0
Helicopters
A helicopter is an aircraft which is propelled and lifted in the air by one or more large horizontal rotors. Focke-Wulf Fw 61 was the first operational helicopter manufactured by Focke-Achgelis in 1936.
1,671 Questions
Why don't helicopters spin around in the air?
Some helicopters feature a second rotor underneath the first rotor that counters the force applied to the body of the helicopter by applying thrust in the opposite direction of the main rotor. This stops the helicopter from spinning around. Others, instead of a second rotor underneath the first rotor have a back rotor that essentially does the same thing, which is provide a equal force to the first rotor preventing the helicopter from spinning =0
Helicopters hover by using their main rotor to generate lift, which counteracts the force of gravity pulling the helicopter down. By adjusting the pitch angle of the main rotor blades, the pilot can control the amount of lift produced to maintain a steady hover. Additionally, helicopters can adjust their tail rotor to counteract the torque created by the main rotor rotation, allowing for stable hovering.
How does the helicopter stay stationary in the air?
Two things keep a helicopter flying, and another keeps it flying straight.
To take off:
1) The blades are shaped like the wings of an airplane and create a difference in pressure (high underneath the wing, low above). This difference in pressure "pushes" the helicopter upwards (lift). But because of gravity, however, there might not be enough lift to take off from the ground.
2) In order to take off, the blades must rotate at supersonic speeds (to be stronger than gravity's push downwards), this make it possible to gain altitude.
To "Fly:"
1) A helicopter's blades in air act like a boat's propeller in water. If the blades rotate at an angle, it will start moving. To make the helicopter hover, the blades must be perfectly straight up. At the same time, the rotating blades make the helicopter itself rotate the other way (about the axis of rotation).
In a GPS, the helicopter would not be going anywhere like this (with no angle on the blades), but the Direction at which it is looking will be changing in circles
2) Helicopters need a way to fix this crazy-out-of-control spinning. They can use a tail rotor for this, but they can also use a "twin" set of blades that rotate in opposite directions (counter-rotating blades).
With the addition of counter-spinning blades, now the GPS will be pointing at 1 direction.
in summary:
1) By keeping the blades rotating fast enough to be lifting with the same force as gravity is pushing down, the altitude is kept the same.
2) By keeping the Blades from spinning at an angle, the Helicopter does not move to the sides.
3) By using a counter-rotating blades set, the helicopter is able to keep looking at one direction.
with these 3 things, Helicopter are able to hover in air, and their GPS can be kept and a fixed height, at fixed position on a map, and at a fixed direction.
What science concepts are involved in helicopter flight?
Helicopter flight involves principles of aerodynamics, including lift and drag. The main science concepts at play are Bernoulli's principle and Newton's third law of motion. Bernoulli's principle explains how differences in air pressure above and below the rotor blades create lift, while Newton's third law states that for every action (downward force of the blades), there is an equal and opposite reaction (upward force of the helicopter).
Why don't helicopters tip over from unequal lift from the two sides of the rotor?
Helicopters have a tail rotor that counteracts the torque created by the main rotor, ensuring the helicopter remains balanced. The pilot can also adjust the pitch of the rotor blades to control lift and maintain balance. Additionally, modern helicopters are designed with sophisticated control systems that help maintain stability in flight.
How does the length of the rotor blades affect the paper spinner stay in the air?
The length of the rotor blades will affect the paper spinner's flight by influencing the lift generated. Longer blades can produce more lift due to a larger surface area, allowing the spinner to stay in the air for longer periods. Shorter blades may not generate enough lift, causing the spinner to fall more quickly.
Is helicopters a type of energy transformations?
No, helicopters are aircraft that generate lift through the rotation of their rotor blades. Energy transformations involve converting one form of energy into another, such as mechanical energy into electrical energy.
Does adding mass to a paper helicopter affect the rotation speed of the helicopter?
If you are adding mass to the outside of the blades, it will make the blades rotate much more slowly.
However if you add mass to the inside of the blades it will increase the rotational speed, however more force will be needed to start the rotation.
How does the helicopter blade works at when takeoff?
During takeoff, the helicopter blade applies lift by generating upward airflow which creates a pressure difference between the top and bottom of the blade. This pressure difference causes the blade to move upward, lifting the helicopter off the ground. The angle of attack and rotation speed of the blades also play a significant role in generating lift for takeoff.
Why does a typical small helicopter with a single rotor have a second small rotor on its tail?
The small rotor on the tail, called the tail rotor, counteracts the torque produced by the main rotor of the helicopter. Without the tail rotor, the helicopter would spin uncontrollably in the opposite direction of the main rotor. The tail rotor helps maintain the helicopter's balance and heading.
How is drag eliminated on a helicopter?
Drag on a helicopter can be reduced by streamlining the body and rotor blades, ensuring smooth airflow over the surfaces. Another way is to use a more powerful engine to generate more lift with less drag. Additionally, adjusting the pitch of the rotor blades to the most efficient angle helps in reducing drag.
"For every action there is an opposite and equal reaction." For the helicopter to make the blade move in one direction, the blade will try to make the helicopter move in the opposite direction.
Since the blade tries to make the helicopter spin, something is needed to keep the helicopter from spinning. So the manufacturer puts a tail rotor on the helicopter.
Why don't helicopters spin in circles?
The back rotor of the helicopter counters the force applied to the body of the helicopter by the main rotor by applying thrust in the same direction as the main rotor. The force from the main rotor is applied in the opposite direction the main rotor is spinning. So say the force the main rotor was exerting on the body of the helicopter was causing the tail to move left then the back rotor would be designed to apply an equal force pushing the tail right to keep it from spinning.
If the back rotor of a helicopter malfunctioned it would begin to spin.
How does the wing shape on an airplane affect its ability to hold weight?
The wing shape of an airplane, particularly its airfoil profile, affects its ability to generate lift. A curved or cambered wing shape helps generate more lift, allowing the airplane to carry more weight. Additionally, the wing design influences the distribution and efficiency of lift across the wingspan.
How does a helicopter get its lifting force?
A helicopter gets its lifting force from the rotation of its main rotor blades. As the rotor blades spin, they create a pressure difference between the top and bottom surfaces, generating lift that enables the helicopter to become airborne. The angle of the rotor blades can be adjusted to control the amount of lift produced.
4 meters/second/second
How a helicopter used of thrust for flying?
The main rotor of a helicopter is actually a set of wings that turn. They produce lift, just like the wings of an airplane. To change direction, the rotor is tilted, and the helicopter is PULLED in that direction.
How do counter rotating propellers on a helicopter increase the lift?
Counter rotating blades on a helicopter are used to replace the traditional tail rotor found on most aircraft. Because the blades oppose each other (and therefore cancel out the torque created by the other blade) a tail rotor is not necessary. This allows all of the engine's power to be used for lift rather than powering the additional rotor.
How does the wingspan of a falling helicopter effect the speed?
It wouldn't, the propellers are designed to propel the helicopter off of the ground, thus the word propeller, not to make the helicopter glide.
The wings are too thin to hold up a helicopter and that is why they spin to gain ground as well as using kinetic energy to lift up. The propellers would eventually bend or snap if the helicopter would be to fall, the speed of the wind would break or damage the propellers.
How come helicopters cannot fly in storms?
A helicopter cannot fly in a area close to storms like tornadoes or hurricanes. The reason is because the helicopter runs off of a careful balance of the air it is suppressing. If something like a hurricane or tornado are sucking in all the surrounding air, then the tornado couldn't fly. The air being pulled out from the helicopter would cause it to go into a tail spin, and thus smashing into the ground and more than likely killing the pilot and all guests.
What is anti resonance isolation system in helicopters?
It is a system provided to reduce vibrations caused from helicopter Rotors or Blades. It is passive Type of Reduction system. It reduces mainly 4/rev vibrations. Generally, this system is fixed in between the Rotors and Fuselage.
Aris system consists of spring, Diaphragm, Pendulum. Spring is for Providing Stiffness & Diaphragm for Transfer motion of spring to Pendulum. Pendulum is to Dissipate Energy.
Helicopters do not defy gravity. They generate lift through their rotating blades, which pushes against the force of gravity to keep them airborne. Without this lift, helicopters would fall to the ground like any other object under the influence of gravity.
How will airplanes fly when the petrol finishes?
The same as always: by generating more thrust and lift to overcome drag and gravity. To do this they will no doubt use engines running on kerosene, as they do today.
If you mean kerosene in your question, then rest assured that it won't run out. There's plenty of fuel in the ground to go around for a long, long time, and even if it did one day run out, technological advances in power supply will probably kick in and give aeroplanes a new source of thrust.
Why does a helicopter lose altitude when flying over a water surface?
When a helicopter flies close to a water surface, the air below the helicopter is disturbed by the movement of the rotor blades. This disturbance can affect the lift generated by the rotor blades, leading to a loss of altitude due to reduced lift. This phenomenon is known as "ground effect."
It's Fuel and Blades.
How helicopters fly and are controlledHelicopters truly are amazing aircraft, and how helicopters fly is what makes them such versatile machines, being perfectly suited to roles ranging from military use to fire fighting and search and rescue.
Helicopters have been around for centuries - well, the principle anyway - but it was Russian aircraft pioneer Igor Sikorskywho designed, built and in 1939 flew the first fully controllable single rotor / tail rotor helicopter - the fundamental concept that would shape all future helicopters.
Why helicopters are so versatileA normal airplane can fly forward, up, down, left and right. A helicopter can do all this plus has the ability to fly backwards, rotate 360 degrees on the spot and hover ie stay airborne with no directional movement at all.Helicopters may be limited in their speed, but the incredible maneuverability mentioned above is what makes them so useful in so many situations.
Above, the directions a helicopter can move in and the associated name of control
Controlling a helicopterHelicopters require a completely different method of control than airplanes and are much harder to master. Flying a helicopter requires constant concentration by the pilot, and a near-continuous flow of control corrections.A conventional helicopter has its main rotor above the fuselage which consists of 2 or more rotor blades extending out from a central rotor head, or hub, assembly.
The primary component is the swash plate, located at the base of the rotor head. This swash plate consists of one non-revolving disc and one revolving disc mounted directly on top. The swash plate is connected to the cockpit control sticks and can be made to tilt in any direction, according to the cyclic stick movement made by the pilot, or moved up and down according to the collective lever movement.
But first, to explain how the main rotor blades are moved by the pilot to control the movement of the helicopter, we need to understand pitch...
The basics of pitchEach rotor blade has an airfoil profile similar to that of an airplane wing, and as the blades rotate through the air they generate lift in exactly the same way as an airplane wing does [read about that here]. The amount of lift generated is determined by the pitch angle (and speed) of each rotor blade as it moves through the air. Pitch angle is known as the Angle of Attack when the rotors are in motion, as shown below:
This pitch angle of the blades is controlled in two ways - collective andcyclic....
Collective controlThe collective control is made by moving a lever that rises up from the cockpit floor to the left of the pilot's seat, which in turn raises or lowers the swash plate on the main rotor shaft, without tilting it.
This lever only moves up and down and corresponds directly to the desired movement of the helicopter; lifting the lever will result in the helicopter rising while lowering it will cause the helicopter to sink. At the end of the collective lever is the throttle control, explained further down the page.
As the swash plate rises or falls, so it changes the pitch of all rotor blades at the same time and to the same degree. Because all blades are changing pitch together, or 'collectively', the change in lift remains constant throughout every full rotation of the blades. Therefore, there is no tendency for the helicopter to move in any direction other than straight up or down.
The illustrations below show the effect of raising the collective control on the swash plate and rotor blades. The connecting rods run from the swash plate to the leading edge of the rotor blades; as the plate rises or falls, so all blades are tilted exactly the same way and amount.
Of course, real rotor head systems are far more complicated than this picture shows, but the basics are the same.
Cyclic controlThe cyclic control is made by moving the control stick that rises up from the cockpit floor between the pilot's knees, and can be moved in all directions other than up and down.
Like the collective control, these cyclic stick movements correspond to the directional movement of the helicopter; moving the cyclic stick forward makes the helicopter fly forwards while bringing the stick back slows the helicopter and even makes it fly backwards. Moving the stick to the left or right makes the helicopter roll and turn in these directions.
The cyclic control works by tilting the swash plate and increasing the pitch angle of a rotor blade at a given point in the rotation, while decreasing the angle when the blade has spun through 180 degrees.
As the pitch angle changes, so the lift generated by each blade changes and as a result the helicopter becomes 'unbalanced' and so tips towards whichever side is experiencing the lesser amount of lift.
The illustrations below show the effect of cyclic controlon the swash plate and rotor blades. As the swash plate is tilted, the opposing rods move in opposite directions. The position of the rods - and hence the pitch of the individual blades - is different at any given point of rotation, thus generating different amounts of lift around the rotor disc.
To understand cyclic control another way is to picture the rotor disc, which is the imaginary circle above the helicopter created by the spinning blades, and to imagine a plate sat flat on top of the cyclic stick. As the stick is leaned over in any direction, so the angle of the plate changes very slightly. This change of angle corresponds directly to what is happening to the rotor disc at the same time ie the side of the plate that is higher represents the side of the rotor disc generating more lift.
Above, the layout of helicopter controls in relation to the pilot's seat
Rotational (yaw) controlAt the very rear of the helicopter's tail boom is thetail rotor - a vertically mounted blade very similar to a conventional airplane propeller. This tail rotor is used to control the yaw, or rotation, of the helicopter (iewhich way the nose is pointing) and to explain this we first need to understand torque.
Torque is a natural force that causes rotational movement, and in a helicopter it is caused by the spinning main rotor blades; when the blades are spinning then the natural reaction to that is for the fuselage of the helicopter to start spinning in theopposite direction to the rotors. If this torque isn't controlled, the helicopter would just spin round hopelessly!
So to beat the reaction of the torque, the tail rotor is used and is connected by rods and gears to the main rotor so that it turns whenever the main rotor is spinning.
As the tail rotor spins it generates thrust in exactly the same way as an airplane propeller does. This sideways thrust prevents the helicopter fuselage from trying to spin against the main rotor, and the pitch angle of the tail rotor blades can be changed by the pilot to control the amount of thrust produced.
Increasing the pitch angle of the tail rotor blades will increase the thrust, which in turn will push the helicopter round in the same direction as the main rotor blades. Decreasing the pitch angle decreases the amount of thrust and so the natural torque takes over, letting the helicopter rotate in the opposite direction to the main rotors.
The pilot controls the pitch angle of the tail rotor blades by two pedals at his feet, in exactly the same way as the rudder movement is controlled in an airplane.
NOTAR is an alternative method of yaw control on some helicopters - instead of a tail rotor to generate thrust, compressed air is blown out of the tail boom through moveable slots. These slots are controlled by the pilot's pedals in the same way as a tail rotor is. To generate more thrust, the slots are opened to let out more air, and vice versa.
NOTAR helicopters respond to yaw control in exactly the same way as tail rotor models and have a big safety advantage - tail rotors can be very hazardous while operating on or close to the ground and in flight a failing tail rotor will almost always result in a crash.
Throttle controlThe throttle control is a 'twist-grip' on the end of the collective lever and is linked directly to the movement of the lever so that engine RPM is always correct at any given collective setting. Because the cyclic and collective pitch control determines the movement of the helicopter, the engine RPM does not need to be adjusted like an airplane engine does. So during normal flying, constant engine speed (RPM) is maintained and the pilot only needs to 'fine tune' the throttle settings when necessary.
There is, however, a direct correlation between engine power and yaw control in a helicopter - faster spinning main rotor blades generate more torque, so greater pitch is needed in the tail rotor blades to generate more thrust.
It's worth noting that each separate control of a helicopter is easy to understand and operate; the difficulty comes in using all controls together, where the co-ordination has to be perfect! Moving one control drastically effects the other controls, and so they too have to be moved to compensate.
This continuous correction of all controls together is what makes flying a helicopter so intense. Indeed, as a helicopter pilot once said... "You don't fly a helicopter, you just stop it from crashing"!
