Classical US multibladed metal wind rotor....?

[topspeed]

Are there any left ?

[bigrockcandymountain]

Do you mean new ones being built or old ones still in use?

Aermotor still makes new ones last time I checked. 

The picture is a Baker Monitor WC that i use to pump water.  We still use a few around here.

[Bruce S]

Looks similar to the ones still sold in Mid-Missouri too , mostly are water pumpers .
Our Botanical gardens has one in the children's section as a water pumper too, but it's so low and covered by trees that it barely does anything.

Cheers
Bruce

[Adriaan Kragten]

Already in 1932, wind tunnel measurements have been performed in Göttingen on a scale model of a multibladed rotor with blades for which the chord increases at increasing radius. The measurements are given in the attachment. The angle beta is the yaw angle. The maximum Cp is only 0.3 at an optimum tip speed ratio of 0.9. So the maximum Cp is much lower than for a well designed HAWT with a design tip speed ratio of about 6 for which a maximum Cp of about 0.45 is possible. The main reasons for the rather low maximum Cp of a slow running multibladed rotor are wake rotation (see report KD 35 figure 4.2) and the fact that a rather large inner part of the rotor has no blades (see KD 35 formula 6.3).

 Rotor no 2, Göttinger Liefrungen 1932.pdf (146.43 kB - downloaded 43 times.)

[joestue]

and the fact that a rather large inner part of the rotor has no blades

could a nose cone improve that problem?

[Adriaan Kragten]

and the fact that a rather large inner part of the rotor has no blades

could a nose cone improve that problem?

Yes, a nose cone can improve that problem. However, making a large nose cone is a lot of work and I think that making the blades longer is cheaper. Blades for which the chord increases at increasing radius are designed in a time when the aerodynamic theory was not yet available. These rotors are used to drive a single acting piston pump which has a peak torque which is a factor pi higher than the avarage torque (see report KD 294). So you need a windmill rotor with a very high starting torque coefficient to get an acceptably low starting wind speed. One may have thought that this is obtained for tapered blades. In the measured curves you can see that Cq is maximal for lambda = 0 and that it has a value of about 0.48.

At Götingen one has also measured in 1932, a rotor with blades with a shape more according to the aerodynamic theory. I have added these measurements as an attachment. You can see that the maximum Cp is now about 0.36 at an optimum tip speed ratio of 1.1. The starting torque coefficient is now 0.6 at lambda = 0. Cq has a peak value of 0.62 at lambda = 0.2. So this rotor has a higher maximum Cp and a higher starting torque coefficient. I don't understand why at this moment there are still manufactures which supply water pumping windmills with blades for which the chord increases at increasing radius. Constant chord blades are much better for a low design tip speed ratio and easier to manufacture.

 Rotor no 5, Göttinger Lieferungen 1932.pdf (15.46 kB - downloaded 39 times.)

[MattM]

I've never seen a piston pump on one but did see a lot of lift pump versions.

[Bruce S]

MattM;
I think the term piston and lift pump are one and the same.
I've had old timers call pistons for years, while others call 'em lift.

Cheers
Bruce S

[Mary B]

I remember helping to pull the well rod and change the leathers on the cup on the lift pump at the farm, then reverse it and lower everything back down the well, put the well house roof back over it... major pain in the...

[Bruce S]

... major pain in the...

YUP!
That and the water always ICE cold  .
Nice in the hot summers before A/C but , maintenance during the winter was not my cup-o-tea

[kitestrings]

Great picture.

I never worked on these.  Maybe they were a pain, but they remind me of an era when things were built to last, and could be repaired; not discarded.  I like old things, but I particularly like old things that still work (hopefully I'm in that group too).

We have a Myers piston pump that a local Plumbing & Htg crew tore out of a camp we were working on - I think I was maybe 20-yo - I picked it out of the trash pile, put a set of leathers in it.  The familiar clickety-clack has been music to my ears ever since.

[Bruce S]

Great PIC! AND even better pick up!

Many an old washing machine's pump has been "salvaged" back home to act as short-term pump,even though you had to prime them first.

Bruce S

[mab]

Great picture.

I never worked on these.  Maybe they were a pain, but they remind me of an era when things were built to last, and could be repaired; not discarded.  I like old things, but I particularly like old things that still work (hopefully I'm in that group too).
...

I'm with you on that it amazes me what some folks will throw away.

I found this factory slave clock on the scrap metal pile at a place i was working; no idea what became of the master clock, but i built a small circuit to pulse its solenoid every 30 seconds and it's worked ever since.

The face is cast iron, about 3 foot across, the numbers and the hands are aluminium

[topspeed]

(Attachment Link)

Do you mean new ones being built or old ones still in use?

Aermotor still makes new ones last time I checked. 

The picture is a Baker Monitor WC that i use to pump water.  We still use a few around here.

Thank you...cool 15 blader.

[SparWeb]

There are a couple in the area where I live (outside Calgary Canada).
They used to be much more common.  Electric pumping is so much more convenient they are only used now in places where electricity is expensive to access.  Of course, the popularity of solar panels has made them a choice for "on opportunity" water pumping, too.

[JW]

 What I got out of this,  is the one who suggested a nose cone (center)

[topspeed]

What I got out of this,  is the one who suggested a nose cone (center)

It seems to be also more efficient than similar propeller types in same size.....30%. It can be recycled unlike the huge HAWTs.

[MattM]

One thing about these windmills is their minimalist approach.

Even the tower has minimal material to get pushed around in the wind.

[topspeed]

One thing about these windmills is their minimalist approach.

Even the tower has minimal material to get pushed around in the wind.

I agree...metal is in good use.

[Mary B]

One thing about these windmills is their minimalist approach.

Even the tower has minimal material to get pushed around in the wind.

The 4 legged angle iron tower actually has more wind resistance than the tubular towers used by the big wind turbines! The tubular towers split the wind instead of catching it...

[bigrockcandymountain]

I think mostly these mills were designed to be hauled back to the farm with a horse drawn wagon and then assembled by hand with no additional lifting apparatus etc.  That is part of the reason for the angle iron tower.  It collapses nicely for shipping, and then is light enough to erect by hand with minimal tools. 

They really are a wonderful design.  I can't say enough good things about them. They still have a very practical value for us pumping water for cattle.  Probably more so the farther backwoods /less developed the area.  Almost anything that goes wrong can be easily repaired with nothing more than some brazing rod.  I estimate the ones we use to be close to 80 years old, and out in the weather their whole life. 

[Mary B]

I think mostly these mills were designed to be hauled back to the farm with a horse drawn wagon and then assembled by hand with no additional lifting apparatus etc.  That is part of the reason for the angle iron tower.  It collapses nicely for shipping, and then is light enough to erect by hand with minimal tools. 

They really are a wonderful design.  I can't say enough good things about them. They still have a very practical value for us pumping water for cattle.  Probably more so the farther backwoods /less developed the area.  Almost anything that goes wrong can be easily repaired with nothing more than some brazing rod.  I estimate the ones we use to be close to 80 years old, and out in the weather their whole life.

Since my county added a no wind turbine in town ordinance  I have been looking at the small pond aerator versions of these, but instead of driving a water pump drive a small generator... hey it is yard art! Would let me sidestep the idiots who signed onto the dumb USA country org garbage

[Adriaan Kragten]

I think mostly these mills were designed to be hauled back to the farm with a horse drawn wagon and then assembled by hand with no additional lifting apparatus etc.  That is part of the reason for the angle iron tower.  It collapses nicely for shipping, and then is light enough to erect by hand with minimal tools. 

These type of windmills have a rotor which is much heavier than the 3-bladed rotor of an electricity generating wind turbine with the same rotor diameter. The rotor is heavy because of the many steel blades and the supporting structure. The head is heavy because of the cast iron reducing gear box and the crank mechanism. These type of windmills make use of a 4-legs angle iron tower with a wide base because the tower must be placed over a well with mostly a rather large diameter.

So these towers have a large base and therefore a high natural frequency. The maximum rotational speed of the rotor is low because of the low tip speed ratio and the used safety system. The rotational speed in rev. per second is therefore always lower than the natural frequency of the tower. For fast running rotors of electricity generating windmills, one often uses a slender tower with a low natural frequency and this frequency is passed by the rotor at already a low wind speed for which there is only a little vibrational energy in the rotor. So fast running rotors normally turn at a rotational speed much higher than the natural frequency of the tower. It is no good idea to use the wide base tower of a traditional water pumping windmill for a fast running rotor because then the rotational speed of the rotor in rev. per second can become the same as the natural frequency of the tower in Hz for high wind speeds and this will result in strong vibrations of the tower. The rotor will always have some mass imbalance or some aerodynamical imbalance and this imbalance starts the vibration of the tower if both frequencies are the same.

[Bruce S]

BRCM;
What kind of height you have on the one in the pic? 15M+?

I had to look a few times to make sure that was in fact a tire that was being used for a water trough


Bruce S

[bigrockcandymountain]

I think that one is 8 or 10m high.  It's very wide open country, so seems to work fine.  I also use the tower with a rope pulley at the top to pull up the pump when it needs leathers.  The pump is only down 4m / 12' or so, so it's an easy job. 

Adriaan is right saying that the towers also had to straddle a large diameter well in lots of cases.  That one is a 30" casing. 

I actually put this mill up when I was a teenager.  The old well caved in, so we had a new one bored about 20' away, and moved the windmill over.  While the mill was down, i went through it and painted the cast parts.  That's why it still has red paint.  That was probably close to 20 years ago now. 

Yes, that is a big earthmover tire.  They are free and should last 100 years or so.  Cows aren't exactly gentle creatures when they all get to the trough at the same time.  It takes a beating.  It's a difficult job to cut out the sidewall.  A reciprocating saw and lots of soapy cooling water.  The other sidewall stays, and the rim hole gets filled with concrete.  I think it holds about 2500L Maybe 3000L of water. 

I guess i should also mention the solar panels.  2x 240w i think.  They run a solar submersible pump.  The solar pump only runs when it is sunny.  No batteries.  Between that and the windmill, there is always water. 

[mbouwer]

In the eighties I made a multi bladed mill with a downward drive and there a transmission drove a dynamo.

[mbouwer]

The steering was by the servo-rotors that turned away by a maximum of 90 degrees when the voltage of the car alternator in the bottom of the mast became too high.

[topspeed]

One displayed on this music video.

[topspeed]

(Attachment Link)

In the eighties I made a multi bladed mill with a downward drive and there a transmission drove a dynamo.

Awesome where is this ?

[MattM]

Primitive central American versions

[topspeed]

Explained: https://www.youtube.com/watch?v=BugXmDxC0WM

[Adriaan Kragten]

I have watched the video of Topspeed. It is a nice explanation of how such a windmill works. However, there is one substantial mistake. It is said that the vane is in parallel to the wind if the rotor turns out op the wind but this isn't correct. As the rotor has a certain eccentricity e and as the rotor has a certain thrust Ft, the rotor moment Mr = Ft * e. This rotor moment must be in balance with the vane moment Mv around the tower axis. The vane moment is the product of the force on the vane blade Fv and the vane radius rv at the aeodynamic centre of the vane blade. So Mv = Fv * rv. Fv is about linear to the angle of attack alfa in between the vane blade and the wind direction. You only get a certain Fv if the vane blade makes a certain angle alfa with the wind direction. So the vane blade is never in parallel to the wind direction for stationairy conditions. The angle alfa depends on the vane geometry and the wind speed. The higher the wind speed, the smaller the angle. The vane moment due to the aerodynamic force on the vane blade around the vane axis must also be in balance with the spring moment Ms around the vane axis.

This safety system is called the ecliptic safety system and more information about it is given in my public report KD 409. I have used a torsion spring around the vane axis because the spring moment of a torsion spring increases only a little for an increasing angle of rotation around the vane axis. The moment of a tension spring varies a lot because the distance of the heart of the spring and the heart of the vane axis is very dependent of the angle of rotation of the vane arm. I have chosen that the tower axis coincides with the vane axis because this simplifies the moment equations a lot.

[topspeed]

I have watched the video of Topspeed. It is a nice explanation of how such a windmill works. However, there is one substantial mistake. It is said that the vane is in parallel to the wind if the rotor turns out op the wind but this isn't correct. As the rotor has a certain eccentricity e and as the rotor has a certain thrust Ft, the rotor moment Mr = Ft * e. This rotor moment must be in balance with the vane moment Mv around the tower axis. The vane moment is the product of the force on the vane blade Fv and the vane radius rv at the aeodynamic centre of the vane blade. So Mv = Fv * rv. Fv is about linear to the angle of attack alfa in between the vane blade and the wind direction. You only get a certain Fv if the vane blade makes a certain angle alfa with the wind direction. So the vane blade is never in parallel to the wind direction for stationairy conditions. The angle alfa depends on the vane geometry and the wind speed. The higher the wind speed, the smaller the angle. The vane moment due to the aerodynamic force on the vane blade around the vane axis must also be in balance with the spring moment Ms around the vane axis.

This safety system is called the ecliptic safety system and more information about it is given in my public report KD 409. I have used a torsion spring around the vane axis because the spring moment of a torsion spring increases only a little for an increasing angle of rotation around the vane axis. The moment of a tension spring varies a lot because the distance of the heart of the spring and the heart of the vane axis is very dependent of the angle of rotation of the vane arm. I have chosen that the tower axis coincides with the vane axis because this simplifies the moment equations a lot.

Yes thanks Adriaan...it will be slightly at an angle...the tail vane. It cannot produce a force needed without it being slightly...like an aeroplane rudder... forced to right...if looked at against wind direction.