Bruce Boatner's posts

Hi Dave,

Thanks for the tip on the meter - they would be very useful and I'm going to order a few.  I'm not losing amp-hour data between visits.  Probably just losing my ability to construct a proper sentence!

Cheers,
Bruce

Hi Dave,
Thanks for your observations.  I've been spending quite a bit of time in the field lately because we're getting into the windy season - prime time for testing. 

Between a call to Xantrex customer service (India?) and my own observations using an ammeter inline with the output of the rectifier, I have determined that all of the information on the CM front panel relates only to what's going on with the diversion load.  This has been verified in a number of ways including the fact that the "Amps" and "Watts" readings are always 0 until the dump load starts to warm up, at which time they indicate values (along with the Amp Hours).

To me this feature is not very useful, as I would really like to observe the charging energy the unit is producing and have a log of Amp Hours since the last time I checked the system.  With an anemometer showing average wind speeds, this could actually be useful performance data.

On the other hand, from a circuit design standpoint, I can see how they can't monitor the power going into the battery, since the controller is wired in parallel.  However, the dump load is on a series output from the controller, so they are able to monitor the activity on that circuit.

Cheers,
Bruce

I was wondering if anyone knows whether (in Diversion Load mode) the readings on the CM display - Amps, Watts and cumulative Ampere-Hours - reflect only what's gone into charging the batteries?  In other words, when there's power being burned off on the dump load, is the display telling you how much energy your wind turbine is generating - or only how much of the energy is being transferred to the batteries?

Thanks!
Bruce

(Contacted by phone)
~BB

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
 

This was shot a couple of weeks ago and aired last Wednesday:

http://www.ksawtv.com/global/video/popup/pop_player.asp?ClipID1=3181071&h1=Boise%20Green%20Living%3A%20Weird%20Wind&vt1=v&at1=WN

Cheers,
Bruce

What's the old saying?  Everybody's famous for 15 minutes?  OK, start your watches.

http://www.ktvb.com/video/index.html?nvid=297052

~ Bruce

Dave - you are too kind.

Marilyn, please go the the cpmach[dot]com web site and get the contact information for Dave Robison.  I have emailed him to expect your call.  Have a chat with Dave, and I'll get your phone number from him as well.  You're just down the road ... relatively speaking, from an Idaho perspective.

Cheers,
Bruce

David,
Thanks again for the kind words.  Those patent applications do have a tendency to grow!  Lots of legal boilerplate in there, trying to cover all the bases.  The best way I've found to navigate such things is to read the introduction and overview, then jump to the diagrams.  When something needs more explanation in a drawing, I search for the paragraph that describes that diagram.  Otherwise it's some pretty tough sledding!

Not sure where the specific scaling ratio came from.  Basically it could be as big as you wanted it.  The furling mechanism would add quite a bit of complexity, but I wanted to show how it could be accomplished.  On the smaller units (up to 5KW), we're going to make the airfoils inexpensive and easy to replace.  However, if a huge one of these was built, you'd probably want to guarantee that it would survive any storm without wing damage - thus the furling.

Right about the dampener evolution.  We've currently settled on a set of elastomeric EPDM dampeners - simple, inexpensive, robust, UV-proof and not affected much by temperature.  There is redundancy built in, and they would probably last a couple of years without maintenance.  Also the ideal geometry/placement of the dampeners took some time to work out.

I did all the drawings with TurboCAD.  It's got a few bugs, but for $129 it's hard to beat.  I've upgraded to TurboCAD Pro now, but those drawings were done in the standard edition.  My patent attorney added the hand-written number & lettering.  He also modified Fig. 8 for the generator on the ground.  It would never work as the figure shows due to lack of support, but it illustrates the idea OK, so I left it in.

Cheers,
Bruce

Hello Everyone,
Here is a link to a marketing presentation that was put together for a trade show in Las Vegas last week.  Hopefully it will shed some more light on the design. [Note: On my browser, I had to start most of the videos using the link at the bottom of the pages.]

http://cpmach.com/ar10.htm

I'm not too happy about all the "guns 'n' ammo" -type references that come up when you Google "Blackhawk AR-10", so we might start calling it the "Tilt Rotor AR-10".

Remember - we're still testing and tuning.  I didn't write the presentation, so don't take it all as gospel.  But we are starting to have some initial enquiries from potential Beta test site customers and distributors, strictly from word of mouth.  Despite the trade show stuff, we really feel more comfortable working at the "grass roots" level.

Hope you enjoy the show. Feedback welcome.

Cheers,
Bruce

Caveat:  The "Tilt Rotor" concept, in numerous variations, is Patent Pending. [See USPTO published applications "Boatner VAWT".] There is enough information disclosed in this presentation and in the patent application for a knowledgeable person to copy this design.

We are working very hard to develop a novel, reliable and cost-effective product built in the U.S.A.  However, based on previous experiences of companies (mostly Chinese) stealing Intellectual Property, I felt it necessary to license this design to an entity with a sizeable legal department and extensive experience defending I.P. internationally.  Please don't give them an opportunity to do what they do best!
~bb

Last spring we took a road trip from Idaho to Texas.  I'd driven a lot of those roads back in the 70's and 80's, and I was amazed at the number of huge wind farms that had sprung up all along the route. Zoning regulations often prevent the manufacturers from putting their brand on the nacelles, but many of the ones we saw were marked "Suzlon".  I'm sure lots of others were Vestas.

I have nothing against foreign companies - everybody's got to make a living.  But isn't that great - here we have a huge opportunity to refocus our declining manufacturing resources and labor expertise to the task of mass-producing wind turbines and what do we do?  Outsource it, as usual.

~bb

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

Hi David,
Thanks for your interest. When I read back over my post I thought to myself "Dude, who's going to read all this?".  Obviously you did, so...cheers!

Yes, the U-J only passes the rotational component through to the drive shaft, and maintains all the other forces neutral.  This turbine produces high torque, due to its long moment arms and large swept area, but it turns at a relatively slow RPM.

I tested the turbine without a load to determine the proper cut-in speed and operating range, then I designed a generator to match the aerodynamic characteristics of the rotor.

The AFPMG (Axial Flux Permanent Magnet Generator - really an alternator) starts producing a charging voltage of 25V at a cut-in speed of 40 RPM (0.625 V/RPM) in about a 7-8 MPH wind.  It is designed to operate mostly in the 40 - 60 RPM range but is capable of running at 80 RPM (~ 1KW) without burning out the coils based on the wire gauge I used.  Of course driving a generator to that level of output is quite a challenge indeed!

Having the basic design parameters for the very low RPM generator, it is easy to mod the stator for a 12V or 48V simply by altering the coil wraps and wire size.  The rotor/magnet wheels remain constant.  Also with its low RPM and high torque we've looked into direct mechanical water pumping.

The NACA 0012 was a jumping-off point for experimentation.  We're building a set of 14% airfoils right now.  The airfoils are foam core with thin aluminum sheeting - accurate, strong, light and inexpensive.

Gyroscopic precession - next post!

~bb

Here are the 3 Blackhawk AR-10 videos currently posted on YouTube so you don't have to search for them.  I noticed they don't come up together on the screen when one is played:

http://www.youtube.com/watch?v=C4-MuOFl1ts
http://www.youtube.com/watch?v=878BqVRpYFc
http://www.youtube.com/watch?v=l4uYqcVN4To

Cheers,
Bruce

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 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