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Date: Sat, 19 Mar 2005 21:53:29 -0600
From: Jim Sower <canarder@frontiernet.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Alternators
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Boy, am I glad to hear THAT!!  Here I was beginning to think that all 
the reliable service I've gotten over the years was a monumental fluke 
and it would all come back to bite me SOON.

Now I can stick with my $30 70A N-D and have it rebuilt for another $30 
if it quits ... Jim S.


Charlie England wrote:

> Marv, I hope this doesn't step on too many toes, but here goes:
>
> Well, he did identify himself as having a financial stake in his 
> statements.
>
> Some of that stuff is probably true for *some* a/c alternators. Some 
> of it is not universally true; some may not be true, period. Some alts 
> have canted brushes, some have perpendicular brushes. Fan orientation 
> will affect airflow to some degree, but thousands of auto alts. are 
> being run successfully in a/c with no fan at all, using blast tubes. 
> The ones with fans still attached still move air when spun the other 
> way. Some car engines spin the alt in the same direction as a/c 
> engines. Some a/c alts might have locking tabs, but not all. According 
> to auto docs, some auto alts are wound delta & some are wound Y. He 
> mentions that alts are birotational then later says that a/c alts are 
> wound backward for backward rotation. He says that the rotor shaft is 
> shorter but the cases are identical. While he's probably correct about 
> special insulations, coatings, etc for turbo'd & turbine hardware 
> designed for extreme altitudes, I strongly doubt that much if any of 
> that applies for stuff found on NA piston singles. It doesn't seem to 
> apply for some electric gear retract pumps, which are straight out of 
> marine outdrive tilt mechanisms. I've witnessed certified a/c 
> alternators work just fine after being rebuilt in greasy floored auto 
> electric shops with auto components. Not on my airplane of course... 
> If anyone needs something overhauled, bring it with you to the rotary 
> spring fling thing & we'll run it 9 miles down the road to the 
> uncertified repair station.
>
> If there's interest, I'll post the article on the aeroelectric list & 
> let Bob Nuckolls critique it.
>
> Charlie
> (feeling irritable after a day of figuring out how much it has cost me 
> this past year to have my money spent where & in ways I don't want it 
> spent)
>
> Kelly Troyer wrote:
>
>> I do not know about everyone elses engines but my 13B turns the same
>> direction as A/C engines built in the US !! I do not know enough to
>> comment about the other differences noted.......
>> -- 
>> Kelly Troyer
>> Dyke Delta/13B/RD1C/EC2
>>
>>
>>
>>
>>     -------------- Original message from "Marvin Kaye"
>>     <marv@lancaironline.net>: --------------
>>
>>
>>     > I thought you'd find this interesting.
>>     >
>>     >
>>     >
>>     >
>>     > Posted by "Hamid A. Wasti" to the Lancair Mail List:
>>     >
>>     > I saw this posted on another list. I am passing it along for
>>     general
>>     > interest, with no warranty for the accuracy of the information
>>     contained in
>>     > it.
>>     >
>>     >
>>     > From Pifer's Airmotive, Inc. Pontiac MI
>>     >
>>     > DIFFERENCES BETWEEN AIRCRAFT & AUTO ALTERNATORS USING A FORD
>>     BELT DRIVEN 12v
>>     > OR 24v ALTERNATOR FOR A COMPARISON
>>     >
>>     > 1. Although alternators are bi-rotational, aircraft engines turn
>>     opposite of
>>     > automotive. This means cooling fans must be canted in the
>>     opposite direction.
>>     > Also, pulley and belt size vary due to coming-in speed.
>>     >
>>     > 2. The thru bolts are of a higher tensile strength utilizing an
>>     > anti-rotation
>>     > device in the form of a lock tab. The rectifier assembly has a
>>     heavy duty
>>     > diode with higher voltage and amp. capacity. Also, one excites
>>     at 90 PIV (Peak
>>     > Inverse Voltage) and the other at 150 PIV. Radio suppression is
>>     designed for
>>     > 108 frequencies and up which is the VHF and 108 and down which
>>     is FM band.
>>     >
>>     > 3. The brushes have a higher graphite content and they utilize a
>>     tin plate
>>     > on
>>     > the brush leads to prevent corrosion.
>>     >
>>     > 4. The stator is of the Delta wind rather than the “Y" wind and
>>     it does not
>>     > utilize the stator terminal. The aircraft unit also carries “H"
>>     insulation
>>     > which is capable of 200 degrees centigrade temperatures. It also
>>     is rated at
>>     > 60 amp. instead of 55.
>>     >
>
>
>>     > 5. The rotor has a shorter shaft and a smaller thread size.
>>     Because of the
>>     > opposite rotation it is wound in the opposite direction. It also
>>     uses "H”
>>     > insulation and Havel varnish.
>>     >
>>     > 6. The front and rear housings are the same as automotive.
>>     >
>>     > With this brief description, I hope I have enlightened you on the
>>     > differences
>>     > between aircraft and automotive alternators. Using automotive
>>     units in an
>>     > aircraft creates a potential safety hazard as well as a short
>>     alternator life
>>     > and unreliability.
>>     >
>>     >
>>     >
>>     >
>>     >
>>     >
>>     > >> Homepage: http://www.flyrotary.com/
>>     > >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
>
>
>
>>>  Homepage:  http://www.flyrotary.com/
>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>>
>
>