Well what you say might be true on "ultra-light" H/C, basically underpowered, but not on "normal" H/C. I have been a H/C pilot in the French Army Aviation for 10 years, then I became an Experimental Test Pilot and, to be honest, regarding the fenestron I didn't see any problem with it. We operated about 300 Gazelles (1/3 SA341 and 2/3 SA342) in the ALAT without any crash due to a mechanical or design issue. The Gazelle was at the end the safest H/C we ever had and none of them ever encountered a LTE. I made my basic training on Alouette II and "combat training" on Gazelle. It was not a big deal, the Gazelle was just easier and more pleasant to fly compared to the Alouette and that's it. Never noticed that there was a "non linearized input" with a fenestron, it was the same. Moreover, we were not warned about any specific limitations or traps in relation with the fenestron. The only "limitation" was that the fenestron requires indeed more power (in hover) than a tail rotor, so that a Gazelle is a little less efficient in mountain flight than an Alouette III for example. Otherwise, no problem. Note that the Dauphin, which is also fitted with a fenestron, is still used by the US Coast Guard (MH65 Dolphin) and they are very happy with it. At cruise speed the fenestron brings even a huge advantage due to the design of the vertical stabilizer: it allows to survive a failure (breaking) of the transmission (Gazelle, EC120, EC130, AS365 Dauphin, EC135). With a conventional tail rotor ... you crash. Note that you can face a LTE with a conventional tail rotor either (R22 or Schweizer300) depending on the wind direction relative to the H/C while on Gazelle we trained to land with tail winds (tactical reasons) without any problem. In other words, depending on the H/C category you are reffering to, the arguments can be inverted. Final point: regarding the rotation direction of the rotor: you are not the first one who refers to "European helicopters". That's wrong. To make it short and simple: seen from above, French and Russian H/C (and only them) turn clockwise and the rest of the world anti-clockwise. Agusta-Westland, which is also European (Italian and British), have their H/C turning anti-clockwise (A109, A129, A139, WG13 Lynx, EH101). Even inside Airbus H/C (originally a merging of Aérospatiale-France with MBB-Germany) the H/C designed in France are turning clockwise (from the Ecureuil to the Super-Puma) while the H/C designed in Germany are turning anti-clockwise (Bö105, EC135, EC145). Regards
@@cloroxmints355 well clorox, probably it is just harder to upload a new edited video than just do that...don't really know his motivation but anyway, the part that was interesting to me is the one that I can't hear
I'd prefer a fenestron for safety. A major part of a helicopter accident and crash is due to tail rotor strike. In a fenestron, the fan is protected by the frame around it. However they cannot make it as big as a regular tail rotor so designers have to limit it to 3ft or thereabouts, compared to around 5 to 6 ft for a conventional tail rotor. The difference in area is quite significant. Thus to compensate for loss of authority, the fenestron have to have more blades and spin about 50% faster. But overall a great design.
Airplane guy, not a helicopter pilot ... lots of helicopter crashes caught on video show tail rotor hitting wire, trees, ground strike ... and the conventional tail rotor just breaks off leading to uncontrollable spin and crash. I feel having the Fenestron shrouded and providing significantly better protection to the tail rotor is one of the biggest safety benefits.
Helicopter guy here, not a fixed wing pilot... can confirm. We devote A LOT of attention to that tail rotor and what's around us when we make an approach and never, EVER walk behind the aircraft while things are still moving.
crikey,if the tail rotor is close enough to strike an obstacle,that means the main rotors pass is merely inches away,stay away from all statics,the only contact other than "air"should be via the skids.
He's talking about engineering details.. linkages and the like. I assume he wasn't supposed to talk about details and so he removed that intentionally.
@@charliethompson4236 Well - our pilots were able to hold hover within a 2x2 feet virtual box while climbing from 100FAMSL up 5000FAMSL and keeping tail oriented in a certain manner. One pilot was even able to pivot around the 2x2 feet virtual while climbing. So while the Alouette 2 was obviously less affected in yaw by crosswinds, this was part of the daily work routine with the Gazelle, so I believe it could qualify at not 'sucking'
@@mdu6 Wow....they must be amazing pilots.....fitting a Gazelle within a 2x2 ft box!! My model one only just fits. ;) As for climbing within a virtual box.....not sure how you can ascertain that you’ve stayed within 2 feet. But hey....I’ll bow down to your superior knowledge
@@charliethompson4236 Stayed within a 2x2box ---- because a 2x2 box was actualy fitted in front of the helicopter. The bottom of the box was a transparent plastic reflector. On the ground we would setup a tripod with a laser. The laser was set verticaly. The helicopter would hover over the laser beam. The beam would show up as a red dot on the reflector. The pilot would literaly climb while keeping the laser within the box. This was use as a giant virtual pole so a surveyor was able to sight the helicopter (up to 20km away) and use this as reference (actually to align teams doing initial positioning of the path for futur powerlines - 1980 technology !)
I feel like this channel is turning into a sponsored ad for Hill Helicopters and their as of yet unseen concept. I just hope they aren't taking advantage of your channel to drum up investors to swindle.
This^^^^! I felt like the channel lost its way once he got involved with “Wottsisface” and the Round the Works Trip and “Inspirational” type channel.....as well as Hill Heli’s. I don’t like being asked to go elsewhere...and look at other channels....it always makes me feel like a customer, or potential customer, rather than a viewer, sharing experiences
Hi~! Nice to meet you and i saw impressed your videos~! And I have a question Why fenestron tail rotor system have fixed rotor?? I know fenestron tail copters tail pitch rotor can make yawing But why have cant move and fixed rotor additional??
Fenestrons work just fine, the problem is pilots that transition from standard tail rotor helicopters without adequate training or knowledge. Eurocopter put out a paper on this that is very well explained. The TLDR is that they are rigged differently in EC products ( now airbus ) so that more pedal throw is used to get the same amount of thrust. It feels weird at first, like going from power steering to manual, but not precisely that. Once adapted to it you will find that you have a finer control feel and can keep the helicopter more accurately trimmed/pointed at all times. I've flown the EC120, 130, and 135 for decades and never had a problem, hot and high or sea level, even parking 130s with some regularity with strong tail winds. I'd wager a round of drinks that if you total up accidents at ANY regulatory authority around the world that have been attributed to LTE or the like, that the majority of these will be in standard tail rotor helicopters and not fenestron aircraft. This may be related to the much higher speed, blade count, and thus much lower angles of attack of the fenestron. Much harder to stall. Also probably to many early Bell and a few MD helicopters that had tail rotors too small for the MGTOW of the aircraft. If you're heavily overpitched and the rotor systems are decaying, well, you're going to have a bad day regardless.
Because when you're selling vaporware, you want to protect your unpatented and obvious ideas like using a cam profile on the pedal inputs to make them feel as linear as a conventional tailrotor. Oooops😬 that was probably a secret.
Why not get rid of the drive shaft coming from the engine and use a powerful brushless dc motor to spin the rotor at stupidly high speeds without worrying about how much power the engine can produce? That is how its done on some small rc choppers
@@pieterpretorius1014 Because electrical failures happen, motor speeds could get out of sync with main rotor. Also, you need to generate enough power to run that generator, and that takes power from the engine too. Electric motors have weight to them as well. Imagine if you had an electrical failure that led to the loss of the engine as well (does happen, and sometimes a failure necessitates an engine shutdown). There are ways to land without a tail rotor (run on) and such, but it's gonna make certain emergency landings unsafe. Mechanical linkage keeps the tail rotor spinning proportional to the main rotor in the event of an engine failure. RC helicopters don't involve life and death the way real helicopters do. Also, RC aircraft can do things real aircraft can't, due to scale, thrust to weight, Reynolds numbers, etc. Electric RC helicopters use motor RPM to adjust thrust, where as real helicopters use constant RPM, and adjust the blade pitch. Again, things can be done, but I just don't see the risks and challenges as worth it, and what would you gain in the end?
Why isnt the relationship between pedal input and tail rotor thrust in fenestrons not linear? Isnt there a direct relationship between pedal inout and angle of attack / lift of the fenestron blades?
I think it's because the smaller section area of the blades requires the higher velocity air. I don't know this for a fact, but it seems it would be the case. If this is the case, it's like trying to accelerate from 5th to 6th gear instead of 1st to 2nd.
To expand on that in your terms of AOA, the air is already coming in at a high velocity so you don't have the range of AOA you might have in a larger, slower blade.
Just curious. Do you believe that this fenestron issue really only affects the smaller trainers, or is it also an issue on the larger helecopters such as an EC-135, 145, and the Dauphins? Fyi, I always wanted to fly helos ever since I was a child, I'm 50 now, at 45 I started my training on an R22, with 53 separate flights, 22 hours, 3 solos, and ran out of money. I plan on getting back into it once I retire and your videos have been great to watch to keep somewhat fresh and into it. Thanks.
Hi! Why did you cut out some of the words and put music? Did you say something wrong? I like your channel, thank you for being there! I'm from Russia and really want to learn how to fly a helicopter) P.S. Sorry for the English if I wrote something wrong)
I did most of my private/instrument/commercial in the Cabri and I agree that the Fenestron is a non-issue as long as you're prepared to move your feet far enough to produce sufficient anti-torque thrust. Coming from fixed-wing aircraft it's not really a big deal, in fact it's just about the same amount control movement as landing a taildragger in a crosswind. I am curious, however, about the statement that a Fenestron loses thrust more quickly with decreasing RPM, due to its higher gear ratio compared to a traditional tail rotor. I heard this same factoid in my training and dutifully nodded my head, but from a physics standpoint it's never made sense to me. Can anyone walk me through an explanation for why this would be?
I think it's not much about the higher gear ratio but due to the fact that it hasn't a linear acceleration like a conventional tail rotor, so because of that, it delivers enough anti-torque force only when the pedal is pressed a lot, and if LTE happens it drops rpm and therefore effectivness much quicker. By the way I'm doing my PPL in a cabri and i will make sure to understand this fully. I am also very cuorios about the feeling i will get when piloting an helicopter with conventional tail rotor, being so used to the fenestron
@@ulsig95 I just don't think the math bears this out. With either system, a 1% decrease in main rotor RPM will lead to a 1% decrease in tail rotor RPM.
@@samuelepampanin7515 If you go to a traditional TR, you may over-correct at first, but overall you'll do less range of travel with your feet in normal operations. You will though use more pedal when in the cruise compared to a Fenestron.
Fenestron design usually use smaller diameter less wide different airfoil blades with higher rpm...so at lower rpms you are maxed out on blade-AOA sooner to provide the same thrust/lift vs a more conventional size/shape blades...I guess...
Some designs are more forgiving than others. I once flew with the Enstrom test pilot in the company's then new F280c. In the hover, he rolled off m/r rpm to 90% but still had t/r authority.
Current FAA regulations require the pilot to safely land with an engine failure and/or loss of electrical power. Not sure you can do that with this new Bell design (or those rideable drones for that matter)
there's probably a good reason for that. If you take a look at most tailrotors standing still you'll see that tey're painted in high contrast colors such as black and white or red. but as soon as they are spinning you wont notice that anymore. About fluorescent/ glowing / reflecting: I bet there's FAA regulations on things like these in order to ensure collisionlights keep their spot as the most visible things on aircraft.
Sounds like Fenestrons would really benefit from going electric. Besides a CG change, the weight difference between driveshaft to gearbox and wire to motor The battery increase shouldn’t add much weight. You wouldn’t need more than a minute or two of augmented power from the battery. So Generator size/weight shouldn’t be that much bigger.
It would still need a gearbox and driveshaft, as there’s no motor you could fit on the tail rotor assembly that would be powerful enough. Also, that hub area is exclusively dedicated to the adjustable pitch components. There would also be a LARGE number of single-point failure modes, which are obviously bad for aircraft design considerations. Scalability would also pose a huge problem; even if it was possible on very small helicopters, it just wouldn’t work for utility or higher-performance transport / VIP / medevac helos.
first question. Why is the fenestron non linear for pedal inputs? second question, are you talking about modifying the conada effect used in the MD Series helicopters?
Two reasons. First, just like a fan-jet, there is a narrow power ban at the top that makes the difference in thrust. A tail rotor, like a prop aircraft, has a much wider power band. Bigger vs smaller blades demanding much higher speed for the same thrust. Physics. Second, as you transition from flight to hover, the center of lift of the fenestron is aft of the center of the rotor because of the cowl blanking air at the front, depending on airspeed. As airspeed decreases, that center of lift comes forward to the center and use the whole T/R in a zero wind hover.
I prefer a fenestron. Two different, methods of flying. With a conventional tail rotor you can make power changes and then apply pedal. A fenestron, slightly different. You have to anticipate pedal needed when using the collective and get the pedal moving early. Example, people criticise an EC120 for lacking power. At sea level anyway can make a steep approach, fully loaded, flare and as you get to raising the lever your right foot is ahead of you and already putting power to the tail. Fly it like a conventional tail rotor and react to power changes second, you will spike it, possibly run out of power and have an accident.
A fensetron allows the tail rotor to be equipped with fixed stator blades. The stator blades will cancel out rotational turbulence from the main rotor and prevent loss of tail rotor effectiveness. For even more lateral stability use a stack of multiple tail rotors and stators, essentially forming an open frame compressor turbine. Though alas the rotor and stator blades closely sweeping past each other will generate lots of noise.
Hey another question, i find an RC heli takes more power to hover than fly forward at reasonable speed, i believe the turbulace of propwash causing a well the heli is fighting, not a problem moving forward in clean air?
I've been a helicopter AME for 30+ years. The best and safest fenestron or tail rotor is NO FENESTRON OR TAIL ROTOR. I'm sold on coaxel main rotor systems or tandem main rotors. Bee safe everyone.
Im thinking its ok! Its power band is high where as a tailrotor can fly at slower speeds depending on a low power situation as the fenestron requires full power band which works great on like a EC 155 which manages itself efficiently.
I’m thinking of electric tail rotors, like Bell’s EDAT (Electrically Distributed Ant-Torque). Could this significantly reduce the problems you have outlined?
Interesting detail, thank you for explaining! I always thought fenestron is superior just because it looks better and more modern while the common tail rotor design is a more conventional and old and therefore maybe outdated, but looks can mislead and it´s vice versa.
"LTE" is due because there is a flow of wind blowing in the direction of & into the tail rotor, therefore resulting in its ability to do its job effectively to compinsate for the torque of the main rotor
Love the safety feature of the fenestron in regards to visibility. As someone new to helicopters, infrequently flying HEMS missions, the big disc around the blades on the H135 and H145 is always clearly visible. If they could do the same for the main rotor system, I’d feel safer in regards to entering the disc with it running ;). Don’t think I’ll ever get used to moving in and out under the disc with engines running! 🙈😰
My experience has been just about the opposite of what is presented in this video with regard to the helicopters I have flown. I flew three versions of the 206 LongRanger, one with the standard bell TR blades, one with the Van Horn blades and one with the Bell high altitude blades (basically a 407 TR) and only the original 206 blades were linear. The Van Horn would generate more thrust off of neutral making it more "responsive" initially then drop off with additional pedal application. It was much easier to overtorque with the Van Horn. As for the Fenestron, the Airbus EC135 and H145D3 version (can't speak for others like the skinny one in the video) is really excellent with plenty of authority in all conditions I have flown in with it. It has a few small quirks such as lip stall that makes for a wiggly situation but control is always maintained. The other advantage to the fenestron is a failure (broken off at the root) of a blade crates a vibration but the aircraft still flies with no catastrophic failure. I was skeptical about flying a Airbus Fenestron but quickly became a fan of the design.
VERY INTERESTING!!! You're the second person I've heard said "Fenestrons Suck." Based on what you're saying, the fenestron appears to have an exponential response. Personally I believe the design is a good concept, it just was not implemented properly. The fenestron is obviously overdue for a design upgrade. That 1:10 main to tail rotor ratio is too much.
So sounds like they aren't necessarily worse, they're just less forgiving and require being understood. Are any helicopters fly-by-wire? Both of these problems could be solved by a fly-by-wire system that inputs the proper amount of antitorque input regardless of the non-linearity, and has flight envelope protection to prevent over-pitching.
I believe only a couple on the market today are fly-by-wire. They are working on that with the new Bell 525 Relentless but it's not out yet. I believe the new Sikorsky S76 is. But I agree it could be fixed that way. Jason from Hill Helicopters has an easy way to fix it.
Great video - Personally I'm a great fan (pardon the pun) of the Comanche off-set fenestron to reduce the rotor noise and give 'some' extra protection. The Comanche - like the F-35, was probably a bit too far ahead of its' time but there is way too much invested in the F-35 for it to fail now and tbh it's pretty damn effective. The Comanche would have been a game changer - sneaking in low & fairly quiet and able to pass real time target locations to other assets. It was a mistake to cancel it but Boeing had a lot of feature updates to contend with. The Army should have accepted a basic model & upgraded it as technology progressed. Personally I think that now either stealth tilt rotors or push-dual rotors are the way ahead - but I think the Comanche was a real missed opperitunity! It just needed more oversight!
@@rsrt6910 For an equal amount of cyclic input sitting on the ground (not centered) they sit much much lower than any conventional helicopter. Only exceptions are microlites. In a perfect world the disc is always level on the ground, in reality (as we've seen recently with yet another lost life) that's not always the case. Lower is always going to be a higher risk.
That was a very well explained video as all of your videos are so basically a regular tail rotor is like driving a Corvette and a Fanta Strachan tell rotor is like driving a 63 impala was sloppy ball joints he just have to get used to oversteer and very cool explanation no and I’m looking forward to booking to an introductory flight with you guys as I live in Abbotsford and see you flying all the time have a great day
@@PilotYellow you were beginning to talk about a ducted fan and this bee bop music started and covered your complete voice explanation ? That was suppose to happen?
Thirty-eight years fast jet and helicopter including Gazelle. I agree heartily with the comment below. Not only is the safety factor of supreme importance but the Fin surrounding the tail rotor is of a lifting section, thus relieving the power requires by the anti-torque penalty in forward flight. The t/rotor drain drain being much reduced. Further more due to the higher RPM of the Fenestron, the torque on the T/rotor drive shaft and gearboxes is lighter and so in less stress compared with the conventional drives. Also, in forward flight the Fenestron rotor is working in relatively less disturbed air and requires no flapping hinges. The conventional tail rotor is flapping back in forward flight and it's thrust vector is consequently tilted aft. The loss of authority outlined in this article is, in my experience, the result of cavalier, cowboy handling. It is true that a bootful of rudder initiating a hover turn will cause overtorqueing and possible loss of t/r authority but flown sensitively the Fenestron is to be recommended. Having flown five different types in my time, the Gazelle was indeed the prince of helicopters and a delight to fly in all aspects of rotary operation..
He mentions a change to Jason's design, then starts to talk about it. That is when the music starts, so it seemed to me Mischa was trying to cover up proprietary information he might be going over. Maybe to be funny, instead of deleting it?
If it has a Fenestron tail rotor it does not look like a Helicopter - it looks like a machine with spinny things on top and in the rear. Notice: I am talking about appearance and nothing else. Not talking about safety, reliability, technology... apearance only.
Well what you say might be true on "ultra-light" H/C, basically underpowered, but not on "normal" H/C.
I have been a H/C pilot in the French Army Aviation for 10 years, then I became an Experimental Test Pilot and, to be honest, regarding the fenestron I didn't see any problem with it. We operated about 300 Gazelles (1/3 SA341 and 2/3 SA342) in the ALAT without any crash due to a mechanical or design issue. The Gazelle was at the end the safest H/C we ever had and none of them ever encountered a LTE.
I made my basic training on Alouette II and "combat training" on Gazelle. It was not a big deal, the Gazelle was just easier and more pleasant to fly compared to the Alouette and that's it. Never noticed that there was a "non linearized input" with a fenestron, it was the same. Moreover, we were not warned about any specific limitations or traps in relation with the fenestron. The only "limitation" was that the fenestron requires indeed more power (in hover) than a tail rotor, so that a Gazelle is a little less efficient in mountain flight than an Alouette III for example. Otherwise, no problem. Note that the Dauphin, which is also fitted with a fenestron, is still used by the US Coast Guard (MH65 Dolphin) and they are very happy with it.
At cruise speed the fenestron brings even a huge advantage due to the design of the vertical stabilizer: it allows to survive a failure (breaking) of the transmission (Gazelle, EC120, EC130, AS365 Dauphin, EC135). With a conventional tail rotor ... you crash.
Note that you can face a LTE with a conventional tail rotor either (R22 or Schweizer300) depending on the wind direction relative to the H/C while on Gazelle we trained to land with tail winds (tactical reasons) without any problem. In other words, depending on the H/C category you are reffering to, the arguments can be inverted.
Final point: regarding the rotation direction of the rotor: you are not the first one who refers to "European helicopters". That's wrong. To make it short and simple: seen from above, French and Russian H/C (and only them) turn clockwise and the rest of the world anti-clockwise. Agusta-Westland, which is also European (Italian and British), have their H/C turning anti-clockwise (A109, A129, A139, WG13 Lynx, EH101). Even inside Airbus H/C (originally a merging of Aérospatiale-France with MBB-Germany) the H/C designed in France are turning clockwise (from the Ecureuil to the Super-Puma) while the H/C designed in Germany are turning anti-clockwise (Bö105, EC135, EC145).
Regards
Thanks a lot. Merci.
@@tomf3150 You're welcome
cool
Why is there music overlay at 5:40 😕
I guess somehow he regretted or he was afraid of lawsuit
I can still read his lips. 😉
@@mcchelicopter why did he leave the clip in at all then it would’ve been easier to just cut out that whole part
@@cloroxmints355 well clorox, probably it is just harder to upload a new edited video than just do that...don't really know his motivation but anyway, the part that was interesting to me is the one that I can't hear
@@mcchelicopter I’m like 85% sure you can’t even do that once you’ve uploaded it
What happened with the audio from 5:48 to 6:08:(
When you are about to explain the difference between the new tail rotor?
I'd prefer a fenestron for safety. A major part of a helicopter accident and crash is due to tail rotor strike. In a fenestron, the fan is protected by the frame around it. However they cannot make it as big as a regular tail rotor so designers have to limit it to 3ft or thereabouts, compared to around 5 to 6 ft for a conventional tail rotor. The difference in area is quite significant. Thus to compensate for loss of authority, the fenestron have to have more blades and spin about 50% faster. But overall a great design.
Could you do a video on the NOTAR,always wondered how good they are,and there limitation? Thanks enjoy your videos 👍🏻👍🏻
I wrote my comment before reading your comment. Im curious too
One downside of notar is there is a delay
And helicopter becomes tail heavy
Airplane guy, not a helicopter pilot ... lots of helicopter crashes caught on video show tail rotor hitting wire, trees, ground strike ... and the conventional tail rotor just breaks off leading to uncontrollable spin and crash. I feel having the Fenestron shrouded and providing significantly better protection to the tail rotor is one of the biggest safety benefits.
Helicopter guy here, not a fixed wing pilot... can confirm. We devote A LOT of attention to that tail rotor and what's around us when we make an approach and never, EVER walk behind the aircraft while things are still moving.
Me too
crikey,if the tail rotor is close enough to strike an obstacle,that means the main rotors pass is merely inches away,stay away from all statics,the only contact other than "air"should be via the skids.
@@rsrt6910 youll only make that error once,but it is kind of obvious.
We need someone who can lipread...
I thought he was beat boxing.
100% 😂
😂
Almost the entire audio of the liberalized ducted fan is missing and replaced with music! Can you fix this?
I came to the comments to see if it was just me! Apparently not! Lol
I thought it might've been intended as self-deprecation about him using excessive jargon... or something “¯\_(ツ)_/¯“
@@_PL_ haha yeah I had a similar thought for a sec and then realized something was way off! 😆
He's talking about engineering details.. linkages and the like. I assume he wasn't supposed to talk about details and so he removed that intentionally.
@@therealxunil2 I also thought that, but he could have just left it out of the video entirely... Lol
It might suck on the G2 but having flown and work for many years on the SA341- Gazelle when correctly designed and implemented it can be great !
The Gazelle has its issues and is actually worse in certain quartering winds, than the Cabri
@@charliethompson4236 Well - our pilots were able to hold hover within a 2x2 feet virtual box while climbing from 100FAMSL up 5000FAMSL and keeping tail oriented in a certain manner. One pilot was even able to pivot around the 2x2 feet virtual while climbing. So while the Alouette 2 was obviously less affected in yaw by crosswinds, this was part of the daily work routine with the Gazelle, so I believe it could qualify at not 'sucking'
@@mdu6 Wow....they must be amazing pilots.....fitting a Gazelle within a 2x2 ft box!! My model one only just fits. ;) As for climbing within a virtual box.....not sure how you can ascertain that you’ve stayed within 2 feet. But hey....I’ll bow down to your superior knowledge
@@charliethompson4236 Stayed within a 2x2box ---- because a 2x2 box was actualy fitted in front of the helicopter. The bottom of the box was a transparent plastic reflector. On the ground we would setup a tripod with a laser. The laser was set verticaly. The helicopter would hover over the laser beam. The beam would show up as a red dot on the reflector. The pilot would literaly climb while keeping the laser within the box. This was use as a giant virtual pole so a surveyor was able to sight the helicopter (up to 20km away) and use this as reference (actually to align teams doing initial positioning of the path for futur powerlines - 1980 technology !)
@@mdu6 So cool
Why the music towards the end? I would have liked what you had to say about the ducted fan. Be safe.
I feel like this channel is turning into a sponsored ad for Hill Helicopters and their as of yet unseen concept. I just hope they aren't taking advantage of your channel to drum up investors to swindle.
remember delorean?
This^^^^! I felt like the channel lost its way once he got involved with “Wottsisface” and the Round the Works Trip and “Inspirational” type channel.....as well as Hill Heli’s. I don’t like being asked to go elsewhere...and look at other channels....it always makes me feel like a customer, or potential customer, rather than a viewer, sharing experiences
@@eddyriley2055 Remember Silver State Helicopters ?????
@@gmacn5375 In Oregon?
Since talking about this subject, is there a downside to the NOTAR system?
It looks goofy maybe?
In the case of MD500 vs MD520N: Costs $700K more, burns 4 more GPH, 80 miles less range.
what on earth happened at 5:41? I really want to hear what you've got to say, but the audio is replaced with music!
Hi, why did you play music over where you were explaining the Hill HX50 tail rotor. It is top secret still?
Hi~! Nice to meet you and i saw impressed your videos~!
And I have a question
Why fenestron tail rotor system have fixed rotor??
I know fenestron tail copters tail pitch rotor can make yawing
But why have cant move and fixed rotor additional??
What's with the beatbox at 5:44? Or is the ducted tail rotor system secret?
Fenestrons work just fine, the problem is pilots that transition from standard tail rotor helicopters without adequate training or knowledge. Eurocopter put out a paper on this that is very well explained. The TLDR is that they are rigged differently in EC products ( now airbus ) so that more pedal throw is used to get the same amount of thrust. It feels weird at first, like going from power steering to manual, but not precisely that. Once adapted to it you will find that you have a finer control feel and can keep the helicopter more accurately trimmed/pointed at all times. I've flown the EC120, 130, and 135 for decades and never had a problem, hot and high or sea level, even parking 130s with some regularity with strong tail winds. I'd wager a round of drinks that if you total up accidents at ANY regulatory authority around the world that have been attributed to LTE or the like, that the majority of these will be in standard tail rotor helicopters and not fenestron aircraft. This may be related to the much higher speed, blade count, and thus much lower angles of attack of the fenestron. Much harder to stall. Also probably to many early Bell and a few MD helicopters that had tail rotors too small for the MGTOW of the aircraft. If you're heavily overpitched and the rotor systems are decaying, well, you're going to have a bad day regardless.
i wanted to know about the linierized ducted fan why did you put music over it?
why is there a song drowning out your words ? time stamp 5:42 to 6:09
Because when you're selling vaporware, you want to protect your unpatented and obvious ideas like using a cam profile on the pedal inputs to make them feel as linear as a conventional tailrotor. Oooops😬 that was probably a secret.
Why not get rid of the drive shaft coming from the engine and use a powerful brushless dc motor to spin the rotor at stupidly high speeds without worrying about how much power the engine can produce? That is how its done on some small rc choppers
@@pieterpretorius1014 Because electrical failures happen, motor speeds could get out of sync with main rotor. Also, you need to generate enough power to run that generator, and that takes power from the engine too. Electric motors have weight to them as well. Imagine if you had an electrical failure that led to the loss of the engine as well (does happen, and sometimes a failure necessitates an engine shutdown). There are ways to land without a tail rotor (run on) and such, but it's gonna make certain emergency landings unsafe.
Mechanical linkage keeps the tail rotor spinning proportional to the main rotor in the event of an engine failure. RC helicopters don't involve life and death the way real helicopters do. Also, RC aircraft can do things real aircraft can't, due to scale, thrust to weight, Reynolds numbers, etc. Electric RC helicopters use motor RPM to adjust thrust, where as real helicopters use constant RPM, and adjust the blade pitch. Again, things can be done, but I just don't see the risks and challenges as worth it, and what would you gain in the end?
@@pieterpretorius1014 verticalmag.com/news/bell-electrically-distributed-anti-torque-edat/
@@SoloRenegade verticalmag.com/news/bell-electrically-distributed-anti-torque-edat/
Love the website .. love the channel .. Maybe you can talk about NOTAR .. Im curious about performance differences. Keep up the good work.
Getting the Pilot Yellow Groove and beat at 5:41 lol...
Hey Yellow!!! On the topic of tail rotors, I was wondering if you could make a video about to Delta 3 Hinge.
Very cool, what’s your take on the NOTAR helicopters that use either bypass from the engine or pressure instead of a tail rotor
I really would like to know it too & get an answer of your question!🚁👍🏼‼️
Why isnt the relationship between pedal input and tail rotor thrust in fenestrons not linear? Isnt there a direct relationship between pedal inout and angle of attack / lift of the fenestron blades?
I think it's because the smaller section area of the blades requires the higher velocity air. I don't know this for a fact, but it seems it would be the case. If this is the case, it's like trying to accelerate from 5th to 6th gear instead of 1st to 2nd.
To expand on that in your terms of AOA, the air is already coming in at a high velocity so you don't have the range of AOA you might have in a larger, slower blade.
How about the NOTAR from Bell Helicopter?
Hey ! What do you think about no tail rotor at all?
Like in a MD520N NO TAR. Can you please make a video on that one?
Just curious. Do you believe that this fenestron issue really only affects the smaller trainers, or is it also an issue on the larger helecopters such as an EC-135, 145, and the Dauphins? Fyi, I always wanted to fly helos ever since I was a child, I'm 50 now, at 45 I started my training on an R22, with 53 separate flights, 22 hours, 3 solos, and ran out of money. I plan on getting back into it once I retire and your videos have been great to watch to keep somewhat fresh and into it. Thanks.
I fly a 135 and have never had a problem...
Fantastic design
Linear ducted fan. Cut to the music 🎶🎵🎶. What was that?
Hi!
Why did you cut out some of the words and put music?
Did you say something wrong?
I like your channel, thank you for being there!
I'm from Russia and really want to learn how to fly a helicopter)
P.S.
Sorry for the English if I wrote something wrong)
I did most of my private/instrument/commercial in the Cabri and I agree that the Fenestron is a non-issue as long as you're prepared to move your feet far enough to produce sufficient anti-torque thrust. Coming from fixed-wing aircraft it's not really a big deal, in fact it's just about the same amount control movement as landing a taildragger in a crosswind.
I am curious, however, about the statement that a Fenestron loses thrust more quickly with decreasing RPM, due to its higher gear ratio compared to a traditional tail rotor. I heard this same factoid in my training and dutifully nodded my head, but from a physics standpoint it's never made sense to me. Can anyone walk me through an explanation for why this would be?
I also made the same remark regarding loss of thrust due to higher gear ratios. Please elaborate.
I think it's not much about the higher gear ratio but due to the fact that it hasn't a linear acceleration like a conventional tail rotor, so because of that, it delivers enough anti-torque force only when the pedal is pressed a lot, and if LTE happens it drops rpm and therefore effectivness much quicker.
By the way I'm doing my PPL in a cabri and i will make sure to understand this fully. I am also very cuorios about the feeling i will get when piloting an helicopter with conventional tail rotor, being so used to the fenestron
@@ulsig95 I just don't think the math bears this out. With either system, a 1% decrease in main rotor RPM will lead to a 1% decrease in tail rotor RPM.
@@samuelepampanin7515 If you go to a traditional TR, you may over-correct at first, but overall you'll do less range of travel with your feet in normal operations. You will though use more pedal when in the cruise compared to a Fenestron.
Fenestron design usually use smaller diameter less wide different airfoil blades with higher rpm...so at lower rpms you are maxed out on blade-AOA sooner to provide the same thrust/lift vs a more conventional size/shape blades...I guess...
Some designs are more forgiving than others. I once flew with the Enstrom test pilot in the company's then new F280c. In the hover, he rolled off m/r rpm to 90% but still had t/r authority.
what happen to 5:42 suddenly change to music
What do you think of that 4 electric tail rotor system that Bell is developing?
Current FAA regulations require the pilot to safely land with an engine failure and/or loss of electrical power.
Not sure you can do that with this new Bell design (or those rideable drones for that matter)
What about NOTAR??
Just a thought ,why aren't tail rotors painted in high visibility or fluorescent colours for greater safety?
there's probably a good reason for that. If you take a look at most tailrotors standing still you'll see that tey're painted in high contrast colors such as black and white or red. but as soon as they are spinning you wont notice that anymore.
About fluorescent/ glowing / reflecting: I bet there's FAA regulations on things like these in order to ensure collisionlights keep their spot as the most visible things on aircraft.
the noise and well disturbed air is usually enough,spin dilutes bright colorings.
I really love your videos, very informative and entertaining. What are your thoughts on the Notar system?
Some music started playing, I could'nt understand, what you were saying in the video. What???
Sounds like Fenestrons would really benefit from going electric. Besides a CG change, the weight difference between driveshaft to gearbox and wire to motor The battery increase shouldn’t add much weight. You wouldn’t need more than a minute or two of augmented power from the battery. So Generator size/weight shouldn’t be that much bigger.
It would still need a gearbox and driveshaft, as there’s no motor you could fit on the tail rotor assembly that would be powerful enough. Also, that hub area is exclusively dedicated to the adjustable pitch components.
There would also be a LARGE number of single-point failure modes, which are obviously bad for aircraft design considerations.
Scalability would also pose a huge problem; even if it was possible on very small helicopters, it just wouldn’t work for utility or higher-performance transport / VIP / medevac helos.
What about NOTAR helicopters?
first question. Why is the fenestron non linear for pedal inputs? second question, are you talking about modifying the conada effect used in the MD Series helicopters?
Two reasons. First, just like a fan-jet, there is a narrow power ban at the top that makes the difference in thrust. A tail rotor, like a prop aircraft, has a much wider power band. Bigger vs smaller blades demanding much higher speed for the same thrust. Physics. Second, as you transition from flight to hover, the center of lift of the fenestron is aft of the center of the rotor because of the cowl blanking air at the front, depending on airspeed. As airspeed decreases, that center of lift comes forward to the center and use the whole T/R in a zero wind hover.
Why did you put music over the bit that Jason said? That was disappointing?
What's happening with the music at 5.41?
I needed to cover up a couple things I said. Not ready to release that detail yet 😉.
@@PilotYellow why?
i wanted to know how a linierized ducted fan works
I prefer a fenestron. Two different, methods of flying. With a conventional tail rotor you can make power changes and then apply pedal. A fenestron, slightly different. You have to anticipate pedal needed when using the collective and get the pedal moving early. Example, people criticise an EC120 for lacking power. At sea level anyway can make a steep approach, fully loaded, flare and as you get to raising the lever your right foot is ahead of you and already putting power to the tail. Fly it like a conventional tail rotor and react to power changes second, you will spike it, possibly run out of power and have an accident.
did you mean "when using the collective..."?
Yes.@@rigilchrist
You need to do a video on Notar's.
What happened to NOTAR?
Patents...
A fensetron allows the tail rotor to be equipped with fixed stator blades. The stator blades will cancel out rotational turbulence from the main rotor and prevent loss of tail rotor effectiveness.
For even more lateral stability use a stack of multiple tail rotors and stators, essentially forming an open frame compressor turbine. Though alas the rotor and stator blades closely sweeping past each other will generate lots of noise.
So I don’t fly helicopters but would it not be possible to have a seperate motor maybe electric for the tail. Would this not then remove LTE?
Hey another question, i find an RC heli takes more power to hover than fly forward at reasonable speed, i believe the turbulace of propwash causing a well the heli is fighting, not a problem moving forward in clean air?
Induced power requirement in the hover is vastly more than in forward flight. This phenomenon is present in all helicopters.
What do you mean by Authority in relation to what you were talking about?
authority means the amount of force the tail rotor can rotate the aircraft with
Did you cut out what you were saying so as not to give away trade secrets?
I've been a helicopter AME for 30+ years. The best and safest fenestron or tail rotor is NO FENESTRON OR TAIL ROTOR. I'm sold on coaxel main rotor systems or tandem main rotors.
Bee safe everyone.
Too bad theyre more expensive
Coaxial is the way to go...maybe an intermeshing like the K-max is the 2nd best...and always fully articulated...
So all the pluses (harder to hit the tail on something, tail strikes, chop head off) are avoided just like you said "if your a good pilot" lol.
Conventional, Fenestron, or NOTAR which one do you prefer?
Im thinking its ok! Its power band is high where as a tailrotor can fly at slower speeds depending on a low power situation as the fenestron requires full power band which works great on like a EC 155 which manages itself efficiently.
Really interested to see how well the HX50 LDF works. So many advantages over traditional tail rotor.
Your discussion about the ducted fan got overdubbed by a techno dance song?
I’m thinking of electric tail rotors, like Bell’s EDAT (Electrically Distributed Ant-Torque). Could this significantly reduce the problems you have outlined?
That extra input was a bit disconcerting when I first flew the EC 120.
hi mischa....why does the R66 seem to have a 30 degree angle on the tail boom?
2:00About the Authority, why can just we trim it like in rc hobby
@@Hans_Magnusson Ok thanks for the information now i get it
Mischa, I would be great to hear you talk about the NOTAR system and it’s relation and effectiveness compared to a conventional tail and a Fenestron
Yes please, I would also love to hear this discussion!!!
Interesting detail, thank you for explaining! I always thought fenestron is superior just because it looks better and more modern while the common tail rotor design is a more conventional and old and therefore maybe outdated, but looks can mislead and it´s vice versa.
"LTE" is due because there is a flow of wind blowing in the direction of & into the tail rotor, therefore resulting in its ability to do its job effectively to compinsate for the torque of the main rotor
Is this why no fenestron on heavy/cargo helicopters?
What happened at 5:41 ?
Then suddenly at 6:07 "So the reason that's so important..."
😂
Love the safety feature of the fenestron in regards to visibility. As someone new to helicopters, infrequently flying HEMS missions, the big disc around the blades on the H135 and H145 is always clearly visible. If they could do the same for the main rotor system, I’d feel safer in regards to entering the disc with it running ;). Don’t think I’ll ever get used to moving in and out under the disc with engines running! 🙈😰
What about the notar system
My experience has been just about the opposite of what is presented in this video with regard to the helicopters I have flown. I flew three versions of the 206 LongRanger, one with the standard bell TR blades, one with the Van Horn blades and one with the Bell high altitude blades (basically a 407 TR) and only the original 206 blades were linear. The Van Horn would generate more thrust off of neutral making it more "responsive" initially then drop off with additional pedal application. It was much easier to overtorque with the Van Horn. As for the Fenestron, the Airbus EC135 and H145D3 version (can't speak for others like the skinny one in the video) is really excellent with plenty of authority in all conditions I have flown in with it. It has a few small quirks such as lip stall that makes for a wiggly situation but control is always maintained. The other advantage to the fenestron is a failure (broken off at the root) of a blade crates a vibration but the aircraft still flies with no catastrophic failure. I was skeptical about flying a Airbus Fenestron but quickly became a fan of the design.
Fascinating; though the random music cutting out the ducted fan explanation was. Jarring. And not great? Would have preferred to hear that,but...
Since i only have experience flying RC helis, can u do a video on flying RC difficulty level and the increadible stunts done by pro RC pilots
rc,much much harder than full size
Why did you overdub the technical explanation?
Were you wrong?
You are a very good teacher.
Voice Audio comes back in at 6:08. If you're wondering...
VERY INTERESTING!!! You're the second person I've heard said "Fenestrons Suck." Based on what you're saying, the fenestron appears to have an exponential response. Personally I believe the design is a good concept, it just was not implemented properly. The fenestron is obviously overdue for a design upgrade. That 1:10 main to tail rotor ratio is too much.
Do a vid on tail rotors fatality
So it hasn't got enough bite under extreme circumstances.
The controller at Essendon (in Australia) called me a gumball the other day in the G2 😂😂
Very informative video. Just out of curiosity why the name "pilot Yellow" is Yellow your name?
Last name is Gelb - German for yellow. He is of German heritage.
Almost spilled the beans there 🤣🤣
So sounds like they aren't necessarily worse, they're just less forgiving and require being understood. Are any helicopters fly-by-wire? Both of these problems could be solved by a fly-by-wire system that inputs the proper amount of antitorque input regardless of the non-linearity, and has flight envelope protection to prevent over-pitching.
I believe only a couple on the market today are fly-by-wire. They are working on that with the new Bell 525 Relentless but it's not out yet. I believe the new Sikorsky S76 is. But I agree it could be fixed that way. Jason from Hill Helicopters has an easy way to fix it.
@@PilotYellow A fix you apparently weren't allowed to tell us about...
Great video - Personally I'm a great fan (pardon the pun) of the Comanche off-set fenestron to reduce the rotor noise and give 'some' extra protection.
The Comanche - like the F-35, was probably a bit too far ahead of its' time but there is way too much invested in the F-35 for it to fail now and tbh it's pretty damn effective. The Comanche would have been a game changer - sneaking in low & fairly quiet and able to pass real time target locations to other assets. It was a mistake to cancel it but Boeing had a lot of feature updates to contend with. The Army should have accepted a basic model & upgraded it as technology progressed.
Personally I think that now either stealth tilt rotors or push-dual rotors are the way ahead - but I think the Comanche was a real missed opperitunity! It just needed more oversight!
The picture quality of your videos is the best I have seen.
It's a shame the main rotor system in the G2 is so low. The added safety of the fenestron is diminished by such a low hanging main rotor.
Not that big an issue because they use a fully articulated rotor system so the blades don't dip any lower than a semi-rigid rotor in a strong wind.
@@rsrt6910 For an equal amount of cyclic input sitting on the ground (not centered) they sit much much lower than any conventional helicopter. Only exceptions are microlites. In a perfect world the disc is always level on the ground, in reality (as we've seen recently with yet another lost life) that's not always the case. Lower is always going to be a higher risk.
How can auto rotation work with the drag of a dead or damaged engine?
the engine disconnects when coasting or off like a bicycle.
Audio got muted by music starting at 5:41 through 6:08 - just FYI, Mischa. Great vid otherwise.
Thanks, that was on purpose
@@PilotYellow - Ahh, gotcha. Thanks for the heads up. 👍
Isn't it trivial to linearize a control system in 2021? Why is this not something one cam or lookup table could do?
How about NOTAR?
Unfortunately I don't have any experience in them so I can't really comment.
I used to get low and look up if i got at on tail rotor side as the heli took off.it would be prolly be quick.lol
That was a very well explained video as all of your videos are so basically a regular tail rotor is like driving a Corvette and a Fanta Strachan tell rotor is like driving a 63 impala was sloppy ball joints he just have to get used to oversteer and very cool explanation no and I’m looking forward to booking to an introductory flight with you guys as I live in Abbotsford and see you flying all the time have a great day
Auto dictate sucks
fix the music insert!
It was put there on purpose.
@@PilotYellow you were beginning to talk about a ducted fan and this bee bop music started and covered your complete voice explanation ? That was suppose to happen?
very well explained
Thirty-eight years fast jet and helicopter including Gazelle. I agree heartily with the comment below. Not only is the safety factor of supreme importance but the Fin surrounding the tail rotor is of a lifting section, thus relieving the power requires by the anti-torque penalty in forward flight. The t/rotor drain drain being much reduced. Further more due to the higher RPM of the Fenestron, the torque on the T/rotor drive shaft and gearboxes is lighter and so in less stress compared with the conventional drives.
Also, in forward flight the Fenestron rotor is working in relatively less disturbed air and requires no flapping hinges. The conventional tail rotor is flapping back in forward flight and it's thrust vector is consequently tilted aft.
The loss of authority outlined in this article is, in my experience, the result of cavalier, cowboy handling. It is true that a bootful of rudder initiating a hover turn will cause overtorqueing and possible loss of t/r authority but flown sensitively the Fenestron is to be recommended. Having flown five different types in my time, the Gazelle was indeed the prince of helicopters and a delight to fly in all aspects of rotary operation..
He mentions a change to Jason's design, then starts to talk about it. That is when the music starts, so it seemed to me Mischa was trying to cover up proprietary information he might be going over. Maybe to be funny, instead of deleting it?
I totally agree that getting my head lopped off by a tail rotor would be "no fun at all." 😇
I miss just the flying videos with the students!!
If it has a Fenestron tail rotor it does not look like a Helicopter - it looks like a machine with spinny things on top and in the rear.
Notice: I am talking about appearance and nothing else. Not talking about safety, reliability, technology... apearance only.
Interesting interlude
They look like helicopters designed by Dyson, the vacuum cleaner people.
Nah, they'd eliminate the visible rotor altogether
@@martenkerkhoff6600 like the MD600E with its NOTAR
Bladeless helicopter go brrrrrrrrr.
Good point , thx for explaining ,,why isnt fun ? Im so used to lose my head with TR ,,however I just fit it back in place like Terminator
Its sound like it might be pilot error to "overpitch" Perhaps flying outside of the design characteristic?