Why Do Helicopters Spin if They Lose Their Tail Rotor? Helicopter Torque Reaction
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- เผยแพร่เมื่อ 3 ส.ค. 2024
- This video explains why helicopters spin if they lose their tail rotor due to the torque reaction created by traditional helicopters (like the Robinson R22 or R44) and the need for a tail rotor (or other anti-torque system).
See notes, tips, related videos & links below.
▬▬▬| Video Content |▬▬▬
00:00 START
00:18 3rd Law of Motion
00:40 Traditional Rotor Systems
02:58 Torque as a helicopter picks up
04:11 Other rotor systems
04:22 More information
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Great video like all others of your channel! Thanks for the free high quality information.
Thank you, that answered a question very well for me!
You are welcome!
I think I understand. The swashplate will tilt forward to tilt the rotor disc forward, to move the helicopter forward. What you might be getting at is the effects of 'gyroscopic procession' - which is a fancy term for the concept of a force applied to a rotating object (like a main rotor system) will actually be felt about 90 degrees later, in the direction of the rotation. We will do a video on that, but in the meantime - have a look search on TH-cam for "Helicopter Physics Series Gyroscopes"
Thank you for your very fast reply. I am familiar with procession but maybe I don't understand how the swashplate affects the rotor blades, yet. It's late here and my brain feels like jello. Could I write you a PM tomorrow about this topic? I am eager to learn more, I love helicopters. :)
Thank you so much.
You are welcome
Sure thing
Thanks MotoKid032, but you are partially incorrect. The R22 does have a counter-clockwise main rotor rotation and the tail rotor does cause drift to the right, but.. the tail rotor THRUST acts RIGHT, the blowing air or tail rotor downwash moves to the left. Thrust acts in the direction of the force - not the direction the air is blown. Think of an airplane - the prop pushes the air backward, but the thrust force acts forward - in the direction of flight and opposite drag (which acts backwards).
Thanks for explaining THRUST. from the picture and arrow i thought it pushes air to the right, which would not solve the problem. Even the word thrust i thought meant to push, so it is pushing but in the other direction.
Awesome explanation! But does the same concept of "every action there is an opposite reaction" apply to helicopters, whose main rotor is driven by a tip jet? This is because from what I have read, rotors driven via tip jet do not transmit torque to the fuselage. So would it be more precise to think that the concept refers more specifically to the shaft drive in the fuselage itself? Thanks!
Yep you are right - tip jets would mean no tail rotor or anti-torque system would be needed.
On the Robinson rotor head: In which direction will the swashplate be tilted to gain a forward motion on the helicopter? I hope you can understand my question. It is kind of hard for me to put this in the right words because a) I am new to all this, trying to understand the basics b) I am not a native speaker :P
Hi myself am a aeroplane flight instructor and I've asked several helicopter pilots (not instructors) this following question but none were able to answer it. So the main rotor generates torque which is then counteracted by the tail rotor. What then happens the torque that is generated by the tail rotor? Granted, the direction of the torque would depend on the direction of the tail rotor rotation and could potentially be negated by the design of the airframe, what happens when the amount of torque (speed of the tail rotor) changes? wouldn't that affect pitch attitude of the helicopter?
Great question. I think the torque is minimal and not noticed by the pilot. The tail and main rotor should remain at a mostly constant speed in flight, tail rotor thrust varies by changing the tail rotor pitch angle, not the speed.
what is ground looping tendency in helicopter during tail rotor cable rupture when rudders become ineffective but not suddenly due to irreversibility of controls
Err not heard f that TBH
sir I cant understand about the small propeller on the tail of helicoter how the propeller is on horizontal axis
Just like the lifting force you get from spinning the main propeller ( It creates a force on Z direction), you get same sorf of force upon the smaller propeller on the back which counters the moment that main propeller creates. By the way the smaller propeller turns 6 times faster than the main propeller to create equilibrium.
Yeah it fights against the twisting motion caused by the engine turning the main rotor
You've got the direction of the tail rotor thrust incorrect. The R22 has a counter-clockwise rotating rotor, so the thrust vector (orange arrow) would blowing left and causing the helicopter to drift right.
Doesn't the torque direction should be perpendicular to the plane of the blade???
Is it true If a failed tail rotor happens, and forward motion is maintained at a good speed, the spin can be somewhat controlled enough to have some control?
Yes, the vertical stabilizer helps with yaw control at fast enough forward airspeed and less than full power (so you might be a in slight descent, depending on weight, altitude, etc) see R22 POH 3-5 (the Note on that page) robinsonheli.com/wp-content/uploads/2020/06/r22-poh-3.pdf
How do helicopters tilt at one end and have their Centre of gravity stay the same?
It is a basic property of center of mass of solid objects (en.wikipedia.org/wiki/Center_of_mass) although some fuel will slosh around moving it slightly as you tilt.
You should get into RC helicopters, it will teach you every aerodynamic aspect of real rotorcraft just on a smaller scale ie. Translating tendency, flap back (blowback), effective translational lift, vortex ring state, transverse flow effect, dis-symmetry of lift. Everything. Join us at rcgroups.com.
Doesn't the tail rotor also generate torque? How do you counter it?
It’s absorbed by the rigidity of the tail itself. In other words, the weight of the helicopter is greater than what the torque of the tail rotor can move
Good question! I guess it doesn't generate enough to make any difference in flight.
let's forget about the tail at the moment, would the helicopter body spin in the same direction as the main rotor?
OK forget the tail rotor thrust. A very smart guy once said "For every action there is an equal an opposite reaction..." - the action of spinning the main rotor blades creates the reaction of spinning the body of the helicopter in the opposite direction.
i know that but i never understand why the helicopter didn't get pulled sideways by the tail rotor which confused me
It actually does a little bit, designers and pilots compensate with opposite main rotor tilt.
@@HelicopterTrainingVideos ah, thanks
action and reaction forces do not apply in circular motion because they are linear
What are major problem of tailrotor?
I'd say the possibility of damage to the tail rotor causing a loss of control
Aah yes I see. So the orange indicates which way the tail rotor is "Pulling", not pushing..Got it, I just had a different way of seeing it in my mind.
How this torque is calculated
How someone comes to know how much thrust is nessasiry to counter this torque
Push enough pedal to stop any rotation
what I don't get is why the body of the helicopter would spin, if the reaction torque from the air was applied to the blades, and not the body. I can't see how that equal and opposite torque is linked to the body of the helicopter.
the rotor needs something to push against in order to spin and since the blades are connected to the helicopter by the shaft there is nothing to stop the helicopter body from getting pushed the opposite direction except the mass of the body and tail rotor
So why not dual tail rotors ?
foot pedals are counterintuitive
Hand controls would be a much
safer intuition
Hmmm, I guess because one works well enough
Sooooo all it takes is for that one part of the helicopter to go out (the tail rotor) and you're pretty much doomed?? Why would anyone get on a thing like that and take that risk?
Yet statistics suggest you are far more likely to die in an car accident and most of us drive without a thought about such risks...
Some punk Jimmy Ollier stole your video and posted it for their self.
Helicopter Torque - Basic Helicopter Aerodynamics
Hope you can lock it down.
Hey, a big THANK YOU! I have contacted TH-cam regarding copyright infringements.
actually you are wrong, the counterclockwise rotation of the blade causes the torque-the orange arrow- which is the counterclockwise rotation of the helicopter.The tail causes a force that goes clockwise- the red arrow. Don't confuse us.
NOPE. You are wrong. If you can't see the physics of it, look at it this way - If you lose your tail rotor in an R22 (or other similar counter clockwise rotor helicopter), which way would your nose rotate? (Check R22 flight manual, emergency procedures section). It would go right, and the tail would sweep clockwise (red arrow) as the torque reaction is no longer countered by the tail thrust (orange arrow).
this video is right... in aviation terms torque the reaction force to a rotating body... don't be bashing people's video when you don't know your shit
At 2.20 wouldn’t the tail rotor thrust be going to the left 🤔
I know it can be confusing - downwash goes one way and the thrust acts in the opposite direction - think of an airplane prop
Doesn't the torque direction should be perpendicular to the plane of the blade???
Errr...