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  • Re: Wheel and static prop balancer

    by » 3 months ago


    Hi Sean

    I have worked with the Microvib balancer years ago.  it was invaluable for vibration analysis as well as prop balancing.  The major drawback is the price as it is a very high quality system.  it will take about 6000 USD to buy a new unit.  Dynavib is less than ½ of that cost and pretty much can do the same things.  For prop balancing it is just fine.  Check suppliers in your country and there may be companies in the EU that i am not aware of that you can get in Australia.  

    So, pro and con.  Big con, cost and time it takes to get proficient at learning how to do it.  This is solved by sitting down with the internet and some time.  All of the companies in general aviation use some type of system.  In your area find a helicopter service depot and they will always have some type of dynamic balance system.  Another con, anytime you remove the prop in theory you have to rebalance.  There are  some simple tricks to limit the problem however.  Always mount the prop in the same bolt holes prop hub relative to the prop flange.  Always keep the same blades in the same location in the hub if a replaceable blade system is used.  For the most part once done unless you damage a blade or take the prop off you should be just fine.  So that is the cons from my view.  

    Pros are simple.  Silky smooth running when done right, the difference can be dramatic if you have never had a fully dynamic balanced prop.  The gearbox will love you, if that is possible but it feels that way.  For the carb engines it will make a huge difference in float, needle, and slide wear since these parts are the most susceptible to micro vibrations over time.  I also believe it reduces stress on the blades of the prop in that they are not flapping out of sync with each other but that is my opinion.

    Best way to buy it for sure is as a club.  If you pay 3000 USD for a Dynavib then everyone chips in each time it is used.  Most clubs who have them have a charge to use it and only the trained person is allowed to work it.  In the USA private shops charge out about 100 USD for a full dynamic balance.  in that way even if you take the plunge and buy it yourself you can pay back your investment over time.  I would avoid units that are not designed for aviation props myself.  

    Just my views, I am sure Roger will get round to a response at some point. 

    Last point.  The recommended max IPS from most prop manufacturers is 1.2 IPS.  (you can work out the hertz equivalent if you but a European version balancer) 

    Cheers


    Thank you said by: Sean Griffin

  • Re: Wheel and static prop balancer

    by » 3 months ago


    Hi Sean,

    I agree with RW and there is no down side to having a well balanced prop and spinner. Like RW said your engine will love you. Many forget the spinner, nuts and bolts, prop pitch and the prop MFG all plays a part here too.

     I use an Aces dynamic balancer. I've had it a long time and it works, but there are newer models out now. I'm not sure of the cost today. You'd have to check with them. In the older days props made out of wood and other heavy materials  that weren't well balanced really needed balancing. It makes a big difference over time on the engine. Most pilots don't know what a normal vibration is and most can't feel the vibration with the human body unless it's getting bad. Now doys many composite props are far better balanced than they used to be and they are lighter than older heavy props. Then add in the way that some Mfg's and people install props. I see planes right from the factory one degree off between blades at times.I personally think anything more than 1/10 of a degree off between blades is a sin.

    I learned how to use a Chadwick balancer when I owned a helicopter. That really needed to be balanced and not just let go.

    I think planes should have a prop balance done. It should be good for a long time unless you cause damage to the prop or add or subtract something from up in the spinner, prop flange and prop area.

    No real drawback to a good prop balance. Here in the USA getting a balance now days is around $350 - $500. If you buy your own balancer then the initial out of pocket cost is a drawback, but you could make that money back by balancing other people's props. Just a thought.

    p.s.

    Many props have weights located in them and sometime they can come loose. That said that vibration is really bad and can easily be felt.

    Todays balancers are better than they were 20+ years ago.

    vibration levels


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


    Thank you said by: Sean Griffin

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