Відео

Thank You

If the tail rotor Thrust in the image with the red arrow, it must blow air to the left, correct? If the tail rotor is blowing air to the right, that will make the body spin faster in a CW direction?? If the thrust of the tail rotor is to the right as indicated by the red arrow, won't that push the tail to the left?

this is way harder than airplane aerodynamics

Thank you for the explanation straight to the point ❤

Dude wtf. Not even 30 s in and its already wrong. If you where talking about an aircraft or a autogyro the trust vector would be right. Or close to Right. But for a helicopter the trust vector is close or sometimes (i e. Hover) identical to the lift vector.

I have always wondered if span-wise flow was controlled in rotor blades. I thought that controlling span-wise flow across the rotor would create more efficient lift of rotors for the same size. I don't see fences or winglets. Need to talk to a rotor aerodynamics guy.

Best channel to understand in few minutes

Thank you for the video May I know why we have tail rotor tendency ? The video tells me there is tail rotor tendency but did not explain in detail why this happen Also why moving the tail rotor up to level to the main rotor will reduce this tendency ? Thank you very much ❤

I am watching this series to learn about helicopters so i can make one in this simulation type game

Sorry dude, your video is OK except for confusing Coriolis Effect with conservation of angular momentum. GO back to the text books and avoid basic mistakes.

Byproduct* That being corrected, I really love this series. Good, simple, and to the point.

What is the magnitude of the torque? Does it only take effect when the rotor is accelerating? Is the tail rotor mechanically in sync with the main rotor? How does the collective pitch effect the torque?

Great video!

Can i share your VDO to my FB page

Excellent video

Thank you! It helped me a lot

These videos are awesome For beginners like me, please make more

searched for a while to have this concept so succinctly explained, thanks!

You oversped your thumbnail!

Hopefully I'm able to regurgitate this today 🙂

The description of blade coning angle in this video is quite correct, but it is only true for rotor heads that have flapping hinges. Early helicopters had blades made of wood, and later with an extruded aluminium spar with bonded ribs and pockets to form the aerodynamic profile. These blades would be subject to bending stresses that could lead to catastrophic failure, so the addition of a flapping hinge allowed the blade to flap up, until the vector addition of the centrifugal and lift forces resulted in a single force that acted along the length of the blade. This removed the bending stresses. The problem with flapping , drag and pitch change hinges in a “fully articulated” rote head is that the bearings operate continuously over a small arc of movement, causing wear, which results in vibration. Frequent overhaul of the rotor head is required to replace the bearings, resulting in considerable cost per flying hour. Modern designs and materials for both the rotor head and blades means that some rotor heads do not have any rotating bearings. The material construction of the blades means that they are strong enough to withstand the bending stresses, and in order to achieve directional thrust from the rotor disc as well as vertical lift, in the absence of flapping hinges, the blades are required to bend slightly. Examples are the AW109 and the Merlin. The MBB 105 has a fully rigid rotor head with only pitch change bearings. The Lynx family has a semi rigid rotor head also with pitch change bearings.

good discussion

Do contra-rotating rotors with no tail rotors produce no drift then? Such as in the Russian Ka helicopters? Also is this a Dutch accent?

Amazing content

Robinsons have a hinge called a coning hinge that allows the blades to cone to take the stress off of them. The centrifugal force keeps them as straight as they can with the applied forces so as the rpm slows down and if you don’t lower collective the blades will cone more but as they cone more they will spin faster and try to pull back flat so it is a constant application of forces.

Why does a venturi tube decrease in pressure?

Pendulous motion also happens because the aircraft is unstable. When a gust of wind blows over the disk, or it starts to move forward, the blades will flap away from the wind. The fuselage will follow. Now the relative wind is from the other direction, so the disk flaps away from it, and is pointing forward again. The pendulous effect swings the fuselage further aft, tilting the disk further forward. It now moves faster forward, flaps away again harder, and the pendulous effect gives a big nose up. Let this happen four times and you crash. "Stick fixed dynamic instability." Cured by a small cyclic movement to stop the flapback in the first place.

The power curve on a helicopter moves out almost constant, then drops gently to the max endurance speed and then rises cubically to high values

The drag curve shown applies to airplanes, not to powered helicopters! No drag in hover, but plenty of POWER

4:30 parasite drag increases quadraticaly, not exponentially ~ V². not. .e^V

Great video but the airspace triangle was missing delta

This video is just another of too many repeating common misconceptions that are false. . First the angle of the wing to the air is called Angle of Attack, not pitch. Pitch is the attitude of the entire aircraft - the nose pitches up and down to change the Angle of Attack of the wing. .. At time 1:35: WRONG. Bernoulli's Principle is about Fluid Pressure and *ACCELERATION*. An increase or decrease in velocity is *Acceleration* . It is NOT "Fast or moving air" that has a lower pressure, but air is *ACCELERATED* toward the lower pressure by the Pressure Gradient. . The Pressure Gradient is the *cause* of the Acceleration. This is Newton for fluids. The Pressure Gradient provides the force to Accelerate the air's mass. Air has mass. . WHEN are you people going to get serious and start understanding physics and applying it instead of blindly repeating misconceptions?? . The longer path is a common misconception. A flat wing has the same length above as below and produces lift just fine. . The upper and lower flows DO NOT meet at the trailing edge at the same time. See Babinsky's video of a wing (below). . The speed-up does not cause the lower pressure. It is the lowered pressure that forms the Pressure Gradient that is the cause of the Acceleration toward the trailing edge. . The down-wash is a RESULT of the same pressures pushing up on the wing. It does NOT "add" to the top-bottom pressure difference in any way. It is a result of those SAME pressures. At time 3:30, While he top-to-bottom pressure difference provides all the lift, it is NOT because "the high pressure has a 'tendency' to move toward a lower pressure." It is because the *upward pressure* on the bottom surface is greater than the *downward pressure* on the top surface. This produces a net upward force. Pressure over an area is a force .. At time 3:54, Your 'reaction' arrows are *WRONG!* The reaction is in the opposite direction to the air's *ACCELERATION* which is upward. The reaction to the drag is *REARWARD*. THEREFORE, the reaction vector is up and to the REAR! Your faulty reaction would increase thrust. . At time 3:48: If it is "dumped downward by the trailing edge", then the lift from that should pitch the wing downward (upward at the trailing edge , thus upward at the leading edge, yet it is well known that lift is centered more toward the leading edge. So, AGAIN, the reaction is distributed over the entire wing due to the pressures. It is very misleading to claim that lift is due to the pressure difference *AND* the Newton's Third Law 'reaction. Lift AND curving of the air are the result of the pressures caused by the wing pushing air around as it moves. Those are *NOT* two sources or causes of lift. . Finally, to say that Bernoulli "causes" lift is also false. Bernoulli shows us, if anything, that the Pressure Gradients that are caused by the wing's motion cause the accelerations of air we see around a wing. . . This 1 minute video explains that it is the curved flow that causes the lowered pressure: ua-cam.com/video/3MSqbnbKDmM/v-deo.html .. This steps you through Bernoulli and lift step by step. *Understanding Bernoulli and lift Correctly:* *rxesywwbdscllwpn.quora.com/*

No, lift is generated by pressure differences originating from the push and pull of the foil through the air: ua-cam.com/video/dgE9xhIjTOU/v-deo.html - nothing to do with Bernoulli or Newton!

Awesome job!

You are BONKERS! How do you expect "overspeeding" main rotor's on helicopters to assume a " cone shaped" profile? The two phenomena are mutually exclusive!.

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Keep up please doing more videos, I mean you are doing really good videos. and I know these videos take time to do, but for real a lot of people will thank you because you're teaching us really well.

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quick and effective. Thanks

once again thanks

awesome please keep doing what you are doing.

thanks

This video is just another of too many repeating common misconceptions that are false. .. At time 1:35: WRONG. Bernoulli's Principle is about Fluid Pressure and *ACCELERATION*. An increase or decrease in velocity is *Acceleration* . It is NOT "Fast or moving air" that has a lower pressure, but air is *ACCELERATED* toward the lower pressure by the Pressure Gradient. . The Pressure Gradient is the *cause* of the Acceleration. This is Newton for fluids. The Pressure Gradient provides the force to Accelerate the air's mass. Air has mass. . WHEN are you people going to get serious and start understanding physics and applying it instead of blindly repeating misconceptions?? . The longer path is a common misconception. A flat wing has the same length above as below and produces lift just fine. . The upper and lower flows DO NOT meet at the trailing edge at the same time. See Babinsky's video of a wing (below). . The speed-up does not cause the lower pressure. It is the lowered pressure that forms the Pressure Gradient that is the cause of the Acceleration toward the trailing edge. . The down-wash is a RESULT of the same pressures pushing up on the wing. It does NOT "add" to the top-bottom pressure difference in any way. It is a result of those SAME pressures. At time 3:30, While he top-to-bottom pressure difference provides all the lift, it is NOT because "the high pressure has a 'tendency' to move toward a lower pressure." It is because the *upward pressure* on the bottom surface is greater than the *downward pressure* on the top surface. This produces a net upward force. Pressure over an area is a force .. At time 3:54, Your 'reaction' arrows are *WRONG!* The reaction is in the opposite direction to the air's *ACCELERATION* which is upward. The reaction to the drag is *REARWARD*. THEREFORE, the reaction vector is up and to the REAR! Your faulty reaction would increase thrust. . At time 3:48: If it is "dumped downward by the trailing edge", then the lift from that should pitch the wing downward (upward at the trailing edge , thus upward at the leading edge, yet it is well known that lift is centered more toward the leading edge. So, AGAIN, the reaction is distributed over the entire wing due to the pressures. It is very misleading to claim that lift is due to the pressure difference *AND* the Newton's Third Law 'reaction. Lift AND curving of the air are the result of the pressures caused by the wing pushing air around as it moves. Those are *NOT* two sources or causes of lift. . Finally, to say that Bernoulli "causes" lift is also false. Bernoulli shows us, if anything, that the Pressure Gradients that are caused by the wing's motion cause the accelerations of air we see around a wing. . . . This 1 minute video explains that it is the curved flow that causes the lowered pressure: ua-cam.com/video/3MSqbnbKDmM/v-deo.html

Even though all terms are given an explanation, I still cannot understand induced flow

😀👍

You correctly showed that Torque is shown by 2 arrows, one each side going in opposite directions, to produce rotation. The tail rotor instead uses a Moment to stop the rotation - its arrow has to be 2 x the size of one of the Torque arrows to stop the turn. But then you are left with an unbalanced force, which causes Drift, which is countered by tilting the rotor mast to the side. This then causes another moment which makes the fuselage roll to one side - which is why most helicopters hang left skid low in the hover.

Some problems with this explanation. Firstly, to reply to David below, the rotors create lift by pushing air downwards, and there develops a column of air above the rotors which has to descend to replace the air which has been pushed downwards to create lift. Sitting in an out-of-ground effect hover creates the most induced flow, because the helicopter needs the most power to sit in an OGE hover. If there is no downwash, there is no lift and no induced flow. But once the chopper starts to move forwards, it gets away from that column of descending air, and the front of the disc sees air that is more horizontal than vertical. this reduces the induced flow, and for the same pitch angle, you get more angle of attack. But then other factors come in such as flapback and inflow roll. Rest assured that there is always induced flow whenever the blades are producing lift, but they can be more efficient when translating through the cleaner air. It is NOT simply poking the cyclic forward that reduces the inflow, rather it is getting into cleaner air.

It's "chord" line, your spelling changes several times. The airflow over the top does not have to meet up with the airflow under the bottom, and in fact it gets to the trailing edge first, sees a gap because the airflow below is going slower, and it moves downwards - causing the downwash. The resultant force is upwards and backwards, which can be split into the vector at 90 degrees to the Relative Air Flow and called Lift, and a component in the same direction as the RAF, called Drag. Your diagram shows an arrow pointing downwards to portray the downwash, and then "Newton's law gives an equal and opposite reaction" which is pointing forwards?? Sorry, but your diagram is wrong. Drive your car at speed, poke your arm out with your hand flat. Then add some pitch to your hand, and feel that your arm is pushed up (lift) and back (drag.)

Precession is only used to convey the concept. A rotor system is NOT a gyroscope, which is a rigid disc attached rigidly to a shaft. The rotor system has hinges to allow flapping, some have lead/lag, and the disc is usually only attached by a flapping hinge in the head. It is in reality, Newton's laws being demonstrated. Apply the force to the blade, it starts to accelerate either up or down. It takes time to reach its highest/lowest point, and by then the blade has turned APPROXIMATELY 90 degrees. By then, the swash plate is changing the pitch angle again and it goes back the other way. It is called Phase Lag, and in the R-22, which has a very light rotor blade, less time is needed to move the blade, so the phase angle on the R-22 is only 72 degrees. But the effect is NOT precession, this name is just used to help students grasp the idea of swash plates, and pitch change horns passing the pitch angle to the blades in advance to allow for the phase lag.

This video is incorrect. It is repeating common misconceptions. . The longer path is a common misconception. A flat wing has the same length above as below. . The upper and lower flows DO NOT meet at the trailing edge at the same time. See Babinski's video of a wing. . The speed up does not cause the lower pressure. It is the lowered pressure that forms the pressure Gradient that is the cause of the speed increase (Acceleration). . The down-wash is a RESULT of the same pressures pushing up on the wing. It does NOT "add" to the top-bottom pressure difference in any way. It is a result of those pressures. .. Babinsky's video: ua-cam.com/video/UqBmdZ-BNig/v-deo.html . This 1 minute video explains that it is the curve in the FLOW that causes the lowered pressure: *ua-cam.com/video/3MSqbnbKDmM/v-deo.html*