Author Topic: Piggott Blades simplification possible?  (Read 38107 times)

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Menelaos

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Piggott Blades simplification possible?
« on: March 17, 2012, 05:27:15 AM »
Hi there, Hi Hough!

I have built many wind turbines so far but last week I visited "Fritzblitz" in Spain and we carved a set of rotor blades for a 2.4m machine. It was great fun and the blades turned out great :-)

Having them finished, I now wonder about some thinks and maybe some people here have already tried things in that fields or even Hough personally can tell me the reasons why he does thinks the way the are printed in the book.

So what did we do:

Forst we carved the windward side (Luvside) of the blades out of the blank peace of wood that we laminated togeter. Thats quite fast and easy. After that the thickness of the blades was marked on the leading and trailing edge. The blade was turned around so that the Lee-side was on top and again with a chiesel and later with a power plander the material was taken away. The next step would be to get everything to the right thickness in the 5 stations on that 1/3 line and when that works out, the shape of the profile towards leading and trailing edge is made...so far so goof and works out fine.

Now what I wonder about:

If I have a straight peace of wood with an even surface (which I can easily make with a power planer), why do I have to bother with the Lee-side so much? I could have all the 1/3 points on the same hight (level) directly on top of my plane peace of wood, only having to make the round shape on the leading edge and the "nearly straight line" towards the trailing edge.
Still this would not affect the angles on the profile on each station.

Of course, on the windward side, I would have to take off more material then  but that sould not be a problem, should it?

So what is the reason to take off material from that peace off woof from both sides at the thickest point of the airfoil instead of only one side?

My guess is, that the way it is done, allows more accuracy during the carving process...
My backround is different. As I am also one of the leading people of that german discussion bord with a small webshop, we were thinking about offering cheap wood blanks.

My idea was to keep the highest point (the 1/3 mark) of the airfoil on top of the even peace of wood (on the Lee-side) and have the windward side waterjet cut. Tins would end up in high accuracy and low costs. All people have to do the is the easiest part: carving down fron that highest point of the airfils towards leading and trailing edge and no more measurements would have to be taken- the thing would be basically fool proof.

I could also have it watercut the way Hugh does it aproaching from both sides but then the peace of wood would have to be turned around on the machine and more cuts would be needed which makes it more expensive....and what we want is a cheap way of doing it.

Or would there be any aerodynamic  disadvantages making it the way I suggested?

Would be nice to getting some help

Max

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #1 on: March 17, 2012, 05:44:39 AM »
höm...after reading my artice again I am not sure If I expressed myself understandable...

To make it more clearly again...what I suspect is:

The LUV side is made first up to a straight line on the leading edge beacause it is easy to rough it out by first makimng the orientation cuts with a saw and then roughing out with a chiesel or whatever power tool before planing it. I then have a straight reference area to mark out and cout down to the thickest point of the airfoil approaching from the Lee side... which is a lot easier that doing it the other way around as I would then have to watch two lines to keep level with.

If I can have the LUV-side waterjet cut with high accuracy, this would not be a problem anymore and the highest point of the airfoil that is on the Lee side can be on the same level throughout the whole profile and only the "roundings" towards the machine-precut leading and trailing edges would have to be made....

Am I confused or has it been done this way and works out without disadvantages other that accuracy problems when done without CNC technics?


Max

Flux

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Re: Piggott Blades simplification possible?
« Reply #2 on: March 17, 2012, 06:52:19 AM »
There are many ways of making a blade.  If you have a specific profile in mind then you need to keep the profile width thickness and shape at each station. It doesn't really matter if the leading edge is a straight line and you get the width of sections by curving the trailing edge or wether you keep things symmetrical about the centre line and end up with curved leading and trailing edges.

If you are going for a non specific hand carved profile then you have an almost infinite number of options.

There is some merit in having a thickness just sufficient at each point for the required strength, but it is easier just to fit the thickness on a straight line joining the full board thickness at the root to the chosen thickness at the tip.

Similarly you can make the width of each section correct at each station and end up with a highly curved trailing edge or curved leading and trailing edges. I find it works just as well to make a straight line joining the tip to the root again. This leaves the inner stations less than ideal width but it works as well and may be better unless you use mppt.

Similarly in the ideal world the front and back surfaces should follow a specific profile. Most people make the front face flat and that doesn't fit any known aerofoil that I have come across, but ClarkY and some of the NACA are nearly flat over most of the surface.  Having made an approximation on the front, you can again make approximations on the back and as long as you have a thick part about 1/3 the way back and a sharp trailing edge it will work. ( unless you have means of plotting power curves you will never know how good or how bad it is, but blade matching will make more difference)

The old Lucas Freelite blade was cut with a flat front face of constant pitch, a chord that was a straight line from tip to root and a back surface that was part of a circle and was undoubtedly cut on a spindle moulder. It was simple and cheap to mass produce and worked well enough, especially considering that it was a very fast blade and these tend to be more critical.

If you can find ways to simplify things to suit your construction methods it will be absolutely fine. If you want to get into high tech methods of production then I would have thought it would pay to start from a specific profile known to be good for wind power rather than go to lengths of automating the production of a non existant hand cut profile.

Flux

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #3 on: March 17, 2012, 08:18:16 AM »
Hi Flux,

That helps a lot...anyway I am not new on airfoils and I know that the one describes in Piggotts book is far away from optimum. If you have time, one can start with rounding both sides of the leading edge in order to reduce stall and carve a little sagging on the front side...but those are Thinks that take time...for a few % of efficiency and for most folks it would be easier to just make the prop a few centimeters lager to compensate for that.

Over there in the US, people carve blades like hell. Over here they are scared of doing that as they feel it might be to complicated...Germans are strange when it comes to precission. It has to be perfect, not just close and they feel they cannot do this by hand...so they do not give it a try at all...

I personally like building props from wood, it is relatively cheap and looks nice and if something breaks, it can easily be fixed with epoxy or you just carve a new blade an thats it.

We do offer Hughs book and had it translated into german by greenstep.

Fpr people that are scared of making laser parts just like magnet discs and welding parts like the chasis, we offer cheap parts for that and also for the blades we would like to give some help. We do not want to offer completed blades. People want to have the feeling that it was them having made the blades :-) We just want to give some help on the critical parts.

A simplification by having the highest points of the airfoils on the same level (but of course keeping the angles right) and precut the the front section of the blade with a cnc machine will help those guys a lot.

I aleays remember when I made my first set of blades. I had an experienced guy teaching me and giving hints, Fritzblitz. He is also a member of this discussion bord, living in the middle of nowhere in the mountains of spain. I am not sure it would have worked out that well without his help. Some thinks you can read again and again and I would not understand it until I did it.

Precutting the with waterjet and moving the highest points of the lee side to the same level already deterines all the measurements needed. All there is left to do is to go don from that highest point towards the trailing an leading edge without having to meassure anything anymore. Everybody should be able to get a straight line done on the trailing edge and round the leading edge according to the right airfoil shape.

I feel that if precut sets were offered, many more people would give it a try.

The pre machining must not have do be complicated! In this case we would laminate the wood and precut it to the desired shape, then have it waterjet cut which is only needed on one side so that it is not nessessary to turn the piece over during process. It then can be made on a cheap 2 Axis machine.

It needs one single cut for the drop section on the front side and then the cuts that give the shape of the profile when viewed from the top. This really goes fast and should not be too expensive but it saves a lot of time and helps unexperienced guys.

Do not get me wrong here, we are not a commercial site: kleinwindanlagen.de

We are a discussion bord like this one with some specials that cost a lot of money. We opended a web shop to support these costs and the money does not go into private pockets- we do it in our free time after working to help people with their constructions.

I am saying this becaus we do not feel that we will sell hundrets of sets of blades. I already thought about building one of those machines and I have finished the plans as well....

http://www.youtube.com/watch?v=LmtMQeoKCu8&feature=related

But I the realised that the efford is enormous and that there are easier ways...
I want people to have it easy finishing the blades with a minimum option of getting someting wrong but not to get a finished product.

I now have already build some blades and for really experienced people like Fritz who have built something like 50 Blades, it takes him about 6 hours to carve a complete set of 3 blades for a 10 feet turbine that then only needs paint to be finished. It would probably take me 2 days although I have experience...but it only takes me about halve an our per blade to do what is left after having it pre machined the way I suggested with a minimum risc left to fv(k it up ;-)

Thats how I approach it...

Max

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Re: Piggott Blades simplification possible?
« Reply #4 on: March 17, 2012, 09:45:26 AM »
I personally don't think it would matter at all, the thing to do would be to care a set that way and test them against a "normally" carved set.
Water jet wood carving is a new one on me I didn't know they did that.
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Flux

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Re: Piggott Blades simplification possible?
« Reply #5 on: March 17, 2012, 10:59:16 AM »
"Over there in the US, people carve blades like hell. Over here they are scared of doing that as they feel it might be to complicated...Germans are strange when it comes to precission. It has to be perfect, not just close and they feel they cannot do this by hand...so they do not give it a try at all..."

Max that is interesting. I suspect the same is true to some extent here in the uk ( except for the precision bit). I hadn't thought about it before but it is probably age related, I was brought up at a time when if you wanted something you had to make it, even if you could find a supplier you couldn't afford it. Now I think about ti I doubt that many younger people here would be prepared to have a go ( not without incentive from one of Hugh's courses anyway).  I made my first blades when about 12 and it didn't seem difficult then apart from the lack of physical strength as a small boy ( it taught me to sharpen dad's plane and spokeshave to make life easy and that is good advice to anyone, without sharp tools woodwork is a disaster).

I am sure you can devise a basic layout that can be done simply by machine and leave the finishing to be done to the standard that makes the owner happy. Too much perfection is a waste of time, I once sent instructions to a carpenter to make a replacement prop for a freelite. He did it and was delighted, some time later i got a chance to see it and it was dreadful ,especially for one trained to work in wood, but it worked and he was happy.  The main thing is to avoid complicated high lift profiles for hand construction, without precision they really are a lot worse than the basic Hugh style blades.

Flux

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #6 on: March 18, 2012, 02:38:26 AM »
Anyway, it might be a cheap or at least not extraordinary expensive way to simplify speed up the carving process. I will report on the results :-)

Max

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Re: Piggott Blades simplification possible?
« Reply #7 on: March 18, 2012, 04:05:27 AM »
I see a lot of woodworkers use wood router duplicators to make airplane props.

Lots of video's on youtube and mostly with homemade duplicators.

Ive never seen or heard of anyone using this method for windturbine blades.

Seems to me a good way to to get accurate repitition (even use a commercial blades to copy from).

Ive used Hughs way and i like it, but i would uses a router next time.

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #8 on: March 18, 2012, 05:24:37 AM »
For the last weeks I really wanted to build a machine like this and I already made the plans and research for cheap material...but still, to get a unit that does not cover the whole work shop and still can be disassembled...and then still has high accuracy I would probably have to spend something line 3000-4000& for a 2 Spindle machine. Well, money is not the problem here and I would have lots of fun building a device like that....

BUT on the other hand it is not really needed for wind turbine blades. Propeller pros are different in shape and construction and I would probably have to make hundrets of blade sets to cover the costs. Furthermore I have to watch the machine during operation and it is not really fast and also I still have to do some work afterwards. All in all this to me does not really seem effective.

One has to see what is most (cost-) effective for the purpose needed. By the time such a machine has roughed a single blade, I have probably also finished what is left to do on the waterjet precut blades and more or less sanding is still required with both versions.

The more simple carving duplicators are cheap to build and deliver good copies but they are dead slow.

For quite a long time I was running after high end airfoils and now returned to simple airfoils whicha re then made a little bigger in Diameter to compensate for what others get with more efficiency for the benefit of availability and costs

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Re: Piggott Blades simplification possible?
« Reply #9 on: March 18, 2012, 06:19:25 AM »
Hi Max.
5 years ago I made a router duplicator ,making blades.
It was made with a long bed with a sort of rail wagon and a pantograph mechanism on it.
On the right side a model blade (black).
On the left side a mill and a blank following  with a finger on the surface of the example model.
Unfortunatly I did not work it out further . To much leeway , slow procedure,
I think the pantograph must have made of metal. ( square tube )
Must work it out later .
Just an idea.
 - Frans -

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Re: Piggott Blades simplification possible?
« Reply #10 on: March 23, 2012, 09:09:17 PM »
Germans versus Americans?  I thought you were about to tell a joke!

I picked NACA airfoils for my blades, which have relatively flat bottom/front sides too.  NACA 3415 to be specific.  I got very very fancy with my carving process.  For those who would object to a complicated geometry like mine, there is a lot of benefit to your simplified approach.  I have seen blades made by carving only one side, then gluing wedges to the root faces, to give them the pitch angle they need to have a correct TSR.

No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

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Menelaos

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Re: Piggott Blades simplification possible?
« Reply #11 on: March 23, 2012, 11:03:39 PM »
There are many ways of doing it. Today I started cutting the wood for my 5m Machine, tomorrow I will glue them together...
I am not yet sure which way I will carve them, the Piggott style or the one I found on Dan Lenox page...
I like the easy way with 3 stations and the flat design that saves wood but I do not like the way the root is made for stability reasons and optics... so I will probably make a mix....
Anyway, this is not as much science as many people think. Near the root up to half way up the blade the desin and shape is not critical at all as hardly any power is produced there anyway. That leaves room for simplifications. Also Piggott found out about that. In his 2003 book the trailing edge was still curved to make a hard life for people with a power planer and belt sander ;-9
Now it is a straight line like in the "american" version.
I really tried to work out things until I got a headage and then remembered tose extrudes aluminium profiles that some guys at "the backshed" and also over here use....with constant cord and pitch- and they perform really well. The guys from that "royal blade fabrication" or whatever their name was again...also do it that way and thus make it really simple to carve...

So what is done in the books now is a straight trailling edge and it would probably also be ok to make a straight line from tip to root concerneing the thickness of the airfoil.

I have seen hundrets of different blade designs also on commercial turbines and the variaty is great...from that and also from my own experiences I concluded the following:

1. The width of the airfoil is not critical at any point. It should be less on the tip for various reasons, mostly for reducing weight to keep centrifugal forces low that pull on the root section in high winds. So a straight line from root to tip like it is done in booth books now is fine

2. The verry same thing applies to the thickness of the airfoil. Tkae a NACA 4412 for example and reduce the hight of the airfoil and you end up with a 4412 which is fine as well. So basically there is no need to make hundrets of staions in between root and tip like Piggott does. Also here a straight line indicating the thickness from root to tip would be absolutely fine...now the Dans have added a middle section...ok...why not...fair enough and helps not to get stuck with the power planer all the time when it comes to the next station where the "line of thickness" makes a downcurve again...

3. The only really important thing is to get the angles right on the side that faces the wind and again 3 stations is more than enough here as the inner half of the blade is not critical with the angles and also not really involved in power production.
and of course the tickest point of the airfoil should be somewhere at about 1/3 from the leading edge...

Doing it that way it will not be high tech but high efficiency of the working process ;-)

Any objections?

Max

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Re: Piggott Blades simplification possible?
« Reply #12 on: March 25, 2012, 02:39:23 PM »
I tend to agree with your simplification approach to carving. I do the same thing: carve a flat front face (windward side) without taking material off the windward-leading edge side from the root all the way to the tip.  Most of the material removed is from the back side. The cord width (at three stations) is cut with a jig saw before blades are carved and lines are drawn to allow you to carve to that profile. I have been doing 12' diameter bladesets lately and I stick with 4 degrees of pitch at the tip and carve as deep as the root will allow. Most lumber I have been using is 2"x 8" milled Doug Fir lumber and some clear cedar. The blades work fine, and are very quiet.  I have set up a jig to cut these with a router and that works really well. Most important is to allow the wood to acclimate to the environment before carving to avoid warping when a lot of material is removed. Leading edge is rounded with a power planer and the back of the airfoil is measured 1/3 cord width from leading edge and also rounded down to the trailing edge with a power planer.  They work fine, and I have seen no reason yet to make it more complicated than it needs to be...at least for the mean time.

RoyR
Have Fun!!!  RoyR KB2UHF

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Re: Piggott Blades simplification possible?
« Reply #13 on: March 25, 2012, 06:20:24 PM »
I think in #2 you meant to write something different, such as "4415... 4412" or thereabouts.  I get the point.
I would add that it is very important to make all of the blades in a set match in size, twist, and weight.  This could be more important than fidelity to any chosen airfoil or width measurement.  Consistency will drive you to make tools such as profile cards, to compare each blade against the same reference, and to work in stages.  I chose to complete only a few carving steps at a time on all 3 blades, before moving on to other refinements, to keep them as similar as possible.  Of course, automating or mechanizing the process will help a lot.

But now that's moving away from your goal of simplification.

To get the "angles right" on the incidence of the blade at the tip and root stations, you are forced to have a curve in the trailing edge.  If you want a straight trailing edge you must make a compromise.  It's probably not a major compromise.  Even the NREL published a test report (years ago) where their untwisted and twisted 12-meter blades seemed to perform equally well.

I am not convinced this is true, however there is some evidence that having a well-twisted blade will help overcome the starting torque of some generators or gearbox arrangements.  My twisted blades may do me a favour in this regard, because my generator is a motor-conversion, not an axial-flux design.  I think you said you are committed to building axial stators in the future, therefore the straight trailing edge will be okay, but remember that there are other generator designs that benefit from a different blade.

No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

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Menelaos

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Re: Piggott Blades simplification possible?
« Reply #14 on: March 25, 2012, 07:42:39 PM »
You are right, I meant 4412 and 4415...misspelled somehow without noticing...

Anyway, all of this stuff is not about havin it the cheapest and easiest way...

The cheapest and esiest way probably is to use those extrudes aluminium GOE 222 airfoils that we will also soon have in our shop. They are cheap, verry robust, weather proof, do not need maintenance or any treatment ans basicall last forever...and most important: they run great.

Those "simple extrudes profiles" are not that simple at all and have great advantages over "high performace blades" in the real world, especially if the location is not perfect and some turbulances can be expected. You have to understand why they are not that simple and why they perform so well...but thats another story...

The point is: making blades from wood is not done because it is cheap or easy but because you do it yourself. You start with some peace of wood and end up with something you have created yourself, thats the point. People like us do not want to buy stuff, the want to make it themselfes and be proud of it...

Thas some kind of philosophy...and for those that wish to do so but who are scared of not having the skills, those simplifications are a great way to go...and some would be happy to have pre-manufactured peaces that they only have to finish off...

That chainsaw method is a really good approach to that...but not everybody has the equipment for that so I like they way of simlifying it for those who have to do it manually...

I am exactly that kind of guy...
At the moment I am carving a 5m diameter prop from wood. And I do it the old fashioned way... I have those extruded aluminium blades in stock that I buy for 30 Bucks/meter and which will last longer and are cheaper and more robust...but I choose to make a wooden prop because I like making it although the timer I buy is more expensive that those finished blades...and many people feel they way I do about this...I believe...
Some guys live in remote areas and only have the cance to carve their own blades...and there are others that live in Berlin city but want to pretent living in a remote area and coose doing it the way they would do it if they were at a diffferent place...

This can be compared to those people that take part in survival courses althoug they have never seen a real forest in their live...just in case...

Sounds odd...? Maybe...but its not really far from reality...

Max
« Last Edit: March 25, 2012, 07:50:48 PM by Menelaos »

gizmo

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Re: Piggott Blades simplification possible?
« Reply #15 on: March 25, 2012, 09:27:55 PM »
I've used both the extruded blades and hand carved blades. I tend to agree, the extruded blades perform well and are easy to use, but timber does have some advantages. If you have the tools handy, like a chainsaw or electric plan, then you cant go past Oz's blade making technique, its cheap and works well, and scales up nicely. For blade lengths over 2 meters I would not use the extruded blades, unless its extended out from the hub. By that I mean, for a 5 meter turbine, use 2 meter blades on 500mm extenders.

I think way too much attention is paid to the root area of the blade. The inner 1/3 of the turbine provides less than 10% of the power, where the outer 1.3 provides over 50%. So when carving the inner 1/3, you may as well concentrate on making it strong instead of a nice airfoil. If your concerned about loosing that 10% of power, extend the blade out an inch and you have more than recovered any power lost in the root.

Also, there is very little twist in the outer 2/3 of the blade, and virtually none in the outer 1/3.

Glenn

« Last Edit: March 25, 2012, 09:30:31 PM by gizmo »

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #16 on: March 25, 2012, 09:40:13 PM »
you are absolutely right. Over here there is a guy working on the university in bremen. Dr. prof. Horst Crome who developed the "Kukate" wind turbine using the aluminium extrusions which is used in 3. wolrd countries ...hundrets of those were installed and keep surviving under all conditions... He uses "half bladers". The inner half of the prop is left without profile and only the outer half is used which generates 75 % of the total power. The none-existant twist is then not critical anymore and as you stated, making the blades a little longer will compensate for the inner half of the ptop anyway...but a lot more effective, also concerning torque. so for 3 4m turbine all you need is 3m of extrudes profile which is equal to about 100$. you the need the Hub and the metal pipes to put the airfol on but you end up with less the 200$....and they work great woth even high effiency...but to be honest...it lokks absolutely forbidden :-D  ...horribly ugly...as I think...but the need for energy compensates for that if really needed and not just wanted for the fun of it...

Max

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #17 on: April 01, 2012, 02:18:17 PM »
I once again want to get back to those simplification option...
The chain saw method is the right way for those who do more than only one set...and I might be wrong in some way that I do not see yet but I feel that one cut would be enough, why using two jigs...?

On Dan Lenox webpage I found those pictures that in a similar way are also in the Plans:




With the red lines he marked what was not clear to him in the beginning. Those red lines are congruent throughout the whole blade...

OK, what people do now is, cut the windward side and then use a band saw to make the Lee side....then on the Lee side round the leading edge and finish off the more or less straight side towards the trailling edge beginning at this  about 1/3 point...

The do it the same when they use the chain saw methos, do 2 cuts....

Now what if we arrage it this way as the following picture shows. Now the blue lines are congruent:



In that case, the second cut on the Lee-side is not needded anymore. and only trailling and leading edge have to be brought into shape. The windward side must be done anyway. Now it would be the windward side that is cut with the band saw to get the thickness on the leading edge end. Working from that line then will be the usual process for making the flat windward side.
In the Dan's Plans, there are inly 3 stations anyway, tip, root and middle. Of course this is simple but it works fine.
One more advantage of the solution I suggest: When only one side is cut away and the other side is nice and flat because it might be flattened with a stationary power planer, the tolerances are a lot less when trying to get the thickness right if the stations and lines between them are marked carefully. As the windward side is a flat surface, there is hardly any chance of not getting it right and equal on every blade. Then getting the hight of the airfoil right will occur automatically...and finally I also feel it is easier to work out the windward side as the whole blade can line up on an table or workbench as the untouched leeside is still flat and even which gives more stability and less error.

and for the chainsaw guys now only one single cut for the windward side is needed anyway which spares one jig...

What do I miss...?

Max
« Last Edit: April 01, 2012, 02:50:28 PM by Menelaos »

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Re: Piggott Blades simplification possible?
« Reply #18 on: April 01, 2012, 03:12:12 PM »
The twist, if the lee side is lying on a flat surface it won't lie flat because it twists, if you are making flat no twist blades I don't see a problem.
I aint skeerd of nuthin.......Holy Crap! What was that!!!!!
11 Miles east of Lake Michigan, Ottawa County, Robinson township, (home of the defacto residential wind ban) Michigan, USA.

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #19 on: April 01, 2012, 03:18:01 PM »
Maybe I am really confused and lacking imagination now but I don't get it...why shouldn't there be a twist anymore???

The absolute twist is on the windward side. I do not feel that anything changes concerning that, does it? The twist will be still there...


edit: hold on, I think you got me wrong. The lee side is of course not flat, you will still have to work out towards leading and trailing edge from the highest point of the airfoil...but before you do that, you will cut the windward side and as all the highest points of the airfoil are on the same level, the lee side will plan on the table BEFORE you go towards trailling and leading edge.

I sometimes have problems making myself clear in a foreign language... :-(

As pictures are multilingual, I prepared another one and moved the stations from the picture of my last post together...that should make it clear now....



So I feel that in general, this method will provide much higher accuracy whatever way (hand work or chainsaw or bandsaw) is used to get it done AND will save a lot of time...but angles will result the same...

I was about to make a CAD-drawing on that...but it is probably faster to just go to my workshop somewhen next week and make a blade sample and to take pictures of that ;-)

« Last Edit: April 01, 2012, 04:04:46 PM by Menelaos »

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Re: Piggott Blades simplification possible?
« Reply #20 on: April 01, 2012, 05:48:33 PM »
OK, I see it now and you are right, I think it's a good plan.
I aint skeerd of nuthin.......Holy Crap! What was that!!!!!
11 Miles east of Lake Michigan, Ottawa County, Robinson township, (home of the defacto residential wind ban) Michigan, USA.

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #21 on: April 01, 2012, 05:52:45 PM »
Ok, I am glad I didn't finally confuse myself ;-)

I am still wondering nobody came up with this before but someone has to be the first and maybe it can help others to get it done more easy and accurate. I will post pictures of how it turned out. Until then, comments are welcome... :-)

Max

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Re: Piggott Blades simplification possible?
« Reply #22 on: April 01, 2012, 06:09:53 PM »
Well it certainly would simplify the chainsaw method, you only need one jig.
I aint skeerd of nuthin.......Holy Crap! What was that!!!!!
11 Miles east of Lake Michigan, Ottawa County, Robinson township, (home of the defacto residential wind ban) Michigan, USA.

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #23 on: April 01, 2012, 06:14:01 PM »
Thats what I thought...so next tool I'm gonna buy will be a chainsaw ;-)
I doubt that my neighbours will be too happy about that :-D

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Re: Piggott Blades simplification possible?
« Reply #24 on: April 01, 2012, 06:23:15 PM »
They will get used to it. ;D
I aint skeerd of nuthin.......Holy Crap! What was that!!!!!
11 Miles east of Lake Michigan, Ottawa County, Robinson township, (home of the defacto residential wind ban) Michigan, USA.

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #25 on: April 02, 2012, 05:33:17 PM »
So today I did make 2 test blades using my new method. I did everythink with hand tools, except a power sander and the band saw for the rough part. It turned out really nice, the best blades I have ever made regarding accuracy. It just can't get wrong. I did it with 6 stations. After drawing all the lines in the beginning I didn't measure anything during the process until everything was finished. I was surprised when the thickness of the airfoil at the highest point on ALL stations turned out to be exactly what it was supposed to be, not a single milimeter off, thats great. It also looks nice. My digital camera broke so I will post pictures tomorrow when my friend is back home.

It really is a lot easier doing it "my" way...

Max

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Re: Piggott Blades simplification possible?
« Reply #26 on: April 02, 2012, 05:43:22 PM »
Mad Max's simplified blade carving method (MMSBCM) pat pending. :)
I aint skeerd of nuthin.......Holy Crap! What was that!!!!!
11 Miles east of Lake Michigan, Ottawa County, Robinson township, (home of the defacto residential wind ban) Michigan, USA.