DynaVibe Blog

The Frog in the Kettle: A Prop Balancing Metaphor

 Thursday, December 31, 2015

The DynaVibe team can’t help but think of the frog in the kettle as a metaphor for prop balancing.  If you’re not familiar with this anecdote, it tells how a frog reacts to two different situations.  If placed in boiling water, it immediately perceives the danger and jumps out.  But if placed in cold water that is slowly heated, it doesn’t react to the gradual change in its environment and is ultimately boiled to death.  This story is a great metaphor for the inability or unwillingness of people to recognize and respond to gradual change.

Photo © 2010 J. Ronald Lee.

What brought this metaphor to mind was an article recently posted by Paul Dye, editor-in-chief of Kitplanes Magazine.  Paul wrote about his experience using DynaVibe to balance the prop on his RV-3, and he stated:  “It’s the old (probably apocryphal) problem of boiling the frog – if you gradually turn up the heat, it doesn’t know that the temperature is rising. With a slight degradation over time, we don’t realize we are losing balance. Then we reset, and all the smooth magic is back!

Paul nails it.  You just get used to the vibration from imbalance.  It often increases slowly, so a gradual change in vibration isn't noticed.  Many pilots and owners just assume that a certain amount of vibration “comes with the territory.”  It’s the price you pay for combustion engine-powered flight.   But it is wrong.  We get a steady stream of feedback from DynaVibe users and customers of shops that use DynaVibe to provide balancing services.  The feedback follows one of two tracks:

A. Owner whose mechanic or friend talks him into balancing the prop:

  • Owner before: “You can balance the prop if you want, but I don’t have a vibration problem.”
  • Owner after:  “Wow, I can’t believe how smooth it is!

B. Owner who is experiencing a vibration and wants to fix it:

  • Owner before: “The vibration is so bad that it is…. (followed by listing one or more symptoms of the vibration, such as avionics failures, a rough RPM range, fatigue cracks, etc.)
  • Owner after:  “Wow, I can’t believe how smooth it is!

We could go on, but we prefer to let the beneficiaries of prop balancing do the talking for us:

From a FlightLevel Aviation customer:  “While our Bonanza was in for its annual inspection late last year, FL approached us with an option to have the prop balanced. The A36 has the big IO-550, and we felt it ran fairly smooth coupled to a 3 x blade prop. For the relatively small additional price, we opted to try it out anyway. The first time advancing the throttle for take-off after the balancing was complete, I had to look a few times at the MP and Tach gauges to insure the engine was making full power! It ran noticeably smoother through all phases of flight, and the only disappointment was that we didn't do it sooner…."

From a KSFB Aircraft Maintenance Center customer:  “Can’t believe the results!  First run showed it was a long way from acceptable; 0.6 IPS.  The second run we homed in on a better solution; 0.19 IPS.  3rd run was spot on; 0.01 IPS. Compare that with the scale on the LHS [DynaVibe balancing report] which calls 0.05 ‘Excellent’.  The ‘feel’ of the plane, just sitting on the ground in the driver’s seat was remarkably different, too.

From Dennis Barker, President of Reynolds Aviation:  “The pilots were thrilled with how the yoke feels after we balance an airplane. They noticed a difference immediately."

There’s more, and you can read other testimonials on our website.  When it comes to dynamic propeller balancing, perhaps Mark Langford said it best to those who haven’t yet done this procedure on their airplane:  “You guys just don't know what you're missing...

Find out what you’re missing by contacting the DynaVibe team to learn more.  Enter your email address in the form below and we’ll respond to you.  Visit the online store to buy your own DynaVibe unit, email us with your questions at sales@rpxtech.com or just call us if you have questions about the process:  469.708.8779.

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Questions? Contact us at sales@rpxtech.com