I pretty much agree with this, though I'd only do it if the engine had mags (e.g., wasn't reliant on DC power to keep running).+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.
Could be me, but I don't consider building a generator fun, it's like a science project for a middle schooler. If you really want to build one, it would be very simple. Basically you need a DC motor. To get an idea look here for some simple wind generators, but bigger to handle charging a 12v battery. You would probably need something about the size of a heat/AC blower motor or electric engine cooling fan motor. You'll need a prop or fan to drive it the desired RPM at the desired airspeed and a regulator. The question to me is why? You'll probably have 50% or more than the cost of buying one invested and probably not be as neat or efficient.What's the fun in that...?
Bicycle generators are biased towards 6v, they produce AC, and about 6watts.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.
1. Some engines don't have a provision for a generator or alternator. Hence you have to work out brackets, belts, deal with vibration, etc.Bicycle generators are biased towards 6v, they produce AC, and about 6watts.
If I were going to do this.. it would be a with a r/c motor, a rectifier bridge, and a vreg of some sort... But.. I wouldn't do it.
what's stopping you from driving off the engine?
That's a key factor, I think...with a homebuilt, you can try weird stuff just out of curiosity. I might try a wind generator at some point, just for fun.You might as well ask, "Why build a homebuilt airplane when you can just buy one?"
I love it when I get a concise, accurate reply. Thank you Ron.1. Some engines don't have a provision for a generator or alternator. Hence you have to work out brackets, belts, deal with vibration, etc.
2. Aircraft without engine-driven electrical systems get a break as far as requirements to carry expensive equipment. For instance, if you don't have an engine-driven generator or alternator, you are not required to carry a transponder *or* ADS-B within the 30 nm Class B veil.
(Large wind-generator-powered light bulb comes on)What we *should* do, in this case, is set up the plane like a consumer appliance. Rather than putting the battery under the cowling, seat, or whatever, make a pull-out drawer that lets you switch batteries in moments.
A lot of the glider contingent is switching to LiFePO4, which would be a much better choice than NiMH, in my opinion. LiFePO4 batteries are pretty light for their capacity, and provide relatively constant voltage as the battery is discharged. I will probably soon be purchasing one to replace my current sealed lead-acid battery..... suddenly I wonder why people stick with the nasty little lead acids.
Lead acid batteries cause fires too. NiMh is a "pretty darned tolerant" cell technology. If there were fires, there's something else afoot. A "sane method" for charging nimh, is just voltage limiting. They can tolerate that without any kind of timer or current limiting.NiMH batteries require a special charger to be charged safely, and I have heard of a couple of inflight fires caused by (factory-installed) NiMH glider battery installations. Not something I want in my airplane...
I built an electric motor in middle school and rebuilt more alternators and generators than I could begin to count. It's really kind of boring, but building a plane is another story. I see building a plane as the ultimate challenge. I've built balsa models and they can be a challenge, so I can hardly wait until the day I can build one.You might as well ask, "Why build a homebuilt airplane when you can just buy one?"