jacobs turbines

[artv]

Hi all ,..Iv'e been searching, all I can seem to find is , people talking about fixing the tail and the the blade hub. Which by the way is a very inventive way to make the blades.The only thing I don't understand is if you twist the blades out of the wind , when it overspeeds, why do you need furling???...Will the turning of the blades not slow it down??..........Also is the generator just a motor conversion or was it specifically designed for this purpose, and are there any ,designs ,drawings or specs??.........thanks ..artv

[bj]

   Search for Tom Sullivan,  as he did a restore on one, and posted on the progress.  Also, there was a link to drawings somewhere in the
thread.
   Good luck, it is an excellent read.

[Flux]

I assume you are talking about the last big machine with the alternator,

The original Jacobs machines used dynamos ( dc generators) and relied entirely on pitch control. I believe the last machine did use some form of furling to control things beyond the range of the pitch governor. With very large rotors if you pitch to feather you need to twist the blades through a very large angle to limit the speed in very high winds. it may be that just adapting the original method didn't work when extended to much larger rotors.

Again I don't know a lot about that last machine, I am sure others will set you right on that, but it is very unlikely to be a motor conversion. As far as I know it is a standard alternator. They built the original dynamos in house in the peak period of the company but when they came back to have another go I think they bought the alternator in and I doubt that it is permanent magnet so why convert a motor.

Flux

[Steve Trumann]

All of the Jacobs machines used furling. The older Jacobs, DC machines were deigned for max 200 rpm. Special generators were built for those machines. His blade and pitch design allowed for more power at low rpm. So when the wind picks up, your blades pitch to more inefficient, add furling to take it more out of the wind. This is all done to keep it from overspeeding and tearing itself apart.
The newer machines are 3 phase A/C. A smaller motor with capacitors supply the juice to a bigger motor which is a standard 3 phase motor which then becomes your A/C generator.
I really don't know where you are going with your questions. But hope this answers some of them.
Steve Trumann

[artv]

Hi thanks for the replies. Basically I was mainly searching for stator designs ,since this machine is from an era that predates neo magnets.In a couple of the searches they linked stator design, but they weren't very infiormative.     Steven ,from what I read it said that these machines could produce up to 1200-1800 watts?? You say these were made to run at 200rpm ,surely they didn't make this much power at this low of rpm,or did they??..........I'll continue the search,the old stuff always seems so much more durable and dependable ,than the new.When it's -30 nobodys vehicles will start ,my old case fires up 3rd crank(hand crank) everytime........gotta love that old stuff..........artv

[Flux]

If you are looking at the earlier designs then they used dynamos ( dc generators with commutators). Don't get yourself too confused about this, the stator in this case is actually the field system. The current is generated in a rotating armature as ac but it is rectified by a commutator and brush gear.

You are right that 1800W at 200 rpm was a considerable challenge in that period and the Jacobs dynamo was large and cleverly designed. A lot of effort went into matching the generator to the blades and that is one of the reasons why Jacobs were ahead of the competition.

Just changing wound magnets for neo is not as straightforward as is generally imagined. Invariably yo can gain in low winds as you no longer have to supply the field current, but unless you look after all the other considerations that Jacobs sorted you don't necessarily end up with a better solution. Wound field machines are rather more flexible in the way they can be loaded.

Flux

[B529]

Hi all ,..Iv'e been searching, all I can seem to find is , people talking about fixing the tail and the the blade hub. Which by the way is a very inventive way to make the blades.The only thing I don't understand is if you twist the blades out of the wind , when it overspeeds, why do you need furling???...Will the turning of the blades not slow it down??..........Also is the generator just a motor conversion or was it specifically designed for this purpose, and are there any ,designs ,drawings or specs??.........thanks ..artv

The furling on the DC machines was use to turn the machine out of the wind for service/problems. Pitching blades controls RPM. For the record the RPM's are closer to 300+. I flew a DC Jacobs for awhile and rebuilt a few. Excellent heavy weight slow turning machines.

[ChrisOlson]

Hi all ,..Iv'e been searching, all I can seem to find is , people talking about fixing the tail and the the blade hub. Which by the way is a very inventive way to make the blades.The only thing I don't understand is if you twist the blades out of the wind , when it overspeeds, why do you need furling???..

My 23-10 Jake has a Fidelity generator and the power output is controlled by the inverter, which controls the field in the generator.  That generator is a 12 lead three-phase with outbound exciter, rated at 20 kva, and the field is 60 ohm 2 amp DC, but de-rated with 23 foot blades on the 23-10 to 10 kW.  The speed of the rotor is controlled by the governor, and unloaded it will run up against the governor @ 15-18 mph wind speed.  Loaded, it starts feathering the blades at around 25 mph.

The furling is used for high wind speeds - the pitch control governor can only limit rotor speed to 195 rpm up to maybe 35-36 mph and then the thrust on the rotor overcomes torque on the gearbox and turns it to the side of the tower.  The blades pitch 60 degrees but in really high winds that still doesn't keep the rotor speed below 195.

The Jake is a bit different because it doesn't have a cut-out like a Bergey.  It stays generating power at 70-90 mph wind speed with the blades feathered and the rotor turned to the side.  The downside to the Jake is its inverter - they'll blow the inverter at continuous high outputs.  WTIC (bought the manufacturing rights to the Jake turbines in 1986) has a new UL1701 inverter and choke available for them now that's more robust than than the old UL508's.
--
Chris

[WindriderNM]

I had the opportunity to get an old Jacobs several years ago but passed it up. I would have had to get it off the tower and across a small steep canyon. It was also about 100 miles away and the blades had rotted away.

[ChrisOlson]

I had the opportunity to get an old Jacobs several years ago but passed it up. I would have had to get it off the tower and across a small steep canyon. It was also about 100 miles away and the blades had rotted away.

The old DC machines are usually not worth more than it takes to get them off their tower and rebuild them, because the cost is prohibitive in most cases after rewinding the generator for 48 volt, etc..  The newer grid intertie machines that are sitting on towers inoperative because of lack of blades are worth some money.  But they usually require a crane to get them down and you'll have $10,000 just in the rotor upgrading the old 1-1/4" governor to the new 1-3/4" and putting new glass blades on.

And then those old machines need several other upgrades - the snap ring on the mainshaft in the gearbox folds over and you need to machine that 4140 CRM shaft for double snap rings to retain the ring gear.  The truck u-joint that drives the generator shaft hammers out - never seen one last more than three years - and you have to replace that with a big LoveJoy with a hard rubber spider.  And then the brake on those old machines was just thin steel and that should be replaced with the new cast brake rotor and heavy duty caliper.

And none of the above covers the fact that the inverter is more than likely dead on these machines that you find sitting idle.

By the time you get done rebuilding a grid intertie Jake that you find someplace inoperative because of missing blades, you'll have $20 Grand in it by the time you get it flying again, if you do all the latest upgrades to it.  Even if you have a good 1-1/4" governor that isn't broke (which is highly unlikely) you'll spend $5,500 on a used set of spruce blades that are still good.  You'll find somebody that says they got a "good" set of blades, but when you did into them with a jackknife they're rotten.  And if you put them on they'll flex and hit the tower in the first thunderstorm and blow all the blades off it and wreck your governor.  Don't ask me how I know.
--
Chris

[B529]

Hi all ,..Iv'e been searching, all I can seem to find is , people talking about fixing the tail and the the blade hub. Which by the way is a very inventive way to make the blades.The only thing I don't understand is if you twist the blades out of the wind , when it overspeeds, why do you need furling???..

My 23-10 Jake has a Fidelity generator and the power output is controlled by the inverter, which controls the field in the generator.  That generator is a 12 lead three-phase with outbound exciter, rated at 20 kva, and the field is 60 ohm 2 amp DC, but de-rated with 23 foot blades on the 23-10 to 10 kW.  The speed of the rotor is controlled by the governor, and unloaded it will run up against the governor @ 15-18 mph wind speed.  Loaded, it starts feathering the blades at around 25 mph.

The furling is used for high wind speeds - the pitch control governor can only limit rotor speed to 195 rpm up to maybe 35-36 mph and then the thrust on the rotor overcomes torque on the gearbox and turns it to the side of the tower.  The blades pitch 60 degrees but in really high winds that still doesn't keep the rotor speed below 195.

The Jake is a bit different because it doesn't have a cut-out like a Bergey.  It stays generating power at 70-90 mph wind speed with the blades feathered and the rotor turned to the side.  The downside to the Jake is its inverter - they'll blow the inverter at continuous high outputs.  WTIC (bought the manufacturing rights to the Jake turbines in 1986) has a new UL1701 inverter and choke available for them now that's more robust than than the old UL508's.
--
Chris

Chris,

how long have you been flying your 23-10?

I took down a beat up, neglected 23-10 a couple years ago for the tower. The governor shaft bearing was gone, have lots of parts I'll never use. If you need anything, let me know. I pulled the blade shafts out of the governor, working on machining smaller shafts and blade brackets plan on using the governor on a DC Jacobs.

A good friend here in Colorado rebuilt one a few years ago, he built a controller to go between the generator and 3 SMA Windy Boys, dubbed it the "Jacky Boy". The utility company would only allow a UL listed inverter to be grid-tied.

Kevin

[ChrisOlson]

I took down a beat up, neglected 23-10 a couple years ago for the tower. The governor shaft bearing was gone, have lots of parts I'll never use. If you need anything, let me know. I pulled the blade shafts out of the governor, working on machining smaller shafts and blade brackets plan on using the governor on a DC Jacobs.

Kevin,

Either PM me or send me an email on what parts you got from the governor that are good.  My blade brackets are busted, but that's pretty normal on the 1-1/4" governor.  I might need some other stuff too, depending on what you got.

Thanks
--
Chris

[kevbo]

The blades are twisted so they have the same effective pitch at the tip and near the root.

When you turn the blades enough to feather the tips, then the root is actually reverse pitched.  So part of the speed regulation is the tips fighting the roots.  and the roots are actually blowing air into the wind which creates a big vortex for the following blade. The hub only sees the net force, but the fighting forces are trying to bend the blades, and these forces keep increasing with wind speed even if the governor keeps the rotational speed within limits.  Further, this creates large drag forces which the bearings and tower have to withstand.   For these reasons you want to limit the pitch control to where only the root reaches zero angle of attack, but this limits the authority of the governor, so once you get to that point, the rotational speed starts increasing in proportion to wind speed. Once you max out the governor range though, you are making the most power possible, you might as well start yawing the thing out of the wind to limit the wear and tear.