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XOAR Prop balancing and tolerance

Discussion in 'CineStar FAQ - Tips and Tricks' started by Gary Haynes, Jan 14, 2013.

  1. Gary Haynes

    Gary Haynes Administrator
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    Just got my first order of PJP-N 15x5 props and am surprised that they don't seem to be well balanced. Using a Dubro balancer 1 pair was good, 3 pairs had one prop out of balance and the last pair, neither were balanced.

    I was able to balance most of them by using a bit of scotch tape near the tips and small bits of electrical tape to get the hubs balanced. But while I was able to get the tips balanced on four of the props the hubs appear to need .38g to .70g to balance properly. I checked this by using double side sticky tape and a series of small washers. Checked their weight on an electronic scale that I use for measuring powder that I calibrated.

    So a couple of questions.

    1. What is the proper balancing procedure for XOAR wood props?
    2. What should be done for hubs that need this amount of weight? How should the weight be added?
    3. What would be considered a prop that is to far out of tolerance and should be returned (i.e. is .70g excessive).
     
  2. Pavlos Antoniou

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    Did you buy the balanced props that cost more than 30e per pair???1

    Also in order to balance the tip you put tape or varnish as spray..! And on hub you put some CA with velcro..:)
     
  3. Gary Haynes

    Gary Haynes Administrator
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    So here's my update on balancing Xoar wood props. I bought several sets of the PJP-N Precision Pair Balances props which are Xoar's premium balanced props. The literature says they are balanced for weight within .5 g for the pair. While that was true for the 5 sets i bought it doesn't mean they are statically balanced. I had a series of emails with Xoar and here was their suggestion on final balancing.

    1. Use varnish on the back of the prop to balance when the prop is horizontal in your prop balancer.
    2. Use some form of weight to balance the hub.

    I had seen some suggestion about using something like scotch type tape on the back of the blade. So here's what I ended up doing.

    3 of the total 10 props were perfect. Several only needed a bit of tape on the back of one blade towards the tip. Those needed a bit of tape on the hub for vertical balance. If i could achieve balance with electrical tape I used that.

    But on 3 of the props, after adding multiple layers of electrical tape I decided to find a better solution. So I pulled out my powder scale that I use for reloading and weighed the tape that was being applied. The low was .38g and the highest was .78g. Xoar told me those were within standard tolerance.

    So I scratched the proverbial brain and thought about using lead tape, the type used for golf clubs and tennis rackets to control swing weight. Bought some at the sporting goods store, about $5 for 1/2 x 36 inch strip. I cut a strip about an inch long then trimmed to the width of the hub. Then weighed it on the scale. Trimmed it to be the weight of the temporary electrical tape and checked the balance again and it was spot on using the DuBro Prop Balancer. After multiple flights the combination of the lead tape and small amounts of cellophane tape on the backside of the blades is working well.

    This same method would probably work with APC props rather than the sanding I used to do on the backsides of the props followed by velcro and CA for the hubs. Certainly a lot neater.

    Xoar.JPG
     
  4. Bryan Harvey

    Bryan Harvey Member

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    Gary, Great info. Are you finding notably better performance with the Xoars than the APC props?






     
  5. Gary Haynes

    Gary Haynes Administrator
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    Bryan when I made the switch I was also changing motors so I don't have a direct comparison. I can tell you the sound they make is totally different from the APC's. In my new configuration they do fly very well.
     

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