Feather, flap, lead and lag. Think of how difficult a helicopter is to fly vs a plane to begin with. At least in concept. 1 control for each axis? A cyclic, collective, and anti torque pedals vs a yolk? Translational lift? Settling with power? Dynamic rollover? Auto rotations? LTE? No airplane pilot must deal with these concepts. Dyssemitry of lift? Omg advancing air vs retreating air? But rotor systems that allow the angle of attack of blades to change on their own by the blades leading, lagging, feathering and flapping solve the issue of angle of attack for the pilot. The pilot controls the direction of the blades and does not have to position the aircraft in a position the way an airplane pilot does just the pitch and position of the blades. The blades being able to bend and flex on their own means the helicopter will not flip over. A pilot can hover which you cannot do in a plane. More control. But tougher to learn in concept.
I would love to see a “differences” video on controls and what they do with conventional vs tandem rotor helicopters such as the chinook. I enjoy your instructional videos. I am a retired airline pilot with no helicopter experience but was always fascinated with them.
Good vid bro. I'm a 30 year licensed structures S - engineer finally taking my M1 here in Canada. I couldn't grasp it all in one go the first time I watched but after some books and coming back to your vid, it all clicked. Thank you🇨🇦🤘🇺🇲
Looking to get all my knowledge to fly a helicopter in less than an hour. So glad I found this channel to help me with my goal. Interested to see first helo that can fly inverted and maintain level flight for a moment.
As I watch videos of helicopters accelerating away after take-off, it seems that there is no noticeable change in angle between the fuselage and the blades as forward cyclic is applied. Does the rotor system (fully articulated) transfer pitching moments to the mast (and thus the fuselage) when cyclic is used, or does the fuselage truly hang from the hub like a pendulum. If it's the pendulum case, that would imply that the only reason the fuselage pitches forward is because the CG is below the hub, and the CG is being "dragged" by the rotor hub. The way you drew your fully articulated rotor, it would seem possible for the blades to impart a (pitching) moment on the mast, because the flapping hinge is a distance away from the center of rotation, and the centrifugal force of the rotor could imply a pitching (or rolling) moment on the mast. Obviously the rotors flap, but the fuselage seems to respond quickly to cyclic inputs making it appear that the rotor and fuselage are moving in unison. Any thoughts?
Your assessments are correct. Fully articulated hubs allow centrifugal forces on blades to pull the hub into alignment with the rotor disk. Semirigid systems require pendular response to adjust fuselage attitude. An unloaded pushover in a Bell H-1 often resulted on rotor impacts with the top of the fuselage as the rotor disk tilted forward and the fuselage stayed level. Needed to be really careful about making aggressive ridgeline crossings.
You are REALLY good at explaining things! I found your channel while trying to find an answer as to why the helicopter in the game I'm making isn't banking correctly (I have the physics wrong somewhere). I haven't quite find the answer, but I've learned so many other things already. Thanks for making these types of videos!
Your videos are great. They make their point clearly and are easy to follow and remember. I look forward to each new one you produce. If you are looking for new topics, in ground hover vs out of ground hover would be a good one to review. Keep up the good work.
Evangelist Geraniotis. I'm glad you enjoy them. I actually already have a video that covers IGE vs. OGE hovers in my "Airflow at a Hover" video. Here's the link: ua-cam.com/video/WVYqjNYgae8/v-deo.html. Thanks again!
May be off subject slightly, but a question for you that’s been troubling me since the first Huey Cobra presented itself in our unit of all standard Huey’s, Viet Nam, 1969: Noticed, even on a quick glance, the Cobra had no “stabilizer” bar. Seemed like pitch change came directly off the upper swash plate via 2 long pitch change rods. No more little pitch change links off a stabilizer bar like on our Huey’s. Because that Cobra was just refueling at our base, it quickly started up and flew off without time for this baffled “C” model Huey pilot to speak with that Cav pilot. What happened to the stabilizer bar (paddles) on now-ancient, 2-bladed, teetering-head heli designs? Thanks in advance from an old hover-lover from days long gone.
Although I appreciated your description of the various rotor systems, I would also have greatly liked to have seen the actual schematics and maybe even a physical example of the items; trying to view these systems on the internet only results in hundreds of redundant examples over and over which ends up with me becoming irritated and finding something else to do. I presently own a vintage Bensen B-8M (in glider configuration only for right now until I install Subaru in it for power). What I'm looking to do is to utilize a three-blade system but don't know how to get all three blades to function the same as a two-blade "teter" system and any information would be Greatly appreciated, Thank You. In the meantime Thanks for sharing the information which you've already posted.
I try to keep this to the basic level that a pilot would need to do. Many engineers work with those schematics but the average pilot doesn’t necessarily need to know the precise blueprint as much as how the systems differ for flight.
I flew UH1's in the Army......the semi Ridgid Rotor design was far better handling than the old Bells we started out in. I imagine the higher end models you see today has the articulate system! Would love to fly one of those Corporate Cadillac's!
Awesome video man. Would be really cool if you could do a hands on demo with a real rotor head. I used to work at a machine shop and i routinely inspected rotor head components of the H3 helicopter, which despite being designed in the 50's, was fully articulated. A truly amazing design by the engineers. The blades can move in all 3 axes, cycling each rotation at 300rpm. If I still worked there I'd be willing to get some hands on video for you but I don't
0:00 saw an apache do this kind of drift onto the parade field as everyone was staging for the change of command. Wasn't as oblique and angle or as fast but he came in like this and then swung the tail around in a drift and arrested his movement all while dropping altitude to the deck. Landed about 30-50 meters away from the head of the entire division marching onto the field. Turned everything with jet and rotor wash and made the whole formation instinctively pause in a completely animal way you may recognize from combat or ...animals. Anyway even the first sergeant had about three seconds of brain reset time before yelling for everyone to keep moving and this is the 101st Airborne so we all have seen helicopters doing stuff before lol. Anyway sky monsters are scary but I'm glad the scariest ones are ours. Can't wait to see what the FVL generation matures into. The SB-1 is already crazy impressive.
Well, the rotor hub is teetering back an forth which allows the main blades to flap up and down so flapping is still going on. It has to or there is no compensation for dissymmetry of lift. What he doesn't go into is what's happening to the lead/lag forces in a semi-rigid rotor system. As the rotor blades are flapping upwards and the center of mass of the blade should be moving closer to the axis of rotation and trying to lead forward, the teetering rotor hub is actually moving the blade away from the center of rotation. These two motions counter each other and the center of mass of the rotor blade itself stays at or very near the same distance from the center of rotation (rotor mast) and thus there are no lead/lag forces to deal with. Likewise, on the side that's flapping downward, where the center of mass of the rotor blade should be moving away from the axis of rotation and lagging behind, the teetering rotor hub is moving the blade closer to the axis of rotation and again, the two motions cancel each other out and lead/lag forces are neutralized or at the very least, kept to a bare minimum so not lead/lag hinges are needed.
Sir will you please make a video to explain Delta Three hinges and offsetting of pitch control arm off the plane. which is done to make the blade feather while flapping. It would be of great help as the bookish language isn't enough for understanding.
It really varies by helicopter. The power turbine section of the engine is turned by combustion and is generally directly linked to the transmission. However, some helicopters (dual engine) have clutches that enable different power outputs from each engine.
Thanks, i was checking out Igor Negada's video of his GTD-350 helicopter turbine restoration. It was the gearbox which i was refering to but didnt know it. I couldnt work out how a turbine rotation translated to the rotor rotation. m.ua-cam.com/video/-gewWyLi1mc/v-deo.html I passed on the schematics i found, he is very apt at parts fabrication a little wasteful with resources but i think his hydrodynamic aerodynamic aptitude is equivelent to half a potato...thats been mashed.
As the blade flaps their mass is getting closer to the axis of rotation, not the point, It is rotating up and down at a radius from the point so that actually never changes.
I don't get your comment. The weight being lifted, it seems intuitive to say that it's tip is getting closer to the center of rotation. The blade length of course doesn't change, but it draws a smaller circle around the center.
The rigid rotor system also flaps because flapping is the only way a rotor system can compensate for dissymmetry of lift. Flapping is the up and down movement of rotor blades as they rotate...The main difference between these rotor systems is how they each allow Flapping to occur either through (1)blades flexing in a rigid system (2)blades flapping as a unit on a pivot point in a semi-rigid system (3)blades flapping individually about a hinge in a fully-articulated rotor system
LeoAero19. Well said. That's what I was getting at by describing rotor systems instead of blades themselves. All systems flap to compensate for dissymmetry of lift. But each system absorbs the stressors of this in different ways. Thanks for the feedback!
Do you have a short explanation on why the design of the bell semi rigid system is different from the R22/44, i see the Robinson has a coning hinge but the Bell doesn't
Morne Petersen. I don't claim to be an expert in either of those airframes. But from what gather, the R22's coning hinge allows each blade to flap independently while the Bell's rotor head is designed with a fixed, pre-cone angle resulting in the coning forces having to be absorbed by the blades. It all boils down to stresses on the blade. The coning hinge takes more strain off the blade than the fixed/pre-cone angle design. But some would argue that the Bell design is more responsive due to less hinges which can create sloppiness in the controls.
In Gyroplane, the semi rigid design has evolved and overcome the need for the lead lag hinge by under-slinging the blade at the hub. This is done by having a mast tower. This tower is typically two plates which extend well above the rotational point of the mast. This allows a swing motion as well as the see saw motion to occur. Ass the blade flaps up to dissipate the lift on the advancing blade, the swinging motion extends the blade outward to compensate for the stresses imparted from that of the Coriolis effect. As for as the progress of hub design, la Cierva’s bamboo rotor wings of his models only flew because of the flexibility of the blades allowing for the dissipation of asymmetric lift. Once a full scale version was built the craft rolled on take off. He then created the flapping hinge. This did not fix the problem Coriolis Effect induced stresses as you have sail lead to blade stress failures so he invented the lead lag hinge. All of these innovations were present in the Pitcairn rotor head as well as the ability to change pitch globally allowing jump take offs. Sikorsky was struggling with his rotor head design and became a licensed Pitcairn dealer at the suggestion of the US Government. Only then was Sikorsky was able to make his machine fly with acceptable degrees of control ability using a single rotor. Effectively Sikorsky stole the rotor head design and the Pitcairn family sued. Sikorsky was awarded government contracts and denied the lawsuit. This happened in 1941 and the lawsuit was not settled until the mid 70’s. The problems were solved more or less before Sikorsky flew in ‘41. If the helicopter industry de evolved itself in rotor head design, that I do not know. There is a great book by Dr. Bruce Charnov, Autogiro to Gyroplane, which tells the rich history of the first rotor winged aircraft. It is a good read, out of print but still available.
@@skipperclinton1087 Mr smart guy? Really? Why the push back? I do not know what the 540 rotor system is. Why should I? I am just relating what I know is to be true about the very early development of the rotor systems and why certain elements came to be. The lead- lag hinges resulted from the change in the cg of the blade as they rose and fell. With out them, stresses on the root of the blade caused failures. The underslung nature of the Gyroplane simple style non powered type employed today and made popular by Igor Bensen found a way of relieving the vast majority of the stresses caused by the flapping motion. That’s it, end of story. I shared this because I expected those who are reading this thread might be interested in knowing the now ancient history of how something came to be. It is trivial knowledge, a well how about that thing.
@@crawford323 whoa, I didn't mean it as an insult, I meant it as a compliment. Your knowledge of choppers is well above my pay grade so I thought you might be able to shed some light on some I learn about. " Bell designed yet another Huey variant, the "UH-1C", intended strictly for the gunship role. It featured the T53-L-11 engine of late-production UH-1Bs, with a modified intake system fitted with prominent air filters; and a new "Model 540" rotor system, with a blade chord increased further to 68 centimeters (27 inches)." All this is a foreign language to me so I was hoping you could break it down into simple layman's terms. Obviously not with your bad attitude.
@@skipperclinton1087 My bad attitude? With the lack of facial expression and or hand gestures to complete human communication, extra care must be imparted when crafting the written word in order to be assured that no extra between-the-lines interpretation of that written word is added. Using the terms “Smarty Pants and bad attitude” could be easily interpreted as demeaning and as a less-than-careful writing style.
@@crawford323 Dude I called you "Mr Smart Guy" as from all the information you possessed on rotary wing aircraft I was spot on. Obviously you took offense to being called a "smart guy". Case of mistaken identity perhaps 🤔
CCCanyon. Well I haven't flown that one, and I'm sure not many others have before the project was cancelled. But I would imagine it would operate much like other rigid rotor systems. Sorry I couldn't be more help.
82ND AIRBORNE OH-58 Guy here...i would use a rubbing compound ( light) then a good polishing with " Rain Dance polish. Buff it out...pilots thought I was effing around with the N-1. Why is that Sir?? We are getting 5 more knots indicated airspeed!! I didn't last long but highly noteable. ( rotor blades of course)
Btw if you understand this one step to the future pilots or engineers you can understand the other two or you can learn about the opposite section first however in the middle requires knowledge of both motor systems
I have to say I'm been looking for an explanation for a few days now, for *why* you would need flapping and hunting and this is the first video that explained it. Just one thing, is the flapping and hunting controlled by anything or is it just a passive hinge? If it's passive, does it has dampening or are the blades allowed to flap and hunt freely?
B.D.B. Thanks! The flapping and hunting are passive movements that are a result of the forces acting on the blades. Because of this there are dampeners and droop stops to help keep everything under control.
Great Video. But I do not believe, that the coriolis force is the reason for the leading/hanging movement of the blades. At that angles the blades are moving up and down the force, resulting from the coriolis force should be hard to measure. I think the aerodynamic effects of the asymetric load in an forward moving helicopter are more valid.
Uwe Först. I'd have to disagree with you. The law of Conservation of Angular Momentum / Coriolis Effect explains why rotating bodies increase in RPM as center of gravity shifts closer to the axis of rotation. Coning shifts this center of gravity and therefore causes rotational velocity to increase. I'm currently putting together a video that explains this in further detail. Be sure to stay tuned in to see it. Thanks for the feedback.
It is no surprise for me that you disagree. All I wanted to say is that, if you bend the blade 5° upwards, the resulting legth of the blade is 99,6% (cos 5°) of the blade. In my opinion is the change of the angular momentum that low, you can ignore it. On the other hand rises the drag of the blade exp2 to the speed. So you have a sigificant difference in drag between the advancing und the oposite blade. Excuse my stupid english. It ist not easy for me to discus this stuff in an forign language.
Uwe Först. By that theory the blade that flaps up would lag due to increases of drag and the blade that flaps down would lead due to a decrease in drag. But extensive blade testing has shown the reverse to be true. Once again I'd stand by my original statement.
That is the "bad Thing" in my Argumentation. I have done some reserch about helicopter Physics. I found some stuff that the blades are moving in that way you are telling us. They are talking about some earodynamic reasons... because I did not exactly understand the way it works together I did not write about the moment of leading and laging... and the reasons. All I want to say is that IMHO the coreolis force is way to low. It is not in my Interest to say that you are wrong. I want to know how it works. You can find my Text at virtual-jabog32.de/forum/viewtopic.php?f=70&t=13161 (sorry it is german) The Vortex videos you have posted on UA-cam where very useful.
@@helicopterlessonsin10minut10 Please do not mix he Conservation of Angular Momentum with the Coriolis Force. These are two different things with different unit of measures. The conservation of Angular momentum is responsible for the blade to speed up when the center of the mass of the blade gets closer to the axle of rotation. It would happen even if the blade would not flap up or down, let say a mechanism would retract the blade like how a car antenna is retracted.. The Coriolis Force is responsible for the stress on the blade when it moves up and down in a rotating coordinate system. It is the cause of the blade lagging forward or backwards. Other example for the Coriolis Force is that the water in the Mississippi River is pushing the western banks because the water is flowing from north to south on the rotational coordinate system of Earth, but does not get closer or further away from the rotational angle of Earth. Otherwise I enjoyed a lot this 10 minutes or less.
jacob i suggest you number your videos and suggest to view them in the order you set them up as. you can always subcategorize eventual additions as in between numbers
@@helicopterlessonsin10minut10 Dear Jacob, first off let me THANK YOU for these wonderful video. EASY to Understand/follow. One more thing, you have already covered the types of rotor system but would u be able to do a DETAILED video on each type of rotor systems, especially the semi rigid type? I intend to build a two seater helicopter on my own and i prefer semi rigid as its simple/less complex.
Helicopter Lessons In 10 Minutes or Less I’m jealous lol that’s awesome, i know you’re probably bias but is the Apache in your opinion the best air frame?
Isn't the rigid rotor the best though, since it eliminates mast bumping and ground resonance problems? It also lets you fly inverted, do loops etc. which you can't do with the other systems.
Poly Hexamethyl. It really just depends. Each system has its own maintenance costs and aerodynamic advantages/disadvantages. Rigid may be the best for aerobatic performance. But I guarantee those blades and rotor system cost a lot more than something like a Robinson's semi-rigid system which may be best for affordability when learning to fly. Thanks for the feedback!
You made a small mistake, the apache uses a rigid rotor system similar to the AH 56 cheyenne. That's why they can aileron roll and backflip just like the red bull Bo 105
Not all. Some helicopters designed to land on navy ships may have negative collective to hold it to the deck. But many helicopters are not designed with negative pitch.
Sagar Dolli. It's what is known as a "soft-in-plane" system. This system is like a fully articulated in that each blade can flap, feather, lead, and lag independently. However, there are no traditional hinges because the blades are composite material that allow bending and flexing.
Thank you for your excellent videos, however, the use of the term ‘semi-rigid’ is confusing and I believe incorrect. Westland Helicopters (UK) have used the term for the rotor system used on the Lynx and Wildcat. Also, there is nothing rigid about the head on the R22 etc, semi or otherwise. Thanks again.
Teetering rotor heads lead lag too, Semi rigid is not the right term for a teetering head, semi rigid rotors have a heavily damped articulation and modern day rigid rotor heads have elastomeric hinges to relieve the loads on the blades, anyhow :)
Teetering heads don't need to lead and lag. As shown in the drawings, they are "underslung", so the upward flapping blade is thrust outward from the hub and the downward flapping blade is drawn inward. The CG of each blade moves inward or outward, changing moment arm, allowing angular momentum to be conserved with no change in blade rotational speed. Think what would happen if our proverbial figure skater simultaneously extended one arm while retracting the other... Their rotation would not change. Hubs with elastomeric hinges are not "rigid". The Cabri G2, for example, with its elastomeric hinges, is a fully articulated system (according to the manufacturer). If it has hinges of any type for lead/lag and flapping, it's not "rigid".
George. I don’t claim to know much about RC helicopters. But I’d assume they aren’t semi-rigid because they want quicker control response and aren’t concerned as much about high speed flight.
Helicopter lessons in 10 minutes or less ... has an intro that feels like three minutes...LOL Other than that, good stuff, excellent use of schematics!
You can see in the video ua-cam.com/video/Pu48f7s5Ru8/v-deo.html a rigid rotor working. There the pitch horn and de pitch link are going up and down, all this is only because the helicopter is going foward? This movement is the somatory, deformation and the necessary swashplate actuation? The maximum lift hapens at this point, where the blade goes up. Then you need less atuation in the ciclic comand. Is this?
Your not entirely correct on your explanation on how the semi rigid operates. Fully articulating head is for more then two blades. The semi ridged was actually the first one to go to production.
Someone said that a true expert is he who can explain his knowledge to the average Joe...and average Joe understands. My hat off to you sir.
Feather, flap, lead and lag. Think of how difficult a helicopter is to fly vs a plane to begin with. At least in concept. 1 control for each axis? A cyclic, collective, and anti torque pedals vs a yolk? Translational lift? Settling with power? Dynamic rollover? Auto rotations? LTE? No airplane pilot must deal with these concepts. Dyssemitry of lift? Omg advancing air vs retreating air? But rotor systems that allow the angle of attack of blades to change on their own by the blades leading, lagging, feathering and flapping solve the issue of angle of attack for the pilot. The pilot controls the direction of the blades and does not have to position the aircraft in a position the way an airplane pilot does just the pitch and position of the blades. The blades being able to bend and flex on their own means the helicopter will not flip over. A pilot can hover which you cannot do in a plane. More control. But tougher to learn in concept.
I would love to see a “differences” video on controls and what they do with conventional vs tandem rotor helicopters such as the chinook. I enjoy your instructional videos. I am a retired airline pilot with no helicopter experience but was always fascinated with them.
Good vid bro. I'm a 30 year licensed structures S - engineer finally taking my M1 here in Canada.
I couldn't grasp it all in one go the first time I watched but after some books and coming back to your vid, it all clicked.
Thank you🇨🇦🤘🇺🇲
2 am, husband already asleep.. and here I am, learning about helicopters. Thank you.
Real helicopter hours
this is an exceptionally good video. I'm a helicopter engineer and learned so much right now. thank you so much!!
Video has helped me greatly on my CPL studies, thank you very much!
Awesome. You filled in a gap in my understanding about why a lead/lag pivot was there in the first place. Well done sir!
There is a nice old school video on youtube about mast bumping for the uh1. Also thank you for the videos! They most certainly help my learning style.
Looking to get all my knowledge to fly a helicopter in less than an hour. So glad I found this channel to help me with my goal.
Interested to see first helo that can fly inverted and maintain level flight for a moment.
As I watch videos of helicopters accelerating away after take-off, it seems that there is no noticeable change in angle between the fuselage and the blades as forward cyclic is applied.
Does the rotor system (fully articulated) transfer pitching moments to the mast (and thus the fuselage) when cyclic is used, or does the fuselage truly hang from the hub like a pendulum. If it's the pendulum case, that would imply that the only reason the fuselage pitches forward is because the CG is below the hub, and the CG is being "dragged" by the rotor hub. The way you drew your fully articulated rotor, it would seem possible for the blades to impart a (pitching) moment on the mast, because the flapping hinge is a distance away from the center of rotation, and the centrifugal force of the rotor could imply a pitching (or rolling) moment on the mast. Obviously the rotors flap, but the fuselage seems to respond quickly to cyclic inputs making it appear that the rotor and fuselage are moving in unison. Any thoughts?
Your assessments are correct. Fully articulated hubs allow centrifugal forces on blades to pull the hub into alignment with the rotor disk. Semirigid systems require pendular response to adjust fuselage attitude. An unloaded pushover in a Bell H-1 often resulted on rotor impacts with the top of the fuselage as the rotor disk tilted forward and the fuselage stayed level. Needed to be really careful about making aggressive ridgeline crossings.
Was able to get a 3 page paper done just watching this video. Very detailed
Thank you for this. It really helped my understanding of the differences. Be safe.
You are REALLY good at explaining things! I found your channel while trying to find an answer as to why the helicopter in the game I'm making isn't banking correctly (I have the physics wrong somewhere). I haven't quite find the answer, but I've learned so many other things already. Thanks for making these types of videos!
Your videos are great. They make their point clearly and are easy to follow and remember. I look forward to each new one you produce. If you are looking for new topics, in ground hover vs out of ground hover would be a good one to review. Keep up the good work.
Evangelist Geraniotis. I'm glad you enjoy them. I actually already have a video that covers IGE vs. OGE hovers in my "Airflow at a Hover" video. Here's the link: ua-cam.com/video/WVYqjNYgae8/v-deo.html. Thanks again!
Another great video/explanation! You are the man Jacob!
May be off subject slightly, but a question for you that’s been troubling me since the first Huey Cobra presented itself in our unit of all standard Huey’s, Viet Nam, 1969: Noticed, even on a quick glance, the Cobra had no “stabilizer” bar. Seemed like pitch change came directly off the upper swash plate via 2 long pitch change rods. No more little pitch change links off a stabilizer bar like on our Huey’s.
Because that Cobra was just refueling at our base, it quickly started up and flew off without time for this baffled “C” model Huey pilot to speak with that Cav pilot. What happened to the stabilizer bar (paddles) on now-ancient, 2-bladed, teetering-head heli designs?
Thanks in advance from an old hover-lover from days long gone.
As usual.....loved it ! Thanks for your time and effort in putting the lessons together for us.
What is the difference between those systems you presented and the Lockheed gyro rigid rotor used in AH-51 and AH-56?
Would you advise me to do a rigid rotar system on a homebuild small helicopter?
If you’re building one it comes down to materials and price. Semi rigid would probably be the most feasible.
Although I appreciated your description of the various rotor systems, I would also have greatly liked to have seen the actual schematics and maybe even a physical example of the items; trying to view these systems on the internet only results in hundreds of redundant examples over and over which ends up with me becoming irritated and finding something else to do.
I presently own a vintage Bensen B-8M (in glider configuration only for right now until I install Subaru in it for power).
What I'm looking to do is to utilize a three-blade system but don't know how to get all three blades to function the same as a two-blade "teter" system and any information would be Greatly appreciated, Thank You.
In the meantime Thanks for sharing the information which you've already posted.
I try to keep this to the basic level that a pilot would need to do. Many engineers work with those schematics but the average pilot doesn’t necessarily need to know the precise blueprint as much as how the systems differ for flight.
@@helicopterlessonsin10minut10 Can we have a four blade rotor system with teetering system?
I flew UH1's in the Army......the semi Ridgid Rotor design was far better handling than the old Bells we started out in. I imagine the higher end models you see today has the articulate system! Would love to fly one of those Corporate Cadillac's!
Awesome video man. Would be really cool if you could do a hands on demo with a real rotor head. I used to work at a machine shop and i routinely inspected rotor head components of the H3 helicopter, which despite being designed in the 50's, was fully articulated. A truly amazing design by the engineers. The blades can move in all 3 axes, cycling each rotation at 300rpm.
If I still worked there I'd be willing to get some hands on video for you but I don't
mate you are a lad, i love your videos
0:00 saw an apache do this kind of drift onto the parade field as everyone was staging for the change of command.
Wasn't as oblique and angle or as fast but he came in like this and then swung the tail around in a drift and arrested his movement all while dropping altitude to the deck.
Landed about 30-50 meters away from the head of the entire division marching onto the field. Turned everything with jet and rotor wash and made the whole formation instinctively pause in a completely animal way you may recognize from combat or ...animals.
Anyway even the first sergeant had about three seconds of brain reset time before yelling for everyone to keep moving and this is the 101st Airborne so we all have seen helicopters doing stuff before lol.
Anyway sky monsters are scary but I'm glad the scariest ones are ours. Can't wait to see what the FVL generation matures into. The SB-1 is already crazy impressive.
Thank you for posting. Good clear explanation helped clear things up for me.
I really like it.
Thank you for your time.
Sir, Your videos are very interesting and imparts lot of knowledge. Thank you for the creative explaination.
Excellent short lessons, keep up the great work! :-)
Excellent video! Thanks for the explanation!
Now fully articulated blade systems compensate for blade hunting, but they are susceptible to ground resonance right?
this helped so much....my textbooks couldn't help me....thank you
Which is recommended for a co-axial rotor system ?
Semi Rigid is feathering and teetering
Fully articulating is feathering, flapping and lead/lag
Well, the rotor hub is teetering back an forth which allows the main blades to flap up and down so flapping is still going on. It has to or there is no compensation for dissymmetry of lift. What he doesn't go into is what's happening to the lead/lag forces in a semi-rigid rotor system. As the rotor blades are flapping upwards and the center of mass of the blade should be moving closer to the axis of rotation and trying to lead forward, the teetering rotor hub is actually moving the blade away from the center of rotation. These two motions counter each other and the center of mass of the rotor blade itself stays at or very near the same distance from the center of rotation (rotor mast) and thus there are no lead/lag forces to deal with. Likewise, on the side that's flapping downward, where the center of mass of the rotor blade should be moving away from the axis of rotation and lagging behind, the teetering rotor hub is moving the blade closer to the axis of rotation and again, the two motions cancel each other out and lead/lag forces are neutralized or at the very least, kept to a bare minimum so not lead/lag hinges are needed.
best explication I have found.
Sir will you please make a video to explain Delta Three hinges and offsetting of pitch control arm off the plane. which is done to make the blade feather while flapping. It would be of great help as the bookish language isn't enough for understanding.
Kush Upadhyay. I’ll add it to the list.
Omg you are so amazing. Thank you so much for this detailed yet short video♥️
Great lessons man.
For anyone interested, the AS365 Dauphin, EC135 and 145’s are other examples of helicopters using rigid rotors 😁
Great explanation. Thank you.
Love your videos! Thanks for making!
Could you do a video on the servo flap driven blade controls as in the kaman k-Max ?
Does the AK 1-3 have a fully articulated rotor system?
Any video explaining the connection from turbine to rotor? Is it a clutch system or a bleed turbine system...how does it work?
Thanks.
It really varies by helicopter. The power turbine section of the engine is turned by combustion and is generally directly linked to the transmission. However, some helicopters (dual engine) have clutches that enable different power outputs from each engine.
Thanks, i was checking out Igor Negada's video of his GTD-350 helicopter turbine restoration. It was the gearbox which i was refering to but didnt know it. I couldnt work out how a turbine rotation translated to the rotor rotation.
m.ua-cam.com/video/-gewWyLi1mc/v-deo.html
I passed on the schematics i found, he is very apt at parts fabrication a little wasteful with resources but i think his hydrodynamic aerodynamic aptitude is equivelent to half a potato...thats been mashed.
As the blade flaps their mass is getting closer to the axis of rotation, not the point, It is rotating up and down at a radius from the point so that actually never changes.
I don't get your comment. The weight being lifted, it seems intuitive to say that it's tip is getting closer to the center of rotation.
The blade length of course doesn't change, but it draws a smaller circle around the center.
What category does the Lockheed xh51 and ah 56 fall into
Is there a fixed-pitch articulated rotor?
Holy crap that intro music made me 20% more productive at work for at least an hour!
what does it mean feathering? is the change of angle of attack right, isn't it?
Thank you so much for the video, it was really helpful!
Thanks Jacob. It couldn't be explained better.
Hi Jacob, Great videos, could you please upload a lesson on the Power Required Curve and LTE? Cheers.
Glenn Silva. Sure thing. I'll add it to the list.
@@helicopterlessonsin10minut10 Can we have a four blade rotor system with teetering system?
The rigid rotor system also flaps because flapping is the only way a rotor system can compensate for dissymmetry of lift. Flapping is the up and down movement of rotor blades as they rotate...The main difference between these rotor systems is how they each allow Flapping to occur either through (1)blades flexing in a rigid system
(2)blades flapping as a unit on a pivot point in a semi-rigid system
(3)blades flapping individually about a hinge in a fully-articulated rotor system
LeoAero19. Well said. That's what I was getting at by describing rotor systems instead of blades themselves. All systems flap to compensate for dissymmetry of lift. But each system absorbs the stressors of this in different ways. Thanks for the feedback!
Great job Thank you , very well said .
Do you have a short explanation on why the design of the bell semi rigid system is different from the R22/44, i see the Robinson has a coning hinge but the Bell doesn't
Morne Petersen. I don't claim to be an expert in either of those airframes. But from what gather, the R22's coning hinge allows each blade to flap independently while the Bell's rotor head is designed with a fixed, pre-cone angle resulting in the coning forces having to be absorbed by the blades. It all boils down to stresses on the blade. The coning hinge takes more strain off the blade than the fixed/pre-cone angle design. But some would argue that the Bell design is more responsive due to less hinges which can create sloppiness in the controls.
Helicopter Lessons In 10 Minutes or Less
Thanks mate, these 10 min clips are great refreshers
thank you brother
In Gyroplane, the semi rigid design has evolved and overcome the need for the lead lag hinge by under-slinging the blade at the hub. This is done by having a mast tower. This tower is typically two plates which extend well above the rotational point of the mast. This allows a swing motion as well as the see saw motion to occur. Ass the blade flaps up to dissipate the lift on the advancing blade, the swinging motion extends the blade outward to compensate for the stresses imparted from that of the Coriolis effect. As for as the progress of hub design, la Cierva’s bamboo rotor wings of his models only flew because of the flexibility of the blades allowing for the dissipation of asymmetric lift. Once a full scale version was built the craft rolled on take off. He then created the flapping hinge. This did not fix the problem Coriolis Effect induced stresses as you have sail lead to blade stress failures so he invented the lead lag hinge. All of these innovations were present in the Pitcairn rotor head as well as the ability to change pitch globally allowing jump take offs. Sikorsky was struggling with his rotor head design and became a licensed Pitcairn dealer at the suggestion of the US Government. Only then was Sikorsky was able to make his machine fly with acceptable degrees of control ability using a single rotor. Effectively Sikorsky stole the rotor head design and the Pitcairn family sued. Sikorsky was awarded government contracts and denied the lawsuit. This happened in 1941 and the lawsuit was not settled until the mid 70’s. The problems were solved more or less before Sikorsky flew in ‘41. If the helicopter industry de evolved itself in rotor head design, that I do not know. There is a great book by Dr. Bruce Charnov, Autogiro to Gyroplane, which tells the rich history of the first rotor winged aircraft. It is a good read, out of print but still available.
OK Mr smart guy, can you explain to me why the US Army used the 540 rotor system on 'B' model gunships in Vietnam and the difference?
@@skipperclinton1087 Mr smart guy? Really? Why the push back? I do not know what the 540 rotor system is. Why should I? I am just relating what I know is to be true about the very early development of the rotor systems and why certain elements came to be. The lead- lag hinges resulted from the change in the cg of the blade as they rose and fell. With out them, stresses on the root of the blade caused failures. The underslung nature of the Gyroplane simple style non powered type employed today and made popular by Igor Bensen found a way of relieving the vast majority of the stresses caused by the flapping motion. That’s it, end of story. I shared this because I expected those who are reading this thread might be interested in knowing the now ancient history of how something came to be. It is trivial knowledge, a well how about that thing.
@@crawford323 whoa, I didn't mean it as an insult, I meant it as a compliment. Your knowledge of choppers is well above my pay grade so I thought you might be able to shed some light on some I learn about.
" Bell designed yet another Huey variant, the "UH-1C", intended strictly for the gunship role. It featured the T53-L-11 engine of late-production UH-1Bs, with a modified intake system fitted with prominent air filters; and a new "Model 540" rotor system, with a blade chord increased further to 68 centimeters (27 inches)." All this is a foreign language to me so I was hoping you could break it down into simple layman's terms.
Obviously not with your bad attitude.
@@skipperclinton1087 My bad attitude? With the lack of facial expression and or hand gestures to complete human communication, extra care must be imparted when crafting the written word in order to be assured that no extra between-the-lines interpretation of that written word is added. Using the terms “Smarty Pants and bad attitude” could be easily interpreted as demeaning and as a less-than-careful writing style.
@@crawford323 Dude I called you "Mr Smart Guy" as from all the information you possessed on rotary wing aircraft I was spot on. Obviously you took offense to being called a "smart guy". Case of mistaken identity perhaps 🤔
Great video but the moment of inertia would be a better way to explain the fully articulated rotor system instead of the Coriolis force
Can you say a word about that here. I don't understand
Great video!
Please explain the rigid-gyro system on AH-56 Cheyenne. :D
CCCanyon. Well I haven't flown that one, and I'm sure not many others have before the project was cancelled. But I would imagine it would operate much like other rigid rotor systems. Sorry I couldn't be more help.
Good vídeo 👍🏾🚁
thank you
What a genius, a+ my man
Love the intros
Wow … you were in an Apache?? 😱 cool 👍
Yep. It’s my day job when I’m not making UA-cam videos.
@@helicopterlessonsin10minut10 wow … cool 👍 thank you for your service bro 👍 I just knew you’re in an Apache when I saw the rotor pod on top 😃
Can we have a four blade rotor system with teetering system?
82ND AIRBORNE
OH-58 Guy here...i would use a rubbing compound ( light) then a good polishing with
" Rain Dance polish. Buff it out...pilots thought I was effing around with the N-1. Why is that Sir?? We are getting 5 more knots indicated airspeed!! I didn't last long but highly noteable.
( rotor blades of course)
The rigid system must still have a swashplate though, right? The blades couldn't be completely fixed in that respect, right?
Btw if you understand this one step to the future pilots or engineers you can understand the other two or you can learn about the opposite section first however in the middle requires knowledge of both motor systems
Great videos! Wish there was a video game version.
I have to say I'm been looking for an explanation for a few days now, for *why* you would need flapping and hunting and this is the first video that explained it. Just one thing, is the flapping and hunting controlled by anything or is it just a passive hinge? If it's passive, does it has dampening or are the blades allowed to flap and hunt freely?
B.D.B. Thanks! The flapping and hunting are passive movements that are a result of the forces acting on the blades. Because of this there are dampeners and droop stops to help keep everything under control.
Starflex is a semi-rigid???
Great Video. But I do not believe, that the coriolis force is the reason for the leading/hanging movement of the blades. At that angles the blades are moving up and down the force, resulting from the coriolis force should be hard to measure. I think the aerodynamic effects of the asymetric load in an forward moving helicopter are more valid.
Uwe Först. I'd have to disagree with you. The law of Conservation of Angular Momentum / Coriolis Effect explains why rotating bodies increase in RPM as center of gravity shifts closer to the axis of rotation. Coning shifts this center of gravity and therefore causes rotational velocity to increase. I'm currently putting together a video that explains this in further detail. Be sure to stay tuned in to see it. Thanks for the feedback.
It is no surprise for me that you disagree. All I wanted to say is that, if you bend the blade 5° upwards, the resulting legth of the blade is 99,6% (cos 5°) of the blade. In my opinion is the change of the angular momentum that low, you can ignore it. On the other hand rises the drag of the blade exp2 to the speed. So you have a sigificant difference in drag between the advancing und the oposite blade.
Excuse my stupid english. It ist not easy for me to discus this stuff in an forign language.
Uwe Först. By that theory the blade that flaps up would lag due to increases of drag and the blade that flaps down would lead due to a decrease in drag. But extensive blade testing has shown the reverse to be true. Once again I'd stand by my original statement.
That is the "bad Thing" in my Argumentation. I have done some reserch about helicopter Physics. I found some stuff that the blades are moving in that way you are telling us. They are talking about some earodynamic reasons... because I did not exactly understand the way it works together I did not write about the moment of leading and laging... and the reasons.
All I want to say is that IMHO the coreolis force is way to low. It is not in my Interest to say that you are wrong. I want to know how it works. You can find my Text at virtual-jabog32.de/forum/viewtopic.php?f=70&t=13161 (sorry it is german)
The Vortex videos you have posted on UA-cam where very useful.
@@helicopterlessonsin10minut10
Please do not mix he Conservation of Angular Momentum with the Coriolis Force. These are two different things with different unit of measures. The conservation of Angular momentum is responsible for the blade to speed up when the center of the mass of the blade gets closer to the axle of rotation. It would happen even if the blade would not flap up or down, let say a mechanism would retract the blade like how a car antenna is retracted.. The Coriolis Force is responsible for the stress on the blade when it moves up and down in a rotating coordinate system. It is the cause of the blade lagging forward or backwards.
Other example for the Coriolis Force is that the water in the Mississippi River is pushing the western banks because the water is flowing from north to south on the rotational coordinate system of Earth, but does not get closer or further away from the rotational angle of Earth.
Otherwise I enjoyed a lot this 10 minutes or less.
Wich one is the bes type???
Sir plx suggest me the material through which I can make rotors at home
Good lesson
jacob i suggest you number your videos and suggest to view them in the order you set them up as. you can always subcategorize eventual additions as in between numbers
DDT DDT. Done! There is now a playlist titled "All Videos in Order" that has everything in sequence.
Helicopter Lessons In 10 Minutes or Less - thanks a million. Most and foremost thank you for your clarity.
Dear DDT DDT, spot on. Having videos in sequence will help us understand better.
@@helicopterlessonsin10minut10 Dear Jacob, first off let me THANK YOU for these wonderful video. EASY to Understand/follow.
One more thing, you have already covered the types of rotor system but would u be able to do a DETAILED video on each type of rotor systems, especially the semi rigid type?
I intend to build a two seater helicopter on my own and i prefer semi rigid as its simple/less complex.
So are you currently a pilot instructor for apaches?
Austin Taylor. That is correct sir.
Helicopter Lessons In 10 Minutes or Less I’m jealous lol that’s awesome, i know you’re probably bias but is the Apache in your opinion the best air frame?
Austin Taylor. By far it’s my favorite. That’s for sure.
Helicopter Lessons In 10 Minutes or Less it’s what I want to fly as well, so maybe you’ll see me in a year haha
Isn't the rigid rotor the best though, since it eliminates mast bumping and ground resonance problems? It also lets you fly inverted, do loops etc. which you can't do with the other systems.
Poly Hexamethyl. It really just depends. Each system has its own maintenance costs and aerodynamic advantages/disadvantages. Rigid may be the best for aerobatic performance. But I guarantee those blades and rotor system cost a lot more than something like a Robinson's semi-rigid system which may be best for affordability when learning to fly. Thanks for the feedback!
You made a small mistake, the apache uses a rigid rotor system similar to the AH 56 cheyenne. That's why they can aileron roll and backflip just like the red bull Bo 105
Don't all helicopters have some negative pitch for auto-rotation?
Not all. Some helicopters designed to land on navy ships may have negative collective to hold it to the deck. But many helicopters are not designed with negative pitch.
@@helicopterlessonsin10minut10 so how do they achieve auto-rotation?
I have a whole video explaining it. Check out my Autorotations Expanded video
Thank you #HLI10OL #SkyBaum 😃
What type of rotor system is on Bell 407?
Sagar Dolli. It's what is known as a "soft-in-plane" system. This system is like a fully articulated in that each blade can flap, feather, lead, and lag independently. However, there are no traditional hinges because the blades are composite material that allow bending and flexing.
What about Hingeless
Hello sr.. really i like it sr
Thank you for your excellent videos, however, the use of the term ‘semi-rigid’ is confusing and I believe incorrect. Westland Helicopters (UK) have used the term for the rotor system used on the Lynx and Wildcat. Also, there is nothing rigid about the head on the R22 etc, semi or otherwise. Thanks again.
Teetering rotor heads lead lag too, Semi rigid is not the right term for a teetering head,
semi rigid rotors have a heavily damped articulation and modern day rigid rotor heads have elastomeric hinges to relieve the loads on the blades, anyhow :)
Teetering heads don't need to lead and lag. As shown in the drawings, they are "underslung", so the upward flapping blade is thrust outward from the hub and the downward flapping blade is drawn inward. The CG of each blade moves inward or outward, changing moment arm, allowing angular momentum to be conserved with no change in blade rotational speed. Think what would happen if our proverbial figure skater simultaneously extended one arm while retracting the other... Their rotation would not change. Hubs with elastomeric hinges are not "rigid". The Cabri G2, for example, with its elastomeric hinges, is a fully articulated system (according to the manufacturer). If it has hinges of any type for lead/lag and flapping, it's not "rigid".
why rc helicopters do not work with two blade semi-rigid teeterig rotor head and are they too unstable? :(
George. I don’t claim to know much about RC helicopters. But I’d assume they aren’t semi-rigid because they want quicker control response and aren’t concerned as much about high speed flight.
Great
muito bom
Coriolis? You mean conservation of angular momentum?
Impressive
Helicopter lessons in 10 minutes or less ... has an intro that feels like three minutes...LOL
Other than that, good stuff, excellent use of schematics!
You can see in the video ua-cam.com/video/Pu48f7s5Ru8/v-deo.html a rigid rotor working. There the pitch horn and de pitch link are going up and down, all this is only because the helicopter is going foward? This movement is the somatory, deformation and the necessary swashplate actuation? The maximum lift hapens at this point, where the blade goes up. Then you need less atuation in the ciclic comand. Is this?
do much to learn
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*Subscribed, Not Subscried ..
Good Luck, From Middle East
Talk the tail rotor and tail fan
I was under the impression that helicopters don't actually fly. They just beat the air into submission.
Kaman Synchopter system?
Your not entirely correct on your explanation on how the semi rigid operates. Fully articulating head is for more then two blades. The semi ridged was actually the first one to go to production.
Lead-Lag is NOT due Coriolis Force.