Strut mounted Generator

[Nigel]

The thread about the camera gimble got me thinking about something...

I'm a photographer and have used a couple gyro systems to stabilize cameras. This of course leads to one thing. Dead camera batteries.

What about taking a bicycle generator (12v 6w) and running it to a lightweight inverter to charge my batts on the trip??

I know that this isn't within the letter of the law but we are only throwing around ideas.

I see the stock dynamo/generators on eBay and such but they are heavier and don't generate the same amount of power.

What do you think??

Thanks

[N74DV]

Re: Strut mounted Generator

Funny you should mention a generator.

I too have been wanting a power system in our Tcraft other than the gel cel battery we use to power the radio. (all towered airports in Phx area).

So I have begun working on a 3 phase AC brushless motor alternator. I have a working prototype and just need to find the right size prop to get the proper voltage.

The motor I'm using is an RC airplane motor capable of 1K watts continuous duty. That's about 80 amps of available power. About 8X more than a T will ever need. The AC output from the 3 legs of the motor/alternator are half wave rectified with 6 diodes and a 13.8v voltage regulator.

It weighs about 85% less than our original wind generator. Problem is certification. Might be able to add it to the airframe similar to my jury strut camera mount and have it noted as a Minor Alteration? I dunno.

[flyguy]

Re: Strut mounted Generator

Question: How do companies that develope products like wind-driven generators for old aircraft get permission for reliability and functionality tests on an actual aircraft. Anyone know? Does the entire aircraft have to be changed to "experimental test" classfication? How do they do that?
DC

[barnstmr]

Re: Strut mounted Generator

So much depends on which FAA office you are dealing with. I doubt any FSDO offices would grant a field approval. So now you're talking STC with the FAA-ACO. Most likely the FAA will want a lot of bench testing for qualification and performance of the generator itself. Assuming you can get the generator qualified against the environmental and reliability requirements, then you gotta make sure the installation meets all of the airplane airworthiness requirements.

Best bet would to be to work with the Alaska ACO on something like this since (as already pointed out) they strap things to struts all the time up there. Still, you'd be lucky if you can get by without some serious flight test work. Any flight tests done with non-certified components installed are supposed to require issuance of an Experimental airworthiness ticket... either for R&D or show compliance.

One thought is that there are prior approved installations on some airplanes (like the L-2) where a generator was mounted on the struts close to the fuselage. And some others on landing gear struts. There might be some precedent there to help convince the FAA of no need to flight test or at lease minimal flight tests as long as the placement is the same as other approved installations.

OH... and the fact that these are old airplanes really makes no difference to the FAA, except that they would use predecessor regulations (CAR 3 or CAR 4a) as were in effect at the time of the airplane TC. But the overall differences are minimal on this sort of thing.

[VictorBravo]

Re: Strut mounted Generator

I volunteer (if needed / desired) to write the "proposal letter" stuff to the FAA, which if worded correctly MIGHT convince them to allow this field approval without too much extensive testing.

Many of us have been thinking about a small brushless alternator/generator mounted to the jury strut or some other place. If you only had 3 or 4 amps that is more than enough for a good radio, a GPS, and even LED nav lights. The lower the current and voltage, the less worried the FAA is likely to be. It would be easier to start off making 2 amps to run a handheld, then go back and expand the capacity once you have an initial OK.

Put in a protective circuit, some sort of a current fuse/breaker AND a temperature fuse. Use some sort of a friction coupling or rubber tube connector between the propeller and the input shaft, so that if the prop fails or the shaft wants to seize, the prop will not force it to turn and create a lot of heat. Put a static wick or ground it to whatever, so a charge cannot build up in the wrong part.

By protecting against all these little things, you have a better chance of the FAA accepting that the device is fail-safe. Contact me off-line if you would like me to be involved.

[N74DV]

Re: Strut mounted Generator

I plan to test my brushless alternator by mounting it to the roof rack of my Dodge Nitro and driving down some desert roads at speeds between 50-100mph to measure the voltage output from the motor. I want to prop the motor accordingly so that at about 70 mph the motor/alternator will generate about 13-14 volts.

I've got a data logging device for logging volts/amps/alternator rpm over time. From that data I can also get watts/amp hours/etc. All data can be charted and graphed.

Problem is I've got what seems like 100 other projects on the table now so might take me a few weeks to get to this one.

Bill I might just take you up on that offer to draft a letter.

[Len Petterson]

Re: Strut mounted Generator

Years ago I remember reading in EAA magazine about a bicycle genrator driven by a prop and puting out 6 volt i my memory don't let me down. Model airplane propp and dc generator.
Keep thinking! One day you get it right!
Len

[VictorBravo]

Re: Strut mounted Generator

Bill I might just take you up on that offer to draft a letter.

OK, I'm here when you need me. This big mouth of mine occasionally needs something legitimate to get involved with...

[SCRed]

Re: Strut mounted Generator

For what it's worth, there already is an STC'd wind driven alternator for the BC12D model of Taylorcraft. It comes complete with a voltage regulator built into the unit. I have had one for the last several years and it works great. It's from Basic Aircraft Products in Evans, GA. Powers all my radios and running lights and keeps my battery charged. If there is interest, I'll post pictures of my Taylorcraft installation. Link below is a manufacturer's page with photos of the unit installed on other aircraft.

http://www.basicaircraft.com/gallery2.htm

[Dan Michaels]

Re: Strut mounted Generator

I don't think it is going to be so much the generator as if you wanted to wire it into the plane. Now your talking a major. Just mounting it up and running a wire to your external items is not going to be a problem.

Weight of the generator is not going to be a problem either it is the drag that you will incur with the extra prop.

They have batteries for laptops that are flat and last 12 hrs or so. Couple that with a solar panel and you can power most anything for as log as you can stand to fly at one time.

How about a solar panel between the wings? Plexiglass over the top. Sorta like a green house roof with the panels sitting under them. Maybe a rigid panel set up off the top between the wings 1/2" or so. My old 150 had a sign mounted on the sides for advertizing.

Dan

[SCRed]

Re: Strut mounted Generator

If you look closely at the photo of my airplane to the left, you'll see the little square nestled under the fuselage between the landing gear. That's where the Basic Aircraft wind powered alternator is mounted. Installation is easy, four adel clamps hold it on to the lower frame. Being mounted in the center of the fuselage there is no problem with asymmetrical drag. I've flown with and without the alternator installed and honestly, I haven't seen any airspeed loss.

The reason I got it is that I do long cross country trips. And I've been yelled at by towers all up and down the west coast for showing up with a nearly dead radio battery. With this alternator, I always have the power I need along with a fully charged battery. This lash up may not work for everyone but it works well for me.

[Nigel]

Re: Strut mounted Generator

I thought about the solar panels between the wings already. I ruled that out when I looked at the price per volt/amp.

The little bike gennie would be enough to put a cigarette lighter in the cockpit which I could then plug a light inverter into. I have the inverter already. It works great as I drive to charge my laptop and camera batteries. It weighs a fraction of what some of them do as it only has one outlet. But it works great.

Lots of power at little cost.

This system would be less than 50 bucks.