@@pepperpeterpiperpickled9805 Hi Peter. I've never thought about it really allthough I do quite a bit of hand and wrist strength exercises. Flying is more of a feel I think? . I wouldn't worry too much about being a bit uncomfortable or un coordinated to start with. You will get more coordination as you go along your flying journey. It becomes 2nd nature quite quickly. Think more about the external factors like, planning your flight properly and sticking to your plan, density altitude, en route weather factors and visibility en route, wires, wind, especially tailwinds, turbulence, fuel management, over loading etc. Those are the things that will keep you alive. Coords will come for sure. Take care and stay calm 🙏🇿🇦👍
Yes. And just as preventable as driving your car into oncoming traffic and dismembering everyone in it. Don't push the cyclic forward abruptly and you will never have to worry. Every design has its drawbacks.
"3 bladed rotor system always has a blade in each QUADrant" ......... spot on bud.... spot on. glad the next generation of pilots are being trained by you. . . . .
@@davidbrayshaw3529 I heard that one blade has the lowest air friction possible and is the most efficient, but if we want to add more power we are forced to use 2, 3 and more blades. So 1 blade designs are usually seen on RC models, 2-3-4 blades on normal planes, a lot of blades on planes line AN 225 Mriya (biggest aircraft on Earth). Same thing we can see with helicopters.
@@denysivanov3364 I am of the understanding that friction relates to the props' surface area, its condition pertaining to damage and subsequent dressing and also pitch. I believe that increasing the number of blades has two significant effects on efficiency. Firstly, by increasing the number of blades the air being "fed" into the following blades becomes "dirty" or disrupted and as a consequence good laminar flow over the following blade is more difficult to achieve. In addition to that the vortices around the tip of the blade create drag therefore increasing the number of blades reduces efficiency. You are correct that increasing power levels usually requires increasing the number of blades which are used. Tip speed and ground clearance are other issues that designers overcome by using additional blades. Years ago I was "hanger rat" )AME working mainly on vintage aircraft. My employer, a licensed engineer, had a saying about the number of blades on a prop that pertained to their efficiency. "Two for go, three for show" but as you point out, you can't avoid having more blades as you increase power.
I have personally witnessed virtually EVERY LOH (OH6 Cayuse - multi-blade articulated rotor system) chop off its tail boom during autorotation flare/landing (two tours, Vietnam). Yes, underslung two-bladed systems can suffer mast bumping and sheer off - I've witnessed that as well - TWICE. ONE: When one of our Assault Helicopter Company UH-1H Pilots took off with a full load of Pax, cranked up to full speed (about 120K) across the Mekong Delta River - then did a cyclic climb. At the top, he committed the fatal error of pushing the cyclic forward to achieve level flight while simultaneously lowering the collective. That sheered off the rotor system with a nose dive straight down into the water. Wasn't bad enough he killed himself, he took three other crew members and eight servicemember Pax along for the eternity ride with his terminal stupidity. We never recovered the helo or any bodies. We had to go back to where they climbed aboard and work our way back to each command to find out WHO was on that helo. SECOND: An AH-1G Cobra pushed to high speed in his gun run firing everything he had. At the end, he too pulled up into an impressive cyclic climb with the same application of cyclic leveling and collective down as before. His gunship nosed over like a wounded badminton bird and zoomed straight down to meet the angels. How did I know this. I was monitoring our Guard Frequency and heard one voice shout, "This is it!" and another voice (the other gunner) screaming - for all of two seconds before silence reigned. His wingman answered my hail and described the entire event to me. I could go on all day with this - I wrote a book about it. Yes, accidents and SH*T happens - LISTEN to your IPs in school - LEARN proper safety procedures - PRACTICE safe and FULL recovery - and DON'T BE STUPID - that damned machine will end you in a heartbeat if you turn off your brain. John (two tours Vietnam, 1,955 Combat flight hours/helicopters).
"You come down like a streamlined brick " on autorotation characteristics according to Colonel Boyer concerning the Hughes OH-6 on page 181 of "Vertical Challenge The Hiller Aircraft Story' by JayP.Spenser.
Another very well presented video on some very interesting rotocraft related stuff.....very well explained too. Why anyone would want to make indignant comments towards your opinions about the various rotor systems and your thoughts for future progress in that area, is beyond me. Your videos are EXTREMELY informative. I always look forward to each one!
Less blade, fewer points of failure but higher stress and loading. More blades, more possible points of failure as more moving parts but they are under less stress and load :)
Atomicskull Nice too meet you here. That‘s right, a two bladed rotor is more efficient than a multi bladed one as well as a two-blade prop is compared to a three-blade on a drone. What i am wondering is, how the wideness of the blades affects efficiency and other properties of the rotor system. Just from looking at different helicopters i discovered that the blades on multi bladed systems are narrower than on a two blade system. In opposite the blades on a drone are often the same width regardless of the blade count.
Most 2 blade rotors are high inertia rotors; meaning if the engine quits you have more time to react before you lose rotor rpm. Three and four blade rotors are generally low inertia, bleeding off speed rapIdly when you lose power. I have done autos in both a Bell 206 (TH57) and a Bell 406 (OH58D), you have a little more time in the 206 to get the collective down and maintain rotor rpm vs its 4 bladed cousin.
what, I thought most 2 bladed were low inertia by their total low head weight and despite getting slightly more outside mass having longer blades, it takes much less time to lose rotor rpms.. thus little autorotation reaction time . 1.5.sec for r22 or something..
@@unagisama5476 its not inertia, 2 blades have less friction then 3, 4 or 5. But with a lot blades more power can be transmitted into air, thats why on big heavy aicrafts-rotocrafts we always will see a lot of blades on rotor/propeller.
I love this channel man I've always loved helicopters and I've always wanted to fly one I've come to realize I'm a poor mother hucker and I'm never going to be able to afford that never but at least I got a channel I can come to and learn all about them and fly ride along with you when you go thanks for that bro thank you very much keep up the good work 👍🙄🇱🇷🇱🇷🇱🇷🇱🇷🇱🇷
Yeah, I would have persued a helicopter pilot career in the army, but my eyes can't differ green as good as normal people can (appearantly) Don't get me wrong, I can perfectly see, but when its dark, its harder for me than for normal people :(
Money won't be your obstacle, you can get a student loan easily enough and go training tomorrow. Your obstacle is gaining meaningful employment after the fact if you are getting a commercial license and plan on doing it for a living. Tough to get a start is putting it mildly, it takes a certain kind of person to do it and openings are rare and highly contested, however it can be done if you are prepared to do whatever it takes. On a side note if all you want to do is learn to hover a helicopter, most people can learn to hover reasonably well with less than 10 hours which you should be able to do for 6-8 K (or even less depending on pricing in that area and the currency you are paying with) which essentially is a cheap crappy used car. Ergo if you can afford a cheap crappy used car you can learn to hover a helicopter reasonably well. If you really love them but don't want to do it for a living its not that expensive to learn how to hover. As you get older and have more spare cash available you can buy an hour or two a month to go scratch that itch whenever you feel like it too.
Oculus Rift S virtual gear, xplane or Microsoft Flight Simulator 2020 out in the fall, and a gaming pc...you can fly a lot of awesome helicopters, including Pilot Yellows Guimbal Cabri, the Epic R66T, Schweitzers, Bell 206, Bell 407, Huey's, oh and Bell 412's plus others. Be broke but at least you can play cheap!
little Q never stop learning, add to your knowledge every day and see where it takes you. One friend of mine a gas boy at a small airport and today he has his helicopter license. And a CFI.
Very informative. I'm not too familiar with helicopters (I'm more on aeroplanes) but, as a aviation enthusiast, being told by someone who works with/pilots rotor crafts is such a treat! Thanks
Pilot Yellow, I have flown both two and three bladed systems. The three bladed system did seem smoother and more stable to me, but from a money point of view I guess the two bladed system is more practical. Anyway, thank you for your interesting topics and great videos. Stay safe and I hope you can fly soon.
Love your content from here in Ireland Pilot yellow! Never even been in a helicopter but they’re so interesting. Your videos are really informative and interesting. Why the heck would anyone want to “hate on you” in the comments 🤷♂️ Keep up the great work and fly safe.
Forgot the dampers, ground resenence, landing gear struts, droop stop pounding. - Extra blade adds drag in autorotation makes for a short steep 'glide' less places to land in a hostile area. - Look between your toes instead of out the windshield
On two blade helicopter the forces to roll the helicopter vary dramatically from when the blade is fore and aft position (low) to the port starboard position (maximum). For similar reasons wind turbines have standardized on the three blade design to reduce cyclic jaw forces.
I'm an airplane guy but your videos are the best If I were learning I would be looking for you. Had a chance to fly helicopters in the Army but I was afraid of the night vision requirements in the early '80s
I’ve ridden in a Bell Jet Ranger and a Schweitzer S269C. The Bell had two rotors and the Schweitzer had three. The Bell vibrated baby when turning to the left, (if I remember correctly), but the Schweitzer was smooth when turn either way. The Schweitzer was a fun little help to ride in. The pilot had a blast flying my brother and I around, chasing cattle that were grazing a few hundred yards from the airport, but when he tried to set it on the peak of the hanger roof he let off the throttle a little too much and it almost fell into the hanger. I don’t advise trying that!
Another great "con" against fully articulated multi-blade heads is Ground Resonance. Usually with the smaller birds and can be catastrophic. This doesn't happen with teetering heads.
Very interesting and well explained! Would be awesome to see pictures of the models you mention while you talk bout them, that's much more video editting work however... Thank you!
A good breakdown but I believe you over stressed mast bumping and down played ground resonance, also the notion that with more moving parts there is that many more things to go wrong
Ok, you talk about Mass Bumping on a two bladed system but you did not mention Ground Resonance on a fully articulated system? I'm a bell guy and I like my 2 Blades, nice auto's and the Heli does not disintegrate on the pad from an unbalanced rotor system.
I didn't see your reply before I chimed in but more of the same. Mast bumping hasn't been a design concern in 20 years with sprague cables and flapping restraint cables (Bell 222). Statistically 2-blades are 2x safer than fully articulated heads. But always fun discussions.
Thank you for this explanation video, I had wondered about why designers went with the different rotor configurations. I have always loved the Hughes/MD/Boeing 367/ 500. Always loved the buzz it made as opposed to the Bell rotor slap. I loved the Hughes 500 AKA civilian model 367 from first time I saw one, and my admiration for it's designers have never faded. Thank you for your videos, one can always learn something if one has an open mind.
Mischa, in an earlier video you briefly mentioned the Enstrom brand helicopter and I believe there was something about either the company or helicopter itself that you did not like. Would you mind elaborating on that (Enstrom does use a 3 blade system). Thank you.
I went from a 2 blade to a 4 blade mod. Now no one complains when I land at night. Watch out for loss of tail rotor authority though. I needed to install 18% more tail rotor thrust.
The greatest benefit of a 2-bladed helicopter is, it is MUCH better than a single bladed helicopter. 😁 But, in all seriousness ... great vid Mischa. Thanks for the info.👍🍻
I know what you mean,but something to checkout,there is footage on you tube of a guy flying single bladed RC helis,on one, he had a head of a hammer where the other blade should be, it's very surprising how good the fly. He is called Nightflyyer ,video is hammerhead.from 2012 ish.
Things I learned during this video: pilots are horrible engineers (but not the other way around). 2 blade helicopters have less rotor wash interference and are actually more efficient. The main reason for adding more rotors is because 1: You can only make them so long 2: Extra blades to absorb extra power 3: less vibration. That’s pretty much it.
The only benefit, in my mind, of Two-Bladed choppers, is that they sound 'better' (cooler). I'll never change my mind on that, they sound like a flying Harley-Davidson... ...but I can accept a less-cool sound, with more safety and stability :(
The storage issue at times is a vital point. True that building a separate shed probably cost less than a blade replacement, but space can be an issue and the folding kit would be, as a manufacturer, my top priority. I went to a school that only could “afford” space for a two bladed but preferred the three blades option If they knew where to park her
definitely stability. a two blade sysyem gives you that "rocking horse' hover that you have to compensate for. Three blade is rock solid, touch the skid down on a dime
There is no "better" about either designs, its just different. 1- Strictly from lift perspective, 2-bladed systems are not inherently worse performers, they just need larger disk area to perform as good.. If physical dimensions are not the issue, 2-blade designs are actually the most aerodynamically efficient, followed closely by 3, and adding more blades subtact from efficiency. This is why there are 2 and 3-blade wind turbines, but we don't really see a 5-6-10-20 bladed wind turbines. Because so long as they are safely away from the ground, there isn't any dimensional contraints and its always better to have longer blades and have a larger disk area, than to add more blades. 2- Closely related to #1, storage advantage goes both ways.. A 2-bladed helicopter of same weight will have greater rotor diameter to retain aerodynamic efficiency. Since tail length is also proportional to rotor diameter, a 2-bladed helicopter of same weight will inherently be longer. A folding multi-blade helicopter will be comperable in width, but smaller in length to a folding 2-blade helicopter. 3- 2-blade will have unique mast bump risk, 3-blade will have ground resonance. Mast bump is pilot-induced 99% of the time, ground resonance is both pilot induced and maintenance-related. 4- A 3 blade rotor will be easier on the pilot and more stable to fly, 2 blade will be much more responsive to controls. 5- Misalignment on 2 blade is easier to notice, but that "advantage" argument goes both ways.. Is it not better to notice a problem early without symptoms getting worse? For example, if one blade has damper issues and drags just a little bit more, its not really noticable with minimal cyclic inputs, like when hovering, but it can have lethal consequences. 6- Misalignment on 2 blades is more noticable, but misalignment plane is (mostly) on a single axis on semi-rigid rotors, so easier to diagnose. On a fully-articulated system there are 3 misalignment planes. 7- Adding more rotor blades to SOME designs work, because they are done so with other constraints. Some are specifically designed for a certain rotor diameter, or started with a puny engine and upgraded along the way to a much stronger engines. Both points apply to AH-1G to AH-1J to AH-1W to AH-1Z evolution: AH-1G with 2-blade (
Great video. This was very informational for a new quadcopter hobbyist here (indoor only). I mention indoor only because I intend to respect airspace and leave piloting to ACTUAL pilots. But I did get a part 107 certificate and understand how to track using B4UFLY apps in uncontrolled spaces under 400ft. Sad you have to mention all this now to avoid getting attacked in comments 😂 I'm sure there are additional considerations in how this applies to quadcopters but generally the effect is the same, more blades = better weight distribution= smoother flight = less turbulence = more efficiency. I will say in my experience with these though there are times where 3 blades seems to grip and corner better at speed than 4 blades but I think that has more to do with the rotor angle than the blade count. 🤔 But when starting a turn for instance... Does the additional distance between the blades allow larger amount of pitch or yaw to be acheived with a single revolution? Consodering pitching and yaw combined? 🤔 (On a quadcopter)? I wonder
Great info and great video. Idea for a new video if you take them. How climates affect the lift. Example: High altitude mountain and cold air compared to sea level and dense humid hot air. Also answer climate questions like: is lighter better for higher altitude; do blades matter in the climate; and does the rotor rmp matter?
Hello, Just Curious, is autorotation more efficient/safer with more blades? I have never flown a helicopter, but wish to in the future. Really enjoy your videos! Thanks
mast bumping is 100% pilot error. Three bladed rotor systems suffer from ground resonance, whereas 2,4,5,6 etc bladed systems do not. There's no free lunch.
@@artmckay6704 Absolutely. A fair amount of ground effect events are also the result of poor piloting, but it doesn't take much to cause the phenomenon.
Great channel ive subscribed I no longer fly full size helicopters anymore its a life style change.. but I fly my huge rc 105 helicopter I guess we never leave them ..
They are in fact more efficient. There have also been some experimental single blade designs where the opposite blade is replaced with a counter weight.
@@atomicskull6405 While hovering. If its moving with a significant speed, the blades are getting fresh air and are not travelling throough the turbulent backwash of the blade before them.
@Misca thank you so much for the invitation to hate! I wish more Tubers offered that up to viewers! Have you flown 4 blade helicopters and if you could do it over again would you learn on a 4 blade system instead of the squirrelly Robinson platform.
With more blades, i.e. 5 blade, can you reduce the length of the blades vs. 2 blades? Does either rotate slower. Is there a simple trade off on drag vs lift on number of blades to consider?
Lots of things to consider. The 500/396 platform is small and more maneuverable but the the 206 flies 100 (216 miles vs 360!) more miles and carries more.
U.S. NAVY have a two engines and four blades UH -1 helicopters. Originaly they had one engine and two blades, they made a big improvement on those helicopters.
I really would appreciate an video of you, talking / discussing with a experienced MD 500, MD-Explorer & especially with a lot of hours on the NOTAR Technology-Helicopters. Hearing about comparing a lot of topics like this here or stability, aerodynamic , etc., etc, ... This would be so interesting!. With kindest regards from Germany ✌🏼
Just discovered your channel. Excellent! A question: 50 years ago, rearming my “C” model Huey on the tarmac in Dong Tam, South Vietnam, an Air Cav Cobra shut down nearby. First one this Huey gunship driver had ever seen up close. After suppressing my envy, noticed the Cobra’s 2-bladed system was completely void of the fly bar (or “stabilizer bar”) with all the accompanying parts & bits seen on my rotor head. From my vantage point, all I saw were 2 pushrods going directly from the swash plate to pitch change links on each blade. How does this “new” (back in ‘69) system work?
The stabilizer bar was removed on more modern helicopters because they found other ways to stabilize the helicopters I believe. However I’m not an expert on stabilizer bars. It’s like the old Bell 47’s have one but a jet ranger doesn’t.
Keep up the videos. No hate but some clarifications: Most of the more recent generations of 2-blade heads (like the Bell 222) have hub flapping restraint springs or other designs having sprague cables. Beyond expense there is also a lot more weight, failure, and maintenance concerns. Statistically 2-blade helicopters are safer especially when pilot error is removed. All factors in play the Bell 206 is 3x safer than a Hughes 396. And the lowest civilian accident rate of all (per 100K hours) goes to the Bell 205. So probably a bigger consideration is turbine/piston. Where the failure rate in turbines is 9/100K hours and pistons fail at 29/100K hours. So which blade is safer? Really points toward the simpler 2-blade teetering head.
@@DavesNotHereMann Thanks mate. I never knew that. What number of blades usually has the lead lag system? Can 2 blades have it or only 3 or more blade systems?
But what about the handling? Do larger and more blades handle smoother than smaller less-blade rotorcraft? Also, at what point can stunts be performed with respect to the rotor count?
Try any stunts on a teetering 2 bladed system and you'll likely be dead in seconds. You have to have 3+ blades and ideally a ridged rotor head like the MBB Bo105. More rotor blades=more mass. More mass=smoother, but slower reaction to force (control force or external force).
More blades the smoother unless you're flying a fully rigid rotor. The Bell 407 has 4 blades and is like a Lexus our BO-105 has 4 blades and it's like a NASCAR but we can go upside down:). Check out our channel if you get a chance.
What I can't get past is the CH 53E Super Stallion that has 7 blades and how that spaces evenly in the rotor disc. 2,3,4,5,6,8 & 9 all divide into 360 evenly but 7 doesn't so how does that work for that rotor system?
Well, it divides as 51d 25m 42.86s and some hairs but this is not a problem manufacturing such a rotor head; in the olden times there was the obvious divider head that could help you make some pretty funky parts (and helical gears with a leadscrew-enabled divider head), now with CNC manufacturing uncanny angles even less of an issue.
Hi just a question is a two bladed rotor safer or easier to autorotate since the blades have more mass and might fly a bit more distance and last longer in the air? Thanks
Perry . Game Developer I think the specs show a Cabri with 3 blades has more rotor mass than a 2 blades Robinson. So you get more time to do the flare with a cabri and also more time to enter autorotation before the rotor speed drops
The most efficient (In terms of thrust output per power input)? A _single_ blade! It can be done as long as you are very careful with balancing and don't mind high RPM for the same thrust.
Can you talk about what "fully articulated"is all about. Also, what has changed in rotor system design from the Enstrom 3 bladed system to a more modern system like on the Cabri?
Been flying commercially on helicopters for over 30 years. Love your passion and instruction brother. Fly safe. 👍🇿🇦
Hey Wayne, as an experienced flyer, are there any exercises you could recommend to practice cyclic/pedal/lever coordination when Im not flying?
@@pepperpeterpiperpickled9805 Hi Peter. I've never thought about it really allthough I do quite a bit of hand and wrist strength exercises. Flying is more of a feel I think? . I wouldn't worry too much about being a bit uncomfortable or un coordinated to start with. You will get more coordination as you go along your flying journey. It becomes 2nd nature quite quickly. Think more about the external factors like, planning your flight properly and sticking to your plan, density altitude, en route weather factors and visibility en route, wires, wind, especially tailwinds, turbulence, fuel management, over loading etc. Those are the things that will keep you alive. Coords will come for sure. Take care and stay calm 🙏🇿🇦👍
@@waynegrobler7432 good point, mate. I appreciate the answer
Mast bumping is such mild word for a catastrophic event that slices the tail boom clean off then usually dismembers or decapitates the pilot.
Mark, right on target. R22 and R44. Turbulence or low G pushover Deadly. jg.
Yes. And just as preventable as driving your car into oncoming traffic and dismembering everyone in it. Don't push the cyclic forward abruptly and you will never have to worry. Every design has its drawbacks.
Meanwhile, the three blades rip themselves apart while on the ground.
@Remain Nameless depends, some helicopter crashes they have had the rotor blades chop into the cyclic controls.
Right but it can only happen due to Pilot error
Thank you for the very thorough explanation that non pilots can understand, great channel !
Hands down best moment of the video was you saying "Wop wop wop wop" 🤣🤣🤣(all with love brother (from CALI))
Watch the beginning scene of "Apocalypse Now"....
Excellent Explanation good service and information with education type
There were lots of helicopters around my old home base (Langley). You knew when there was a Huey around. :-)
"3 bladed rotor system always has a blade in each QUADrant" ......... spot on bud.... spot on. glad the next generation of pilots are being trained by you. . . . .
Wrong.. It always have at least 1 blade in one of the 4 quadrats.. But you can't have a blade in each of the 4 quadrats with 3 blades..
@@hisheighnessthesupremebeing thanks tips, yea i know, it was a joke. i was quoting him.
So what you're saying is that my single blade helicopter design is just going to be just terrible?!?
ua-cam.com/video/wxY9snBbAAw/v-deo.html
Not at all, your design will work just perfectly.
Please post the video of your attempts on here.............
@@davidbrayshaw3529 I heard that one blade has the lowest air friction possible and is the most efficient, but if we want to add more power we are forced to use 2, 3 and more blades. So 1 blade designs are usually seen on RC models, 2-3-4 blades on normal planes, a lot of blades on planes line AN 225 Mriya (biggest aircraft on Earth). Same thing we can see with helicopters.
@@denysivanov3364 I am of the understanding that friction relates to the props' surface area, its condition pertaining to damage and subsequent dressing and also pitch. I believe that increasing the number of blades has two significant effects on efficiency. Firstly, by increasing the number of blades the air being "fed" into the following blades becomes "dirty" or disrupted and as a consequence good laminar flow over the following blade is more difficult to achieve. In addition to that the vortices around the tip of the blade create drag therefore increasing the number of blades reduces efficiency.
You are correct that increasing power levels usually requires increasing the number of blades which are used. Tip speed and ground clearance are other issues that designers overcome by using additional blades.
Years ago I was "hanger rat" )AME working mainly on vintage aircraft. My employer, a licensed engineer, had a saying about the number of blades on a prop that pertained to their efficiency. "Two for go, three for show" but as you point out, you can't avoid having more blades as you increase power.
However, my zero blade helicopter has a flawless safety record.
I have personally witnessed virtually EVERY LOH (OH6 Cayuse - multi-blade articulated rotor system) chop off its tail boom during autorotation flare/landing (two tours, Vietnam). Yes, underslung two-bladed systems can suffer mast bumping and sheer off - I've witnessed that as well - TWICE. ONE: When one of our Assault Helicopter Company UH-1H Pilots took off with a full load of Pax, cranked up to full speed (about 120K) across the Mekong Delta River - then did a cyclic climb. At the top, he committed the fatal error of pushing the cyclic forward to achieve level flight while simultaneously lowering the collective. That sheered off the rotor system with a nose dive straight down into the water. Wasn't bad enough he killed himself, he took three other crew members and eight servicemember Pax along for the eternity ride with his terminal stupidity. We never recovered the helo or any bodies. We had to go back to where they climbed aboard and work our way back to each command to find out WHO was on that helo. SECOND: An AH-1G Cobra pushed to high speed in his gun run firing everything he had. At the end, he too pulled up into an impressive cyclic climb with the same application of cyclic leveling and collective down as before. His gunship nosed over like a wounded badminton bird and zoomed straight down to meet the angels. How did I know this. I was monitoring our Guard Frequency and heard one voice shout, "This is it!" and another voice (the other gunner) screaming - for all of two seconds before silence reigned. His wingman answered my hail and described the entire event to me. I could go on all day with this - I wrote a book about it. Yes, accidents and SH*T happens - LISTEN to your IPs in school - LEARN proper safety procedures - PRACTICE safe and FULL recovery - and DON'T BE STUPID - that damned machine will end you in a heartbeat if you turn off your brain. John (two tours Vietnam, 1,955 Combat flight hours/helicopters).
"You come down like a streamlined brick " on autorotation characteristics according to Colonel Boyer concerning the Hughes OH-6 on page 181 of "Vertical Challenge The Hiller Aircraft Story' by JayP.Spenser.
"Pax" Did Uber finally corner the helicopter ride market?
What is the name of your book?
Thanks!
@@wageslave387 No, PAX was used a long time in the aviation industry before the Uber industry silliness.
Another very well presented video on some very interesting rotocraft related stuff.....very well explained too. Why anyone would want to make indignant comments towards your opinions about the various rotor systems and your thoughts for future progress in that area, is beyond me. Your videos are EXTREMELY informative. I always look forward to each one!
Less blade, fewer points of failure but higher stress and loading. More blades, more possible points of failure as more moving parts but they are under less stress and load :)
Ima make a 20 blades helicopter
Also smaller "footprint" while in operation.
Two blades are more efficient.
@@FIRE_STORMFOX-3692Not sure if that would even fly given each blade would be right in the disrupted wake of the one in front of it.
Atomicskull
Nice too meet you here. That‘s right, a two bladed rotor is more efficient than a multi bladed one as well as a two-blade prop is compared to a three-blade on a drone. What i am wondering is, how the wideness of the blades affects efficiency and other properties of the rotor system. Just from looking at different helicopters i discovered that the blades on multi bladed systems are narrower than on a two blade system. In opposite the blades on a drone are often the same width regardless of the blade count.
You are the best Instructor very clear and concise instruction straight to the poit.
Most 2 blade rotors are high inertia rotors; meaning if the engine quits you have more time to react before you lose rotor rpm. Three and four blade rotors are generally low inertia, bleeding off speed rapIdly when you lose power. I have done autos in both a Bell 206 (TH57) and a Bell 406 (OH58D), you have a little more time in the 206 to get the collective down and maintain rotor rpm vs its 4 bladed cousin.
Couple more things: There is no "ground resonance" with teetering heads. Far cheaper and less complex. Statistically 2x safer.
what, I thought most 2 bladed were low inertia by their total low head weight and despite getting slightly more outside mass having longer blades, it takes much less time to lose rotor rpms.. thus little autorotation reaction time . 1.5.sec for r22 or something..
@@unagisama5476 its not inertia, 2 blades have less friction then 3, 4 or 5. But with a lot blades more power can be transmitted into air, thats why on big heavy aicrafts-rotocrafts we always will see a lot of blades on rotor/propeller.
See an Enstrom for a counterpoint. Lot of inertia with a three-blade rotor.
And the high blade solidity with more blades
I love this channel man I've always loved helicopters and I've always wanted to fly one I've come to realize I'm a poor mother hucker and I'm never going to be able to afford that never but at least I got a channel I can come to and learn all about them and fly ride along with you when you go thanks for that bro thank you very much keep up the good work 👍🙄🇱🇷🇱🇷🇱🇷🇱🇷🇱🇷
Yeah, I would have persued a helicopter pilot career in the army, but my eyes can't differ green as good as normal people can (appearantly)
Don't get me wrong, I can perfectly see, but when its dark, its harder for me than for normal people :(
My thought exactly.
Money won't be your obstacle, you can get a student loan easily enough and go training tomorrow. Your obstacle is gaining meaningful employment after the fact if you are getting a commercial license and plan on doing it for a living. Tough to get a start is putting it mildly, it takes a certain kind of person to do it and openings are rare and highly contested, however it can be done if you are prepared to do whatever it takes. On a side note if all you want to do is learn to hover a helicopter, most people can learn to hover reasonably well with less than 10 hours which you should be able to do for 6-8 K (or even less depending on pricing in that area and the currency you are paying with) which essentially is a cheap crappy used car. Ergo if you can afford a cheap crappy used car you can learn to hover a helicopter reasonably well. If you really love them but don't want to do it for a living its not that expensive to learn how to hover. As you get older and have more spare cash available you can buy an hour or two a month to go scratch that itch whenever you feel like it too.
Oculus Rift S virtual gear, xplane or Microsoft Flight Simulator 2020 out in the fall, and a gaming pc...you can fly a lot of awesome helicopters, including Pilot Yellows Guimbal Cabri, the Epic R66T, Schweitzers, Bell 206, Bell 407, Huey's, oh and Bell 412's plus others. Be broke but at least you can play cheap!
little Q never stop learning, add to your knowledge every day and see where it takes you. One friend of mine a gas boy at a small airport and today he has his helicopter license. And a CFI.
Very informative. I'm not too familiar with helicopters (I'm more on aeroplanes) but, as a aviation enthusiast, being told by someone who works with/pilots rotor crafts is such a treat! Thanks
I really enjoy your videos. Your presentations and positions are informative.
I enjoy your teaching style!
Pilot Yellow, I have flown both two and three bladed systems. The three bladed system did seem smoother and more stable to me, but from a money point of view I guess the two bladed system is more practical. Anyway, thank you for your interesting topics and great videos. Stay safe and I hope you can fly soon.
Hey Brian, what do you mean by 'practical'?
@Remain Nameless thanks mate
Love your content from here in Ireland Pilot yellow! Never even been in a helicopter but they’re so interesting. Your videos are really informative and interesting. Why the heck would anyone want to “hate on you” in the comments 🤷♂️ Keep up the great work and fly safe.
Your videos are amazing! I love people who know what they're talking about and who know how to convey it visually. Very effective learning method:-)
I'm learning soooo much from you...truly grateful for the information you share. Thank you.
Forgot the dampers, ground resenence, landing gear struts, droop stop pounding. - Extra blade adds drag in autorotation makes for a short steep 'glide' less places to land in a hostile area. - Look between your toes instead of out the windshield
On two blade helicopter the forces to roll the helicopter vary dramatically from when the blade is fore and aft position (low) to the port starboard position (maximum). For similar reasons wind turbines have standardized on the three blade design to reduce cyclic jaw forces.
I'm an airplane guy but your videos are the best If I were learning I would be looking for you. Had a chance to fly helicopters in the Army but I was afraid of the night vision requirements in the early '80s
I’ve ridden in a Bell Jet Ranger and a Schweitzer S269C. The Bell had two rotors and the Schweitzer had three. The Bell vibrated baby when turning to the left, (if I remember correctly), but the Schweitzer was smooth when turn either way. The Schweitzer was a fun little help to ride in. The pilot had a blast flying my brother and I around, chasing cattle that were grazing a few hundred yards from the airport, but when he tried to set it on the peak of the hanger roof he let off the throttle a little too much and it almost fell into the hanger. I don’t advise trying that!
Another great "con" against fully articulated multi-blade heads is Ground Resonance. Usually with the smaller birds and can be catastrophic. This doesn't happen with teetering heads.
There are more than just teetering and fully articulated. There are also rigid and semi rigid.
So can a two blade suffer from ground resonance?
even a two blade heli can suffer ground resonance
@@simeonkioi3844 not on a teetering head. It's kind of the reason teetering works.
Hey Mischa, very informative video. By the way, we'll never hate on you. 😁
Good Explanation,The flapping sound of two blades is very distinctive
That was very informative, thank you. Greetings from Australia 🇦🇺
Excellent tutorial. Please keep them coming
Very interesting and well explained! Would be awesome to see pictures of the models you mention while you talk bout them, that's much more video editting work however... Thank you!
Mischa, great content, you should have mentioned MI-26 with 8 bladed rotor system.
And it's so damn big
Again, another great shot of information from my favorite helicopter personality. Thanks again
Thanks for this! Glad to thumbs up. As a humble request - having a photo pop up of the various helos you’re talking about would be awesome :)
Love the song at the end
Crikey, I was not aware that rotor blades were so expensive!
Thanks so much for a great video.
last I heard there is a two year plus wait for new Bell 2129huey) blades.
That three-blader also has a Finestron tail rotor, too.
A good breakdown but I believe you over stressed mast bumping and down played ground resonance, also the notion that with more moving parts there is that many more things to go wrong
Thank you for the video, great explanation. More of these informational take videos would be awesome. Thanks!
Ok, you talk about Mass Bumping on a two bladed system but you did not mention Ground Resonance on a fully articulated system? I'm a bell guy and I like my 2 Blades, nice auto's and the Heli does not disintegrate on the pad from an unbalanced rotor system.
I didn't see your reply before I chimed in but more of the same. Mast bumping hasn't been a design concern in 20 years with sprague cables and flapping restraint cables (Bell 222). Statistically 2-blades are 2x safer than fully articulated heads. But always fun discussions.
Thank you for this explanation video, I had wondered about why designers went with the different rotor configurations. I have always loved the Hughes/MD/Boeing 367/ 500. Always loved the buzz it made as opposed to the Bell rotor slap. I loved the Hughes 500 AKA civilian model 367 from first time I saw one, and my admiration for it's designers have never faded. Thank you for your videos, one can always learn something if one has an open mind.
Gavin Green 369, actually
Did you know Frank Robinson designed the 4 blade tail rotor for the 500?
Love the Bell 2 blade thong slap ;)
I really enjoy your videos. Your around the world trip was wonderful.
Mischa, in an earlier video you briefly mentioned the Enstrom brand helicopter and I believe there was something about either the company or helicopter itself that you did not like. Would you mind elaborating on that (Enstrom does use a 3 blade system).
Thank you.
Loved your simple explanation. However you didn't mention ground resonance of multi-bladed rotors.
I went from a 2 blade to a 4 blade mod. Now no one complains when I land at night. Watch out for loss of tail rotor authority though. I needed to install 18% more tail rotor thrust.
Makes sense. You need to compensate for additional rotational mass.
The greatest benefit of a 2-bladed helicopter is, it is MUCH better than a single bladed helicopter. 😁
But, in all seriousness ... great vid Mischa. Thanks for the info.👍🍻
I know what you mean,but something to checkout,there is footage on you tube of a guy flying single bladed RC helis,on one, he had a head of a hammer where the other blade should be, it's very surprising how good the fly. He is called Nightflyyer ,video is hammerhead.from 2012 ish.
There's no reason why a single bladed helicopter wouldn't fly
Things I learned during this video: pilots are horrible engineers (but not the other way around). 2 blade helicopters have less rotor wash interference and are actually more efficient. The main reason for adding more rotors is because 1: You can only make them so long 2: Extra blades to absorb extra power 3: less vibration. That’s pretty much it.
Thank you for teaching in simple English
This is awesome. You're the man.
good review of multi rotor benefits. well done. DG
The only benefit, in my mind, of Two-Bladed choppers, is that they sound 'better' (cooler). I'll never change my mind on that, they sound like a flying Harley-Davidson...
...but I can accept a less-cool sound, with more safety and stability :(
The storage issue at times is a vital point. True that building a separate shed probably cost less than a blade replacement, but space can be an issue and the folding kit would be, as a manufacturer, my top priority. I went to a school that only could “afford” space for a two bladed but preferred the three blades option If they knew where to park her
But i like to hear two bladed helicopter's noise it gives me a kind of joy
I don’t fly helicopters but I’ve been around the EC135’s quite a bit with the air part of the ambulance company I work for! Interesting info thanks
definitely stability. a two blade sysyem gives you that "rocking horse' hover that you have to compensate for. Three blade is rock solid, touch the skid down on a dime
There is no "better" about either designs, its just different.
1- Strictly from lift perspective, 2-bladed systems are not inherently worse performers, they just need larger disk area to perform as good.. If physical dimensions are not the issue, 2-blade designs are actually the most aerodynamically efficient, followed closely by 3, and adding more blades subtact from efficiency. This is why there are 2 and 3-blade wind turbines, but we don't really see a 5-6-10-20 bladed wind turbines. Because so long as they are safely away from the ground, there isn't any dimensional contraints and its always better to have longer blades and have a larger disk area, than to add more blades.
2- Closely related to #1, storage advantage goes both ways.. A 2-bladed helicopter of same weight will have greater rotor diameter to retain aerodynamic efficiency. Since tail length is also proportional to rotor diameter, a 2-bladed helicopter of same weight will inherently be longer. A folding multi-blade helicopter will be comperable in width, but smaller in length to a folding 2-blade helicopter.
3- 2-blade will have unique mast bump risk, 3-blade will have ground resonance. Mast bump is pilot-induced 99% of the time, ground resonance is both pilot induced and maintenance-related.
4- A 3 blade rotor will be easier on the pilot and more stable to fly, 2 blade will be much more responsive to controls.
5- Misalignment on 2 blade is easier to notice, but that "advantage" argument goes both ways.. Is it not better to notice a problem early without symptoms getting worse?
For example, if one blade has damper issues and drags just a little bit more, its not really noticable with minimal cyclic inputs, like when hovering, but it can have lethal consequences.
6- Misalignment on 2 blades is more noticable, but misalignment plane is (mostly) on a single axis on semi-rigid rotors, so easier to diagnose. On a fully-articulated system there are 3 misalignment planes.
7- Adding more rotor blades to SOME designs work, because they are done so with other constraints. Some are specifically designed for a certain rotor diameter, or started with a puny engine and upgraded along the way to a much stronger engines. Both points apply to AH-1G to AH-1J to AH-1W to AH-1Z evolution: AH-1G with 2-blade (
Awesome analysis. Engineers perspective.
Thank you! This is the kind of in-depth discussion I was looking for when I started googling.
Thank You, well worth my time reading.
Outstanding overview, I don't know why I bother watching videos when I can find gold in the comments like this.
So does this mean when you have a helicopter in whisper mode so it is making no sound from the blade is that because of having more blades?
Well explained 👌🏻
From my time in the Navy, I assumed all helicopters had folding blades. I guess you learn something new all the time.
Great video. This was very informational for a new quadcopter hobbyist here (indoor only). I mention indoor only because I intend to respect airspace and leave piloting to ACTUAL pilots. But I did get a part 107 certificate and understand how to track using B4UFLY apps in uncontrolled spaces under 400ft. Sad you have to mention all this now to avoid getting attacked in comments 😂 I'm sure there are additional considerations in how this applies to quadcopters but generally the effect is the same, more blades = better weight distribution= smoother flight = less turbulence = more efficiency. I will say in my experience with these though there are times where 3 blades seems to grip and corner better at speed than 4 blades but I think that has more to do with the rotor angle than the blade count. 🤔 But when starting a turn for instance... Does the additional distance between the blades allow larger amount of pitch or yaw to be acheived with a single revolution? Consodering pitching and yaw combined? 🤔 (On a quadcopter)? I wonder
Great explanations
Great info and great video. Idea for a new video if you take them. How climates affect the lift. Example: High altitude mountain and cold air compared to sea level and dense humid hot air. Also answer climate questions like: is lighter better for higher altitude; do blades matter in the climate; and does the rotor rmp matter?
Max Captain that’s great thanks
Hello, Just Curious, is autorotation more efficient/safer with more blades? I have never flown a helicopter, but wish to in the future. Really enjoy your videos! Thanks
No: Because the higher disk loading and lower inertial energy with smaller blades.
Great video. Keep them coming.
No mention of ground resonance with the fully articulated system. How come?
3 or more blades makes perfect sense to me. I certainly wouldn't want to fly in something where the blade roots could bump the mast!
mast bumping is 100% pilot error. Three bladed rotor systems suffer from ground resonance, whereas 2,4,5,6 etc bladed systems do not. There's no free lunch.
@@225degrees oh, I didn't know about the ground resonance problem and that's a problem that can go from zero to oh no in 3 seconds......
@@artmckay6704 Absolutely. A fair amount of ground effect events are also the result of poor piloting, but it doesn't take much to cause the phenomenon.
What is the max weight for a student to be able to learn on a Cabri G2 helicopter
Great channel ive subscribed I no longer fly full size helicopters anymore its a life style change.. but I fly my huge rc 105 helicopter I guess we never leave them ..
Thanks for a great video
Thanks I always like to learn
Shouldn't 2 bladed rotors have increased efficiency compared to rotors with higher blade count?
They are in fact more efficient. There have also been some experimental single blade designs where the opposite blade is replaced with a counter weight.
@@atomicskull6405
While hovering.
If its moving with a significant speed, the blades are getting fresh air and are not travelling throough the turbulent backwash of the blade before them.
Ok
@Misca thank you so much for the invitation to hate! I wish more Tubers offered that up to viewers!
Have you flown 4 blade helicopters and if you could do it over again would you learn on a 4 blade system instead of the squirrelly Robinson platform.
With more blades, i.e. 5 blade, can you reduce the length of the blades vs. 2 blades? Does either rotate slower. Is there a simple trade off on drag vs lift on number of blades to consider?
So along with the more blades and engine,is that why so many people love the MD 500 platform?
its really simple(or at least it was) and fast too.
The MD 500 is sooo sexy!😎
I love the 500, it’s such an attractive and agile chopper!
The old 500D sounds cool
Lots of things to consider. The 500/396 platform is small and more maneuverable but the the 206 flies 100 (216 miles vs 360!) more miles and carries more.
Would like some technical study and information on Blade folding and what G.A. types are available and cost...?
U.S. NAVY have a two engines and four blades UH -1 helicopters. Originaly they had one engine and two blades, they made a big improvement on those helicopters.
I really would appreciate an video of you, talking / discussing with a experienced MD 500, MD-Explorer & especially with a lot of hours on the NOTAR Technology-Helicopters.
Hearing about comparing a lot of topics like this here or stability, aerodynamic , etc., etc, ...
This would be so interesting!.
With kindest regards from Germany ✌🏼
Greetings from Chile , what about ground resonance ?
thank you very helpful you rock Mischa!!
Thanks for the informative videos! 🤙🏼
I really enjoy this series. What is the typical lifespan of a set blades?
Just discovered your channel. Excellent! A question:
50 years ago, rearming my “C” model Huey on the tarmac in Dong Tam, South Vietnam, an Air Cav Cobra shut down nearby. First one this Huey gunship driver had ever seen up close. After suppressing my envy, noticed the Cobra’s 2-bladed system was completely void of the fly bar (or “stabilizer bar”) with all the accompanying parts & bits seen on my rotor head. From my vantage point, all I saw were 2 pushrods going directly from the swash plate to pitch change links on each blade. How does this “new” (back in ‘69) system work?
The stabilizer bar was removed on more modern helicopters because they found other ways to stabilize the helicopters I believe. However I’m not an expert on stabilizer bars. It’s like the old Bell 47’s have one but a jet ranger doesn’t.
@@PilotYellow Thanks for responding. If you run across information on “how”, please share.
Keep up the videos. No hate but some clarifications: Most of the more recent generations of 2-blade heads (like the Bell 222) have hub flapping restraint springs or other designs having sprague cables. Beyond expense there is also a lot more weight, failure, and maintenance concerns. Statistically 2-blade helicopters are safer especially when pilot error is removed. All factors in play the Bell 206 is 3x safer than a Hughes 396. And the lowest civilian accident rate of all (per 100K hours) goes to the Bell 205. So probably a bigger consideration is turbine/piston. Where the failure rate in turbines is 9/100K hours and pistons fail at 29/100K hours. So which blade is safer? Really points toward the simpler 2-blade teetering head.
100%
Went from zero knowledge on "why" to a point of understanding. Thanks!
What about ground resonance? Does that not affect odd number bladed choppers? So 3, 5 and 7 blades?
any bird with whats called lead lag hinges is susceptible, doesnt have to do with odd # of blades.
@@DavesNotHereMann Thanks mate. I never knew that. What number of blades usually has the lead lag system? Can 2 blades have it or only 3 or more blade systems?
But what about the handling? Do larger and more blades handle smoother than smaller less-blade rotorcraft? Also, at what point can stunts be performed with respect to the rotor count?
Also great video btw; thanks 4 postin
Try any stunts on a teetering 2 bladed system and you'll likely be dead in seconds. You have to have 3+ blades and ideally a ridged rotor head like the MBB Bo105. More rotor blades=more mass. More mass=smoother, but slower reaction to force (control force or external force).
More blades the smoother unless you're flying a fully rigid rotor. The Bell 407 has 4 blades and is like a Lexus our BO-105 has 4 blades and it's like a NASCAR but we can go upside down:). Check out our channel if you get a chance.
What I can't get past is the CH 53E Super Stallion that has 7 blades and how that spaces evenly in the rotor disc. 2,3,4,5,6,8 & 9 all divide into 360 evenly but 7 doesn't so how does that work for that rotor system?
Well, it divides as 51d 25m 42.86s and some hairs but this is not a problem manufacturing such a rotor head; in the olden times there was the obvious divider head that could help you make some pretty funky parts (and helical gears with a leadscrew-enabled divider head), now with CNC manufacturing uncanny angles even less of an issue.
8:20 "the wave of the Future" yeah but the Bell 505 tho
I like bell 430. But i heard that its bad helicopter to fly... Is that true? Can you explain that in any other video?
Hi just a question is a two bladed rotor safer or easier to autorotate since the blades have more mass and might fly a bit more distance and last longer in the air? Thanks
Perry . Game Developer I think the specs show a Cabri with 3 blades has more rotor mass than a 2 blades Robinson. So you get more time to do the flare with a cabri and also more time to enter autorotation before the rotor speed drops
Can a helicopter be flown upside down and if so can it be used as a lawnmower????
No hate here! Thanks! Great info and subject.
The most efficient (In terms of thrust output per power input)? A _single_ blade! It can be done as long as you are very careful with balancing and don't mind high RPM for the same thrust.
Great video, The more blades the better 🚁
I have a 6 rotor. It's great.
is it possible to design a rigid 2 blade system ?
Can we redesign the R22 blades to fully articulated but still maintain 2 blades But no mask bumping issue?
I thought a two-blade has more inertia than a four-blade? In case of an auto.
whar is going on with the military ka50 where there are opposite direction spinning blades ?
Can you talk about what "fully articulated"is all about.
Also, what has changed in rotor system design from the Enstrom 3 bladed system to a more modern system like on the Cabri?
Isn't ground resonance a 3 or more bladed system phenomenon?