Solidworks 3D model of prop

[Boss]

This is kind of a mis-mash of files but it is what I have now

These are made with Solidworks







I shrunk the images so the moderators won't yell at me again

Kevin just added wood texture

I'll make them 640X480

Let me figure out how to display a file

http://www.otherpower.com/images/scimages/9419/blade2.EPRT

http://www.otherpower.com/images/scimages/9419/blade2.SLDPRT

http://www.otherpower.com/images/scimages/9419/blade2.STL

[JW]

Hi Boss,

 I can comfortably say, that is the exact opposite, that current blade design geometry is taking place, here on the board.

 For example, at the 'root' of each blade, it is smaller than the 'tip' in width measurement(on your blade design). Now, im not going to go, into twist or anything, but, I suspect you may have a good design there, for a StarWars AirBoat, providing that you have developed internal dampners of some sort. In short, the flex at the 'root' of your blades would be a bitch...

 Perhaps this might occur to you, as you install those super-duty hub rotor plates. I suppose, if you were using a 'passive load/dump-load' then this would be really obvious staring up at the tower. Any sort of mill braking, such as shorting the leads when the mill is furling, would be scary.

JW

[JW]

Ahhhhhh Haaaaaaaa,

 I see I got your 'blade' orientation backwards.

Ive been a solidworks user since 1999. But have never used camworks.

Would you please, put some bolt holes in the blade, before you photo-render, then render and assembly drawing....

JW

[Boss]

I made a couple more still images of the ends of the props





Now what we will do with this now that we have it in the computer I do not know.

We intend to continue to build our props by hand out of wood.

I was fun learning Solidworks

[JW]

I still dont see any flange axle bolt-holes...

 

Jw

[Boss]

Problem is I only have the viewer here at home I can't change anything only take snapshots of what Kevin already did. I may head in to town tomorrow and work with Solidworks at the college.

[scorman]

Nice Brian,

I was able to download the 3D to the viewer and turn it all around and enlarge the end.

I see you use a small radius on the leading edge and then a larger radius to the thickest section, then a flat slope to the trailing ...I haven't figured out how to do the slope from thin tip to twisted root yet ...working on it

spent too much time trying to make the NACA profile work ..may duplicate your idea

keep up the good work,

Stew

BTW ..that Solidworks is the most UNINTUITIVE program I have ever used!!!

and I thought AutoCad was bad!

[Boss]

I don't know the terminology of CAD, but I watched very closely. Kevin was having difficulties getting the radius to follow the thickness of the blade as it went from the tip to the root (the fat end.) Not being familiar with the capabilities of Solidworks, I naively suggested he select points on the radius at the smaller end and again at the larger radius and use the router looking icon to shave the selected points  away. I'm sure that when I get in front of the software again this will not be at all how he did it, but that is usually the way it works out for the newbie. It'll take a couple of do it myself projects before I know what I'm trying to say. I will try it though. This won't make me a pro, but it'll still be fun, until the beginners luck wears off.

     

[twombo]

Brian/Stew

Solidworks IS very powerful, but it IS a major pain to make any progress with.

Rhino3D is FAR more user friendly. There is a free tryout download available at:

http://www.rhino3d.com/eval.htm

25 saves is all you get, but that is enough to get ya going.

Also has great pricing for students and educators. The educational user price is $195.00 and which is non-transferable, but it can be used for commercial work even after the user leaves the educational environment.

No financial interest, but I use the crud out of it because it is so easy to work with.

Mike

[blueEnergy group]

Has anyone here tried using TurboCAD?  Any thoughts about its usability and learn-ability relative to Solidworks and AutoCAD?

Cheers,

Mathias

[fungus]

I like Sketchup a lot ..

very fast and easy to learn and pretty powerful with the tools ..

http://sketchup.google.com/

[SparWeb]

Are you going to make templates from the CAD, or go all the way and CNC the wood?

Is there such a thing as a CNC draw-knife?  :^)

Can your friend Kevin create a basic airfoil profile sketch in one plane at the root, copy it to the tip (and scale it down), and then produce a blended surface between them?  That's not quite the correct way to do it, but if he can do it for the whole blade, then he can do so for small span-wise segments of blade at a time - to get the twist right.

That might make more sense than starting with a solid primitive and successively removing complicated shapes to represent the faces and fillets.

[scorman]

Steven,

I think what you are asking about is what I figured out this afternoon.

In SW, there is a function called "loft".

I placed a 9 inch NACA4425 in one plane, created another parallel plane 48 inches away,

then planted a 3 inch NACA4415 tipped at 15 degrees and lined it up at the leading edge.

One click and it fills in the entire blended 3d surface from root to tip, twist and all.

I will post after I finish up the mounting stub ( with bolt holes !!) and/or tubular spar

Stew Corman from sunny Endicott

[JW]

I dont care what anyone says, Solidworks is worth every penny for the license, I have a commercial licence.

 I started out with AutoCad, and I think it totally sucks... As ive been using solidworks for 9 or so years, I can draw most anything. Everthing I know is self-tought.

 Boss,

 You are most likely using e-drawings, then taking snapshots of that. To make the blade profiles the solidworks program uses a 'draft' feature.

 Trust me, if the guy who's drawing for you, has any experience with solidworks, it'll take like 2 seconds to throw in some bolt-holes. Actually, to make a hub, and 120* bolt circle is really easy to do. Then the blades and hub could be mated in an assembly file in less than 30 minutes. I realise a 5 point hub bolt circle will be a bit mor complex, but any version after 2000 has the polygon feature.

The drawings are very nice by the way...

JW

[JW]

This is the funny thing about solidworks, there is like 3 different way to do just about anything. Im sure the loft feature would work just as well, as long as one can navigate the 3plane structure of solidworks, just about anything can be drawn, now, that being said, its still real easy to draw something that could be extra difficult to make, but would draw up just fine.

Most draftsmen dont actually get there hands dirty, so some translation is often necessary from a hands on guy. The first time i used the helix feature and drew a compression spring. I knew this is a great cad program. But drawing actual threaded hex bolts is not easy to do.

 If i was to attempt to import a drawing like this, into a cnc milling machine, id use a 3/8in ballmill on the spindle.

JW

[scorman]

JW,

" But drawing actual threaded hex bolts is not easy to do."

a while ago I spent time googling for a SW library of standard hardware such as bolts, uBolts, threaded rod, springs, etc ...couldn't find anything usefull ...I can't believe that every time someone else needs  3/8-18 3inch hex head bolt, they have to draw the damn thing from scratch ...I hate wasteing time "reinventing the wheel"

If anyone can contradict my above statement, I'd be very appreciative

Stew

[scorman]

This is what I have from today:

NACA4415 blade with flat foot ..tapered from 3inch to 9 inch x 48 inches long, twist from 6 to 20 degrees ..requires 1 3/4" thick stock

3 blade rotor assembly:

I have uploaded the eDrawings as well so if you download the free viewer, you can rotate, zoom, etc:

http://www.solidworks.com/pages/products/edrawings/viewer.html

here are the two above models:

http://www.otherpower.com/images/scimages/7526/NACA4415__foot.EPRT

http://www.otherpower.com/images/scimages/7526/turbine_4415_foot.EASM

Stew Corman from sunny Endicott

[JW]

Those are some sweet drawings, Stew.

 Its my opinion, that it would be more user friendly,(the blade design)if the 'base' of each blade were mitered, to 60* included or 120* at the 'bolted end'.

 In that way, 3 blades would essentally mate together at the miter'd ends. Not unlike a frame-set. It would be really easy to balance the three blade assy/prop.

 I like what youve done, with the block type of end, for the base of each blade.

In most cases with the dual-rotor machines, its a 5 bolt pattern connecting the hub with the blades. Obviously with this,(five bolt pattern) one of the blades is going to have less reinforcement, in the way of bolt-holes, so a flange is needed to re inforce the assembly. Also, an easy way to locate the exact centre of the blade assy will be especialy easy with the points on the mitered ends.

 I feel in actual practice, with the dual rotor type machines, the bolt holes are the last thing to happen @mounting the blades. Usually the bolt holes are hand drilled at the time of fitting up, with the wood blades.

"a while ago I spent time googling for a SW library of standard hardware such as bolts, uBolts, threaded rod, springs, etc ...couldn't find anything usefull ...-Stew"

I ran into the same thing.

Cheers

JW

[MattM]

It looks nice.  You've obviously been practicing your cadd work.

The blades would probably not perform quite as well as you would hope.  You have a very limited pitch to the blades which is fine if the wind is blowing extremely hard and you want uber-speed.  Unfortunately you trade a lot of your mechanical advantage of the blade at low wind speeds for that high wind speed performance.  This is why the typical blade has twist, to take advantage of both ranges of wind speed.

I know that the typical blade is nearly zero pitch at the extreme and has most of the pitch at the inside of the blade.  But if one looks at it from a mechanical perspective you'd think the pitch would be best at the extremes and the least pitch at the interior.  The wind turbine is on the opposite spectrum from a powered propeller, therefore the design should be different.  In that way the wind would be using the blade as a long lever and need much less pressure to startup rotation and the thickest area of the wing would be prime real estate for the most extreme wind speeds.  Also the highest pressure would be at the hub and it would force air out to the extremes, keeping air attached to the blade which would help reduce noise.  Just thinking out loud here.

[scorman]

sorry for the bad links ...I had forgotten that this server doesn't like blanks in the title names

here are the two eDrawing files:

http://www.otherpower.com/images/scimages/7526/NACA4415foot.EPRT

http://www.otherpower.com/images/scimages/7526/turbine4415foot.EASM

Stew

[DanB]

Hi MattM!

Basically the drawings Brian created are just about exactly the blades the Scotty makes for us, and Scotty showed Brian (Boss) Kevin and Jessica how to carve them - then they made drawings.  I carve them slightly differently but this is very close.  It is a compromise between... easy to make - good performance - inexpensive materials (designed to be build from a 2x8)

'The blades would probably not perform quite as well as you would hope.'

I think they perform very well and they're very quiet.  

'  You have a very limited pitch to the blades which is fine if the wind is blowing extremely hard and you want uber-speed.'

Not really - they start in very low winds and run at TSR between about 8 (at startup) and 5 (at furl) - this depends on the alternator and the load.

'  Unfortunately you trade a lot of your mechanical advantage of the blade at low wind speeds for that high wind speed performance. '

No - we dont actually ;-)

 'This is why the typical blade has twist, to take advantage of both ranges of wind speed.'

No - that is not why typical wind turbine blades have twist...  the twist is to take best advantage of any wind speed.  Even if windspeed was always exactly the same  -  say 10mph with no variation 24/7 you would still want twist.  These blades actually do have twist, and when I carve them I'd do things slightly (only slightly) differently.  In practice though it makes little difference.  Lots of wind turbine blades make the compromise of having no twist to ease manufacture and the loss in power is small.

'I know that the typical blade is nearly zero pitch at the extreme and has most of the pitch at the inside of the blade.'

Yes - actually lots of blades (ones that run really fast) have negative pitch!

  'But if one looks at it from a mechanical perspective you'd think the pitch would be best at the extremes and the least pitch at the interior.'

I think you misunderstand how wind turbine blades work.

'  The wind turbine is on the opposite spectrum from a powered propeller, therefore the design should be different.  In that way the wind would be using the blade as a long lever and need much less pressure to startup rotation and the thickest area of the wing would be prime real estate for the most extreme wind speeds. '

Again - I think you have 'drag machines' stuck in  your head.  These are more like 'airplane wings' than 'airplane propellers)  I wont get into how wind turbine blades work and why here - there is a lot of good reading on that but you definitely have some misconceptions I think.  

There is good stuff on Hugh Piggotts website: scoraigwind.com

This is a cool site too: http://www.windpower.org/en/tour/wtrb/blades.htm

And there are lots of others...

[Boss]

"The consensus is in: No new oil fields of any significance have been discovered in ten years"

Absolutely FALSE.

back in 2004 we found more oil in the Gulf of Mexico.

"The discovery was made in the Walker Ridge area of the Gulf of Mexico, about 435 kilometres southwest of New Orleans and 280 kilometers off the Texas coast."

the findings increased the known reserves of world oil by approximately 30-40%.

Also, did you know that between the U.S. and Canada we have at least 2 trillion barrels of oil contained in tar and oil permeated sand? ..Wikipedia numbers..

U.S. EPA/DOE? numbers but that figure at 6 trillion back in 2006, i can't find the webpage right offhand.

It costs about $30 to extract one barrel of oil from approximately one ton of sand.

That number includes infrastructure costs for a reasonable payback time, the actual value is something like $6-9/ton.

The oil is there, peak oil is artificially caused by the government, and shares many reasons with the fact that we haven't built a refinery in the past 31 years. (or new roads, for that matter).

My grandfather was an offshore driller for 25 years, and Never found a dry spot, as long as you were 5 miles offshore, and drilled down below 5000 feet.

About %40 of the drilling was off the coast of Cali, but the rest was off the coast of Alaska, south America, Europe, and Washington state.

none of the oil fields mapped at the time (1960's-1980's) are in current use.

The State of Washington permanently denied drilling attempts for oil fields within their legal reach.

When "they" say the CO2 in the atmosphere was at one time 20 to 80%, where do you think all that went?  Ca(CO3)?

How much CaO2 or CaOH do you think the earth could really handle before it is so caustic that life could not exist prior to the CO2 leaving the atmosphere?

[Boss]

Whoops, I didn't mean to repost someone else's comments. Is there a way on this board to delete a comment?

[MattM]

You said, "the twist is to take best advantage of any wind speed."  It may be true in a literal sense it cannot be true in a perfect world.  You can only get optimal performance out of a very narrow scopes unless your blade is dynamic.  You are either going for performance in the middle or at an extreme, if not taking both extremes and giving up something in the middle.  But due to limitations of a fixed design there is no way to have it both ways.

I simply proposed aiming for low wing startup speed and using the thickest section of your blades for the real workload, whichever target that may be.  Your pitch might be matched to a 12 mph wind speed average.  Or it may be matched to 9 mph wind speed.  Or it may be matched to 20 mph wind speed.  But you definitely can only have it one way.  Since the average wind in most areas is more like 12 mph I'm suggesting that people would benefit by using more pitch at the wing tips to get rotation to begin at the lowest wind speeds.  During the low end of the wind speeds a moving blade is much quicker to get into cut-in speeds than one that sits idle, correct?  Of course it is.

I've read up on aerodynamics for the past thirty years and the concept of a wing and a wind turbine are not really related.  From what I've read on the internet on these hobbyist websites is more conjecture than science.

Lift according to your latter link is supposed to help move the blades along but this is contrary to the physics; your aircraft wing with that design uses lift from a vacuum which is not present in those conditions.  Their diagrams entirely ignore the fluid pressure on the side of the blade facing the wind.  The vacuums on the wing will be the blade tip, trailing edge, and underside; vacuum in this case is slowing the blade down not speeding it up.  The only time you would experience lift in the classical sense of a wing is when the airflow comes to a point where the rotational speed of the blade overcomes the effects of the wind's positive pressure.  Lift during acceleration of the blade will always be induced drag, which is not what you want in the case of a wind turbine.

I just would like to see more sound science being used today in these devices; the typical website supplies more garage science than anything remotely bleeding edge.  Look at Faraday's theory used to figure coils used stators; you have a very well defined formula for configuring coils yet people always end up guessing what should or should not work.  Not a problem since the formula is based on pretty tough metrics to gather for oneself.  In the end its more of a guess since the exact science is not perfectly figured out in each case.  In my opinion the current state of blade design is no better than the average attempt at coil design.  The theory is there, its just we are all too dumb to figure it all exactly out and can only rely on partial truth.

Quite frankly a partial truth is not the whole picture.  But as it is at this point in time, the first comment when someone offers theory contrary to popular conceptions is that the poster whom offered the contrary opinion "doesn't understand".  Its an argument at that point made purely based on fallacy.  I really wish people would avoid saying such utter rubbish.

[TomW]

MattM

Twist:

Think it out. The wind is the same but the linear speed of the prop changes at different points on the blade. This affects "apparent wind" direction, etc. essentially it takes a steeper pitch to screw the same distance into the wind in the center than the tips, as it were. Thus we use a twist that alters this factor.

Good luck getting it figured out.

TomW

[JW Peters]

Hello All; I can generate a DXF drawing that can be a starting point for a lot of you. It can be modified by most Cad programs. The drawing can be in several formats. Sections(3DLine),Wireframe(3DFace),Sections(Polyline),Mesh(Polyline). Just give me the Airfoil,Hub size,Target wind speed,Number of blades,Tip speed ratio, Outer diameter, Inner Diameter, Hub thickness,Hub Diameter,Angle of attack, number of sections in the length, and anything I missed and I will create the drawing for you that will have the proper twist and taper. The drawing will be similar to this. JP  http://www.otherpower.com/images/scimages/1803/finish100.dxf

[joestue]

Holy crap

[joestue]

and you didn't reply to either your post nor mine.

Oh God i love this board, btw was the debate over changing software primarily driven by these kind of issues? i didn't pay attention to any of it.

[TomW]

MattM;

I think you should tell us where your vast knowledge comes from? Books? TV? The Internet?

DanB has built and flown more turbines than most have even seen.

I suggest you back off a step or 5 and think how it looks when a user with an entire day [yes a whole day] of membership talks trash like you are talking to the founder of this excellent resource thats for builders not talkers. Equity counts here.

Ok now, put up or shut up, Bud.

TomW

[Boss]

Hi Mathias

I live in northern New Mexico

Recently I joined NMSEA and met a man named Eric Biderman who has an axial flux wind turbine who lives near Ribera. He mentioned that the guy from Blueenergy built and erected the turbine. Are you the person who he was speaking of?

[Boss]

Yes "loft" that's the function. I just asked Kevin. I will try and get him on here to post so this newbie won't keep mis-speaking terms.

Now as far as the bolt hole positions, isn't the exact position of the holes determined after the three props laid out and the hub plates overlaid?

 

[MattM]

I'm sure he can handle criticism.  He is an adult after all.  Nowhere did I label his theory or practice in an insultingly way.  I merely rebuked his argument that someone doesn't know because their opinion is different than his own.

Funny, I don't remember reading your resume on here.

[spinningmagnets]

I Googled "home made CNC" and got these:

http://www.oneoceankayaks.com/madvac/madvac_index.htm

http://www.brusselsprout.org/CNC/

http://www.hackaday.com/2006/07/12/how-to-build-your-own-cnc-mill/

http://www.stanford.edu/~hydrobay/lookat/big/cnc/xyz-03.jpg

http://hackedgadgets.com/2007/06/21/home-made-cnc-machine/

Looks like a fun winter "stuck inside" project.

BOSS, beautiful work! I'm not going to pretend I understand any part of this, but I know what I like when I see it.

I know I haven't made anything yet, and I am certainly not a trained engineer, but it is my understanding that stress hates a sharp inside angle. If the blade profile co-ordinates could be CNC'd, perhaps it would be useful for the area where the blade root meets the squared flange to be rounded and blended? Like a "C" instead of an "L".

MattM, the 10' wind-gen (5' blade) is a popular starter project, perhaps you could publish a drawing of your proposed blade cross-sections including width, curve, and angle, with one drawing each for the 0', 1', 2', 3', 4', and 5' positions (on a separate post, of course) This would allow every one to get a picture of what you are trying to reference. Testing should clarify that it is good at "X" and poor at "Y".

Until then, I'm afraid I will have to continue to be one of those cave-men who will stick with a known wind-gen blade type that provides well-known results.

"When cryptography is outlawed, only 47DE6FD will have 1D10E3A4D41E"

-Backyard Skunkworks @ 4hv.org