Helicopter performance depends on the length of the rotor blades . For heavy lifting, a large rotor works best, but short blades reduce drag and ultimately allow for higher maximum speeds. ... When the rotor spins fast, centrifugal force stretches the spring, and the blade tips expand, increasing overall length.
How does the size of a helicopter’s blade length affect the speed and number of rotations?
The longer the blade, the lower the possible rotor RPM since the tip approaches supersonic speed more quickly.
Are Longer helicopter blades better?
Aerodynamics dictates that large and slow rotors trump faster ones; moving a volume of air more slowly is inherently more efficient than a smaller fan pushing the same amount of air much faster. ... For structural reasons, longer blades are thicker blades , so the longer the blade gets, the more it sags from the rotor hub.
What is the most challenging factor in the development of helicopter?
Hovering is the most challenging part of flying a helicopter. This is because a helicopter generates its own gusty air while in a hover, which acts against the fuselage and flight control surfaces. The end result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be.
How does the speed of rotation affect the flight of a real helicopter?
Increase the rotor speed so that the helicopter flies vertically upward . The rate of vertical ascent should be slow and steady.
Do helicopters have 2 or 4 blades?
Helicopters have between 2 and 8 main rotor blades . The larger the helicopter, the heavier it weighs and needs more lift to be produced. By using more blades, designers can increase the entire rotor system surface area while keeping the size of each rotor blade as small as possible.
Why are helicopter blades so thin?
The blades of a helicopter are long, narrow airfoils with a high aspect ratio , a shape that minimizes drag from tip vortices (see the wings of a glider for comparison). ... Tips of some helicopter blades can be specially designed to reduce turbulence and noise and to provide more efficient flying.
What are the three basic flight conditions of a helicopter?
There are three basic flight conditions for a helicopter: hover, forward flight and autorotation .
How do helicopters go forward?
The rotor blades are pitched lower in the front of the rotor assembly than behind it. This increases the angle of attack — and creates lift — at the back of the helicopter. The unbalanced lift causes the helicopter to tip forward and move in that direction.
Can helicopters land if engine fails?
Unlike a plane, which can glide a large distance with no power, a helo has no way to slow down—or so the thinking goes. ... Actually, helicopters have a built-in mechanical control called the collective pitch lever that allows them to descend slowly and land even if the engine dies. This maneuver is called autorotation .
How high can a helicopter fly?
| Helicopter Name First Flight Highest Altitude Records | Mil Mi-8 1961 30,000 feet | Boeing CH-47 Chinook 1961 >18000 feet | AgustaWestland AW109 1971 13,800 feet | Sikorsky H-60 Black Hawk 1974 19,151 feet |
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Are helicopters supposed to fly?
A helicopter does not want to fly . It is maintained in the air by a variety of forces and controls working in opposition to each other, and if there is any disturbance in this delicate balance, the helicopter stops flying, immediately and disastrously. There is no such thing as a gliding helicopter.
What are the 3 types of helicopter tail rotor?
Main rotor systems are classified according to how the main rotor blades are attached and move relative to the main rotor hub. There are three basic classifications: semirigid, rigid, or fully articulated . Some modern rotor systems, such as the bearingless rotor system, use an engineered combination of these types.
Can a helicopter fly without a tail rotor?
One significant advancement in the last decade has been the no-tail rotor, or NOTAR, helicopter. ... As you now know, vertical-lift flight is impossible without a tail rotor to counteract the torque produced by the main rotor.
How many times does a helicopter blade rotate in one minute?
A helicopter also needs a powerful engine and a large transmission to reduce the engine’s rotation rate to something appropriate for the large rotors. For example, a U.S. Army UH-60 Black Hawk engine’s output of 20 900 revolutions per minute turns the main rotor
