What kind of wind turbine is this?

Ken, you sound like you know your stuff.  Question: Giromill = fixed pitch blades and Cycloturbine = pitch of airfoils change relative to wind direction and rotation position?
Thx!
Nick

I stopped by the farmer's house and got some information on the turbine.  I did some research and contacted the company that is building it.  I've updated the YouTube video info based on what they told me.

David - They emailed me and said they'd been keeping the development of this turbine pretty quiet, but they plan to have an unveiling of the product later this month. Right now this is the only one in existence, and you're right - it's totally a new approach. They said they were going to post the YouTube videos and info, so I decided to pull my video because it had obviously become moot!  I will email back the engineer and ask him to monitor this thread.
Nick

Hi Carla,
I am the chief engineer on the Blackhawk Project. Thank you for your observations regarding the information (or lack of it) pertaining to the AR-10 Tilt Rotor.

First, the AR-10 is not a product yet - it is currently in the middle of an extended testing cycle that is dependent on a number of factors, including wind conditions at the test site.  I'll be glad to discuss any technical aspects of the design, but until we get a large enough statistical database, I feel very uncomfortable about making any unsubstantiated claims regarding performance based on wishful thinking.  This industry is rife with that kind of stuff, and I refuse to be a part of it.  I'm trying to do my best to rein in the marketing guys, but they don't have much specific technical detail to work with - thus all the vague language.  But like most people who've watched it fly, they're pretty excited about it and want to get it on the market.

Secondly, it's impossible to keep anything a secret forever, and when you have a unit deployed, even at a remote site, it is just a matter of time before a knowledgeable person recognizes it for what it is.  Therefore we have decided to release the YouTube videos and take some control over the accuracy of the information.

This has been a fascinating project to be involved with and I've gotten some incredible support, both financially and from the CPM machine shop.  The project is internally funded and so does not need to solicit investors.  We're currently building 10 identical units for Beta site testing through the Spring of '09.  Our goal is to keep all the manufacturing in the U.S., even though we could obviously have it done cheaper in China.

It's refreshing to find a forum like this where people actually seem to know what they're talking about, and are civil.  I'd be glad to answer any questions about the design.

Cheers,
Bruce Boatner
The Blackhawk Project LLC
Boise, ID

David,
Thanks for the kind words.  You raise a very interesting point regarding autorotation.  You know, I've never really thought about it in exactly those terms, but in fact you're right.  (BTW I got this idea while studying aerodynamics for my helicopter pilot's exam.) 

Simply put the helicopter puts energy into the air while a wind turbine takes energy out of the air, both via an impeller.  During helicopter autorotation the airfoils are executing a very complex combination of both functions.  Now I'll have some fun thinking about that!

Surprisingly, when I conducted the patent search I found that nobody had previously associated these basic rotor head/VAWT design concepts.  The patent is called "Vertical Axis Wind Turbine With Articulating Rotor", or VAWT/AR for short.  It encompasses both the teetering rotor (2-bladed ala Bell 47/Huey/JetRanger or Robinson R22/44), and fully articulated rotor systems (3+ blades).

The cyclic pitch function on the VAWT/AR is an interaction between the tilt of the overall rotor (which is easily seen in the videos), and the instantaneous Angle Of Attack (AOA) of the airfoils (which is not easy to see).  As Ken Hall rightly observed, this is a type of Cycloturbine, wherein the AOA of the airfoils is constantly being controlled to provide a beneficial lifting force to produce rotation, based on the instantaneous relative wind impinging on the airfoils.  It is reliably self-starting, and has an interesting characteristic of being able to respond to increased loads by increasing torque.

The center of inertia of the entire system is located at a still point at the geometric dead center of the universal joint in the hub.  Thus there is no wobble or vibration at any speed or any rotor tilt angle.

The airfoils are canted in such a manner as to produce lift on two perpendicular axes simultaneously.  There's the normal rotational lift, but also vertical lift created by a fixed angle of the airfoils (pitch bearing housings) mounted relative to the rotor arms.  The lift created in the perpendicular dimension causes a tilting action...which causes the overall rotor to align itself with the wind...which causes the proper AOA to be set for each airfoil...and it's off to the races!

There's no ground effect, but we do need to get the turbine up higher into cleaner wind.  It's convenient right now to make quick adjustments.  In terms of external shrouds etc., one should consider the materials used to construct such are more efficient when "put to work" on the moving sections of the turbine, based on what I've read, anyway.

This all sounds pretty complicated, but today I sent the CNC parts for a new protytpe out for anodizing, and they all fit easily in a fairly small box.  Also the airfoils are a simple NACA 0012 style, like typical symmetrical heli blades, so there's nothing exotic for production.  So there's a relatively complex set of physics being executed by a relatively simple set of mechanics.

And we haven't even talked about how it automatically compensates for gyroscopic precession!  Way too much information, I'll bet...

Cheers,
Bruce

  hi folks,

 for anyone interested in wind turbines or those folks just interested in interesting things i would recommend having a look at this new wind machine.

 bruce, i looked at the video shot a few more times trying to get my head around the center of rotation.

"The center of inertia of the entire system is located at a still point at the geometric dead center of the universal joint in the hub.  Thus there is no wobble or vibration at any speed or any rotor tilt angle."

  it looks like your universal joint/hub design takes all the side to side loads as well as the thrusting loads into the hub assembly and only lets through the rotational torque to the alternator/generator. nice...that also means it's reasonably easy to swap out different spec generators based on wind resources and power needs?

 i looked up that four digit airfoil. was that 12% by design
or trial and error.

 i hope you can tell us more about your choice for the powerplant as well as the gyroscopic precession correction methods you teased us about.

 all the best.

Gyroscopic precession seems pretty complex and mysterious at first, but in fact it is simply due to the fact that mass cannot change direction instantly - there is always a delay between the application of force and the movement of the mass.  In the case of a gyroscope, the response to a force is seen 90 degrees after the application of the force.

In other words if you press down at the 12 o'clock position, the clockwise-spinning gyroscope will dip at the 3 o'clock position.  This is simply because the mass passing the 12 o'clock position BEGINS to respond to the force, but it does not reach its full excursion until it reaches the 3 o'clock position.  No mass can respond instantaneously.

In helicopter rotor heads, the desired change to the pitch of the rotating blades must be applied exactly 90 degrees prior to the position that it will take effect.

In the VAWT/AR Tilt Rotor, gyroscopic precession must be compensated for, or the system will not run at its full potential TSR (Tip Speed Ratio - but for a VAWT, rotor speed relative to wind speed).  Here's why:

Let's say there's no wind and the AR is still, with its rotor level.  The wind begins to blow, and the rotor tilts into the wind, causing the airfoils to pitch correctly to produce rotational lift, and the rotor begins to turn.

Now the rotor starts to spin up, faster and faster, and as it does the effects of gyroscopic precession begin to take effect, causing the low tilt point of the rotor, which is supposed to be directly into the wind, to start to drift over to a point 90 degrees to the side. 

If the rotor were allowed to tilt 90 degrees off the windward mark, it would stop running very quickly, because the airfoils would not be positioned correctly to produce lift.  In fact, the airfoil that is swinging directly upwind - that should be perfectly faired into the wind - would start acting like a giant speed brake!

Early prototypes showed that without some means of correcting for gyroscopic precession, the turbines would settle into a tilt angle about 45 degrees between the optimal position and the show-stopper position.  The TSR would then be limited to around 1.5, whereas I've measured a TSR of 3 when correcting for gyroscopic precession.

How the VAWT/AR corrects for this is quite simple.  As I said before, as the rotor tilt angle starts to move away from the optimal windward position, the airfoil swinging in the upwind position begins to present drag because it is not perfectly faired into the wind.  However, due to the fixed cant angle of the airfoil relative to the rotor arm, any non-zero pitch in this airfoil is translated into a lifting force on the rotor arm, thus raising it back into its proper position. 

Remember, though, that gyroscopic precession is acting on this force as well!  But in this case it turns out to work in our favor, the final result of which is to nudge the rotor back into its proper windward tilt position.

So the airfoils are performing triple duty: 1) rotational force (produce rotor torque), 2) tilting force (orient the rotor to produce proper instantaneous airfoil AOA), and 3) correct for gyroscopic precession.  Once again, complex physics, simple design.

Cheers,
Bruce

I have been following the blackhawk ar-10 prototype. I am excited about a alternative source of power. I live in Fairfield and have many acres of land and god only knows enough wind to power the blackhawk. I would certainly be interested in having a test site set up on my property. I would love to be a part of this project. I have no brain power, however I do have wind power.  Thanks for your contributions to the earth Bruce. Thanks Marilyn Dillard

  Thanks for the educational reading. Jim

Hi Mitch,
For some reason I'm not getting alerted via email of postings, so I'm glad I happened to stumble upon your posting.  Dave did copy me on his response to your email.

Your project in Maine sounds fascinating, so congratulations.  Not to repeat what Dave told you, I'm really hoping we can work together into the future on projects of mutual interest like this.  We have found that peoples' visceral reaction to the tilt rotor turbine is quite profound when they encounter it for the first time.  I don't know exactly how to explain it, except that it has a sort of presence about it "in person" that doesn't necessarily come across in pictures & videos.  I'm sure you'd enjoy working with the machines. I'm confident the quietness and aesthetics of the turbine will fit the kind of quality plans you have in mind.

We're finishing up the CNC parts for a run of 10 production/Beta site units, which we hope to start installing in January, after evaluating a number of sites near enough to establish a "Pony Express" route for gathering test data.  The current run is also allowing us to capture the true build costs for the unit, which in turn will dictate what we can sell them for.  We've decided to build 100% of the unit here in the U.S., even though we could make a lot more money by having some of the components manufactured in China.  Currently it's looking like the Beta Site units are going to sell for around $5800, but this is UNOFFICIAL.

We plan to go into full production sometime in 1Q09, and will probably be building about 100 units per quarter, depending on demand.  Right now we have approximately 150 requests for the 10 Beta units, but until we actually start qualifying individual sites, there's no way to know how many of those are for real.

I hope you don't have to go back to Iraq, but thanks for serving.  I was an Army crewchief on a DeHavilland Otter, and some of my adventures in Viet Nam have found their way onto the internet.  No telling what the situation in Iraq will be by 2010.  Things seem to be changing pretty fast.  Perhaps in the long run the impact of your work at Wolfe Neck's Farm may be just as important for making our country more secure.

Thanks again for your interest,
Bruce
 

You seem to be separating the mills and the turbines by the end work performed.  While it is true that windmills are best at mechanical tasks and turbines are usually making electricity, that is not what separates them.  Windmills can generate electricity and turbines can pump water.

Windmills are drag machines. Their “sails” or blades are pushed by the wind.  There is very little or no lift generated by the blades.  Turbines use airfoils that generate a substantial amount of lift.

Your belief that HAWT’s must be pointed upwind is incorrect.  While the majority of them are upwind machines, downwind designs do exist. Here is a good write up on some of the differences.
http://www.windpower.org/en/tour/design/updown.htm