I agree with Don. "When it come time to overhaul/repair/replace the generator, it's a good time to consider upgrading to an alternator." Generators have a commutator that grinds on the brushes, creates dust that gets in the bearings and lasts about 500 hours. Power coils are in the rotor and spin and sooner or later fail. In an alternator, the power coils are stationary, and the field (with a smaller coil) rotates. Two brushes connect the field via slip rings with lower current requirements. An alternator should last many times longer then a generator.
I learned to fly in (and my first airplane was) a 1957 C172 with a 35 amp generator. At night we had to be careful not to run everything all the time. Running the landing/taxi lights along with everything else would run the battery down. Practicing night landings, when I reduced power to descend to the runway the intercom got quiet, radio wouldn't transmit. Shut off the lights and the 35 generator would keep up. We upgraded radios and I did instrument rating in that airplane. Couldn't find 35A AGS (5/16 diameter) fuses and used 35 AGC (1/4 inch diameter). Most of the instrument training was at night. We burn a few generator fuses. Got good at changing them in the dark. The rear bearing went out on the generator, bought the Cessna Service Kit for Cessna/Ford and installed it with 337 and IA inspection. It was more work than you would initially think and I am an Electrical Engineer by both training and profession. Upgraded system from 35A to 60A, new main buss, breakers, new larger cables, Zeftronic controller... No longer any problems with power, run the lights all the time. Later sold the plane a bought a newer one. I have a Piper Apache twin with dual 35 amp gens. We've flown it about 800 hours and we've replaced both generators, one of them twice. There is not room for an alternator (requires modifying the cowling). Generator repair guy said the correct bearing and seals are hard to find the China parts that are readily available do not last. So when our Ercoupe's generator stops generating, we'll probably go for a lighter weight Alternator conversion. Probably 20 to 30 amps. I like this B&C one. Have to ask about an STC... http://www.bandc.biz/alternator30ampshomebuiltlessgear.aspx mitch ---- Donald <[email protected]> wrote: ============= I have not dropped out of this discussion, but my buddy Hartmut gave me some statements that warranted some research. The suggestion that the alternator was invented because automobile generators don't produce at idle, and therefore were not useful in automobiles but were the ideal for aircraft got me to thinking. I submit that the alternator was invented as a far superior way to generate electricity over the generator. In fact, since it produces alternating current its use was difficult until the widespread development of the diodes to make that into DC, which is why they became popular on automobiles when they did. I dug back in my memory banks, I started driving with generator equipped cars and my first experience with alternators was over 20 years later. In all that 20 yers, I never recalled a single problem issue with not producing electricity at idle. We had batteries that took up that slack in fine shape, even with the power hungry radios of that era and headlights, and it was recharged as soon as you were driving again. Data uncovered on the internet suggests that the average life of a generator was something in the 20k to 30k miles area, while alternators are considered to have a lifespan of 125-150k miles. Continuing to play devils advocate, I also found that there are absolutely NO aircraft engines being offered today with generators! Now don't get me wrong, I am NOT advocating that one should go convert their perfectly good ercoupe generator system to an alternator for those reasons alone, but when faced with major overhaul and replacement of generator parts, perhaps going to a modern efficient alternator with a solid state regulator, MAY be a better choice. For me, it sure seems like the best choice. In addition, in my case my 13 amp system would still not be sufficient to run my strobes, radio, transponder, landing lights, GPS, ANR headsets, electric artificial horizon, and the kick butt stereo system all at once!! --- In [email protected], ALAN FAIRCLOUGH <texasavia...@...> wrote: > > I have one of each. > > The reason for the alternator is that my 13 amp generator did not provide > enough juice. > The sum of the lectrical devices should be less than 75% of the XX amp output > of the generator. > In my case it was a 13 amp generator. > > On an appraoch at night, I have the GPS, the transponder, the radio, the nav > lights,the collision avoidance thingy and the strobes running, as well as > instrument lights. When I flip on the landing lights my GPS goes dead. > > Now, on one plane I have a 25 amp generator. On the other a 60 amp alternator. > With the alternator, although it never puts out 60 amps, there is still power > for everything. > > Alan Fairclough > N87333 > N94694 > -- Learn2fly www.chickashawings.com 2+2=4! http://www.myspace.com/pianomitch
