1, single-rotor type
Helicopter engine driven rotor to provide lift, the helicopter lifted in the air, the single-rotor helicopter's main engine at the same time also outputs power to the tail of the small propeller, the onboard gyroscope can detect the helicopter slewing angle and feed back to the tail rotor, through the adjustment of the pitch of the small propeller can be counteracted by the large propeller produced by the different speed of the reaction force. Twin-rotor helicopters usually use relative rotation of the rotors to counteract the unbalanced lift generated by the rotors.
2, dual-rotor
Twin-rotor helicopters have two kinds, one is the *** axis double rotor, that is, the two rotors with the same axis, such as the Russian production of the card-27 helicopter, etc.; The other is a split-axis double rotor, that is, the two rotors are separated from the farther, each with its own axis, typical representative of the U.S. Chinook helicopters. Twin-rotor helicopters can also be categorized according to the relative position of the two rotor axes into longitudinal twin-rotor helicopters and transverse twin-rotor helicopters, as well as transverse cross twin-rotor helicopters.
The helicopter's rotor blade angle can be changed by a mechanism called a "tilt disk", which enables the rotor cycle to be varied to change the attitude of the helicopter by changing the lift at different positions on the rotor rotational plane, and then the direction of flight by changing the direction of the lift.
At the same time, after the helicopter lifts off the ground, the engine is kept at a relatively stable rotational speed, and the helicopter's ascent and descent are controlled by adjusting the total pitch of the rotor blades to get different total lift, so the helicopter realizes vertical takeoff and landing.
In October 1930, Italian Corradino D'Ascanio's helicopter was recognized as the first helicopter in the modern sense of the word, flying more than 800 meters ahead of the 18-meter altitude, D'Ascanio's helicopter with a *** shaft reversing double propeller.
In the 1930s, German Heinrich Focke designed the FA-61 helicopter, which continued to give public relations performances at various Nazi rallies, but the FL282, designed by German Anton Flettner, was arguably the first mass-produced helicopter, with nearly 1,000 produced for the German Navy in World War II, although it played no role in combat.
The VS300, designed by Igor Sikorsky (VS stood for Vought-Sikorsky, when Sikorsky was part of the Vought Aircraft Company), was the first to use a tail rotor, and really laid the groundwork for the modern helicopter
Expanded Facts
1, Advantages
The helicopter's outstanding features are that it can do maneuvering flight at low altitude (a few meters above the ground), low speed (from hovering) and constant nose direction, and especially can take off and land vertically in a small field. Because of these characteristics make it has a wide range of uses and development prospects.
In the military has been widely used in ground attack, landing, weapons delivery, logistical support, battlefield rescue, reconnaissance and patrol, command and control, communications, anti-submarine mine clearance, electronic countermeasures. In civilian use, it has been applied to short-distance transportation, medical care, disaster relief, emergency rescue, lifting equipment, geological exploration, forest protection and fire-fighting, and aerial photography. The transportation of personnel and materials between oil wells and bases at sea is an important aspect of civil use.
2, shortcomings and improvements
Current helicopters relative to fixed-wing aircraft, high vibration and noise, maintenance and repair workload is larger, the use of higher costs, lower speed, shorter range. The future direction of helicopter development is to improve in these areas.
Baidu Encyclopedia-Helicopters