Eurocopter test new Quiet blades
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Eurocopter test new Quiet blades
Well this sounds like good News soon we can have Whisper mode like "Blue Thunder" and "Airwolf".
" Eurocopter make Decisive step towards lowering noise emissions and vibrations through adaptive rotor controls
On 8 September 2005 at 2 p.m., the experimental helicopter of the type BK 117 lifted off from the Eurocopter site at Donauwörth for its official maiden flight with an electrical flap control system. This means that Eurocopter has now reached a milestone in the development of a trendsetting helicopter control technology and thus positioned itself ahead of the international technology competition concerning the area of so-called "adaptative rotor systems," surpassing the key competitors Japan and the U.S.
Significantly Lower Noise and Vibration Levels
The primary objective of this new type of control method is to reduce the system-inherent, relatively high noise level of the rotor blade tip vortices to levels significantly below those of modern Eurocopter helicopters with limit values already below the required standards.
At the same time, the vibrations that components and passengers alike are subjected to shall be reduced significantly in order to increase the comfort of passengers during the flight and expand the capacity of future helicopters and thereby promote commercial utilization of these aircraft.
The development program concerning adaptative rotor systems is sponsored by the German Ministry of Economics and Labor and is based on cooperation between the partners Eurocopter Deutschland (management, design, production, controls, tests), the EADS Corporate Research Centre CRC (piezoceramic actuators), DaimlerChrysler (energy supply, data transfer), as well as the German Aerospace Center DLR (controls, data transfer).
Flaps at the Blade Trailing Edge – Piezoceramic Actuators
The control system uses three flap modules located at the trailing edge of each rotor blade. The piezoceramic actuators integrated into the blades respond with a length change to varying electrical voltages and thereby move the rotor flaps 15 to 40 times per second.
Actuation is carried out by means of an optical waveguide via a controller without requiring pilot interaction. It neutralizes the blade slap noise typically associated with helicopters that are descending and lowers the overall noise level by up to 6 dBA (a decrease around 10 dBA corresponds roughly with a 50% lower noise impression).
The asymmetrical impinging flow of a rotor generates vibration that can be reduced by as much as 90% by generating counter-vibration, which in turn increases the service life of important components as well as passenger comfort.
Eurocopter COO Friedrich Dörhöfer and the Ottobrunn Eurocopter project team around Michael Stephan were completely satisfied with the results of this first flight: "The now tested demo system has yet to be miniaturized and optimized for commercial utilization. And as technology leader for bearingless rotor systems, we are currently integrating another, further improved flap type into a bearingless rotor of the latest generation,” explained Dr. Valentin Klöppel, Aeromechanic and Flight Control Program Manager at Eurocopter. “The technology will be generally applicable to all larger helicopters once all tests have been successfully concluded. This is likely to be in 2012 or beyond.”
" Eurocopter make Decisive step towards lowering noise emissions and vibrations through adaptive rotor controls
On 8 September 2005 at 2 p.m., the experimental helicopter of the type BK 117 lifted off from the Eurocopter site at Donauwörth for its official maiden flight with an electrical flap control system. This means that Eurocopter has now reached a milestone in the development of a trendsetting helicopter control technology and thus positioned itself ahead of the international technology competition concerning the area of so-called "adaptative rotor systems," surpassing the key competitors Japan and the U.S.
Significantly Lower Noise and Vibration Levels
The primary objective of this new type of control method is to reduce the system-inherent, relatively high noise level of the rotor blade tip vortices to levels significantly below those of modern Eurocopter helicopters with limit values already below the required standards.
At the same time, the vibrations that components and passengers alike are subjected to shall be reduced significantly in order to increase the comfort of passengers during the flight and expand the capacity of future helicopters and thereby promote commercial utilization of these aircraft.
The development program concerning adaptative rotor systems is sponsored by the German Ministry of Economics and Labor and is based on cooperation between the partners Eurocopter Deutschland (management, design, production, controls, tests), the EADS Corporate Research Centre CRC (piezoceramic actuators), DaimlerChrysler (energy supply, data transfer), as well as the German Aerospace Center DLR (controls, data transfer).
Flaps at the Blade Trailing Edge – Piezoceramic Actuators
The control system uses three flap modules located at the trailing edge of each rotor blade. The piezoceramic actuators integrated into the blades respond with a length change to varying electrical voltages and thereby move the rotor flaps 15 to 40 times per second.
Actuation is carried out by means of an optical waveguide via a controller without requiring pilot interaction. It neutralizes the blade slap noise typically associated with helicopters that are descending and lowers the overall noise level by up to 6 dBA (a decrease around 10 dBA corresponds roughly with a 50% lower noise impression).
The asymmetrical impinging flow of a rotor generates vibration that can be reduced by as much as 90% by generating counter-vibration, which in turn increases the service life of important components as well as passenger comfort.
Eurocopter COO Friedrich Dörhöfer and the Ottobrunn Eurocopter project team around Michael Stephan were completely satisfied with the results of this first flight: "The now tested demo system has yet to be miniaturized and optimized for commercial utilization. And as technology leader for bearingless rotor systems, we are currently integrating another, further improved flap type into a bearingless rotor of the latest generation,” explained Dr. Valentin Klöppel, Aeromechanic and Flight Control Program Manager at Eurocopter. “The technology will be generally applicable to all larger helicopters once all tests have been successfully concluded. This is likely to be in 2012 or beyond.”
Sounds complex. That would only be utilised in military operations you would think. I would love to see a schematic of the system and a breakdown of all its components. Wouldn't fancy seeing the price tag for it though.
Not enough $$$ ...
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The thing most interesting to governments is the reduction in noise levels over cities.
I would suggest that once government bodies become aware of the commercialised version of this, they will make it mandatory in their new tender requests, which will speed further development and integration into future models.
I would suggest that once government bodies become aware of the commercialised version of this, they will make it mandatory in their new tender requests, which will speed further development and integration into future models.
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bellfest,
This page has many links to the use of piezoceramics in helicopter rotor blades; Rotor Concept - Active Blade Twist - Electromechanical
If I may be so brash as to make comment, Active Rotor Blades is what will take rotorcraft into the 2nd generation. The aerodynamics of the rotor will continue to improve as the amplitude and the frequency of this 'blade morphing' are increased.
It should be noted that this improvement for the single main rotor will result in an extreme improvement for helicopters that have aerodynamically interactive twin main rotors. This is the primary reason why the intermeshing, the interleaving, and to a lesser degree the coaxial, configurations represent the future of rotorcraft.
Spelling correction
This page has many links to the use of piezoceramics in helicopter rotor blades; Rotor Concept - Active Blade Twist - Electromechanical
If I may be so brash as to make comment, Active Rotor Blades is what will take rotorcraft into the 2nd generation. The aerodynamics of the rotor will continue to improve as the amplitude and the frequency of this 'blade morphing' are increased.
It should be noted that this improvement for the single main rotor will result in an extreme improvement for helicopters that have aerodynamically interactive twin main rotors. This is the primary reason why the intermeshing, the interleaving, and to a lesser degree the coaxial, configurations represent the future of rotorcraft.
Spelling correction
Last edited by Dave_Jackson; 17th Sep 2005 at 23:44.
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The use of on-blade controls will certainly be a new chapter in helicopter control, and this is a great second step (another similar concept was flown about 3 years ago, successfully.)
The small tabs allow the blade's lift to be adjusted a small amount (for now!) and thus noise and vibration can be quelled, theoretically.
In the future, this technique could control the entire blade pitch range, thus doing away with the swash plate and pitch change link assembly.
This doe not have much to do with Dave's assertions about intermeshing rotors being the entire future of rotorcraft, a thought which has no great backing from the rest of the helo community!
The small tabs allow the blade's lift to be adjusted a small amount (for now!) and thus noise and vibration can be quelled, theoretically.
In the future, this technique could control the entire blade pitch range, thus doing away with the swash plate and pitch change link assembly.
This doe not have much to do with Dave's assertions about intermeshing rotors being the entire future of rotorcraft, a thought which has no great backing from the rest of the helo community!
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Swords or pistols?
Nick sez ~ "..... Dave's assertions about intermeshing rotors being the entire future of rotorcraft,"
Nick then continues ~ "a thought which has no great backing from the rest of the helo community!"
Heck Nick. It was only a few months ago that you stopped knocking the coaxial configuration.
Dare I ask why? The following book review gives a peek at what was outside the box.
"Editorial Review:
The result of 15 years research, this book is the first comprehensive account of the development of auto-gyros and helicopters in Germany during the period 1930-1945. It sheds much light on an area of considerable aeronautical achievement, which has until now been unjustly neglected.
German progress in this field has been overshadowed by developments in other areas. Yet by the end of World War II, despite minimal funding, lukewarm official support and bitter inter-service rivalries, the Germans were, undoubtedly, technologically way ahead of their American counterparts in the development of rotating wing aircraft. This book, which will become the definitive work on the subject, is fully illustrated throughout with many photos which are believed to have been unpublished until now."
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Aesir,
Yes, the Kaman rotor uses a large servo-flap tab that flys the blade to its position, but the servo-flap is mechanically controlled, and has its own swashplate and other mechanical control components, so it does not represent the step change that the piezoelectric tabs do on the latest designs. The servo-flap has the power to fly the rotor, so there are no hydraulics needed.
Some details:
http://www.helis.com/howflies/servo.php
The Hiller rotorhead also used a small paddle system (90 degrees to the two blades) that flew the semi-rigid rotor system to its new position.
Here is a picture of that rotor:
http://www.scalehelis.com/hiller/hiller13.jpg
Here is a good (but technical) paper on the piezo-electric flap, with a few sketches:
http://www.pkn.co.za/pap-HGFEF.html
Yes, the Kaman rotor uses a large servo-flap tab that flys the blade to its position, but the servo-flap is mechanically controlled, and has its own swashplate and other mechanical control components, so it does not represent the step change that the piezoelectric tabs do on the latest designs. The servo-flap has the power to fly the rotor, so there are no hydraulics needed.
Some details:
http://www.helis.com/howflies/servo.php
The Hiller rotorhead also used a small paddle system (90 degrees to the two blades) that flew the semi-rigid rotor system to its new position.
Here is a picture of that rotor:
http://www.scalehelis.com/hiller/hiller13.jpg
Here is a good (but technical) paper on the piezo-electric flap, with a few sketches:
http://www.pkn.co.za/pap-HGFEF.html
Last edited by NickLappos; 18th Sep 2005 at 02:40.
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"This does not have much to do with Dave's assertions about intermeshing rotors being the entire future of rotorcraft, a thought which has no great backing from the rest of the helo community!"
I imagine this will change as Vne is pushed up, in response to competition from V22 derivatives. v-RRPM will then also become the next milestone, to reduce advancing tip compressibility effects (and drag in general). Clearly such a large design transition would be a large undertaking, and require careful aerodynamic justification regaring vibration and stability.
The servo flap will clearly not work near the root, due to the reverse flow region. For this reason i also can't imagine swash plate control being totally removed for commercial machines - although cyclic trimming does make sense. For military apps a fully servo blade maybe does make sense as part of FBW system.
Perhaps, it is fairer to comment that a practical efficient intermesher requires a number of enabling technologies - which are now becoming commercially viable. An intermesher "champion" needs to collate all these techniques, then begin some proof of concept test work to demonstate to the industry that this approach is cost effective...
Mart
I imagine this will change as Vne is pushed up, in response to competition from V22 derivatives. v-RRPM will then also become the next milestone, to reduce advancing tip compressibility effects (and drag in general). Clearly such a large design transition would be a large undertaking, and require careful aerodynamic justification regaring vibration and stability.
The servo flap will clearly not work near the root, due to the reverse flow region. For this reason i also can't imagine swash plate control being totally removed for commercial machines - although cyclic trimming does make sense. For military apps a fully servo blade maybe does make sense as part of FBW system.
Perhaps, it is fairer to comment that a practical efficient intermesher requires a number of enabling technologies - which are now becoming commercially viable. An intermesher "champion" needs to collate all these techniques, then begin some proof of concept test work to demonstate to the industry that this approach is cost effective...
Mart
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Piezo actuators
Nick,
The reading material you provided concerns the response characteristics of the actuator it self. Looks non-linear but manageable. But this is just the characteristic of one component.
Is there other reading on how the overall control loops are designed ? What is the prime objective function for instance.
d3
The reading material you provided concerns the response characteristics of the actuator it self. Looks non-linear but manageable. But this is just the characteristic of one component.
Is there other reading on how the overall control loops are designed ? What is the prime objective function for instance.
d3
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delta3,
The idea is that the small tab can make the blade move very quickly, a small amount. This allows the blade to be controlled in its higher harmonic responses (it can be "rung" like a bell at frequencies faster than one per revolution). This allows the blade to be 'moved out of the way" of the noise producing vortex, and also allows the aircraft to control the higher frequency vibration that the blade passes onto the aircraft.
Higher harmonic control was tried about 20 years ago in two research programs (one at Sikorsky) but these older programs used the main servo to muscle the blade at the higher frequencies. This proved to be a real wear problem for the servo, and also produced muddled results, since the entire blade was being feathered. The tabs that EC are using are placed where they make the best contribution to the solution.
It is a fine idea, and EC are to be applauded for trying it out.
However, don't let Dave hyjack the concept to put lipstick on his pet pig, the intermeshing rotor (not a bad idea, but a bit of a mania to dave, who can think of nothing else, it seems. Dave, find a backer and make one for Pete's sake!)
On-Blade control is an idea whose time has come for all rotorcraft. Today it can help quiet and smooth out the helo, in a few years it can simplify the control system, allow very high frequency control, and eventually do away with the mechanical claptrap that makes helos expensive, heavy and costly to buy and maintain. It is the natural servo system for fly-by-wire controls.
The idea is that the small tab can make the blade move very quickly, a small amount. This allows the blade to be controlled in its higher harmonic responses (it can be "rung" like a bell at frequencies faster than one per revolution). This allows the blade to be 'moved out of the way" of the noise producing vortex, and also allows the aircraft to control the higher frequency vibration that the blade passes onto the aircraft.
Higher harmonic control was tried about 20 years ago in two research programs (one at Sikorsky) but these older programs used the main servo to muscle the blade at the higher frequencies. This proved to be a real wear problem for the servo, and also produced muddled results, since the entire blade was being feathered. The tabs that EC are using are placed where they make the best contribution to the solution.
It is a fine idea, and EC are to be applauded for trying it out.
However, don't let Dave hyjack the concept to put lipstick on his pet pig, the intermeshing rotor (not a bad idea, but a bit of a mania to dave, who can think of nothing else, it seems. Dave, find a backer and make one for Pete's sake!)
On-Blade control is an idea whose time has come for all rotorcraft. Today it can help quiet and smooth out the helo, in a few years it can simplify the control system, allow very high frequency control, and eventually do away with the mechanical claptrap that makes helos expensive, heavy and costly to buy and maintain. It is the natural servo system for fly-by-wire controls.
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Progress
Nick said "... the intermeshing rotor (not a bad idea, ..."
Today, you give recognition to the Intermeshing.
Tomorrow, recognition for the Interleaving???
The few more sessions of 'technical logic' and you will be completely weaned from the 'tail-rotor phobia-itous' malady.
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Quiet rotor blades
Hmmm,
Very recent experience has shown that you can indeed optimise the current - fixed format - blade to be pretty quiet, but you do have to pick your stage of flight. I'm pretty sure that current 'solid' blades when optimised for quiet over-flight might not produce their best when in the hover. So be warned, when looking at current quiet systems, make sure they deliver what you need, and understand what they do deliver when not operating at their design point.
On Nick's point....about intermeshing rotor discs....I thought one of the major barriers to intermeshing/contra rotating systems was mast head drag....was this not the public issue of the demise of the Advancing Blade Concept? I guess that if you can actively manage all the blades in a contra-rotating head, you can maintain disc separation but you do still need a rotor head.....and these can be draggie little beasties.
Please tell me I have the wrong end of the stick on this...I do know you are somewhat more hands-on than I ever will be.
Very recent experience has shown that you can indeed optimise the current - fixed format - blade to be pretty quiet, but you do have to pick your stage of flight. I'm pretty sure that current 'solid' blades when optimised for quiet over-flight might not produce their best when in the hover. So be warned, when looking at current quiet systems, make sure they deliver what you need, and understand what they do deliver when not operating at their design point.
On Nick's point....about intermeshing rotor discs....I thought one of the major barriers to intermeshing/contra rotating systems was mast head drag....was this not the public issue of the demise of the Advancing Blade Concept? I guess that if you can actively manage all the blades in a contra-rotating head, you can maintain disc separation but you do still need a rotor head.....and these can be draggie little beasties.
Please tell me I have the wrong end of the stick on this...I do know you are somewhat more hands-on than I ever will be.
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Tab control law
To Nick :
Quote :
----------------------------------------------------------------------
This allows the blade to be 'moved out of the way" of the noise producing vortex, and also allows the aircraft to control the higher frequency vibration that the blade passes onto the aircraft.
----------------------------------------------------------------------
Nick what is the formal input ?
Noise, vibration amplitude, pilot feedback..
Control function would then be to adjust tab angles to reduce vibrations, based on some higher level model on BV interaction, depending on speed (horizontal and vertical), collective etc..
Is that the idea ?
d3
Quote :
----------------------------------------------------------------------
This allows the blade to be 'moved out of the way" of the noise producing vortex, and also allows the aircraft to control the higher frequency vibration that the blade passes onto the aircraft.
----------------------------------------------------------------------
Nick what is the formal input ?
Noise, vibration amplitude, pilot feedback..
Control function would then be to adjust tab angles to reduce vibrations, based on some higher level model on BV interaction, depending on speed (horizontal and vertical), collective etc..
Is that the idea ?
d3
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At the risk of threadjacking... 
"The few more sessions of 'technical logic' and you will be completely weaned from the 'tail-rotor phobia-itous' malady."
Dave, i feel that Nick provides a very good grounding in helidynamics - i've learnt a thing or three. The tail rotor in itself is not a bad concept, but retreating rotor aerodynamics at high speed definately lend weight to the symmetrical helicopter. Like all things in engineering it will come down to cost and reliability (which is cost anyway). The piezo-actuator trimmer is another enabling technology, which may help catalyse the transition.
"I thought one of the major barriers to intermeshing/contra rotating systems was mast head drag"
True, but intermeshing presents a smaller profile to coaxial. I prefer mechanical systems where practical, but accept the piezo-actuators and electro-actuators in general will help to reduce the complexity (hence drag) of any head system.
Mart
"The few more sessions of 'technical logic' and you will be completely weaned from the 'tail-rotor phobia-itous' malady."
Dave, i feel that Nick provides a very good grounding in helidynamics - i've learnt a thing or three. The tail rotor in itself is not a bad concept, but retreating rotor aerodynamics at high speed definately lend weight to the symmetrical helicopter. Like all things in engineering it will come down to cost and reliability (which is cost anyway). The piezo-actuator trimmer is another enabling technology, which may help catalyse the transition.
"I thought one of the major barriers to intermeshing/contra rotating systems was mast head drag"
True, but intermeshing presents a smaller profile to coaxial. I prefer mechanical systems where practical, but accept the piezo-actuators and electro-actuators in general will help to reduce the complexity (hence drag) of any head system.
Mart
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Graviman,
Nick gives me the stick and I give it to him. It's all in good fun ~ I think.
It's like religion. The particular religion one believes in is probably the religion that they were previously immersed in. US Rotorland was baptized in the name of the tail-rotor.
Heck, the disciple Igor had a helicopter with three tail rotors; all pointing in different directions.
Nick gives me the stick and I give it to him. It's all in good fun ~ I think.
It's like religion. The particular religion one believes in is probably the religion that they were previously immersed in. US Rotorland was baptized in the name of the tail-rotor.
Heck, the disciple Igor had a helicopter with three tail rotors; all pointing in different directions.
