VERY LIGHT BATTERIES

Discussion in 'General Experimental Aviation Questions' started by oldcrow, Jan 16, 2020.

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  1. Jan 23, 2020 #41

    Dan Thomas

    Dan Thomas

    Dan Thomas

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    If I were you I'd avoid a metal prop on an A-65. The crankshafts in those old engines weren't hardened and they crank easily, and finding a replacement crank is nearly impossible after you've had a prop strike and have cracked the crank. They've been out of production for a long, long time. A wooden prop is much more likely to shatter and save that priceless crankshaft.

    I had an A-65 crank break in flight due to a crack that very likely started long before when someone had a prop strike and the mechanics did what they did back then---they "dialled" the crank to see how much runout there was , thinking that if the crank was bent much it needed further checking. Over the years it was found that cranks could twist a lot during a propstrike and spring back close to normal, but a crack would have started. The small Continentals tend to crack their cranks way at the back end of the engine, between the first and second rod journals. Don't know why, but I've seen it.

    Your inspector shouldn't be insisting on a generator or whatever unless you have a transponder or ADS-B. I had just a Com and fed it using the small sealed lead-acid battery used for emergency stopping on trailers with electric brakes. You can get them rather inexpensively, with a plastic battery box and everything. Mine had a button on the lid that when pushed would light up some LEDs to tell me how much power I had left. Handy. I think I paid $30 for the whole thing.
     
  2. Jan 23, 2020 #42

    dog

    dog

    dog

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    [QUOTE="Dan Thomas, If I were you I'd avoid a metal prop on an A-65. The crankshafts in those old engines weren't hardened and they crank easily, and finding a replacement crank is nearly impossible after you've had a prop strike and have cracked the crank. They've been out of production for a long, long time. A wooden prop is much more likely to shatter and save that priceless crankshaft.

    Thanks for the info.
    My project came with an a-65 built and the parts from two more, including cranks, and a case that
    has very obviosly been in a sudden stopage event.
    I was useing it to see if I could get enough torque through the tach drive to glom on a starter, but while I could spin the crank up ,it just seemed too
    marginal,if I had the skill set to build a beefier oil pump/tach drive It could work.
    I like the idea of the model T trick way better.
    As to the prop,the metal one is here and paid for,and has a hub bolted to it, new bolts,nice paint,cut down a bit and re pitched.
    Id go with wood primarily to lighten the plain up a bit, and would just work on not testing the potentialy forgiving characteristics they display when run into things.


    " The small Continentals tend to crack their cranks way at the back end of the engine, between the first and second rod journals. Don't know why, but I've seen it."

    I might just dissasemble the motor and have the crank and rods, mag fluxed or zyglowed.
    I do have the bearings from the broken a 65 case
    thats here AND a specimin microscope,so I will try and match wear patterns with one of the two extra cranks I have.

    Your inspector shouldn't be insisting on a generator

    Good to know.
    And yes those trailer brake batteries are probably perfect, The Menonites sell them for the trailers they bring in, and I think my last one was $30.
    Nice and light.Sealed too.Right size to fit in behind my instument panel.AND I have one that is my trailer right now,suffering some serious neglect.
    Will pull it and see if it comes back to life holds charge,and runs a 10 amp load? for ??then back off
    to 5 amps and time it again.
    I will start a thread when I have photographic documentation,of hopefully sucessfull model T trick starting and supper light weight battery install.
     

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