How does helicopters fly

Kensington Jones Feb 22, Sep 4, Hi, darian! We encourage you to take a Wonder Journey to find out!! Nov 4, Wonderopolis Apr 11, Higgins' Class Jan 3, We are learning about force and motion. How does a helicopter use force and motion? We really liked the picture of the first helicopter. Is it difficult to peddle the human helicopter? How does the helicopter go up?

Higgins' class. Wonderopolis Jan 3, DeJanae R Nov 14, Wonderopolis Nov 14, We hope he was okay, Seto K! Ryleigh Nov 13, That video was so cool Did it take a lot of time to reach 10 feet with the helicopter? Wonderopolis Nov 13, Danielle Nov 13, Loved the wonder of the day! Sincerely Danielle :. Awesome, Danielle!! We're so glad you liked our Wonder today!

It's so fun to Wonder with you! Arav V Nov 13, I did not know know that you need both hands and feet to operate a helicopter.

We are glad you learned something new, Arav V! Thanks for joining us at Wonderopolis today! Wonder Friend "T" Nov 13, So I've known a lot about helicopters and people call them choppers and are used in war to deploy units of men and also fight in wars if you have a chopper gunner. Daniel C Nov 13, This was fascinating because I was starting to build a remote control helicopter and this helped thanks! Thomas's Tigers Nov 13, We all loved seeing the helicopter Wonder!

All of us would love to ride in one! We are still wondering about tomorrow's Wonder! From Merrick Could it be a review of the all time favorite Wonders? We learned today that the man was pedaling the helicopter and it was so cool!

We learned that the helicopter was designed by Sikorsky, a Russian engineer. When it crashed they still kept trying and trying. They believed in themselves. The video taught us that you never give up, even if it breaks. We learned that helicopters are different than airplanes because they can go up and down. Maybe we will design our own helicopters! We would like to drive a helicopter. Berkleigh Nov 13, I thought that today's wonder looked really interesting and fun!

It is probably really hard to do. I liked today's wonder! Jordan Nov 13, I was excited to see your helicopter. How long did it take you guys to make the helicopter? I love who you guys made the helicopter.

You guys must have used lots of leg power. Santino Nov 13, I'm really impressed on how you guys never gave up even when it broke down. You guys just went on and fixed it and I'm really amazed. I think you guys can get to the 10 ft mark. You guys are great. Great wonder! Nov 13, That was fantastic how they made the helicopter. Erick Nov 13, I hope that they make it to ten feet to get the money. Katelyn Nov 13, I think it is real neat that it is possible to go at least 8 feet in the air with a helicopter that is hand made.

Michael Nov 13, I think it was cool when it was flying to 8 feet high. Then it was even more cool when it reached 8. I noticed that it took a lot of people and work to build the helicopter. Emily Nov 13, I think that is really cool that a person is able to fly and control a helicopter.

Also how can you not crash the helicopter when you have to land? I'm surprised that Henry got up to 8 feet. Bryleigh Nov 13, I thought today's wonder was very cool!!! I don't think I will ever fly a helicopter, but I might! Great Wonder!!! Julian Nov 13, They have a lot of perseverance. Even when the helicopter broke they still kept going. I wonder if they made ten feet? Jason Nov 13, I think that you are working hard to make that Helicopter and then when the Helicopter broke you don't give up on fixing the Helicopter and that was amazing that Henry made to 8 feet.

That was a good plan to make a helicopter by hand. Azhir Nov 13, I loved that they put all that effort to bulid a helicopter to go 10 feet in the air. I also like that they tried a bunch of tools to make a helicopter fly. I think that would be the amazing thing to do if I created it.

Pablo Nov 13, It must have took a great effort to be able to fly it without messing up at all. Kamaria Nov 13, I think that they pushed themselves to the maximum and they deserve to get the money!

It looks pretty easy to get it to fly but it also looks pretty easy to crash. Henry Nov 13, That was intense how Collin fell down when he was pedaling and spining the wheel. Henry went 8 feet. That was cool. Carla Nov 13, It was so terrible when the second man got in and got hurt but they at least did 8 feet. Aniyah Nov 13, They work from their blades that spin round and round on the top and then the pilot pulls the airplane up with his controller then the next thing you know it's in the air and that's how I think how it works.

Dylan Nov 13, Very cool, Dylan! We Wonder what your favorite part of today's video or article was?! Reasor's Class Nov 13, The neutral position of the cyclic stick changes as the helicopter moves off from to hover in forward flight.

Trim control can adjust the mechanical feel in flight by changing the neutral position of the stick. Collective pitch lever controls the lift produced by the rotor, while the cyclic pitch controls the pitch angle of the rotor blades in their cyclic rotation.

This tilts the main rotor tip-path plane to allow forward, backward, or lateral movement of the helicopter. The power required for flight is the second work that must be transmitted to the shaft of the rotor. In general, for a helicopter in forward flight, the total power required at the rotor, P , can be expressed by the equation. Inductive power is consumed to produce lift equal to the weight of the helicopter. From the simple 1-D momentum theory the induced power of the rotor, P i , can be approximated as.

The profile power required to overcome the profile drag of the blades of the blades of the rotor is. The parasite power, P P , is a power loss as a result of viscous shear effects and flow separation pressure drag on the fuselage, rotor hub, and so on. Because helicopter fuselages are much less aerodynamic than their fixed-wing counterparts for the same weights , this source of drag can be very significant [ 1 ].

The parasite power can be written as. In addition, when calculating the power required of the helicopter, the required power of the tail rotor must also be calculated. It is calculated in a similar way to the main rotor power, with the thrust required being set equal to the value necessary to balance the main rotor torque reaction on the fuselage.

The use of vertical tail surfaces to produce a side force in forward flight can help to reduce the power fraction required for the tail rotor, albeit at the expense of some increase in parasitic and induced drag. The power needed to rotate the main rotor transmits to the main rotor from the engine through the transmission Figure But the main rotor cannot get all the power, which is developed from the engine, as part of it is spent for other purposes and does not go to the main rotor.

This part of the power of the motor that is transmitted to the main rotor is called available power. It is defined as the difference between effective power and total loss.

Excess power—this is the difference between the available and the power required. The rotor downwash is unable to escape as readily as it can when flying higher and creates a ground effect. When the rotor downwash reaches the surface, the induced flow downwash stops its vertical velocity, which reduces the induced flow at the rotor disk Figure Influence of ground effect on the induced flow. Figure 15 shows the effects of this on the power required to hover.

If the hover height in ground effect must be maintained, the aircraft can only be kept at this height by reducing the angle of attack AoA so that the total reaction produces a rotor lift exactly equal and opposite to weight. It shows that the angle of attack is slightly less, the amount of total rotor thrust is the same as the gross weight, the blade angle is smaller, the power required to overcome the reduced rotor drag or torque is less and the collective control lever is lower than when hovering out of ground effect.

Influence of ground effect on the rotor drag. These conclusions are also true to flight in ground effect other than the hover, but the effect is smaller. Autorotation is an emergency mode. In the case of vertical autorotative descent without forward speed without wind, the forces that cause a rotation of the blades are similar for all blades, regardless of their azimuth position [ 2 ].

During vertical autorotation, the rotor disk is divided into three regions as illustrated in Figure 16a : driven region, driving region, and stall region. Figure 17 shows the blade sections that illustrate force vectors. Force vectors are different in each region, as the relative air velocity is lower near the root of the blade and increases continually toward its tip.

The combination of the inflow up through the rotor with the relative air velocity creates different aerodynamic forces in each section along the blade [ 2 ]. Autorotation regions in a vertical descend and b forward autorotation descend.

Force vectors in vertical autorotation. In the driven region, illustrated in Figure 17 , the section aerodynamic force T acts behind the axis of rotation. This force has two projections: the drag force D and lift force L. In this region, the lift is offset by drag, and the result is a deceleration of the blade rotation.

There are two sections of equilibrium on the blade—the first is between the driven area and the driving region, and the second is between the driving region and the stall region. At the equilibrium sections, the aerodynamic force T coincides with the axis of rotation. There are lift and drag forces, but neither acceleration nor deceleration is induced [ 2 ]. In the driving region, the blade produces the forces needed to rotate the blades during the autorotation.

The aerodynamic force in the driving region is inclined slightly forward with respect to the axis of rotation. This inclination provides thrust that leads to an acceleration of the blade rotation. By controlling the length of the driving region, the pilot can adjust the autorotative rpm [ 2 ].

In the stall region, the rotor blade operates above its stall angle maximum angle of attack , causing drag, which tends to slow rotation of the blade. Autorotative force in forward flight is produced in exactly the same scheme as when the helicopter is descending vertically in still air.

However, because of the forward flight velocity there is a loss of axial symmetry in the induced velocity and angles of attack over the rotor disk. This tends to move the distribution of parts of the rotor disk that consume power and absorb power, as shown in Figure 16b.

A small section near the root experiences a reversed flow; therefore, the size of the driven region on the retreating side is reduced [ 1 ].

Helicopter stability means its ability in the conditions of external disturbances to keep the specified flight regime without pilot management [ 3 , 5 ]. Let us consider the longitudinal motion of a helicopter on the hovering regime Figure Longitudinal motion of the helicopter in hover. Recall that a helicopter, like any aircraft, is considered statically stable, if it after a deviation from the steady flight regime tends to return to its original position. Suppose, for example, that as a result of the action of a wind gust U the thrust T is deflected backward see Figure 18b.

Under the action of the horizontal component, the helicopter will start to move back with a speed V x , and under the action of the moment M it will start to rotate relative to the roll axis, increasing the pitch angle with the angular velocity q see Figure 18c. Both effects: both the translational velocity and the rotation of the fuselage, and hence the axis of the rotor, will cause the resultant forces T on the rotor to tilt to the same side, opposite to the original inclination.

This will cause the appearance of a horizontal component and a longitudinal moment, already oppositely directed, due to which the helicopter will tend to return to the initial pitch angle and to zero forward speed. This means that the helicopter is statically stable in pitch angle and hover speed. Its static stability is due to the properties mentioned above: speed stability and damping.

Consider, however, the further movement of the helicopter. The inclination of the resultant in the direction of parrying disturbance is too great because of the presence of velocity stability. It leads to the fact that the helicopter in its movement to the initial position skips the equilibrium position and deviates in the opposite direction, but already by a large magnitude. The motion of the helicopter takes the character of oscillation with increasing amplitude.

The aircraft, which in the free disturbed motion ultimately leave the initial equilibrium state, is called dynamically unstable. Thus, a helicopter on a hovering regime is dynamically unstable. The roll motion on the hover has a similar character. The difference here is manifested only in the period and the degree of growth of oscillation, which depend on the moments of inertia of the helicopter, different in pitch and roll.

The helicopter is neutral in the yaw angle and the altitude on the hover. This means that the helicopter does not tend to keep a given course angle or a given flight altitude. At the corresponding disturbances these parameters will change. But their change will continue only as long as the perturbation is working. At the end of the disturbance, the course angle and altitude will not change. It can be said that the helicopter is stable with respect to the yaw rate and the vertical speed. This stability is explained by the fact that the main rotor at an increase of the airspeed in a direction opposite to the thrust reduces its thrust, and conversely, when this speed decreases—increases the thrust, thus creating a damping force in the direction of the axis of rotation.

Therefore, the tail rotor creates a large damping yaw moment on the helicopter, and the main rotor—a damping force for vertical helicopter movements.

In forward flight, the efficiency of helicopter control and the derivatives of the damping moments and moments of stability with respect to the main rotor speed vary insignificantly. However, the moment derivative with respect to the angle of attack, which for the main rotor corresponds to the instability, begins to play an important role.

This instability can be compensated if the fuselage of the helicopter has a stabilizer, which improves the desired degree of stability in the angle of attack. But it is difficult to provide satisfactory longitudinal stability even with well-designed stabilizer. In the forward flight, the roll movement is strongly connected with the yaw movement, just as it does on the airplane.

The own lateral motion of a single-rotor helicopter during a forward flight, as a rule, is periodically stable. In the low-speed modes, while the relationship between the roll and yaw movements is still small, and the roll motion, like the hovering, is unstable, the lateral motion of a single-rotor helicopter is unstable. Static stability of helicopters with two main rotors differs slightly from the stability of the helicopter with one main rotor.

The tandem main rotor helicopter has a significantly greater longitudinal static stability, and the coaxial main rotor helicopter has a greater lateral stability. This is explained by the change of main rotors thrust at a disruption of the equilibrium. So, the helicopter, essentially, cannot maintain a steady flight regime. There are four basic controls used during flight.

They are the collective pitch control, the throttle, the cyclic pitch control, and the antitorque pedals Figure Basic helicopter controls. The collective pitch control changes the pitch angle of all main rotor blades. The collective is controlled by the left hand Figure As the pitch of the blades is increased, lift is created causing the helicopter to rise from the ground, hover or climb, as long as sufficient power is available. The variation of the pitch angle of the blades changes the angle of attack on each blade.

The change in the angle of attack causes a change in the drag, which reflects the speed or rpm of the main rotor. When the pitch angle increases, the angle of attack increases too, therefore the drag increases, and the rotor rpm decreases. When the pitch angle decreases, the angle of attack and the drag decrease too, but the rotor rpm increases. To maintain a constant rotor rpm, which is specific to helicopters, a proportional alteration in power is required to compensate for the drag change.

The purpose of the throttle is to regulate engine rpm if the system with a correlator or governor does not maintain the necessary rpm when the collective is raised or lowered, or if those devices are not installed, the throttle has to be moved manually with the twist grip to maintain desired rpm.

Twisting the throttle outboard increases rpm; twisting it inboard decreases rpm [ 2 ]. The helicopter's rotating wing assembly is normally called the main rotor. If you give the main rotor wings a slight angle of attack on the shaft and spin the shaft, the wings start to develop lift. In order to spin the shaft with enough force to lift a human being and the vehicle, you need an engine, typically a gas turbine engine these days.

The engine's driveshaft can connect through a transmission to the main rotor shaft. This arrangement works really well until the moment the vehicle leaves the ground. At that moment, there is nothing to keep the engine and therefore the body of the vehicle from spinning just as the main rotor does. In the absence of anything to stop it, the body of the helicopter will spin in an opposite direction to the main rotor.

To keep the body from spinning, you need to apply a force to it. Enter the tail rotor. The tail rotor produces thrust like an airplane 's propeller does.