705 South 5300 West
Unit #4 - 5
Hurricane, UT 84737

435-627-0942

made in America

 

 



POWERFIN BALANCING BLADES

       Jan 2010: SAFETY DIRECTIVE
Replacement Blades for PowerFin Propellers made prior to 2009: WEIGHT BALANCING
(click here to download this information in a PDF file)


ADDING WEIGHT TO THE BLADES

IMPORTANT

 APPLY THE FOLLOWING PROCEDURE AT YOUR OWN RISK

It is a mistake to attempt to equalize the weight of the blades by weighing them individually on a scale and making them all the same. If you try this you will ruin your propeller.

IMPORTANT

 APPLY THE FOLLOWING PROCEDURE AT YOUR OWN RISK
       

Weight, for the purpose of creating balance in a propeller, must be added so the moment of each blade is equal. At POWERFIN, we have a special jig that allows us to check each blade one at a time. You can't easily make this jig so you have only one option; you must obtain equal moments on the blades in your propeller by comparing them to each other. This can only be done with the propeller assembled as a unit using some sort of balancing device that checks the prop as an assembled unit.

There are various methods used to indicate a balanced or out of balance condition on a propeller. Perhaps your local group of flying friends or your local dealer has a system established to balance propellers as a unit. Though the cost of a mechanical device such as the Propmaster Digital balancing tool is quite high, this particular device is very effective to indicate an out of balance condition on a propeller assembly. There are certainly less expensive, but less accurate ways to indicate balance on a propeller. The method below does not describe how to observe the out of balance condition of a propeller, only how to add balance weight to a propeller blade once an imbalanced condition is observed. The purpose of these directions is to indicate how and where to add required balance weight in order to leave the blade with no blemish or severe alteration.

Follow these directions very carefully to achieve accurate results. Please remember only the factory can make weight changes to the blade without voiding an existing warranty. To use the process described below will void any warranty on the propeller. 

There is a cavity molded into the blade where the balance weight goes. This cavity is accessed through the root of the blade. The depth of the cavity is slightly different on each blade. This is not important. What is important is to know where the cavity ends on each blade and to mark the blade on the outside to indicate this.

  1. Disassemble the propeller blades from the hub.

  2. Remove the orange plastic caps in the root of the blades.

  3. Take a straight, stiff wire (a straightened coat hanger, a piece of piano wire) and plumb the depth of the cavity in the root of each blade. Put the wire in the hole, find where the cavity ends, and carefully mark the wire so that you can put a mark on the outside of the blade to indicate exactly where that cavity ends on that blade. It is important to use a piece of wire that is thin enough to be sure you are hitting the bottom of the cavity. With a wood dowel or stick, the thickness may give a false reading. The cavity tapers and a stick that is too thick will become wedged in the sides of the cavity, not reaching the bottom.

  4. Take a piece of masking tape, and lay it on the outside of each blade according to the mark on the wire. Measure and mark each blade separately. The cavity depth will be different on each blade. 

  5. Reassemble the prop, leaving the masking tape markers in place. Try to approximate the pitch you think is proper when reassembling the propeller. Also, be sure the blades are pulled outward so that they seat properly in the hub before attempting to check the balance.

  6. As an assembled propeller, using your chosen method, determine the blade or blades with the lighter moments, if any. Remember, there numerous ways to do this and some are better than others.

  7. Add additional, small pieces of masking tape to add weight to the blade. Place them right over the markers that indicate the end of the cavity.

  8. When the propeller seems balanced, disassemble it once again.

  9. Take the original marker pieces of masking tape, and any that were added to make the blades balance, and peel them apart from each other.

  10. With each separated piece of tape, roll it into a little ball and put it into the root of the blade it came from. Don't tamp the tape into the ends of the cavities. Centrifugal force will force them into place. Tamping the weight in place may cause damage to the cavity.

  11. Replace the orange caps and reassemble the propeller.

  12. IF you are careful, these steps should serve you well


    POWERFIN Propellers manufactures Light Sport propeller applications which include UAV, LSA, Ultralight, and Experimental propellers as well as wind energy generating blades.

POWERFIN is dedicated to combining the best of good-ole-American-fashion integrity and innovation with advanced composite technologies.
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