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I thought of the PMR1C-14 regulator first, but then noticed that it doesn't have any over voltage protection. Thus I figured that this totally experimental endeavor needs all the protection it can get so that I don't burn out some expensive instruments or in your case radio. While $75 is more attractive than $180, in this case $180 may be less.
 
Stewart, we probably should have split this thread off into "experimental wind generator". But as Pete says, probably should have over voltage protection no matter what direction one goes.

pb
 
I inderstand what you're talking about. An old friend used a similar device on his no-electrics Luscombe until he opted for a small solar panel laid on the glare shield. An inexpensive solar charge controller should suit you well. It won't know what's making the power but will condition that power just the same. Size the controller to suit your wind generator's output.
 
If you use that dynamo, you'll need to use the Kubota reg with it. From what I've been able to find, it's an AC generator that will need the output rectified and regulated in order to be usefull.

Also, speed of the wind turbine should be of no concern (barring mechanical damage) as long as the voltage regulator is functional. It will limit voltage to the setting, no matter the speed of the turbine and current draw is limited to what is 'asked' for by the system with peak limit set by current sensor or by saturation of the windings.

Web

So far it is just an idea in my head. I do have a Kubota tractor with one of these and it is more than adequate in keeping the battery charged. And the current battery is at least 20 years old. My idea is to make a prop out of wood and bolt it to the flange on the pulley. Those two lugs provide plenty of materiel for some sort of attaching device for the plane.

This is one. http://www.worthingtonagparts.com/Kubota-Alternator-AEP-Dynamo-Assembly-NEW-WN-15531-64017
KUB-A1-TO.gif

This is the regulator. https://www.dbelectrical.com/produc...e=&network=g&gclid=CNj6i9XGv9MCFUhXDQodI8YClA I must admit that the wiring has me confused, even though I have the tractor manual. My thought is to perhaps use a B&C regulator in the airplane.
There is lots of information on line about this Kubota system.
 
Thanks Web,
The Kubota regulator wiring will take some research as there are six wires involved. Two from the dynamo, the other four need investigating. I'll have to dig into the Kubota manual. Is it safe to assume that voltage spikes and/or over voltage would/should not be a problem?
 
If it is rectified and regulated it should be smooth enough to not cause problems. A cheap and easy way to smooth it out further is to run the power through a filter designed for car stereos.

Web
 
I found this picture. I'm assuming the connections are:
Light circuit = not used unless to power an inop light. Or to ground the inop light?
Battery +(positive) ignition = ?? Perhaps not used in this application?
Battery +(positive) = Main Buss
Battery -(negative) = aircraft ground
2 Stator wires = dynamo connection
Should an on/off switch be in one of the stator wires? Or which wire?
apm6000-2__58672.1471293411.jpg
 
Without seeing the mfg's diagram, I'd say:
-Stator wires (2) to the dynamo
-Battery Positive to main buss, through breaker
-Battery Negative to airframe ground
-Ignition to the 'field' breaker, in series with one half of master switch
-Light, most likely grounds when system not charging

Anyone have a picture from a Kubota maintenance manual for verification?

Web
 
This is what I see from that diagram

-1.25Sb = dynamo stator
-WR = Battery charge light, goes positive when charge system is inop.
-1.25B = Ground
-R = Ignition switch (on/off), 'field' for us.
-1.25Sb = dynamo stator
1.25W = Battery (+), main bus for us.

Web
 
I'd do the math on how many RPM's that tractor alternator usually runs at, versus the prop speed you can expect. Not that I can.....but I've been around some home brewed small wind turbines, and it can be a long series of trial and error before finding the sweet spot. You may find you need a 2' dia. prop on the thing, or with a reasonable sized prop, cruise at 200 mph, or somewhere in between! The people making that store bought little wind generator earned whatever they are charging for it.
 
Here is a good diagram so you can understand what you're hooking up. The red wire is above D1 and D2 heading through fuse 3 and on to the batt. The curiously named AC terminal is just switched DC to the circuit, there is no field. This is an interesting method of regulation, its basically an unregulated alternator(no field) with a pair of SCR's (S1 and S2) to mimic the cut-in and cut-out functions of an old regulator. It just hammers the full wave rectifier (D1-D2) between fully on and off like a switching regulator, with very little heat buildup. It does make me worry about electrical noise. You may need to get a cap across the red and ground as close to the reg as possible or an inline inductor in the red wire, like in the car stereo kits.
 

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I'd do the math on how many RPM's that tractor alternator usually runs at, versus the prop speed you can expect. Not that I can.....but I've been around some home brewed small wind turbines, and it can be a long series of trial and error before finding the sweet spot. You may find you need a 2' dia. prop on the thing, or with a reasonable sized prop, cruise at 200 mph, or somewhere in between! The people making that store bought little wind generator earned whatever they are charging for it.
Yes that little wind generator is a nice unit. However it's output capacity of 4 amps is too low for my application. The Kubota manual does not give the dynamo capacity. Somewhere I've seen 8 amps listed with an alternate 15 amp capacity being available. I should go visit the Kubota dealer near here 15 minutes away and pick their brains.

I measured the tractor pulley diameters. Drive = 5.5" dia, Dynamo = 2.5" dia By my calculations this gives an approximate ratio of 2.2/1. My tractor generally runs at 1500-1800 rpm. When running the snow blower I push it up to 2200 rpm. So that gives a dynamo rpm of 3300-3960 up to 4840 rpm. The maximum rated rpm of the engine is 2500 which gives a maximum dynamo speed of 5500 rpm.

Should we design the prop to turn 5500 rpm at the Vne of the airplane and just accept whatever the rpm is at cruise speed? Or perhaps 20 or 30 mph below Vne since we seldom go to Vne? Perhaps Vne and accept the 80% efficiency factor to have it come out right?

5500 is a high rpm which indicates that a shorter prop diameter is desired. Long props generate more drag thus restricting their limit rpm. The high drag is related to the proximity of Mach 1 tip speeds where the drag curve spikes upward sharply. Short props require more blade area to develop the required amount of power Thus more blades. This explains the short multi-bladed prop on the Gennipod which appears to be made of molded plastic.

I see the prop design as being the most difficult portion of this project. At 5500 rpm an aluminum prop would be critical to fit, finish and balance in all blades. Any errors could mean a catastrophic failure. That is why I would prefer wood which can tolerate these issues. Plastics come in many different formulas and would be suitable however I consider that to be outside of my home building capabilities. Maybe Gennipod would sell their prop separately? Would it apply to this combination?
 
If it is rectified and regulated it should be smooth enough to not cause problems. A cheap and easy way to smooth it out further is to run the power through a filter designed for car stereos.

Web
Web,
Thanks for your help. Is the 10KuF, 40vdc capacitor which is shown in this schematic what you are referring to? Connected in the same manner?
http://www.bandc.aero/pdfs/504-500_REV_H.pdf

Prop Tip Speed
Generally the optimum maximum tip speed of a prop is about Mach 0.80. The following calculator gives a diameter of 37.5" which = Mach 0.80 at 5500 rpm. This is a larger diameter than I would have expected so that basically eliminates a Mach limitation from our prop since 37.5" is a lot more than I would like. This means that we can concentrate on the pitch and chord of the blades to achieve 5500 rpm. It appears that a two blade prop may be satisfactory. I had a T-craft with a 6 volt wind driven generator with a two bladed prop of maybe a foot or so in diameter, worked fine running a tube HF/LF radio and lights.

With this it looks as though a pitch of 40" will give 5500 rpm at 157 mph. Or 30" at 118 mph. This doesn't sound right, seems that it should be a higher pitch at the lower speed. Back to the drawing board.
http://www.warpdriveprops.com/propspd2.html

Some other links to assist in prop design:
http://www.culverprops.com/pitchselection.htm
http://n-lemma.com/indoorrc/propcalc.htm
http://www.propellersexplained.com/
 
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Thanks Glenn.

I didn't know you read this site.

I did called Earth X and they asked me to let them know if I found a good one. They didn't have a suggestion for me.

No charging system and with Li-Ion batteries causing problems in the Jets and it being charged only on the ground while not attended, I want to be sure I don't have a fire.

Stu
Stu,
Remember, the Earth X batteries are not the same Li-Ion that have issues with thermal runaways and spontaneous self-ignition. These are Li-Fe-Po batteries that have a very different chemical composition. The worst damage I've heard of them causing was a result of using the wrong battery (counter to their recommendations) and charging it completely inappropriately. Even then, it basically just melted into a slag-heap without catching fire. I think they are MUCH safer than the "traditional" (if you can call it that) Li-Ion batteries.
 
I use the combination of Powerfilm rollable 21 watt solar charger and the Moringstar controller to charge the Lithium Iron battery in my non electric PA-11 for my comm radio. I use it when I think I may need to top off the battery when I am out and about and parked. It worked fine for me to Oshkosh and back as well as in the Idaho backcountry.


21Yx7WNjCKL._AC_US160_.jpegr21a_106BF99625643.jpeg

http://www.powerfilmsolar.com/produ...duct&productID=271517&productCategoryIDs=6578
https://www.amazon.com/Morningstar-...225980&sr=8-7&keywords=morningstar+controller
 

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Web,
Thanks for your help. Is the 10KuF, 40vdc capacitor which is shown in this schematic what you are referring to? Connected in the same manner?
http://www.bandc.aero/pdfs/504-500_REV_H.pdf

Yes that cap is set up as a filter. If alternator noise is an on going issue I've had some luck with using a car stereo filter. They are much more sophisticated circuits whose sole purpose in life is to make DC current SMOOTH.

Web
 
Web,
Is there a particular car stereo filter which we should look for? Is it connected in series or parallel to what? Should it be soldered, crimped or plugged in or does it matter? Years ago the VP of an aviation radio manufacturer (EDO-air) told me to attach a disc cap across the points in the regulator on my 185 to eliminate noise. It has worked fine now for decades.
 
They are usually just a box with a circuit card inside. I've seen them with two, three, and four wires to connect. Just different styles. In a nutshell, they take vehicle DC power in, the internal circuitry smooths out any AC component to the current flow, and sends the DC to the stereo. No particular brand or model that I'd recommend of any others, just go to a car stereo place and see what they offer. Capacitors 'suck up' the peaks in the voltage and discharge them during the lows. Inductors (coils) work similarly but with current flow instead of voltage. The best filter assemblies use circuits made up of combinations of capacitors and inductors to eliminate any AC component of a power supply and output a steady current flow at a steady voltage. These filters are a science in themselves.

The caveat to this is that power supply filters only work to eliminate noise that is introduced through the power supply to the radio or intercom. Noise introduced from other sources, such as bundling a coax with audio wiring, will NOT be eliminated by these filters.

Web
 
Pete,

So I have this kubota dynamo in my hand. It is probably overkill in amp rating, and that could work for you or against you. It has an 18 amp output at 6000 rpm, and more importantly a 12A/2400 and 9A/2000 rpm. In speaking with the Gennipod guy, as you said of the biggest issues is finding a suitable prop due to the torque load. The torque required to start this spinning is large enough that it may not turn on the ground at all. Really surprised me how much is required to turn it by hand.

That said, a prop that is sized enough to provide the torque to spin it will probably be the one that just gets to 2000 rpm in cruise. It will be interesting to see. This would be the first aspect of the project to nail down, before even considering wiring it up.

One thing I just noticed is the paperwork shows an "alternator turn on speed of 2145 rpm" and a "Voltage set point" of 11.36. I'm sure someone can educate me on these, as I'm not sure how that relates to the dynamo instead of the regulator. You'll want it working under 2145 I expect.

pb
 
pb,

That sounds encouraging. We won't need to turn it as fast as we thought. I'm thinking that 8 amps would cover everything turned on including about 3 amps left over to maintain the charge in the battery. So if we can develop a prop to turn it at 23-2400 rpm at a high cruise, it should be enough. What do you figure your maximum amperage draw needs to be in your plane?

I once had a Stearman with a fertilizer spreader agitator powered by a four bladed wooden prop which was maybe a foot and a half in diameter. That airplane didn't go any faster than your Cub and there would have been a sizable load on the prop.

Do you have a drill press which you could spin the dynamo with as a test rig? This would give you an idea of what rpm would be needed for the output desired. Then as Web said the amperage output would be dependent on what the system was calling for. If we tried to make the prop to turn about 2400 at normal cruise there would a safety margin if the plane went to Vne.

You're getting me worked up about this, it's time to start getting serious. I need to do some learning about prop specs. The blade needs to have a twist in it so that at each station it screws itself the same amount through the air. This means that it needs to be flatter toward the tip because that section is moving faster. This will take some math set up on the computer spreadsheet. Once I get this figured out it will be easy to play with different pitch angles.
 
Pete,

Before you get ahead of it all, keep in mind that while the little Gennipod isn't "designed' for 110 mph, it's because his airplane and those around him cruise at 75, and his own amp load is 4 amps or less. He designed to meet his goal. So, if someone wants to test one for awhile north of 100 mph, one may find that it's a prebuilt solution that would suffice. And spinning faster will probably get the amps up over 6 as well. He uses a solid state regulator too. For my own 90 mph and lower draw, the Genni would probably be the smart way for me to go, and it would probably work fine. But I like different mousetraps too.

So that said, yes, I can spin it on a drill press, but I'd need to understand how to measure the output with a meter and no load. And is this with a regulator inline, or just the dynamo?

I've thought about the prop used for ag pumps, and I'd sure hope we wouldn't need to get to that point. That size of a prop would probably not be of interest to me, between the logistical size, aesthetics and most importantly, the drag aspect. There are a number of small outboard props that may be of a suitable diameter, but my guess is they will be too flat of a pitch. Piranha props offer a nice composite prop with interchangeable blades on the hub, there by allowing different pitch props. I've not looked up what pitch range they offer.

When you're spinning the prop, you provide torque with a flat, low pitch prop. When you're trying to extract torque from a spinning prop, you need a course, high pitch prop. And most small outboards don't have the hp to drive a high pitch prop. One option is to take a larger high pitch prop and start cutting down the blades to get the diameter you want, while testing to ensure it keeps spinning the unit.

If you want to do some online homework, see if you can find a multi-bladed (think axial flow) fan blade, or as he calls it, an impeller, with a 4-6" diameter.

Other aspects - Probably need to machine a replacement shaft with provisions to allow a prop flange, or mounting method. The current flat head provides no attachment means that would ensure alignment.

pb
 
Okay, disregard machining a new shaft. The outer flange that makes up 1/2 of the "pulley" will remove separately with the shaft. A new 1/8" prop flange with tab provisions to index on the flat sides of the shaft end would suffice for a prop mounting flange.

pb
 
OK here are some starter numbers to whittle a prop. I've chosen a speed of 90 mph and 2400 rpm. There will be some aerodynamic inefficiencies so you may want to make some allowances to start.

Start here: http://www.culverprops.com/pitchselection.htm
enter 2400 rpm and 90 mph this gives a prop pitch of 40"
Click on "view entire guide" The chart agrees with 40"

Then: http://n-lemma.com/indoorrc/propcalc.htm
scroll down to "Prop-calc".
Next to P= enter 40 then next to r= enter the number of inches from the center of the prop. The answer a= the number of degrees of the blade angle at that station.
At the 4" station = 57.8*, 5" sta = 51.8*, 6" sta = 46.7*, 7" sta = 42.2*, 8" sta = 38.5* and so on as far as you want to go.

Make a flat surface on the side facing forward (direction of flight). Make a curved section like the top of a wing for the aft side. I would make the hub of the prop to match the pulley diameter on the dynamo. Drill 4 holes for attach bolts through the hub into the pulley flange. I would make a spinner shape for the hub to smooth the airflow.

Then look here: http://www.propellersexplained.com/ I wish that I had this book, it looks interesting. Notice the shape of the Whirlwind 200 prop blade. That is my shape of choice mainly due to what I have read from other sources as being the most efficient shape for all around good propeller performance. It was a Reno winner.

So pick a diameter which suits you and start making wood chips. Don't forget to very carefully balance the prop both vertically and horizontally. Be fussy about matching the shape of the two blades at each station. A coat of varnish on one blade or part of a blade is an acceptable means of adding weight. Be fussy about matching the shape on each blade at the same station. If the shape differs between the blades you could get a vibration which could be misinterpreted as an unbalance.

You need to just pick a size to start then based on what you learn you can make a second prop with the appropriate changes.
 
So that said, yes, I can spin it on a drill press, but I'd need to understand how to measure the output with a meter and no load. And is this with a regulator inline, or just the dynamo?
I would just mock up a circuit with the regulator to an old battery. Hook up a 12 volt light bulb and a multimeter and see what happens.

What we don't know about the little Gennipod is if it is capable of more amps at a higher rpm. As you have noted the Kubota is capable of 18 amps.
 
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Oh boy.
I have no time to whittle away on wood prop fabrication. I don't see that happening. Modifying an existing with a suitable base starting point would be my direction, but even that is probably not in the near future due to other priorities.

I'll see if I can pull some amps from it once I have a regulator, but that will take some time to set up as well.

Pb


Sent from my imitation glass cockpit using SuperCub.Org mobile app
 
A car stereo filter is a simple combination of a series inductor and a parallel cap. Xcom recommends a 25 mF cap. A decent inductor will look and weigh like a small transformer. Most car stereo filters are over priced for inadequate components, build your own.(if it turns out you need it)
To spin test a Kubota, any test not including the no-field regulator(which includes the rectifier diodes,see my last post) will be invalid. This thing is not at all like any alt typically used in aircraft or cars. Sorry I got so techy with my last post, people seem to skip over when it gets too dense.
 
If you want to do a simple test in a drill press:

Connect up the regulator to the dynamo. Rig up, both a voltmeter and ammeter to read the regulated output of the system. Hook up a lamp that will draw aprox 1 amp. Spin the dynamo faster and faster until the voltage stabilizes. Note the voltage and rpm. Now add more lamps to bring the load up to your projected maximum (8 amps?). Increase the rpm's until the voltage comes back up to stabilization.

This will give you an idea of your minimum and maximum rpm's needed to bring the system on line and to reach max current capacity.

Web
 
My little Kubota makes its rated power at 3200rpm. With a quick eyeball of the pulleys I'm guessing the alternator needs at least 7000 rpm, maybe 9000 for full rated power. Too much for a drill press. Check out the 20-30% scale props for the big RC's, they turn in that region, with a wide variety of dia and pitch. There are more 3 and 4 blade props being made, I suspect to get the solidity factor you'll need due to restricted prop dia, you'll need more than two blades. Mount it on your pickup well above the cab in undisturbed air and go for it. Try running the props flat side first, the alt doesn't care which way it turns.
 
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My little Kubota makes its rated power at 3200rpm. With a quick eyeball of the pulleys I'm guessing the alternator needs at least 7000 rpm, maybe 9000 for full rated power. Too much for a drill press. Check out the 20-30% scale props for the big RC's, they turn in that region, with a wide variety of dia and pitch. There are more 3 and 4 blade props being made, I suspect to get the solidity factor you'll need due to restricted prop dia, you'll need more than two blades. Mount it on your pickup well above the cab in undisturbed air and go for it. Try running the props flat side first, the alt doesn't care which way it turns.

Sky, It has an 18 amp output at 6000 rpm, and more importantly a 12A/2400 and 9A/2000 rpm.

This unit is going to take some torque to spin it. The RC blade aren't going to provide that.
 
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