# Anyone understand how to produce this wind-driven generator?

Discussion in 'Instruments / Avionics / Electrical System' started by spduffee, Feb 28, 2015.

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1. Feb 28, 2015

### spduffee

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This idea is from 2001 and the person who made it (Mattias Jonsson) has not been seen on the Piper forum since 2010. I like the idea, but have no idea how to put it all together. Does anyone have any idea how to piece it together, or have a lead on an equally good DIY wind driven generator for aircraft use?

Thanks,

Shawn

2. Feb 28, 2015

### JamesG

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The article kinda spells out how to go about building one. If you want an OTS (off the shelf) one, I would look at some of the bicycle generator kits. They at least pass a nod to concerns over weight. But I'm not sure if they go up to a full 12V or not. Unless you are flying cross country, really a "total loss" system of just a battery is usually good enough for most day flyers. Its the simplest, lightest set up.

3. Feb 28, 2015

### TFF

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With the new LIPO4Fe batteries, the total loss systems are better. They charge very fast, very light, small. You can carry a wall wart charger and have it full charged from very low in less than an hour. Solar panel could be an option out where no power. A 4 lb battery can be 400 cc amps. Some of the aerobatic guys can get a weekend flying to a contest, the contest flying, and return home on one charge if the engine is an easy starter; starting Lycoming 0-360s.

4. Feb 28, 2015

### FritzW

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Lot's of good u tube videos on how to do it. It looks like brushless model airplane motors are all the rage.

I tried an old bicycle generator with a model airplane prop and didn't have any luck. It could have been the diameter and pitch of the prop or my 50 cent garage sale generator was für Scheiße But my little Toyota pick-up couldn't go fast enough to spin the prop.

5. Feb 28, 2015

### spduffee

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There are two articles in that attachment. The second one explains more, but it's the first one I like, on the Cub. I have zero comprehension of aircraft electrical systems or any other for that matter. I can buy the R/C Pylon Brand Hi-Tork starter, but then what? That's my dilemma. How does it tie into the battery to recharge it? Where does the propellor mount to? See...zero.

Fritz - you were probably responding just as I was. If you have a Youtube example to share?

6. Feb 28, 2015

### FritzW

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I'll be hanging out with the geek squad tomorrow. I'll see if they can sketch up some practical stuff. One of them probably knows the Mouser part numbers by heart

I'm guessing you saw the Gennipod and didn't like the price: GeniPod

Edit: I'd bet Wanttaja is the guy to talk to, you might shoot him a PM.

7. Feb 28, 2015

### spduffee

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Thanks Fritz! The BPE14 is more than twice the price of the GeniPod. There's got to be a better, less expensive way.

8. Feb 28, 2015

### Wanttaja

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Oh, oh.

The Fly Baby group's engine guru, Harry Fenton, once did a writeup on wind generators:

" A couple of basic problems with wind driven alternators- drag and consistent voltage output through the airframe speed range. Typically, the alternator is tuned for max output when in cruise. However, when the airplane is at pattern speed, the alternator has no output as it is turning too slowly.

"Drag is an issue, too. The alternator has to be a pretty good size and the prop can provide a lot of drag. I had a torpedo shaped wind driven alternator on my old Stinson 105 and it cut the airspeed by 5mph and made a pretty loud whirring noise when it ran. "

Harry's solution...which I agree with, and an earlier poster also recommended... is just to run with just a battery and plug in a charger when the plane is parked. I flew most of one season with the generator of my Fly Baby inoperative. Wasn't a problem, even with my starter. I've got kind of an "APU" port on the belly of my airplane that makes charging the battery pretty simple.

Ron Wanttaja

Last edited: Feb 28, 2015
Pops likes this.
9. Feb 28, 2015

### Dana

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The article doesn't give much info because there isn't much to it. But neither of those articles are intended as a ful DYI; they're just a brief report on how somebody did it.

Forgive me if I'm being too basic: Any permanent magnet DC motor can be a generator. Connect it to a battery and the battery runs the motor. Force the motor to turn backwards, against the way the battery wants to spin it, and you have a generator, charging the battery. A diode or two, blocks the forward current from the battery so it doesn't spin like a fan on the ground, but the current still goes the other way to the battery. Stuff requiring power in the plane simply connects to the battery (presumably through a master switch and fuse(s).

The generator's output voltage is proportional to how fast you spin it, so you fiddle with the little prop to get it spinning at the right speed. You do this in flight, before connecting anything other than a voltmeter to the generator output! Too slow and it won't charge the battery; it has to be more than the battery voltage, but not too much. Too fast, too much voltage, and the magic smoke starts to leak out of the battery or your radios.

It's really best to run the generator output through a voltage regulator, though, to keep it consistent and avoid overcharging.

How the prop mounts to the motor depends on what the motor shaft looks like.

The one on a Cub, I'm surprised such a non TSO'd installation is allowed in Europe where the rules are so much more strict.

Dana

10. Feb 28, 2015

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Solar panel. A 1x1 ft section will just be too little to power a basic plane during flight. With a battery, you never have to bother with charging again, it's light, simple and fool-proof.

11. Feb 28, 2015

### Pops

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I have been flying my airplane 7 years on the 5 amp model airplane starting battery for my electrical needs. I keep it charge with a $10 HF solar panel (With coupon) Since I'm working on putting dual ignition on my VW engine ( have the extra set of heads drilled for 10 mm plugs) . The ignition will come on automatic if the slick mag misses a beat, so the ignition will be battery friendly. Dan 12. Feb 28, 2015 ### Dana ### Dana #### Super ModeratorStaff Member Joined: Apr 4, 2007 Messages: 8,668 Likes Received: 3,048 Location: CT, USA Dan, is the solar panel mounted on the plane or do you plug it in when on the ground? Dana 13. Feb 28, 2015 ### spduffee ### spduffee #### Well-Known Member Joined: Sep 22, 2011 Messages: 567 Likes Received: 122 Location: Renton, WA Too basic? Not for me, Dana. Thanks for the walkthrough. Maybe I should invest in one of those "basic aircraft electrical" books I have heard of, or visit the nearest kid's science museum to learn from the 6 year olds. The Cub is in Sweden, didn't say where. Maybe he lives somewhere remote. 14. Feb 28, 2015 ### Wanttaja ### Wanttaja #### Well-Known Member Joined: Sep 15, 2013 Messages: 1,266 Likes Received: 1,451 Location: Seattle, WA As a "professional user*" of solar panels for ~38 years, I have considered one. The small units are trickle chargers, which apply a small charge current over a long period. The real-time power level is probably enough to cover use of a small radio, but if one has a starter (like me), an afternoon's worth of flying probably isn't enough to seriously make up the battery drain. The power level of a solar panel isn't constant...it's affected by 'Beta Angle,' the angle to the sun. At my latitude, a panel pointed straight up on an airplane will deliver, at most, less than 70% of its rated power. A solar panel depends on the sun being present, of course...and I live near Seattle. When someone tells me, "stick it where the sun doesn't shine," I tell them I'm already there. An ancillary factor is that I keep my plane in a hangar. An airframe-mounted solar panel will only get an average of an hour or two of exposure every week. Had a former hangar-mate with a Vari-Eze with a nose-mounted panel. Didn't do him much good. All of these objections go away with a hangar-mounted panel that one connects to the airplane when parked. Good way to do it...long-duration trickle charge, just what you want. The problem is, I'm in a rented north-facing hangar and the owner won't let me put stuff on the roof. Ron Wanttaja *I've worked in space operations since graduating from college. Everything is powered by solar arrays. 15. Feb 28, 2015 ### TFF ### TFF #### Well-Known Member Joined: Apr 28, 2010 Messages: 11,710 Likes Received: 3,315 Location: Memphis, TN I would not try to only operate on a solar panel, but if flying to the next airport over and going to be yapping with buddies for an hour or two, one, trickle charging, would help out during the day until back to base. Now days with LED lighting you could do safe sunset flights and not suck stuff down. 16. Feb 28, 2015 ### autoreply ### autoreply #### Moderator Joined: Jul 8, 2009 Messages: 10,732 Likes Received: 2,542 Location: Rotterdam, Netherlands Many sailplanes have them too. It's enough to be barely draining a radio and a significant stack of (economic) electronic flight instruments. Transponders mean you need twice the area or are draining significantly. Both about 500 NM north of Seattle latitude Didn't think the starting thing through, I preferably don't use an engine, let alone a starter at all. Having a while during flight-prep and waiting around helps a lot. 17. Mar 3, 2015 ### sigma ### sigma #### Member Joined: Feb 28, 2015 Messages: 8 Likes Received: 5 Location: new york, ny Sorry to jump in a little late. I would first ask, what is the goal? Redundant power? Does the plane not have an alternator? The easiest thing might be a small alternator? If that won't work, a backup battery would be lighter than a generator+prop. Someone check my math, but i think for pure emergency power, 7 alkaline AAA batteries would last at least an hour! (For the transponder that is, or do you want to power a whole bunch of stuff?) If you really wanted (a not a pricey) wind generator , the R/C stuff is probably the way to go. As others mentioned you have to match up the propeller pitch to mission, and also have the motor as the right RPM or it will have low efficienc+output. Probably not worth it except on a sailplane. One comment on the original JPG story: i would not rely on the main battery for voltage regulation. While I suspect that works fine, why are we using this thing -- is the battery defective? If it is defective, it likely won't make a good voltage regulator for us. In fact it might pull us to zero power from the generator. So i'd switch over to the generator as emergency power instead, with a voltage regulator, and maybe a very small battery for speed changes. p.s. you might find something like this useful for monitoring backup batteries -- very inexpensive. but not av-grade suitable at most for R/C or maybe backup power on a bigger ship : Mini 3-wire Volt Meter (0 - 99.9VDC) ID: 705 -$7.95 : Adafruit Industries, Unique & fun DIY electronics and kits ps don't forget the fuse.

18. Mar 3, 2015

### Dana

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I can't speak for the original poster, but I've thought of building a wind generator too. The idea is to power a handheld radio and perhaps a GPS without having to worry about charging the batteries before flying or whether they'll run out on an extended trip.

On some aircraft (mine is one of them) there's no practical way to mount an alternator, and not having an engine driven electrical system can be an advantage... it exempts you (at least in the US) from some requirements like the Mode C veil, or the coming ADS-B requirement.

Dana

19. Mar 3, 2015

### cluttonfred

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+1 on the idea of a total-loss battery system charged on the ground with a "smart" charger that can be left plugged in without damaging the battery. It's also not hard to carry a small, AC-DC 12v trickle charger and/or a roll-up flexible panel for cross-country flights. I posted these comments in a similar thread on the Eagler's Nest forum asking about wind generators, but I actually now think a total-loss system makes more sense.

20. Mar 3, 2015

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