Blue Edge rotor blade from Eurocopter

[Senior Pilot]

Eurocopter's Blue Edge rotor blade has three flaps added onto the standard design, which "move up and down at 15 to 40 times per second, using piezoelectric motors that also help to reduce the blade-vortex interaction."

TechEBlog (http://www.techeblog.com/index.php/tech-gadget/eurocopter-s-blue-edge-rotor-blade-makes-helicopters-silent)

http://media.techeblog.com/images/silent_helicopter_blade.jpg

Looks and sounds like a radical design :ooh:

dBS1NRsYuF8

[skadi]

thats not quite correct,
the BLUE EDGE Blade is not equipped with piezo-activated elements. The noisereduction comes from the design, so its not an active system.
The PLUE PULSE Blade ist the active system!

Eurocopter highlights its innovation and bluecopter® technology at Heli-Expo 2010 (http://www.eurocopter.de/site/FO/scripts/myFO_publication.php?news_id=661&lang=EN)

Blue Edge™: This revolutionary main rotor blade provides a passive reduction in noise levels, using a double-swept shape that is very different from present-day blades. The aim of this program is to reduce the noise generated by so-called blade-vortex interactions (BVI), which occur when a blade impacts a vortex, created at the tip of the blade of any helicopter.

A five-blade Blue Edge™ main rotor has been flying since July 2007 on an EC155 testbed, logging 75 flight hours and demonstrating noise reductions of 3 to 4 dB, as well as very good performance of the blade. With this safe and simple means of measureable noise reduction for helicopters now validated, Eurocopter is ready to move Blue Edge™ into production applications.

Blue Pulse™: This piezo-active rotor control system has the primary objective of reducing noise levels generated by the interference of the rotor blade tip vortices from one rotor blade with the following blades. In addition, it will significantly reduce vibrations within the helicopter airframe, increasing passenger comfort and extending the service life of sensitive components,

The control system uses three flap modules located at the trailing edge of each rotor blade. The blades’ piezoelectric actuators move the rotor flaps 15 to 40 times per second in order to completely neutralize the “slap noise” typically associated with helicopters during descent. The Blue Pulse™ technology has been flying since 2005, showing a noise reduction of up to 5 dB. Eurocopter’s evaluations with Blue Pulse™ are continuing on an EC145, while the development of a miniaturized system for production applications is advanced.

skadi

[froggy_pilot]

The blade has a "double sweep" shape, see latest issue of rotor journal 21042010Rotor (http://www.eurocopter.com/w1/jrotor/85/#/19)

If you want to know more about the actuators/flaps http://www.noliac.com/Files/Billeder...ILING_EDGE.pdf

[MartinCh]

I guess it's time to stop calling helicopters 'choppers' and use 'whipper' or 'buzzer' etc.

I'm sure Police forces and military later on would be very interested. Or companies operating from dense urban areas to avoid noise pollution.

BTW, Does the design change any properties of vortex ring state, regime and related stuff, since the blades should reduce interference and vortices as well. Anyone?

[RVDT]

5 blade Blue Pulse 145 has been flying since at least 2005!

[riff_raff]

I guess it's time to stop calling helicopters 'choppers' and use 'whipper' or 'buzzer' etc.MartinCh,

Buzzer would be quite apt for this rotorcraft (http://www.flightglobal.com/blogs/as-the-croft-flies/2010/06/eads-to-wow-ila-with-diesel-electric-hybrid-helo.html) from EADS.

Word from Germany is that EADS Innovation Works, the corporate research and technology arm of EADS, will unveil at the ILA show in Berlin next week a full-scale mockup of a helicopter powered by an innovative two-stroke diesel engine as part of hybrid electric propulsion system for the vehicle.

The company says such a design could cut fuel burn and emissions by 50% while cutting noise with electric-only takeoffs and landings

http://www.flightglobal.com/blogs/as-the-croft-flies/hybrid%20helo.JPG

Regards,
riff_raff

[Graviman]

That is an incredible demo of how much noise is normally generated by tips travelling at speeds where compressibility becomes an issue. Notice the anhedral tips to shed the vortices further away from the tip for higher efficiency. Without reading up, not sure whether the angled leading and trailing edges benefit vortex shedding (retreating) as well as compressibility (advancing).


Must admit, riff, i'm not sure why use two stroke OPOC when you could use a 4 stroke with very high boost turbocharger. These can be designed to run very quietly indeed. There are various boosted two strokes out there but they never seem to achieve the "theoretical" power/weight benefit claimed for 2-stoke over 4-stroke. Unless this design is already high boosted (maybe with supercharger/decompressor to regulate volume flow rate).

[riff_raff]

Graviman,

I don't think that EADS diesel-electric hybrid concept would be practical for an extremely weight sensitive application like a rotorcraft. At least not with power densities available in current technology electric motors and batteries. This type of thing looks good on a powerpoint slide, but once you get into the details of designing two complete propulsion systems (one electric and one diesel) you'll find that the weight, cost and complexity are not worth the benefits. A diesel/electric hybrid system only works well for vehicles that are not weight sensitive (like a tank or a locomotive) or for a vehicle that operates most of the time at a small fraction of its max power (like a car driving in the city). If what you want is reduced rotor noise then variable speed and/or high-frequency IBC (like Blue Pulse) is the right approach.

As for the merits of two stroke versus four stroke recip engines, that debate was settled long ago. On paper the two stroke would seem to have an advantage. But in practice, the four stroke gives better reliability, fuel consumption and lower emissions for an installed weight that ends up being equal to the two stroke. It's kind of like the old joke about turbine engines being mechanically simple because they only have one moving part! :8

Regards,
riff_raff

[Graviman]

Riff, agreed.

For fixed wing there is an arguement for hybrid, with engine (or Intelligent Energy fuel cell ) providing take-off or go-around power. Helis max power requirement is usually in the hover, so it needs to be sustained.

Now that i'm involved in diesel engine design, i can see the difficulties with many engine concepts targeted at aircraft. Aero emissions isn't as tight as for their ground vehicle cousins, but no need to introduce problems like inconsistent scavenging and combustion. I would not be suprised if developments involving turbine LP stages and piston HP stages enter discussions soon. Actually, i would keep an eye on the humble flywheel. ;)

With new rotor technologies, like Blue Edge and Blue Pulse, improving machine efficiency i would be interested to see how disk loading evolves in the coming years.

[dangermouse]

Fwd swept leading edge Check
Aft swept trailing edge Check
Anhedral tip Check
Composite Construction Check
Reduced Noise Check
Increased Performance Check

hasn't someone been here before? (about 25 years ago)

:ok:

DM

[Graviman]

Agreed, dangermouse - the best ideas are developments of existing technology. ;)

This design will have benefitted from recent software developments in Computational Fluid Dynamics and Fluid Structural Interaction. From the image (assuming blade droop is not playing with perspective) it looks like this design takes the BERP concept to the whole outer 1/2 span of the blade. The biggest problem would have been controlling flexure and stress from centrifugal and inflight loads. Turbine blade designers have hours of fun trying to make sure the section shear centre, inertia centre, and aerodynamic centre stay consistent along the span. With this much sweep i'd be interested to hear what sort of fun the blade structural & design guys had. Notice how the sweep back extends just a little beyond the sweep forwards for example.

[Dave_Jackson]

Could some of the noise reduction be due to replacing the swash-plate with a swish-plate (http://www.unicopter.com/B329.html#Swishring)? http://www.unicopter.com/Chairshot.gif


Anonymous :uhoh: