Autorotations (The Basics) in Helicopters
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- เผยแพร่เมื่อ 22 ธ.ค. 2017
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This video covers breaks down Autorotations, more specifically the basics. This subject has quite a lot of information when considering pilot techniques, environmental factors, etc. But what I'd like to do with this video is set the ground work for general knowledge at the most basic level. From there, I'd like to work on a follow-up video expanding more in-depth.
To set the stage, we'll start by defining an Autorotation. This is a condition where the rotor system is being driven by the upwards flow of air rather than by engine power. As the name implies, in an autorotation the blades "rotate" "automatically." This is important because it gives helicopters the ability to have a controlled glide to the ground in the event of an engine(s) failure.
To expand on this, we talk about the stages of an autorotation.
1. Level Flight: let's set the stage by saying we have a helicopter flying straight and level at 500' above ground level (AGL). At this point, the engines turn the blades enough to overcome drag produced by the pitch of the blades. This produces enough lift to overcome weight and the helicopter can maintain level flight. It's important to note that in this stage the airflow is downwards through the rotor disk.
2. Entry: at the onset of engine failure the pilot instinctively lowers the collective to maintain rotor RPM. If the pilot did not do this, drag on the rotor system would cause it to slow down out of limits and make the rotor system useless. In order to maintain aircraft control, the rotor must be maintained. So as the collective is reduced, the rotor decouples and spins freely, a rate of descent is established, the airflow now moves upwards through the disk, and the helicopter enters an autorotational profile.
3. Descent: while in the descent the helicopter has somewhat of a glide instead of fall. The pilot is looking for a suitable area to maneuver the helicopter while cross checking instruments to maintain rotor RPM, airspeed/attitude, and trim as appropriate. A good cross check is key.
4. Flare: at some point near the ground (approximately 100' but dependent upon conditions like aircraft design, density altitude, weight, etc.) the pilot trades this airspeed for a reduction in rate of descent. This is accomplished by "flaring." This is accomplished by an aft cyclic input and results in the flight path trajectory leveling out and becoming more parallel to the ground. In the event the pilot is landing to an unimproved area (e.g. not a runway), the pilot would use this flare also as a means to reduce all forward airspeed to prevent rollover on landing.
5. Touchdown: at the end of the flare as the helicopter begins to settle the pilot cushions the landing with collective application.
When performed correctly, this whole maneuver allows the pilot to turn an engine failure into a safe touchdown instead of a crash.
Looking back at the actual autorotation, there are changes in the aerodynamics of the rotor system. The rotor system is broken down into 3 distinct regions:
A. Stall: this takes place in the first 25% of the blade radius area closest to the hub. Here exists a stall region where the airflow exceeds the critical angle of attack and stalls. This is turbulent, non-lift producing airflow.
B. Driving: here the rotor extracts energy from the upwards flow of air. This region drives or increases rotor RPM and exists roughly 25%-70% of the blade radius area.
C. Driven: lastly, this area of the rotor system is being driven by the driving section. This is the rotor-absorbing, lift-producing area of the rotor which is located in the last 30% of the blade radius area furthest from the hub.
In forward flight these regions shift towards the retreating blade side due to its lower Angle of Attack. However, this is compensated for by blade flapping and cyclic feathering. For more information showing why that takes place, check out my video:
Compensation for Dissymmetry of Lift ( • Compensation for Dissy... )
That wraps up basic autorotations. Much of this material that I pulled into this video and many others is outlined in depth detail by detail in Shawn Coyle's book Cyclic and Collective. It's a great book for expanding your professional reading library and I'd recommend checking it out. Here's a link to the book (amzn.to/2ifQGLx)
Like I said before, there is a lot more information out there addressing tips, techniques, environmental factors, autorotations with turns, etc. I'm interested to see what you guys and gals have to share on the subject. Leave your comments and questions below.
Thanks for watching and Safe Flying!
Just thought I'd let you know: You make these videos so well that they actually recommended us to watch your videos during Primary phase at Rucker. You are literally becoming part of the Army Aviation curriculum! We can't thank you enough for your videos man.
$$$ is it coming? Obviously deserved...
Not only at Rucker, but also in all around the world.
Currently at Rucker. Verified they still recommend.
To be honest, this didn't really explain anything about how it works. If you have air flowing upwards for instance, are you able to put negative pitch in to force the blades to spin? Using positive pitch should only slow the blades more and more until the stop or move the opposite direction, assuming you have enough altitude and don't hit the ground before that which you likely would
@@ScienceBitch123 negative pitch?
Autorotation sounds like a word invented by the first helicopter manufatures to put insurance companies minds at ease.
What word would you use?
@@meow121.5 energy preservation
@@snorttroll4379what about the law of angular conservation of momentum? I feel like I've heard that somewhere before 😏
I came to comment because I took the SIFT this week and scored in the high 70s. This channel was my only resource for the Aviation Information section. There wasn’t a single question on that section I couldn’t answer, it was all covered somewhere in your videos. Fantastic resource!
I'm completely new in helicopter flight. I'm studying for the SIFT test in the Army. I just started and you explanation was better than what the manual explains. Thanks. I'll be looking into your videos. Thanks again.
So is nobody gonna mention how this man managed to freehand draw a perfect arrow?
I work at a helicopter manufacturer and while I am not a pilot, these videos really help me understand a topic the seriously interests me. Thanks
I'm here to learn how to do this in Arma III
Hey Jacob, I have been studying for the SIFT and must say that your videos have really clarify a lot of my questions. Thank you!
Hey Daniel, just curious if you were able to get in? I’m currently working on my CFI/CFII and finishing up my Bachlor’s. It seems like pulling teeth getting information on how/where to start.Any advice? I’m a prior enlisted Marine with a good reelistment code
Received this new video on Christmas day. Was a great present! Thanks and fly safe.
I think there's nothing like Auto rotations that really brings out a lot of confidence in a pilot. Knowing if something goes wrong you can safely Glide the helicopter to the ground and maintain an AirSpeed and an RPM and come close to Landing directly on the spot you choose or even Landing directly on the spot you choose I think brings a pilot's Confidence from like 20% up to like 200%. You know the saying aviate, navigate, communicate? Like first you fly it that's the most important part. Navigating is second. And the radio is certainly the last most important part. I find that doing less auto rotations makes you a perfectionist and you actually start paying a lot more attention to things like your attention gets drawn to correcting your direction too much or putting too much attention on the radio. I suppose if you're not doing that at all maybe that's a good thing. I suppose a person could perhaps not paying enough attention to where they're going and they're getting lost or actually not communicating whatsoever not paying attention to the radio at all or stating who they are talking to who they are where they are what they're doing Etc. And of course what I'm saying is totally subjective it's totally perceptive of my own self. Everyone is entirely different. I think practicing Autos non-stop just puts a person at ease about a potential engine failure. And of course you know don't over inject yourself with too much confidence because practicing auto rotation and an actual engine failure or not the same thing. To me personally though I find my attention is way more directed towards the aviating part and wanders less when I constantly practice auto rotations. It just makes me a totally different kind of competent person and when I don't practice them as much I find I get nervous and my attention wanders a lot. As though I'm always thinking about things too much. Doing the auto rotations removes a lot of that nervousness and lack of focus. You know I've heard people when they stop training when they're beyond the student phase and they're beyond the CFI phase even though they've gone through the whole flight school endeavor and have moved on to other jobs that the job actually only requires auto rotation practice training like every once in awhile it's not something you go out and do every week anymore. Wow I don't know how I feel about that. I guess it's part of the process if you do it enough times you do like 10,000 auto rotations and your confidence is really high you move on and do other things and they don't require that as much. That whole concept is so foreign to me at this point. I think I just become kind of a wreck of a pilot if I don't practice Auto rotations enough. Some instructors even treat auto rotation training as though it's like a "privilege that we might not necessarily be doing today unless you just want to have fun." I guess some students really take advantage of the adrenaline rush or something? I find a lot of those same instructors they'll get really mad when you start paying too much attention to navigating or using the radio when you're flying. 😂 see I'm probably distracting everybody who would read this by using my own perception to paint a picture. Not everybody is me. Not everybody learns the way I do. Privilege or not I think the practice of it is so important not just for the actual practice of Auto rotations practicing auto-rotating Landings to me take so much Focus off of the nervousness and lack of confidence that you have one flying when thinking that some emergency might happen that you can't handle. To be the constant practice of auto rotations removes that nervousness and I believe that nervousness causes your attention to not be put properly on certain things at a certain time. In which case you might start doing things backwards you start communicating then navigating then aviating. You start becoming too much of a perfectionist and not just doing naturally things in a certain order when needed. To me that has a domino effect as well when you become nervous like that you stop doing the things that actually help you do the navigating communicating preparing ahead of the flight which is where all that navigating and communicating should be prepared for way ahead of the flight so you focus on just the aviating when you're flying. To me the practice of normal Glide Auto rotations, minimum Glide and maximum Glide with AirSpeed in between 55 and 70 and 90 knots and RPM usually between 97% to 108% for the 70 knots normal glide profile and otherwise 90% RPM for minimum or maximum Glide and understanding your three bank accounts with two accounts pertaining to kinetic energy with the rotor RPM and forward thrust consisting of that and the last account being potential energy which is your altitude and understanding the trade off should be like just as much of your training as normal flying. So when I say that I think flying the helicopter should be like 50% out of rotations I mean 50% of your helicopter training should be engine off in the other 50% should be engine on even if Technically when you practice Autos the engine isn't actually off but you are still taking advantage of the freewheeling unit there's a decoupling in the transmission is no longer providing power to the rotor RPM from the engine as though the Sprague clutch is engaged and the induced flow is inverted and no longer is the correlator being affected by you moving the collective up and down. Yes some instructors do think that you can do too much auto rotation training. See now to me because it improves my confidence I believe it makes you less likely to over focus on navigating and communicating and not properly focusing on Aviation then navigating and communicating I feel like it removes your confidence and you become distracted you may be stop planning as well as you stop PreFlight planning as well you probably don't prepare your navigating and communicating as well with less PreFlight planning you put too much attention on the navigating and communicating and your flying unless attention on the aviating. And true to what instructors say what makes you really good at Auto rotations is a combination of how are you usually handle the collective and cyclic and pedals and how you plan your approach most of the time with your sight picture in your normal flying and when you're doing auto rotation you're just practicing maintaining AirSpeed and RPMs and using your ability to do good approaches and handle the collective and cyclic without expecting the engine to power the RPMs. Therefore the instructor seems to put more time on your normal approach and shallow approach and steep approach and hovering and quick stops Etc. Yet I just can't help but feel like auto rotation training cannot be emphasized enough and totally changes the mindset of a student the way that people think a solo changes their mindset of a student. You could easily say the same thing about a solo right. You're only repeating the same thing you do with the instructor just by yourself. Yet is considered SO ESSENTIAL. Same way I feel about autos. To me there's nothing like 5 or 10 good Autos throw in some 180°s the totally improves the confidence and coordination and removes the distracting wandering mind and give the student a boost of adrenaline wakes him up gets his mind thinking in the proper direction and gets his attention properly on just enough things at a time to where you can properly aviate and then the navigating and communicating doesn't seem so distracting. But of course like I said I'm speaking from my own perception. This is how my mind works this is how my brain benefits from these exercises. Now of course I don't understand the instructor that thinks that "too much autorotation training is just for fun and the student doesn't need a constant adrenaline Rush dumped into his mindset just whenever he's bored and he needs to focus on many other aspects of flying just besides Auto rotations." But I suppose if I understood many of the other students that want to take advantage of this maybe I'd get the instructor that says they wanted to deter from this direction. Anyway that's how I feel about that
Jacob, thanks . I've learned so much from your presentations and it made me go out and learn more. Liked the lecture portion and the illustrations. Waiting for more.
Sharon Burns. I'm glad you like them. Stay tuned for more!
Love all your videos, great drawings and very simple and easy to absorb and pass on to others. Thank you!
thank you very much for doing this video, i can't wait for the advanced auto session!!
Awesome explanation...you are doing very good job and helping lots of pilots....thankyou
Hmmm. AD bakchodi mat kar... Learn something from AK singh... He is a self made heptr pilot 🤣🤣😂😂
Very well explained, nice job!!
I’m currently in autorotation training lessons on the EC120B, although they are simulated with engine not being idled and without touchdown on the ground, so the ground where we touch down is meant to be at low hover height.
Victor plead with your instructor to let you do a full touchdown auto to the ground. That last 15 feet is critical.
1.what happens to the upward flow of air while increasing collective pitch to initiate flare?
2. how main rotor blade generates lift with upward flow of air, and how pressure difference works above and below the blade here?
Amazing educational videos. Nice work...
Thanks Jacob, Great short brief on Auto's.
Thank you , you explained it in just starting and that explanation makes sense
At my school, they say for our power-on autos we should start flaring at 40ft. Of course, different helicopters from what the Army uses, we use R-22s. Great video! Love your stuff for refreshers.
It depends on the helicopter weight and altitude. As both increase, the flare has to start sooner. 18,000 lbs of helicopter at 8000’ MSL would crash into the ground if you waited until 150’ to start a flare.
@@helicopterlessonsin10minut10 Great points. Thanks for the response!
Thank you so much!!! Your videos are the best! 💙
Again Jacob-outstanding job in making the complicated simple. Looking forward to future lessons!
Thanks for this. Learning about autorotation because of Kobe
RIP Legend.
What Zit Tooya same
Awesome videos keep it up!!
Awesome vid sir...thanks a lot...another grt help from u..👏
thanks for all ur videos. apppreciated
Thank you! Clear as a daylight
Do you alter the blade pitch during autorotation so that it spins to wind blowing up through it instead of down?
Do you flip the blade pitch back coming in to landing to generate lift and cushion the landing?
I realised the flare is important because there might not be enough kinetic energy left in the rotors to halt descent without stalling the blade. This is similar to the landing of the space shuttle - the upward point at the end allows the craft to "swoop" in instead of plummeting into the ground at 120 mph down 360 mph horizontal.
In my readings I see that the DRIVEN REGION does produce some lift but this lift however is offset by drag due to the Total Aerodynamic Force(TAF or Resultant Lift on Airfoil) being behind the axis of rotation. In an auto, the DRIVING REGION's TAF is in front of the axis of rotation producing a continual accelerating force that supplies thrust and accelerates rotor rpm. Collective Feathering changes the size of the DRIVING REGION which changes the rotor rpm . In an auto, a pilot needs to adjust collective to keep the rpm within limits otherwise he stalls out or the blades fatally cone upwards. Lift is no longer a significant force in an auto..using the continual inward airflow to keep those rotors spinning so you can glide safely to the ground is the main idea of an Autorotation.
Safely to the ground is a whole
nother story... Where you land or ditch...
Thank you for posting, learning is still fun!, i see the entire blade has differ stall speeds, nice i learned just now!!!!!!!!
AH-64 was very to autorotate because of tail wheel, and a lot of rotor inertia. Good presentations sir👨✈️
Thanks Jacob, Cant wait for the advanced lesson on Auto's, really helpful!
Very informative. I invite helicopter pilots to fly in a gyroplane as flights are in an autorotative state a all times. Flares to landing without power on short final are quite easy to perform and are a fun way to land. (Comparing Apples to Oranges) but getting on the deck safely is what it's all about.
thanks alot man , your videos are helpfull.
What about the kinetic energy stored in the rotors, doesn't that play a part, doesn't the rotor speed decay during flare/landing?
This is such a good one.
Hi man, really liking your videoes. Ive got a quiz from my instructor for my next theory lesson: "WHY does your rate of descent decrease with increasing airspeed?" I know the fact that forward flight is more ideal for an autorotation of numerous reasons, and also know that if your airspeed gets to high, your ROD will start to increase again? What and why is happening here? It probably has something to do with the last part you mentioned, about the changes in the rotorsystem transitioning into forward flight, but I cant seem to make the connection. Is it ETL, hitting Vy or??? Thanks
Hey there! great video but I have a question about entering an autorotation state with 0 rotor speed? Is this trickier to do to overcome the inertia and drag of the blades? Any insight on this would be great!
Michael Fadar. Autorotations with zero airspeed aren't that big of a deal if you are at a lower hover with zero airspeed because you would just cushion your way down. However, higher altitude autorotations with zero airspeed can be fairly dangerous. You'd have to lower the collective to maintain rotor rpm and then pull in everything towards the bottom to arrest the sink rate. The dangerous part is that you'd be entering into a potential settling with power condition as you cushion. But just like with a regular in-flight autorotation, the blade rpm has to be maintained at all times during the descent. I hope this helps.
Airborne with 0 rotor speed is impossible, 0 airspeed is improbable.
Good vídeo 👍🏾🚁
To understand auto rotation I just imagine holding a small fan in my hand ( the one kids are using on the beach). If theres no wind, then you need to run with it to make it turn. That is the equivalent of lowering the nose and gaining speed to create a relative wind in a way. Obviously the very first thing is to lower the collective and by doing so you change completely the angle of attack of the blades . This angle of attack changes allow the flow from the bottom now ( the relative wind you have now created) to allow the blades to keep turning. If you don’t do that, the blades will stop turning because not changing the angle of attack of the blade will stall the blades immediately.... then you will drop like a stone. When you descent, keeping the blade turning at a certain speed will store energy that will need to be dissipated in the flare and landing. But you will have one chance and one chance only! i guess the lighter the blades, the less time time you will have as there is less energy stored in the blades. The heavier ( and the more) the blades are I guess the blades will have more momentum, so you will have more time to dissipate the energy stored? Is that correct?
But coming to the ground we flare but do we lift the collectif again or just keep it as it is for the decent
Hey, i am no expert and was here only out of curiousity but i have a question. So while ascending the air flow is downward, so if the helicopter is descending and the air flow is reversed wouldnt the rotors spin counter opposite to before ?
thanks for this. I've never flown a helicopter, only RC heli's. The one thing I wanted to confirm is that when you say :"lower the collective" you're actually reversing the relative pitch of the rotors to what would be negative pitch, and then at the last moment using that rotor momentum to generate lift by changing back to positive pitch. Do I have that right? And if so - is there any sort of "feel" or "lockout" in the collective handle to prevent using negative pitch while under power (say, on the ground or close to it?)
Thank u so much!
What are the effects of change of all up weight and change of Rotor rpm?
Great video about autorotation. Jacob, is it possible to make a simplified video about airspace? There are alot of components dealing with this topic but I thought I would reach out to see if you could break it down in your easy-to-understand way. Im sure there are a few folks, beyond myself, who are trying to have a better understanding of airspace.
It’s on my list of subject areas to expand out into later on. At the moment I’m mostly focused on aerodynamics but I’ve got a decent sized list of topics covering FAA rules that I can spread into.
If the wind is traveling through the rotor disc in the opposite direction during an auto, why do the blades still spin CCW as in normal flight?
Hi, can you please tell me which and from where from should i buy the study materials for becoming a commercial helicopter pilot. It’s my dream. I did hard work for 5 years to follow my dream. Please tell me the books for all 7 subjects. Thank you very much
nice vid, just finished reading chickenhalk, now i understand what was meant by the term autorotation, thanks
Try Guts N Gunships by Mark Garrison. It's right up there with Chickenhawk.
@@kevinwarren3998 oh sweet will lookinto 100‰ always up for a good book nice one
I just have a question... Is a heli in autorotation technically losing altitude faster than a heli in free fall? Or how does it work? Cuz this autorotation looks like some big propeller blowing air upwards therefore increasing descent..
Hey man when are we getting more videos!?! They help so much!
Currently doing what this aircraft was truly meant to do. Will make more when I get back.
@@helicopterlessonsin10minut10 Be safe chief!
Hi, you say when the engine fails, lower the collective to the "Autorotation" position, then you describ it as "The Driven Region". . . So how does decenting through the air, drive the rotor in the same correct direction, without the change of air flow direction also causing the blade rotation direction to reverse. ?
Great! Thank you
Thank you, you explain it clearly. i came here because those misinformation short video that says autorotation can keep the helicopter on the air, giving the pilot time to look for save landing
Pitch management is key 👍😎
Ok this is cool.. thanks
I'm having a hard time finding one bit of info (I'm getting lost in the bulk of information) -- after initially lowering the collective when entering autorotation, WHEN and by HOW MUCH is the collective raised or lowered during the steady state descent? How does the pilot determine this? Or is collective kept in the full down position until near landing?
Collective is adjusted(raised or lowered) to maintain rotor RPM value within safe limits of operation so as to achieve an effective flare.
thanks bro
Do the three regions only occur during an autorotation or also in regular flight? And if they do still occur during regular flight, are they swap around on the blade radius because you have downward airflow instead of an upward airflow?
Yes. These are regions associated specifically with non-powered flight. Check out my “Dissymmetry of Lift Expanded” for the regions during powered flight
If your engine quits how does the rotor turn and keep any rpms. When my car engine fails my wheels stop turning, if I could control the rpms of the wheels then my engine didn't quit. What am I missing here? Do you define "engine failure" differently?
How can you have different regions of drive or driven on the same blade? Unless it's front /back regions along its length
It all comes down to total aerodynamic force which differs because different parts of the blades have different air speeds. The tip of the blades travel faster than the root.
Great video/in what condition would you recommend autorotation? Engine total failure, partial loss of RPM? what are the conditions that have to be met to autorotate (speed, altitude etc.) great video, thanks!
OthelloCarouge. You should enter an autorotation anytime you have lost all engine power. You never get to pick when engine(s) completely fail on you so you must always be ready to enter an autorotation despite airspeed, altitude, etc. . If you've lost power and keep collective pitch applied the rotor will slow down and become useless for you. However, if engines are working and just rotor RPM is low, you should immediately adjust the collective to maintain rotor within limits. This should not require as drastic of a collective reduction as entering an autorotation. I hope this helps.
With the EC120 Colibrí you also get into autorotation in case of engine fire in cruise flight and if you have tail rotor loss of authority, but in the latter case as this type of helicopter has fenestron tail rotor you can have good control of the aircraft as long as you keep 65kts or more and then choose when to enter autorotation. In such case engine should be idled to prevent the helicopter from yawing at the end of the manoeuvre.
You simply just need to keep the "rotor in the green." So if you have a complete power loss it may be due to engine failure or something more complicated like an Engine Governor/Control unit. In this case the rotor RPM will decrease rapidly. So you have to lower the collective rapidly and flare the aircraft in the entry phase. Then you have to check engine instruments (usually TGT in turbines or Engine RPM in pistons) and confirm what you have. If you have a slight power loss, you may get a reduction in Rotor RPM, but not alarming. Especially in a twin engine helicopter. You should diagnose the same way. But you don't respond to any cockpit warning sounds or lights, just what did the rotor do. There isn't any point, as is dangerous low level, to dump the collective at every little problem. So with a slight power loss, then you keep flying the best you can, diagnose then either make a powered descent into a powered landing, or powered descent in an auto at the bottom where you actually roll off the throttle yourself, a non-powered descent and fixing the problem to fly away... The scenarios are endless. But the main point is, ROTOR IN THE GREEN! ;-)
I have a question plz if anyone can answer...
What should we do when we need to increase or decrease autorotation in helecopter chut down on the ground ??
Sorry for my english
So is an autorotation principally the act of taking stored energy in the rotor blades and by increasing the collective, turning it into kinetic energy by increasing the rotor blade pitch?
Michael Lenoch. More specifically, the first part of an autorotation involves reducing collective (reducing pitch) to turn potential energy (altitude) into kinetic energy (airspeed/rotor rpm). The second half of an autorotation is when all of the kinetic energy is expended to reduce rate of descent and cushion the landing.
Awesome explanations Jake.. you also could have shown or explained how energy change influences in performing an autororation. I.E from high potential energy to kinetic energies of the out of speed of the helicopter and the speed of the rotors... you also forgot to mention that as the inflow air from below is called THE RATE OF DESCENT FLOW. Other than that man im really getting he best outta these videos quick review. im foing my ppl in SA just finished the principles of flight in was just digging dip and here you were. Any way i want to be a pilot bt really scared of heights. any advice?
Mbuyi-Gereon Lopa. Thanks for the feedback. I was trying to keep that first video short and simple with the intent of diving deeper in later videos. I don’t really have any tips on heights haha. Sorry.
@@helicopterlessonsin10minut10 helpful either way... Please do video on flight maneuvers. Balnce turn Rate of climb and rate of decent. HPR and HPA would also mean alot
Is flying in autorotation the same as flying an autogiro?
During Entry and Descent, would the helicopter be in a nose down attitude?
Generally level attitude. Nose down would be if needing to gain airspeed or slow the rotor.
So I have a question. U lose engine. As the chopper falls you start auto rotation. Pls explain why the whole helicopter doesn't rotate uncontrollably? I ask because I thought what stopped a chopper from spinning uncontrollably was the tail rotor contering the rotation that would be caused by main rotor alone. If you are falling in autorotation without engine power I suppose the tail rotor wont turn. Or just the turning of main rotor is linked to synchronize with tail rotor regarless of it being powered by en engine or just the wind caused by free fall of gravity?I hope that made sense.
Also I understand this varies but +/- what is minimum altitude to pull this off safely?
Thanx in advance for any answers
jaime delgado when the engine power is disengaged the torque is not a factor.
@@kamron8558 thank u. I had a feeling that would be b the case but wanted to make sure. Happy New year.
sir in autorotation what is the significance of rod and the heptr with high all up weight induces more rod than the lighter one if yes then why please answer
Pradeep bisht. I'm sorry but I don't understand your question.
pradeep due to high AUW obviously rate of descend will be more.
Its clear that the main blades are rotating because of the upward flow of air during autorotation.....
and my doubt is how we can rotate tail rotor, and from where the tail rotor getting power to rotate during autorotation?
It’s all linked to the main rotor via the transmission. If the main rotor is turning, so should the tail rotor.
But if engine fails and top blade spins because of free fall of Helicopter then what powering the tail rotors to counteract the counter spin of helicopter relative to spinning top blades ( according to Newton's third law in circular motion ) ?
The main and tail rotor are directly linked. So turning one will spin both.
But if the engine fails isn't the rear rotor also stopped? So how does one counteract the momentum of the main rotors or is their momentum negligible at this point?
None of the rotors stop. The rotor energy maintained by the descent is able to maintain enough rudder authority to control yaw.
I believe you're assuming that the tail rotor is not mechanically linked with the main rotor and that both rotors get their power from the engine individually, which your comment would make sense.
In reality though, the main rotor and tail rotor are both mechanically connected, so if the main rotor spins, it'll also drive the tail rotor.
it's unclear for me, as if the airflow is reversed through the blades due to descent, the airstream momentum acting on the blades tends to reverse the rotation of the rotor as well (or at least to decrease the RPM) but not to increase the RPM... unless a negative blade pitch is applied; not sure if its possible, though I'm not a professional.Would you like to clarify?
My question exactly... I am having a hard time understanding this... And no one to explain porperly...
I'm no pilot nor an expert, but it is my understanding that immediately after the moment the engine fails, you lower the collective all the way down to change the angle of the blades so the upward flow of air through the rotor maintains its RPM.
If you don't lower the collective, this upward flow will reduce rapidly the RPMs as the angle of the blades oppose to this flow.
After establishing the autorotation you must maintain the rotor RPM within its limits of operation. Same case with the airspeed and glide slope recommended for this situation. This means you input corrections to collective, pedals and cyclic all the way down to ground.
has the advanced auto video been posted yet?
Not yet. I’ve currently got a backlog of videos and not enough time to make them. Sorry for the delay.
Is the Pitch up during the flare proper at each hélicoptère ?
I’m not sure I understand your question but the aircraft does pitch up during the flare. The amount of flare varies based on airspeed. The aircraft should never flare so dramatically that it begins to climb in altitude.
@@helicopterlessonsin10minut10 you have to low the collective, if you won't climbing during flare
Thank you for answering me,
My question was, flare the aircraft is giving nose up with so and ao degrees....is this nose up different for each aircraft ?
So the blades have to spin the opposite direction?
After how much later of engine failure should a pilot enter into autorotation and on what factors does it depend ? Can this duration be be different for same helicopter at different conditions ?
Actin Bisht. Thanks for the feedback! You should immediately reduce collective when an engine fails in order to maintain rotor RPM. Rotor RPM can decay rapidly to a dangerously low level if you do not make corrections within just the first few seconds. This can vary greatly depending on rotor system inertia (high vs. low system), how much pitch is applied, the type of failure in the engine (full engine failure vs. partial engine failure), etc. It is best to have a thorough understanding of your airframe in order to make better decisions during emergencies.
Thanks for sharing. During autoratation, since the tail rotor is also power off, how to prevent or minimum the helicopter from spinning?
Ho Mun Wai. Due to the fact that the main rotor is not creating thrust, there is no torque effect to compensate for with the tail rotor. So during an autorotation there is no longer the need for left pedal applied. The pilot actually needs to apply right pedal to take out the anti-torque correction in order to keep the nose straight.
During descent that makes sense, but would you have to compensate for torque when flaring? and if so, how, if we have nothing driving the tail rotor? Forgive my ignorance, I've never flown anything in my life.
The tail rotor and main rotor are connected with separate gearboxes so the main will drive the tail
@@matthewdowdy3933 Thanks a lot. Very insightful. Brilliant engineering.
Cool
It was a good video bro
But can you please ellobrate that during Autorotation :
1. Which part of advancing blade produces lift and which part is stalled region
2. Which part of re-treating blade produces lift and wihich part is stalled region
Note: Main rotar is rotating Clockwise
Just nitpicking here. During autorotation, the lifting regent (C) also contributes to the force that keeps the rotor spinning. The same force generated by the wings of a glider pushes it forward.
Normally AOA = increase in foward airspeed? But in autorotation = decrease in foward airspeed?
You want to decrease angle of attack in the blades to keep the blades rotating at normal rotor RPM. If you did not reduce collective, the drag on the rotor would cause it to rapidly decrease.
Sir can you tell me what is termination again? Plz. ( 5:00 )
This is the final phase where you apply collective to cushion in order to make the landing as survivable as possible.
Would you touch the collective during the flare, or only after you’ve leveled out? Thanks for the very helpful video!
Thank you chief! wish we get cross each other. I was a 15r now i am in flight school.
Your videos always start out with Army helicopters. Are you an Army aviator?
William Eudy. I sure am.
is it actually possible, to autorotate-land the apache with 0 forward speed?
Most helicopters (including apaches) can do hovering autorotations. But the higher you get with zero forward airspeed the more you risk getting into a vortex ring state.
@@helicopterlessonsin10minut10 copy that, thank you.
i always thought that the helo has always some minimal (oc depending on which helo) forward speed when touching down with autorotation.
I read that the pilot, who was flying the helicopter that crashed and killed country music star, Troy Gentry, attempted this maneuver, and it seems it did not work. There are many articles that say the crash was the result of "pilot error", though it seems the autorotation maneuver is a common one, that can be used in case of engine failure - or as in this case - the pilot purposely shuts down the engine. Shouldn't the upward airflow have actually made the rotors speed-up? I'm trying to understand what exactly was the "pilot error" here. Thanks
I haven’t read into any investigations on the accident. But upwards flow of air doesn’t speed up rotor RPM unless all of the pitch is taken out of the blades.
If a household fan is blowing against a breeze and the power goes out, the breeze will blow the blades of the fan in the opposite direction. Why don't the blades on the helicopter do the same thing?
I think a way to ilustrate autorotation is to study another flying machine, the autogyro plane / gyrocopter. It flyies without power to main rotor.
Song?
It's called "Level" from the Splice app.
Clear as mud to me
How helicopter turns left to right or right to left?
Using the cyclic control you would increase pitch on one part of the rotor disk and decrease lift on the opposite side. This tilts the rotor and can turn the helicopter in flight. If at a hover, just use pedals to change the direction the helicopter is facing.
@@helicopterlessonsin10minut10No no I know about that, I mean...
Let's assume that the main rotor of a helicopter rotates from left to right then the helicopter will start to rotate in opposite direction (from the Newton's third law of motion). So a tail rotor is needed to maintain it. If I want to rotate the helicopter from left to right, I need to stop the force that produced by the tail rotor then the helicopter will automatically start to rotate from left to right. If I want to rotate the helicopter from right to left, can I increase the speed of the tail rotor or ... ?
If my English is wrong, please forgive me😁🥰🤗.
You won’t change the speed of the blades. You change the pitch of them. So to pedal turn right, you change the pitch in the tail rotor to change angle of attack.
@@helicopterlessonsin10minut10 Thank you.
If the rotor is connected to the engine and the engine dies why doesn't the rotor stop?
How can the Russian k-52 Alligator rotate?
You increase pitch of one of the the lower disks at a time. Depending on which way you want to turn will determine either the upper or lower rotor disk to increase pitch on.
@@helicopterlessonsin10minut10 That is little complex to me. 😞
i still dont understand the aerodynamic force that causes the blades to gain rpm, it have thought an upwards flow would make the blades loose rpm and want to spin backwards
I'm not a pilot, but it would seem to be that the collective is lowered to the point that the blades would be at a negative angle of attack.
ya, but show us the blade angles
How nice of physics to allow for a chance to survive a heli engine failure 😅
Every time I see someone with a board explaining mostly they don't know that much. The number of blades + the weight of the helicopter play also a big role ; th-cam.com/video/05_WFvh9ISk/w-d-xo.html. Besides there are a lot of "specialists" of autorotation landing but they put some power back on last moment "but it doesn't do anything" in real life is to avoid helicopter damage. So in real life there is not emergency help from the engine. I isn't that easy ,
The question is, what is auto rotation. Please define.
Autos to touchdown? YES or NO? I am now inclined to prefer the European practice.
Most dual engine helicopters don’t train all the way to the ground because the likelihood of both engines failing at the same time is so low and the number of accidents in training is so high. But many single engine helicopters still practice autos all the way to the ground. So it really depends on what you fly.
I'm going to crash a helicopter into my neighbors house because he mows his lawn too early in the morning
Here after Miami helo crash into the ocean