vinh, Hue, Dannang and HoChi Minh city.
Helicopter Vietnam has a wide range of helicopter services for:
– Corporate travels and Tours
– Investment Survey
– Medical evacuation
– TV and Movie work
– Oil industries
– Aerial Photography
– Mining Exploitation
– Forestry – Construction
– Viewing Red River and Halong Bay
– Viewing Mekong Delta and River
– Viewing Sapa
– View scenic Hai Van Pass, Langco beach,
– Hue Citadel and Myson
– Sea Cruise and viewing helicopter
– Adventure touring
– Events & Mice
– Special charter flight