Interview with mr. Jacobs

[dinges]

A friend of mine (who wishes to remain anonymous as he doesn't want to be seen in public associating with me) sent me this link. It's a 1973 interview with mr. Jacobs, one of the men behind the famous Jacobs turbines that electrified farmers in rural America from the '30s to the '50s. I've read it with much pleasure:

http://www.motherearthnews.com/UnCategorized/1973-11-01/The-Plowboy-Interview.aspx

My favourite line: "Oh sure, I'm kind of freak, see. I want things to work forever. I built my plants to last a lifetime."

As a side note: does anyone have good, detailed pictures of Jacobs turbines that show the varipitch mechanism, or knows where to find these online ? I'd be very interested in them yet can't find them online. Or if someone has a Jacobs they're restoring to old condition and could make a few detailed, close-up pictures that would be great.

[luckeydog]

the Jacobs machine was a truly great machine.

there is a member on my website who has a Jacobs machine

who has a great deal of info on this machine.

he is a real neat Guy who loves to talk wind power.

he goes by the user FoxTrot70

you can follow some of his post here http://www.coloradowindpower.com/e107_plugins/forum/forum_viewtopic.php?32

[electrondady1]

thanks for the link.

this jacobs fellow , what a great man

[richhagen]

Peter, I read the whole interview, interesting, trial and error with a little science mixed in it sounds like.  Fascinating results.  My school days are behind me, but I suspect if I had to write a biography, Mr. Jacobs would make an interesting subject.  Rich

[jmk]

 I really enjoyed reading that post. It helps to understand more about wind plants. I wish I could help him put his plant up he bought in New Mexico. I bet his stash of goodies would be of great fun to use. My neighbor has one that quit running after twenty some years. I wonder if he just needs brushes or points in to get it back up running again. I wonder how hard they are to change? I also wonder what he made his seals out of that made them last so long. It's to bad he doesn't get on this site to help with designs. Someone should be making his machines. They do work great!

[vawtman]

Nice posting Peter.

[bob golding]

thanks for that. he was a true visionary  will have to investigate his blade designs further.

cheers

bob golding

[dinges]

Glad to hear you enjoyed the interview too.

JMK, the interview was taken in 1973. By then mr. Jacobs was already 70 years old. If he were alive today (I don't know if he is) he'd be 104 years old now.

Luckeydog, thanks for the info. I'll be contacting FoxTrot70 soon.

Here's another interview, this time with someone from NASA, doing a major windturbine project in the mid '70s. It is in stark contrast with the work of Jacobs. It's not an enjoyable read, but it is illustrative...

http://www.motherearthnews.com/Alternative-Energy/1976-05-01/The-Plowboy-Interview-Donald-Cooksey.as
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I tried looking up the final report of that NASA windturbine but couldn't find it. Actually, I found it, but it's not available on-line. Unlike Sandia the NASA charges $$ to get a chance to read the report:

http://ntrs.nasa.gov/search.jsp?R=306903&id=3&qs=N%3D4294877489

The link to the 2nd interview was also given by the same person who wished to remain anonymous. Besides, RonB would kick my @ss if I outed him in public.

[RobC]

Jacobs pitch control pics. http://www.baywinds.com/new/Governor%20&%20Blade%20Installation.htm

[Ungrounded Lightning Rod]

The Jacobs interview just gave me an idea...

If I read it right his system uses a ring/pinion gear combo - like the automotive differential he used in his kid-on-farm design - to send the power toward the ground as shaft rotation.  And he does his furling by a flyball/spring governor controlling blade pitch, allowing him to use a fixed tail (except for "shutdown furling").  Differentials are easy to convert but the governor would be a pain.

I'd thought of using a differential like this previously, but had dismissed the idea because the torque on the drive shaft would tend to turn the blades away from the wind.  But the fact that he made it work got me thinking again:

 - With enough of a ratio the torque would be small.

 - The gear ratio also improves things for the generator.  B-)

 - The tilted-tail-pivot furling system requres a nontrivial yawing torque to operate.

So it seems to me a simple homebrew mill could be built by using an automotive differential with a yaw pivot concentric with the drive shaft and a furling tail.  This would put the genny on the ground where it's easy to work on and eliminate slip-rings or twisting cables, allowing long-term unattended operation.

[neilho]

Quote: So it seems to me a simple homebrew mill could be built by using an automotive differential with a yaw pivot concentric with the drive shaft and a furling tail.  This would put the genny on the ground where it's easy to work on and eliminate slip-rings or twisting cables, allowing long-term unattended operation: unquote

Seems possible- the differential idea has been tried. One problem with the automotive differential is that the output shaft faces down and the pinion seal, not designed for submersion, leaks gear oil. In the Jacobs design, the hi-speed gear engages the lowspeed gear at the top and the hispeed seal is located above the lube level so is sealing only against lube splash. IIRC, the rotor shaft is also offset slightly from the centerline of the yaw pivot/output shaft (I think to compensate for rotor torque) and the rotor shaft is tilted up slightly to get the center of the rotor close to the tower, shed some gust loads and maintain blade to tower clearance. The resulting gearbox is easy enough to design and make in an OEM situation, but almost impossible to adapt from a standard auto differential. It might be possible to buy a Jacobs gearbox  cheaply, though. There were several hundred installed in So. California in the '80s but had reliability problems and were undersized for a windfarm situation so were taken down.  

 Seems to me a driveshaft running the length of the tower is going to have more frequent maintenance problems than a twistcable or even sliprings. Imagine the length of the shaft needed and the number of bearings and bearing supports required to keep a (relatively) skinny shaft straight and free from resonance, then compare it to the simplicity of a nonmoving wire. For a machine that requires simple, simple, simple for longevity, a shaft running the full length of the tower seems like needless complication. I've heard some talk about the design, but never the results of, such an arrangement. I'd like to, though.....

neil

[Ungrounded Lightning Rod]

I agree with your point about the seals and geometry of the differential.

I don't agree with the one about the shaft.  It can be a hollow pipe (as drive shafts are), supported by the upper U joint at the base of the gearbox.  It should not require damping because its resonances will be far above the frequencies of any significant excitation.  In particular, it will be spinning far below even its lowest bending mode resonance, so it won't suffer from the resonance problem of high-speed turbines.

Long shafts in a lifting mode are not an issue for windmills:  They are how patent windmills have been getting the power down to the water pump since their original deployment.  Other than requiring static and dynamic balancing to avoid annoying vibration I don't see how spinning a pipe (below the first bending resonance) will be much different.

[RP]

I don't know...  I have this image in my mind of 40 feet of 1.5" pipe swinging around like a vertical jump rope.

[JF]

Dear Mr Dinges and other colleagues

In reply to where you can find usefull illustrations concerning the Jacobs wind turbine.

May I suggest the following titles from two wind energy "guru's" which can be obtained by the international inter-library service.

"The Homebuilt, Wind-Generated Electricity Handbook" by Michael A. Hackleman

Earthmind, Peace Press - ISBN 0-915238-05-5  - Lib. of Congress cat. nr. 75-36307

California USA 1975

This book is mainly concerned with the dis-assembly and the re-building of the

JACOBS and WINCHARGER 1930's small household-size wind turbines.

Alone Michael Hackleman's section on tower erection is more than worth a carefull study.

Likewise a good drawing and photograph of the JACOBS governing mechanism may be

found on page 136 of "Wind Power" by Paul Gipe - James and James - ISBN 1-902916-54-9

London UK 2004.

With greetings and best wishes to all friends and colleagues - JF

[Ungrounded Lightning Rod]

Which is what you get if it spins at the frequency of the lowest bending resonance.  Not for any lower spin rate (even for a piece of string...).

[neilho]

Thanks for the reply. Now I see the source of my misunderstanding. You're thinking low speed, I was thinking hi speed, still in Jacobs mode (about 1200 rpm at the alternator, IIRC). My mistake. Agreed that a hollow shaft would be stiffer.

 From this online calculator (http://www.wallaceracing.com/driveshaftspeed.php) a 1053 steel driveshaft 18" OD, .083" wall thickness, 500" long, would weigh about 650 lbs and have a critical speed of 484 rpm. So long as the mill doesn't run faster than about 450 rpm, it'd work.

Maybe there's something I'm missing here, but it looks as if an 18" diameter 40' long driveshaft, a 1:1 ratio gearbox, and a separate generator/alternator ground mount would be required to avoid using a twistcable. It's not a tradeoff that appeals to me.

But....here's an idea- a driveshaft that large could BE the tower. Support it with bearings at guywire connections and use the tail to keep the gearbox/rotor etc from spinning about the yaw axis. It could tilt down easily around the lower ujoint and the gin pole could be mounted at guy wire connections.....hmmm. Off we go, into the wild blue yonder:-)

[Ungrounded Lightning Rod]

...here's an idea- a driveshaft that large could BE the tower

Nice idea but you're supporting the tower weight on the U-joint bearings.  Let's think about that a bit.

 - Thrust bearing to support the weight near the bottom?

 - HAH!  Skip a U-joint at the bottom (and top).  Mount the genny assembly (including thrust bearing) with compliance in two dimensions and tilt the whole thing when you want to bring the mill down.

= = = =

I think I'd rather stick to using the shaft just for power.  You can suppress various oscillation modes by putting a bearing (mounted on some energy-absorbing material like rubber) somewhere near the velocity antinode.  One in the middle suppresses all the odd harmonics, one a quarter-way up strongly suppresses the second harmonic.  Hmmm...  Put one 3/8 down and one 1/4 up and you suppress 1, 2, (3), 4, ((5)), (((6))), (((7))) and 8 is the first completely undamped resonance.

(For your "shaft is the tower" config your guy-wire bearings would also perform this service, transferring the building oscillations into vibration of the guys.  You'd have to analyze the resonances of the guys to make sure they don't pump up.  And that's a bitch, because they're like guitar strings and the tension varies wildly with the wind loading.  B-(  )

Also:  Lightening the material (relative to the modulus) for a given cross-section geometry raises the resonance.  Would be interesting to see where the first critical frequency is for an 18" glued-up wooden tube.  B-)

[RP]

Ah, I see. You're talking about the bending resonance (I agree).  

I was thinking more of an imbalance / imperfection in the straightness of the pipe with centrifugal force making it worse at high speeds.

[scorman]

this had been part of another thread:

http://www.otherpower.com/images/scimages/284/jacobs10.jpg

Stew Corman from sunny Endicott

OT, I had thought that the Jacobs profile was flat on one side as in the USNPS4, but in a recent meeting with Jerry Ball in Belleville (Wellington?), Ontario this past weekend ...he showed me an example of a machine carved wooden "Jacobs" that he had manufactured (up to 28 ft long), that had a slight concave surface, not unlike the 18 ft GOE222 that Dave B has built ..any comments??

[dinges]

Thanks for the references.

Also, there are some good drawings and explanations to be found in the Jacobs patents; we uploaded a few to this IRC gallery:

http://www.anotherpower.com/gallery/Variable-Pitch

[SparWeb]

Peter,

Thank you for the fascinating interview.  Several quotes made me sit up straight:

"I developed a brush made up of a layer of graphite, then carbon, then graphite, then carbon."

"We licked that one by developing what we called our "reverse current relay". "

I'm currently sitting at my office desk with the electrical schematics of a 1950's helicopter spread out beside me.  I just realized that this helicopter regulates its own engine-driven generator with field coils stimulated through a "reverse current relay", just as Jacobs describes.  

"The bearings themselves were pretty good, see, but the seals around the races would dry out and let the grease inside get away after a few years."

Another thing I've encountered in some helicopter components.  Sealed bearings AREN'T.  Some things never change....

"...it's not very smart to completely stop a windplant propeller. The ice mostly freezes on the lowest blade and that'll wreck your plant if you turn it loose. It's much better to let the propeller swing around a little bit during a winter storm."

Q: "What if an individual wants to go out and build his own windplant the way you put your first ones together...with materials he finds in junkyards and other odds and ends?"

JACOBS: Well I haven't been active in the field for 15 or 18 years now. There's a lot of new stuff I'm not familiar with...but I'd say that some of the AC generators and the rectifiers now available should make that pretty easy. "

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