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Thread: DR-107 Weight reduction and Aerovoltz review

  1. #1

    Join Date
    Oct 2012
    Location
    Brookline, NH
    Posts
    12

    DR-107 Weight reduction and Aerovoltz review

    Hello Everyone,


    In my DR-107 weight reduction program this winter I have successfully removed 41.2 lbs!! Removed alternator completely, -10 lbs, went to light weight x-drive starter, -5.5lbs, removed -8.5 lead weight from tail, removed firewall starter solenoid, -1lb, added oil filter adapter +2.2lbs, went from gel cell to Aerovoltz 16cell battery -18.4. My C.G. is just aft of the midpoint with 10 gallons of fuel, so I'm pretty happy. If I find I need more aft C.G. I'll put some of the lead back in the tail.


    Since I'm not running an alternator I wanted to see just how many starts I'm going to get out of a charge on the 16 cell Aerovoltz. I only have a handheld comm, the fuel pump and a hobbs meter, so not much draw other than starting.


    Turned the engine over for 30 to 40 seconds with no plugs to get oil pressure. Then with plugs in, mags off, did 20 start cranks of 3 to 4 seconds each with 15 second break in between. Monitored battery voltage and temperature. Around the 18th crank started to notice voltage drop off (down to about 9.8 volts during cranking). At 2 seconds into the 20th start crank it hung up on the compression stroke, voltage quickly dropped to +/-7 volts. Battery temp was up to 105. Let it rest for 2 minutes voltage recovered to 12.1 volts and was able to do a 3 second 21st start attempt.


    Not wanting to damage my new battery I figured that was more than enough for my needs. This season will be the final test, but so far I think this is going to work very well. The battery is still mounted just aft of the spar, don't know if longer run would affect it much.


    I'm using Aerovoltz balance charger to keep the battery charged up, figured that was cheap insurance against damage.


    Now to loose 10lbs off myself and I'll be really happy!!


    Russell

  2. #2

    Join Date
    Dec 2011
    Posts
    30
    Thats Amazing that you could find that much Non-essential weight to remove Russell , I can tell you that your 10 lbs will be harder & take longer to remove .

    From one 1D driver to another , What does that put your E.W. at now ?

  3. #3

    Join Date
    Oct 2012
    Location
    Brookline, NH
    Posts
    12
    With O-360 and 2 blade wood/fiberglass Prince Prop, now at 878 lbs and E.W.C.G. of 74". This is 1" forward of the old E.W. C.G. but with me (when I loose 10 lbs) in the a/c with 10 gallons I'm at 1128lbs and 80" C.G (in the mid range). Could come aft quite a bit and to do good tumbles I may have to but figured since I'm new to the aircraft best to error on the mid to forward end of the C.G. for now. Last fall I removed the old battery completely just for a test that flight that brought the C.G. to about this range. During the test flight I didn't notice anything significantly different.

    I have another 3 or 4 pounds in the panel I could get rid of if I go to electronic instruments but into some bigger $$$ to do that.

    I may not move the battery aft, since it is so light weight putting it in the tail only moves my C.G. aft .3" but then adds the weight of all the battery cable to get back there. The lead needed in the tail to do the same C.G. change probably weighs less than all the battery cable to make that long run.

    Russell

  4. #4
    Cary's Avatar
    Join Date
    Aug 2011
    Location
    Fort Collins, CO
    Posts
    82
    This reminds me of a conversation I had with my son some years ago as we were getting ready for the annual Ride The Rockies bicycle tour. I was lamenting the weight of my bicycle and how I should perhaps trade it in for a lighter version that might weigh only 17 lbs. instead of my bike's 35 lbs. His comment: "Dad, you could lighten the load a lot if the rider lost 20 lbs."

    Cary
    "I have slipped the surly bonds of earth...,
    put out my hand and touched the face of God." J.G. Magee

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