DynaVibe Blog

Case Study: Lee Household Flour Mill

Thursday, May 26, 2016

Royal Lee Organics is a subsidiary of Standard Process®. Since 1929, Standard Process has been dedicated to the field of nutritional supplements and the whole food philosophy introduced by Dr. Royal Lee. Royal Lee Organics provides organic ingredients as well as a re-designed version of Dr. Lee’s household flour mill that was originally designed in 1949.

When Dr. Lee first developed the mill in the 1940’s, he was concerned about what was happening to flour. In order to avoid spoilage, commercial mills were discarding the germ and the bran through a process called extraction, resulting in a less nutritious ingredient.  Dr. Lee provided an alternative, allowing bakers to purchase and store grains in their natural state and mill them at home when needed.  The result was fresh flour with all of its naturally occurring nutrients.

The original Lee flour mills were manufactured by hand, and many of them from the past 50 years are still in use which is a testament to the reliability and durability of the design.  The previous manufacturing process, however, was expensive and time-consuming, so the engineering team made some changes to the flour mill in order manufacture it in a production environment. 

One of the challenges the engineering team dealt with involved the rotating disk inside the mill.  This disk creates an air current that rubs the grains up against the stone, an action that reduces the grains into flour.  This disk rotates at high speeds, between 5,000 and 10,000 RPM.  Anytime a component that rotates at such high speeds is out-of-balance, it will create problems.  The least of these problems is that the machine becomes louder, which is unpleasant for the user.  A more damaging consequence is that vibrations from out-of-balance conditions can cause early life failure of the motor.  For these reasons, the Lee engineering team spent a lot of time determining what to do about balancing these rotating disks. 

The team considered sending the disks to a third party for professional balancing, but that option proved too expensive and impractical.  Instead, the team developed a manufacturing process that produces disks that are true and round. This resulted in a component that is as “in-balance” as possible.  To verify this, the Lee Engineering team built a testing procedure using the DynaVibe GX2 system to measure vibration of the motor and rotating disk.  Now, the vibration level of every flour mill is tested before it leaves the factory, ensuring that they fall within the specification limits the engineering team developed through various trials.

DynaVibe is helping assure that consumers are getting flour mills that live up to the traditions of quality and reliability for which the brand is known.  The full vibration spectrum and balance data that DynaVibe provides also gives the Lee Engineering team baseline metrics and set of benchmarks the team can use to further improve the design of the mill in the future.  With DynaVibe, there is certainty about how much vibration may exist and where it comes from. This helps ensure that the flour mills that leave the factory meet the standard of excellence.

To learn how DynaVibe can address your equipment balancing or vibration analysis needs, simply enter your email address in the box below.  Shop for a DynaVibe system in the online store, or contact us with your questions at 650.800.3092 or sales@rpxtech.com.

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Predicted Financial Impact of UAVs in the Billions

Friday, May 20, 2016

In the space of a few years, Unmanned Aerial Vehicles (UAVs) or drones have gone from being in the domain of the military or hobbyists to mainstream.  An article in Business Insider shares data from a PricewaterhousCoopers report predicting that drones could replace billions of dollars of human labor, as the chart from this article shows:

As the chart illustrates, drones are projected to have the biggest commercial impact in the infrastructure and agriculture sectors.  For example, human inspections of wind turbines are costly and potentially dangerous.  SkySpecs, a startup company deploys drones to conduct safe, automated inspections at about half the cost of human inspections.

The RPX Technologies team recently participated in the Association for Unmanned Vehicle Systems International (AUVSI) Xponential exhibition, where the interest in dynamic balancing and vibration analysis for drones was high.   It’s easy to understand the reason why:  The commercial use of UAVs almost always involves high quality, high-resolution video or photography, and vibration impairs this application. Furthermore, sustained vibration can lead to failure of airframes, instruments and engines in just the same way it does in sport, general and commercial aviation aircraft.  Commercial drone operators are discovering that DynaVibe helps ensure they are delivering the highest quality services to their clients, while also keeping their fleets at maximum readiness. 

DynaVibe is a dynamic propeller balancing and vibration analyzing system.  Simple to use, it allows UAV owners and operators to quickly measure and resolve propeller vibration.  While vibration dampening mounts and gimbals can help minimize the effects of vibration, the best approach is to eliminate it altogether.  Eliminating vibration is of particular importance with UAVs, because these lighter structure aircraft are more prone to shake from vibration than are larger, heavier aircraft.

The DynaVibe GX2 also allows users to conduct full-spectrum vibration surveys to identify and resolve vibration from sources other than the propeller.  The benefit of dynamically balancing and analyzing the vibration of drones is the smoothest, quietest flight to enable maximum resolution of photography, and highest possible uptime of all flight systems.  To learn more about the benefits of DynaVibe for UAV operations, contact us by phone at 650.800.3092 or by email: sales@rpxtech.com.  Shop in our online store for DynaVibe. Or, simply provide your email address in the form below and we’ll contact you.

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DynaVibe and UAVs

Saturday, April 30, 2016

Unmanned Aerial Vehicles (UAVs), or drones as they are commonly known, are subject to the same vibration issues as other propeller-driven aircraft.  An unbalanced prop assembly can create vibrations that damage the engine, airframe instruments and interfere with the mission.

Excessive vibration can interfere with the mission of a UAV, particularly those used for surveillance, reconnaissance, and aerial filming or photography.  Vibration can distort the image.  Vibration dampening camera mounts and gimbals are commonly used in UAVs to deal with this problem, but the ideal solution is to eliminate the source of the vibration.  Balancing the propeller assembly with DynaVibe easily does this, and the DynaVibe Classic provides an affordable solution for UAV operators who need to the highest possible image quality.

For more information about the benefits of dynamically balancing UAV propeller assemblies, contact the DynaVibe team by phone at 650.800.3092 or by email: sales@rpxtech.com.  Visit our online store to shop for DynaVibe, or simply provide your email address in the form below and we’ll contact you.

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LOBO puts DynaVibe in Engine Test Kits

Thursday, March 31, 2016

Bob Pastusek is vice-president and a board member of the Lancair Owners & Builders Organization – LOBO – and is their go-to maintenance guy.  A few years ago, the LOBO Board became concerned that people were not tuning up their airplanes properly; they were not following all the recommended engine and airplane manufacturer’s guidelines in doing their condition inspections.  “Experimental owners are not obliged to follow them,” said Pastusek.  “Nonetheless, like putting air in your tires or oil in your engine, some recommendations are more significant than others.  We came to the conclusion that some people were not doing some of the important ones, based on accidents and probable cause findings that indicated maintenance wasn’t as good on these airplanes as it could be.”

In December 2014, LOBO put together a kit of materials for testing and inspecting the engines, specifically Continental aircraft engines.  “This worked out really well for us,” Pastusek continued.  “So at the fall LOBO fly-in, we asked what people (members) thought about it, and the feedback expressed a desire to include some additional equipment in the kit. One of the principal requested pieces of equipment was a prop balancer.” 

Pastusek first learned about the DynaVibe propeller balancing system at Oshkosh four or five years ago.  He bought one for his local EAA chapter and has used it several times to help chapter members balance their props.  “Having personal experience with DynaVibe, knowing that it works and that it is a reasonably priced piece of gear that our average homebuilder could figure out how to use, we bought new DynaVibe systems to include in our three engine inspection and tune-up kits.

Pastusek recognizes the importance of keeping the prop in balance.  “It makes the airplane engine run smoother, with less wear-and-tear on the engine.  The aircraft is much more pleasant to fly.”  In general, Lancairs use factory-balanced, high-end adjustable pitch props.  “They come pretty well balanced; we generally don’t have an issue with props significantly out-of-balance.  However, there are a couple of things that homebuilders can do, particularly in mounting the spinners and things like that, that can cause them to be out of balance.  It’s a very easy thing to check and improve.  If you find the prop out of balance and fix it, it really makes the airplane run a lot smoother.  These are very large engines in relatively small and lightweight aircraft, so a prop imbalance will shake the airplane around pretty well.”

The LOBO engine test kit with the DynaVibe prop balancing system is expected to be available to members in April 2016.  “We think the DynaVibe is a relatively sophisticated but easy tool to use in the field,” Pastusek concluded.  “It works like a champ.”  

The affordable DynaVibe Classic propeller balancing system is just $1,495 shop for it the DynaVibe online store.  If you'd like to know more about DynaVibe, please contact us at 650.800.3092, sales@rpxtech.com, or simply enter your email address in the form below and we'll contact you!

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Why Statically Balanced Props Still Need Dynamic Balancing

Monday, March 14, 2016

A balanced propeller assembly is important not just for having a smooth flying experience, but also for the health and longevity of an airplane’s engine, instruments and airframe.  Statically balancing a propeller can help reduce vibrations, but to reduce prop imbalance-induced vibration to the minimum, dynamic balancing is recommended. 

This story of a Beechcraft Super Musketeer illustrates the importance of dynamic prop balancing, even after static balancing has been performed.  This Beech had a 200 horsepower Lycoming engine and a constant speed prop.  The airplane had long experienced a vibration problem, but the owner had never attempted to resolve it.  The airplane’s propeller was last statically balanced in 2000.

Even though a prop has been statically balanced, once mounted, things can change because the entire propeller assembly comes into play, not just the perfectly balanced, ready-to-mount prop.  

It takes just the slightest change in mass anywhere in the propeller assembly to change the balance and introduce a vibration.  These numbers illustrate this reality:  a perfectly balanced prop, offset by just .0005 inches during installation, can cause a vibration of .6 Inches per Second (IPS)!  This scenario occurs more often than most pilots or owners know, because many props don’t have an indexing mechanism to ensure that during mounting, the prop it is perfectly centered with the crankshaft.  The dynamic balancing process corrects these “coupling” errors that can result when mounting a prop.

In the case of the Super Musketeer, the prop imbalance was discovered when the owner brought it in for some maintenance.  The mechanic had access to a DynaVibe balancing system and did a quick prop balance check.  This check revealed a severe vibration of 1.5 IPS, well above the FAA specified maximum limit of 1.2 IPS for prop vibration.  A vibration of this magnitude mandates removal of the prop for static balancing.  The mechanic pulled the prop off and sent it to a prop shop for inspection and static balancing.  The mechanic and owner were surprised to discover that during the previous static balance from 15 years ago, the weight had been added to the wrong prop blade, making the balance and vibration problem worse, not better.  The owner had lived with this problem, simply assuming that some level of vibration is a product of combustion. 

After the static balancing was complete, the mechanic remounted the prop on the Super Musketeer and dynamically checked the balance.  The static balancing process had reduced the prop vibration by about half, to .67 IPS.  Using the weight solution provided during the initial dynamic balancing check, the mechanic added the prescribed weight where indicated and did a second balancing run, which showed the vibration had dropped to .04 IPS, well below the level that is discernible by the pilot or passengers.  The following report was generated by the DynaVibe GX2 and shows the results of the dynamic balancing runs, including the level of vibration detected and the weight solution calculated to resolve the detected vibration, and where to install it:

The owner’s feedback after dynamic balancing was that his Musketeer felt like a totally new airplane!  Static balancing, followed by dynamic balancing, is a great way to get a smoother flying experience and take stress off of the engine, instruments and airframe.  You can get similar results:  shop for DynaVibe in our online store, or if you have questions, please call us at 650.800.3092, send email to sales@rpxtech.com or enter your email address in the form below.  

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When Prop Balancing Isn't Enough: Troubleshooting Complex Vibrations

Friday, February 26, 2016

This webinar was part of the EAA webinar series and was originally broadcast on February 24, 2016.  It features RPX Technologies co-founder Matt Dock as presenter.


To learn more about using DynaVibe to dynamically balance your prop, or to conduct a vibration survey to pinpoint more complex vibrations, please call us at 650.800.3092 or by email:  sales@rpxtech.com.  If you prefer, enter your email address in the form below and we'll contact you! Shop for DynaVibe by visiting our online store.

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Video: Vibration Surveys with DynaVibe

Tuesday, February 23, 2016

There's increasing talk about vibrations surveys - what they are, why and how to do them - for good reason: vibrations damage aircraft. A vibration survey will allow you to pinpoint the source of a vibration so that you don't have to pay for speculative maintenance in an effort to resolve it.  We've written a lot recently in this blog about vibration surveys, and now we've done one better: we can show you the process in our new video!

We set up an RV-12 with a Rotax 912 engine for balancing and vibration surveying with the DynaVibe GX2, our dynamic prop balancer that also has vibration survey capability.  In just over three minutes, the video will show you the process sequence and sensor placement for collecting a vibe survey.  You can watch it here:

If you are new to the concept and practice of vibe surveys, please review some of our older posts that discuss this subject.  Even better, we welcome your inquiries on how and why to perform vibe surveys, and how to interpret the results you're seeing.  Feel free to call us at 650.800.3092, send email to sales@rpxtech.com or simply fill your email address in the form below to have us contact you.  To shop for a DynaVibe system, visit out online store.

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Smooth Sailing at Chris Air with DynaVibe

Monday, February 22, 2016

David Trotter is Director of Maintenance at Chris Air, an agricultural operator that flies out of Lake Village Municipal Airport (M32) in Lake Village, Arkansas.  David recently purchased a DynaVibe Classic, and after using it contacted us to share his experience using the system. 

David balanced three of his aircraft, getting the prop imbalance balance on one of them down to .01 Inches Per Second in four run-ups.  David shared, “We would normally be flying the airplanes about 40 miles to another shop for prop balancing.  By my estimation we have already paid for the unit!”

A Chris Air Thrush whose prop was balanced by DynaVibe

Learn how you can get these same benefits from DynaVibe by calling us at 650.800.3092, sending email to sales@rpxtech.com or by providing us with your email address using the form below.  Visit our online store to shop for your own DynaVibe!

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Airboat Balancing with DynaVibe

Monday, February 15, 2016

Props are every bit as critical to the performance of airboats as airplane propellers are to aircraft.  DynaVibe balances both equally well, as the principles of balancing don’t differ from airplanes to airboats.  The benefits are also similar:  less stress on the engine, the propeller, the mounts, instruments and hull.

Airboat propeller balancing with DynaVibe

Here are two stories of airboat prop balancing with DynaVibe.

An owner who had installed a modified 502 V-8 engine in his airboat experienced a problem on the 5-bladed prop he was using.  After just 10 hours of use on the prop, the blades cracked, resulting in a catastrophic failure.  Because the owner had balanced the prop at installation with DynaVibe, he had the diagnostic data to allow the blade manufacturer to rule out imbalance as the cause of the failure.  Instead, the manufacturer determined that there wasn’t sufficient blade surface for the horsepower of the engine: the powerful engine was spinning the blades too fast.  The manufacturer provided a new, 6-bladed prop at no charge to this owner.  The new prop was also balanced, going from an initial vibration of .65 Inches Per Second (IPS) to .06 IPS on the final run.  This owner shared, “It felt really good having the information from the DynaVibe balancing runs to go to the prop manufacturer on a warranty claim, which they quickly honored.”

Another airboat owner got help balancing his prop from a DynaVibe GX2 user.  This airboat was running a Whirlwind prop on a Chevy engine with a Rotator brand reduction, and it was experiencing a pretty bad vibration in RPM transition at about 1/3 power.  This initial balancing run revealed a severe vibration of 2.35 IPS, which after a series of balancing runs was reduced to .13 IPS.  The GX2 owner shared, “At the last weight addition, it (the vibration) cleaned up significantly.”  The following photo shows the balancing setup for this airboat:

An airboat prop set up for balancing with DynaVibe

DynaVibe owners can use their existing systems to balance airboats to get better performance and improve reliability.  To learn more about using DynaVibe to balance airboats, call us at 650.800.3092 or enter your email address in the box below and a DynaVibe team member will contact you.  Visit the online store to shop for DynaVibe.  We welcome your questions!

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Engine Trend Monitoring with Vibration Surveys

Wednesday, February 03, 2016

For any operator, particularly the ag aviation operator, having an engine go out-of-service unexpectedly is not only frustrating, but potentially revenue-impacting, or worse, life-threatening.  It’s not possible to predict all engine failures in advance, but it is possible to detect many of them through the use of a full-spectrum vibration survey.

A full-spectrum vibration survey, or vibe survey for short, is a procedure that uses engine-mounted sensors to measure the frequency and magnitude of vibrations emitted by an engine.  Certain frequencies of vibrations map to specific problems or potential problems.  In other words, a vibe survey can tell you a number of things about what’s going on inside your engine based on the presence of vibrations.  Identifying these vibrations early, when they’re relatively small, allows the operator to address them before they result in a failure.  For this reason, a vibe survey is an excellent preventative maintenance tool. 

Conducting a vibe survey doesn’t take long, and most of the time is spent setting up the airplane with a phototachometer, reflective tape and an accelerometer to measure the vibration.  Once the airplane is set up, the engine is run up to operating RPM and with the push of a button, the vibe survey data is captured.  The photograph below shows the set up on a Grumman Ag-Cat with a Garrett TPE331 engine and a 3-blade prop:

Grumman Ag-Cat set up for dynamic prop balancing and vibration analysis

Vibe surveys measure vibration in Inches Per Second (IPS).  In general, the maximum, acceptable level of vibration is .15 IPS.  However, vibrations at this level probably escape the notice of the operator, but a vibe survey can detect a vibration that an operator can’t yet feel.  Vibrations of .50 IPS are substantial enough that, over time, they can damage the engine, airframe or instruments. 

Most of the time, vibrations are the result of propeller assembly imbalance, a condition corrected by dynamically balancing the prop.  Typically, a vibe survey is done as part of dynamic propeller balancing.  The table below shows the actual result of a series of prop balancing runs performed using a DynaVibe GX2 prop balancer and vibration analyzer on the Ag-Cat.

Grumman Ag-Cat dynamic balancing runs table of results

The second column in the chart above shows the vibration magnitude for each successive prop balancing run.  Subsequent columns show the recommended weight and location for adding that weight to balance the prop.  At the end of the third balancing run, the vibration was almost eliminated, and was at a low enough level to not require further balancing runs.

Sometimes vibrations are more complex, and the value of a vibe survey is revealing the source of the vibration, particularly if the cause is something other than the prop.  In the case of this particular Ag-Cat, the post-prop balancing vibe survey looked like this:

Vibration survey from a Grumman Ag-Cat with a Garrett TPE331 engine

After prop balancing the only significant vibration remaining is the 3-per vibration (100 Hz) caused by the 3-bladed prop passing near the ground.  This vibration is not a concern as it will go away once in the Ag-Cat is in the air.

Vibe surveys are a great way to do engine trend monitoring.  Conduct a vibe survey on a new engine or anytime an engine has been overhauled.  This baseline vibe survey then serves as the benchmark for comparing future vibe surveys done at regular intervals.  The approach allows detection of vibrations when they’re relatively slight, before the operator can feel them.  The operator is alerted to their presence and can continue to monitor them and address them before they grow to the point where they can damage the engine, or worse, result in a failure. 

Matthew Mitchell, who operates Mitchell Flying Service based out of Perry Municipal Airport (F22) in Oklahoma, has been flying since 1990 and puts about 250 to 300 hours per year on his Grumman Ag-Cat.  Mitchell has two TPE-331 engines that he rotates as needed.  Anytime Mitchell puts an engine together, he likes to have a baseline vibe survey done.  This allows him to monitor the health of that engine while it is in use.  Regular vibrations surveys can help operators like Mitchell to identify problems before they cause a shutdown or result in a failure.

The DynaVibe GX2 system is the most affordable way to do dynamic propeller balancing and vibration surveys for engine trend monitoring.  To learn more, contact the DynaVibe team at 469.708.8779 or sales@rpxtech.com. You can also enter your email address in the form below if you want us to contact you.  If you'd like to shop for a DynaVibe GX2, visit our online store.  

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Questions? Contact us at sales@rpxtech.com