Sorry. Despite the title of this post, there is no easy way. It's a challenging process. In fact, getting my instrument ticket was one of the most difficult accomplishments of my life. And it took about three years. One issue is that there is an infinite amount of information to learn if you want to "know it all:" Weather, regulations, charts, safety, procedures, etc, etc, etc... and, oh yea, how to fly the plane. When I finally finished, I looked back could see what would have been a much more direct path to the finish line because the expectations I put on myself were somewhat impractical. I would like to share that faster, simpler path with you.
Let me start by saying that I'm not a CFII. So this is nothing more than my personal opinion based on my experience. But I hope it is helpful for you as well.
First, let's review what is needed for an airplane instrument rating under Part 61:
Paraphrased so it is digestible (see FAR 61.65 for the exact wording/requirements), here is your simplified checklist:
Completing this checklist can be overwhelming. Here's the efficient, step-by-step process I wish I had before I started:
Step 1: LOG hood time and clean up your logbook
Start now! Keep a hood in the plane and put it on any time that you are flying with an appropriately rated safety pilot. Start early and log every minute you can. Seriously.
Also, take a look at Form 8710. You will have to fill that out prior to your check ride. There is a ridiculous amount of information needed that is difficult to calculate from your logbook entries. My recommendation is to get your logbook electronic somehow, and be sure you have all of the columns listed in the 8710 so you can fill out the form. You don't need this distraction the night before your checkride. You need to be studying. Get this done. Start today and chip away at it over time.
Step 2: wrap up your cross country hours
Be smart. If you're flying around on the weekends, try to hit that airport a couple of more minutes away so you can count the flight as a cross-country.
#1 and #2 are difficult to quickly "knock out" if you're ready to test. So start those ASAP!
Step 3: Pass the written.
Here's how to do it:
a) Watch the King Schools instrument videos. Pay attention when you watch them and watch them again and again until you "get it." Yes, I know they are dated. But I've watched several other training videos that are newer and my opinion is that the King's program is the best for test prep.
b) When you're finished with the King videos, buy the Sheppard Air Instrument Prep and follow their instructions. That will narrow down what seems to be an infinite amount of information to a more reasonable amount that will actually fit in your head.
c) Now, go pass the written. Get it over with.
One thing to note here, is that I have not said a word yet about flying with a CFII. Let me hop on my soap box for a minute. I think you should respect your instructor's time and be prepared ahead of time by doing your homework. If your CFII is teaching you what is in the book, you're being lazy and inefficient. Don't do that. Learn what you can on your own and go to your CFII with questions. Pass your written so you have some idea what you're doing. Then go fly.
Step 4: Start flying with a CFII
Start immediately after passing your written and don't stop. All of that information from #3 will start draining from your head the minute you leave the exam room. Don't let that happen. Start using what you learned and keep your momentum.
Here are some initial thoughts on flying:
Your Instructor: Get someone that will challenge you and be sure you have good chemistry. This person is going to teach you skills on which your life will some day depend. If you're not comfortable with your instructor, find a new one ASAP because switching later will cost you more time and money.
Your Airplane: I think the right airplane is a C172 with a Garmin GNS430/530 unless you are on a professional route. Then a G1000 is probably more appropriate. Also a complex, high performance airplane wouldn't be my first choice because you will already have your hands (and head) full. And, you could use time to think and a 172 isn't going anywhere quickly. That's good while you're learning.
Step 5: Accumulate hours
Fly an hour with your CFII, practice hours-on-end using a flight sim like FSX or XPlane, then go practice with a safety pilot. Rinse and repeat. Just remember that the sim is free! Use it. Electrons cost a hell of a lot less than 100LL + airplane + instructor.
By the way, you need the sim to be as realistic as possible. For instrument training, this really means the equipment. Be sure the equipment is as close as possible to what is actually in your plane. We had a GNS430, and my opinion the 430 interface is absolutely horrible. To help, I bought a 430 panel for XPlane from RealSimGear. You can run a MUCH more accurate GNS430 simulator with that equipment that way the menus match the real thing. That's what you need. You also manipulate the GPS with real knobs, not a frickin' mouse. Anyway, I love it. Great investment. Highly recommended.
Step 6: Prepare for the check ride
Ok, crunch time! It should be obvious when you're ready for the flight portion of the test, but now you need to get a TON of information in your head at once for the oral. Here's what I recommend:
a) Download, print, and study the ACS. It is free on the FAAs website. There's no excuse for not familiar with this document when you show up for your checkride. Read it. Study it. Know what to expect!
b) Buy the book "Instrument Pilot Oral Exam Guide by Michael D. Hayes." No brainer here. Read it cover to cover then...
c) Buy 200 note cards and start going page by page through the Oral Exam Guide and start filling them out. Pay particular attention to items that are mentioned in the ACS.
d) Divide your note cards into piles. "Easy, Hard, and 'have to know per ACS'" Study them every day in the obvious order. Trust me on this one. I'm the last person you will see carrying around note cards and my family was shocked. But the cards were the most valuable thing I had when preparing. And frankly, I learned ten-times more while making the cards using the book than I did when I read the book. Don't skip the cards!
e) Finally, buy and binge watch the Real-World-IFR course from PilotWorkshops. They are a TON of help in the oral because they really teach you how to think, not just regurgitate the regulations. If you want to impress the examiner, this is the icing on the cake. Crazy good stuff and a fantastic educational format.
Step 7: Schedule the checkride
Let's face it, nothing gets finished without a deadline. So when you think you're about ready to test, find a DPE and get it scheduled a month or so in advance. That will force you to get serious and consider it crunch time.
Step 8: Go do it
Good luck. And don't get all freaked out if you make a mistake during the flight. Noone is perfect. Just relax, fly through any mistakes, and keep on keepin' on!
I hope all of this is helpful. If so, shoot me an email at email@example.com ! I would love to hear from you. And don't forget to buy a DynaVibe before you leave the site! Ok, that was shameless...
Pilots and mechanics alike understand that when a propeller is out of balance, the best thing to do is dynamically balance it. A significantly out-of-balance prop can produce pronounced vibrations that are obvious to pilots, thus becoming a catalyst for getting the prop balanced. The benefits of having a balanced prop are well documented: smoother and safer flying, and lower maintenance costs.
Aircraft vibration is often insidious, slowly and imperceptibly increasing over time. It may not become obvious to pilots until it is severe, because engine mounts dampen what they feel, reducing the amount of vibration felt in the cockpit. However, persistent, low-level vibration can impact the instruments, engine and airframe. Because these low-level vibrations are harder for pilots to feel, they tend to go unresolved as they produce cumulative damage to critical components.
Wayne’s Aircraft Maintenance Services uses a Dynavibe GX3 dynamic balancer and vibration analyzer to help its clients detect and resolve vibration to prevent damage to instruments and other components. The vibration is most often the result of out-of-balance props. Their shop is located in hangar M7 at the Miami Executive Airport, and among their clients are three flight schools located at the airport. Cory Cappe, Director of Maintenance, uses the DynaVibe GX3 while maintaining aircraft for these schools and for his private customers. "Previous to balancing these propellers with DynaVibe, the flight schools were having an issues with instruments and mounts going bad, because of vibration, so we are [now] balancing their aircraft every six months." Since regular balancing of the flight school aircraft began, there have been fewer instrument failures reported.
Cory found that gyro instruments are particularly prone to damage from vibration, requiring costly repairs or replacement. Investing in regular dynamic prop balancing provides a far less costly measure of protection against instrument failure. Vibration can damage engines and airframes as well. Problems such as fatigue cracks or cracked exhaust systems are indicators that vibration may be compromising an airplane’s structural or mechanical integrity.
Cory’s private customers can also feel the difference when they have their aircraft dynamically balanced. A Bonanza came into the shop whose owner reported a bad vibration that he noticed during takeoff. The vibration was so pronounced that the pilot had concerns about flying the airplane. Using the DynaVibe GX3, the initial balancing run on this airplane revealed a vibration between .50 and .60 Inches Per Second (IPS). Vibration of this magnitude definitely indicates a need for balancing, and if left unresolved, can rapidly cause serious damage to the airframe, engine and instruments. Dynamically balancing this Bonanza with DynaVibe reduced the vibration down to just .03 IPS, and the pilot reported that he no longer felt the vibration.
The use of DynaVibe at Wayne’s Aircraft Maintenance Services is resulting in satisfied customers that experience smoother flying and fewer instrument failures. In the first year of usage, the company’s investment in DynaVibe is paying off.
Air2 innovated the provision of helicopter-assisted utility construction and maintenance services for extra-high voltage (EHV) transmission lines throughout North America. The company maintains and flies a fleet of MD 500 helicopters with pilots, crew, and mechanics that are highly trained and specialized for the work they do.
The high voltage power lines the crews at Air2 work on are too in demand to take out of commission for repairs. The Air2 team flies their helicopters into very close proximity to these lines, taking advantage of a thorough understanding of the properties of electrical transmission. The same properties that allow birds to land on power lines without getting electrocuted allow Air2 crews to do their important work, actually transferring linemen from the ship to the line while in hover just feet away from the line. It’s a process you must see to fully appreciate:
Given the critical nature of the work that Air2 does, keeping its ships maintained and in proper track and balance is essential. Tim Galeotti is an Air2 mechanic who helps maintain the eight-ship fleet. Performing regular track-and-balance procedures is part of the maintenance routine. “Well, track and balance, of course, affects the whole aircraft,” says Galeotti. “The closer you can get that reading or vibration down to none in the aircraft, of course, extends the life of your aircraft parts.”
Before acquiring a DynaVibe GX3 with the DynaTrack optical blade tracking accessory, Galeotti had access to two track-and-balance systems from different vendors. Both of these systems had their limitations and both were complicated to use. One broke frequently, and the software on the other one was unreliable. Given the importance of the track-and-balance procedure and the frequency with which Air2 does it for their fleet, having reliable track-and-balance gear is important. Another important factor is gear that is easy to use and allows mechanics to complete the process quickly, “because time is money,” states Galeotti.
Having used other track-and-balance gear, Galeotti was impressed with how easy it was to perform the main rotor track and balance on the MD 500 using DynaVibe with DynaTrack. “I was quite impressed because I've used several other devices,” said Galeotti. “What I found really nice was how user friendly it was. I mean, you didn't have these multiple buttons you had to push to get your result, and all we need is a clock angle, its reading; then, we can just plot it out on a chart. Also, with the tracker, it was nice to show exactly how to move that blade up and down in terms of how many inches or half-an-inch, or whatever you need to do.”
One reason the DynaVibe system with DynaTrack is easy to use is because you don’t need another person to hold, aim, and operate a light gun to do blade tracking. A single person can do everything needed to capture accurate readings. The DynaTrack optical blade tracking accessory attaches to the inside of the ship’s windscreen via a suction cup. The pilot or mechanic simply presses the “push-to-talk” button to measure one or two channels of vibration plus blade track, logging results from up to eight flight conditions per flight. “Holding like a gun... it's hard to hold there and get that image,” says Galeotti about the gun tracking systems he’s used, “but this [DynaTrack] here just takes it. I like that.”
The DynaVibe GX3 and DynaTrack is portable, allowing Galeotti to take the system anywhere the ships go, enabling the track-and-balance procedure to complete even in the field. “It's one of the simplest devices I ever used, and the smallest and lightest. In comparison to others I've used, it's top-rated I'd have to say. For the money that you spend on that, in comparison to others, you all have a product which is cheaper and works better.”
RPX is experiencing record sales for its helicopter track-and-balance kit. The helicopter community is responding enthusiastically to the solution’s ease-of-use and affordable price.
As we work with customers to help them obtain and use DynaVibe with DynaTrack to perform track-and-balance procedures, we get lots of questions about how our system works. This post will share a collection of questions we routinely get, with our answers. If you have questions or want more information about how to track-and-balance your ship, please contact us!
Q: What is the difference between DynaVibe and DynaTrack? Do I need one or both?
A: The DynaVibe GX3 is the handheld system that enables dynamic balancing, vibration analysis, and track-and-balance. An optical tach (a.k.a, phototachometer or phototach) attaches to the GX3 to measure RPM, as do one or two accelerometers to measure vibration magnitude. DynaTrack is an optional optical blade tracking GX3 accessory that enables blade tracking. A complete track-and-balance kit consists of a DynaVibe GX3 (which includes the optical tach and accelerometer) with DynaTrack.
Q: Is the DynaVibe and DynaTrack kit suitable for track-and-balance of 3 or 4 blade helicopters?
A: Yes. The kit will let you work with helicopters that have up to 6 blades.
Q: How big is the system?
A: The DynaVibe GX is a handheld system, as the photo shows, it is small and highly portable, easily used in the field.
Q: Are the accelerometers used by the DynaVibe system permanently fixed to the cables?
A: Yes, the DynaVibe accelerometers and cables are a single, fixed unit. We are aware that competing track-and-balance systems use accelerometers with detachable cables. We know that this question expresses a concern about having to replace the entire unit should a cable get cut or damaged. The good news for our customers is that a complete DynaVibe accelerometer and cable costs less than a cable for our competitor's track-and-balance system! RPX has the most affordable solution for doing track-and-balance.
Q: Does DynaTrack measure the main rotor rpm?
A: The main rotor RPM is measured by the optical tachometer attached to the DynaVibe GX3. The DynaTrack (also attached to the DynaVibe GX3) measures the blade track error.
Q: Does the DynaVibe GX3 system have an input for a magnetic pickup?
A: No. DynaVibe uses the industry's state-of-the-art optical tachometer. This approach is better because it is sometimes difficult to make proper adjustments with a magnetic pickup.
Q: How we can install the optical tachometer in, for example an AS350 helicopter? Should it be placed vertically to the blade or at some angle?
A: This photo shows the setup of the DynaVibe optical tach and accelerometer on an AS350. For most applications, the optical tach is mounted near the transmission and detects a strip of reflective tape on one of the blades grips.
Q: You state that your system can collect up to 8 flight condition reports. How are those condition reports saved? Do I have to clear the SD card where they are stored after every set of measurements?
A: You can get readings (IPS, phase, and track) for up to 8 different conditions per flight. These conditions are per the manufacturer's procedures, or whatever conditions you choose. Once you have completed a flight, you can review all of the conditions for which you captured readings, whether just 1 or all 8. When you begin a second flight, the new flight data will copy over the first flight data. You can go to the track log to review the data you’ve captured. You do not have to manually clear that data for a new flight and new data collection.
Q: Can you tell me about the Push-to-Talk button? What is its purpose?
A: The PTT button is what lets you do pilot-only data collection, if needed. It enables unit operation with a remote (in-cockpit) PTT switch so you do not have to hold the unit or push its buttons to capture readings. This allows for single-person operation, letting a pilot collect that data while concentrating on flying the aircraft. Using DynaTrack does not require two people.
Q: For what helicopters do you have Application Notes?
A: RPX has already published application notes for Bell 205, 206, 407, OH-58, EC350; Hughes 300, R22, R44, and Rotorway. We are regularly completing new Application Notes. Keep in mind that an Application Note is not required to use DynaVibe for track-and-balance on a helicopter, but it is helpful for installation and operation purposes. RPX Application Notes follow the manufacturers recommendations for track-and-balance, so if you have the maintenance manual and corresponding balance charts, you have what you need to track-and-balance using the system.
Q: Can you tell me about calibration? How long does it take?
A: A new DynaVibe GX3 unit comes already calibrated. As with many aviation tools, annual NIST-traceable certification is required for tools used on certified aircraft. For the DynaVibe GX3, recalibration costs just $249 USD. To have it recalibrated, just contact us for an RMA number and then send the unit and accelerometer(s) to RPX; there is no need to send the entire kit. We can complete a recalibration in one day, not including the shipping time.
Q: What kind of guarantee or warranty covers DynaVibe and DynaTrack?
A: We provide a money-back guarantee for the first 30-days after purchase. If you’re not satisfied with the system, you can return it for a full refund. A limited, lifetime warranty covers the purchase of new DynaVibe GX3 systems and DynaTrack accessories. Other accessory items are covered for a one-year period.
Q: In which format is the output file that contains the measurement data?
A: DynaVibe provides its output in the form of an HTML document, so no proprietary software is required to view the data, and it is easily shared.
Q: Are DynaVibe software updates available for free?
A: Yes. Software updates are free and obtained on the support page of the RPX website.
Q: Is it possible to review a User’s Manual for this device?
A: Yes. To obtain one, simply contact us through the website, by email or telephone and we will send you a free, current copy.
If you have other track-and-balance questions, please contact us!
RPX Technologies is pleased to announce that the DynaVibe GX3 with the Turbine Sensor has been accepted by Williams International as vibration analyzer equipment which meets the test requirements for the Williams FJ44 and FJ33 engines. For less than $6,950, Williams Jet Service Centers can equip themselves to perform turbine vibration surveys more profitably.
The DynaVibe turbine system provides Williams Jet Service Centers with affordable equipment for accurate, high-frequency vibration measurement. The system maintains accuracy up to 1.2 million Cycles Per Minute (CPM) and utilizes a high-quality, high-frequency flat-response sensor to deliver measurement data reliably. This system is accepted for Williams-mode acquisition and reporting, providing an ideal vibration survey solution for Williams Jet Service Centers.
Pricing & Availability
The DynaVibe Turbine Vibration Analysis Kit includes a DynaVibe GX3 meter, one turbine sensor, cables, and a manual in a protective case. The kit is available to purchase now for $6,950. Existing DynaVibe GX3 owners can add the turbine sensor to their current GX3 system for $2,955. To learn more about or purchase the DynaVibe Turbine Vibration Analysis Kit, or to add a turbine sensor for existing GX3 units, contact RPX Technologies at +1.405.714.2516 or firstname.lastname@example.org.
It’s been a decade since RPX Technologies began offering DynaVibe propeller balancing equipment to the aviation industry. In that time, we have collected a lot of data about the state of prop imbalance. Our data tells us that about 80% of props are out-of-balance, and when they are dynamically balanced, owners, pilots and mechanics report that the difference is amazing.
What does it mean when we say that 8 out of 10 general aviation aircraft are flying with an unbalanced prop? Technically speaking, it means that the measurable vibration exceeds .15 Inches Per Second (IPS), which is the maximum acceptable vibration level after dynamic balancing. We’ve seen vibration levels that are much greater, and the greater the magnitude, the more damage the vibration can do to the airframe, engine and instruments.
Eliminating vibration is important just for the maintenance benefits alone. But if that is true, why are so many airplanes flying with unbalanced props? The reasons vary, but often it is because of a false assumption that vibration is just the price you pay for having a combustion engine that turns a propeller at a high RPM, and therefore it must be lived with. Don’t buy in to this false assumption!
We’ve seen many DynaVibe users eliminate vibration completely, or get it well below .10 IPS – a level of acceptable vibration. What would YOUR plane feel like after using DynaVibe? The reactions and feedback we get from DynaVibe users that experience flight with a balanced prop answer this question. These comments have a similar theme, and we never tire of hearing them. Here are some we’ve collected through the years:
These are just a sampling of the testimonials we’ve collected from customers about the results they get from using DynaVibe to balance their props. They can feel the difference after balancing. We’ve made it easy and affordable for you to feel the difference too, with the DynaVibe Classic prop balancer costing just $1,495. Contact us to learn more about how you can enjoy smoother, safer flying while lowering your maintenance costs.
As the creators and inventors of DynaVibe – the RPX Technologies dynamic balancing system – we’re naturally proud of the innovation it represents, as well as its affordability. DynaVibe with its accessory DynaTrack optical tracker, or the optional turbine kit, is a leading-edge, state-of-the-art system for prop balancing, blade tracking and turbine vibration surveys. So what?
In the 10 years since RPX was founded, we’ve learned some important truths about how customers perceive and evaluate solutions. We can make some wonderful claims about how affordable DynaVibe is, how easy it is to use, how it makes quick work of prop balancing, or even how differently an airplane or helicopter flies once props are balanced or blades are in track. But, despite the claims we can make about DynaVibe, we’ve learned there’s just one customer question we must answer: “Why should I care?”
In the decade we’ve served the aviation industry, we’ve collected a lot of prop balancing data. We know this: there’s an 80% chance that the general aviation aircraft you are flying has an unbalanced prop. What does that mean? From a technical sense, it means that the measurable vibration exceeds .15 Inches Per Second (IPS), the maximum acceptable vibration level after dynamic balancing. At .15 IPS vibration may not seem like much, but it is not a lack of vibration. Four out of five GA aircraft are flying with vibration levels of .15 IPS or greater.
What’s the problem with this? Vibration only has negative consequences. Your unbalanced prop is either:
Or some combination of these three things.
Dynamically balancing your prop is a quick and easy fix. We have a page on our website – and numerous blog posts – that all share the testimony of those who have rid their aircraft of vibration by using DynaVibe. If we were to summarize, in the sentence, what we often hear after balancing, it would be “I can’t believe the difference!” or “It feels like a brand-new airplane!” You will feel a difference when you dynamically balance your prop. If it could, your plane would thank you.
RPX also sells the most affordable track-and-balance system for helicopters, that also is very easy to use, and streamlines the track-and-balance process. But again, “Why should I care?” is a fair question.
The track-and-balance process is a bit more complex than the prop balancing process, and historically, the equipment has been more complex to use as well. Since we entered this market with our DynaTrack solution, we found that many shops who had older track-and-balance gear were frustrated with it. It was hard to use, took too long to complete the process, or both. The result in many cases was that tracking on blades on some ships wasn’t done, or done very often, because the process was too difficult.
We’ve found that there are two types of users who really value DynaTrack. One is the user who previously could not afford the $20,000+ price tag of a track-and-balance system. At under $7,000, our system is within reach of almost everyone!
The other type of user that has grown to love DynaTrack is the one who was frustrated with their old system. Ours is really easy to set-up and use, and because it is so affordable, you can replace your old, frustrating equipment with the DynaTrack which is easy to operate. With our patented Blue-Track technology, it is easy to accurately track blades under a wider variety of sky conditions, saving you a lot of time and frustration. Because DynaTrack is so affordable, you can have a couple at the shop so your mechanics can work on multiple ships simultaneously and an additional tracker in the field which would increase productivity and make you more money.
In summary, customers care about DynaTrack because it is less frustrating to use than your existing equipment and it will make you more productive. DynaTrack is also contributing to cleaner air around the shops that use it. Not because of carbon emissions, but because its use is not accompanied by cursing. Track, balance, done! No profanity needed.
RPX Technologies announces that its DynaVibe and DynaTrack optical blade tracking accessory have been accepted by the Robinson Helicopter Company for R22-series and R44-series helicopter tracking and balancing purposes.
During the 2018 HAI Heli-Expo, RPX personnel will demonstrate DynaVibe and DynaTrack in booth C4043. This complete track and balance system is simple-to-use, allows users to complete the process quickly, and is priced at less than $7,000 making it the most affordable track and balance system on the market.
RPX provides application notes specifically for Robinson, and the DynaVibe system has built-in setup information for R22-series and R44-series helicopters, streamlining the track and balance process.
“I have used the DynaVibe multiple times to adjust the Robinson R22 track and balance of the main blades, balance the scroll/squirrel cage fan and balance the tail rotor,” stated Mark Young of Tropic Airpower. “I actually got the tail rotor to 0.00 IPS with the DynaVibe. It is very easy to set up. I love the option of being able to take multiple readings per ground run and in-flight checks. Keeping the track and balance correct ensures good reliability of all components on the helicopter. This is a great instrument; I’m very satisfied over all.”
To learn more about using DynaVibe and DynaTrack with your R22 or R44-series Robinson helicopter, contact us using the yellow tab below.
Absolute Aero, with its team of experienced, FAA-licensed A&P and IA mechanics, specializes in maintaining, upgrading, and inspecting a broad range of single and multi-engine aircraft. Working from the Hayward Executive Airport (KHWD), the company uses a DynaVibe GX3 to provide dynamic balancing services to its customers, keeping the revenue in house for these procedures that they used to send out to a prop shop.
In fact, the difficulty scheduling work through the local prop shop provided Brandon Thompson with motivation to purchase DynaVibe. “We'd always used our local propeller shop but it was too hard to schedule them when we needed them and that's why we looked into buying our own equipment.” Absolute Aero now uses DynaVibe on a regular basis, balancing a prop on average every month.
DynaVibe makes dynamic propeller balancing easy. “It is intuitive, and if you just do what it says and you let it find its own solution, it does work very well,” said Thompson. In addition to making the balancing process simple, the DynaVibe GX3 streamlines the process as well through its automatic weight solution calculation feature: “There have been times where it has taken six or seven runs to get it nailed down, but a lot of times it's one or two runs and we nail it down right away.”
Thompson’s experience validates industry data that many general aviation aircraft – up to 80% – are flying around with out-of-balance props. Because of the prevalence of unbalanced props, Absolute Aero’s customers feel a difference after balancing with DynaVibe. “I actually balanced one and the owner didn't know that we had done it. He came in after flying it and he's like, ‘you must have balanced it, because it's a whole new airplane!’ We enjoy using it. When you are able to let DynaVibe process what's actually happening and follow it to the solution, it does very well.”
With high performance airboats, the raw power can approach 1000 HP. As with aircraft, an unbalanced airboat propeller will quickly turn some percentage of that raw power into damaging or even catastrophic vibrations. RPX Technologies recently spoke with Steve Boser, Sensenich VP of Engineering, about using the DynaVibe GX to balance an 850 HP airboat.
Sensenich Propeller Manufacturing Company manufacturers lines of propellers out of carbon fiber, aluminum, wood, or wood composites for aircraft, UAVs, and airboats. Of course, Sensenich propellers are statically balanced during manufacturing and subsequent servicing. However, as with any prop, a dynamic balance after installation can balance the influence of the entire rotating assembly into which that prop is now integrated.
A Sensenich customer that manufacturers airboats was encountering some balancing challenges with their assembly. “My airboat sales manager reached out” says Boser. “He said ‘Hey, is there anything we can do to help these guys out? I don’t think it’s a static balance issue. It’s a pretty novel installation.’”
“There’s a total of 16 blades,” says Boser. “That’s an eight-bladed propeller on the front. Then there’s an eight-bladed propeller on the back. There’s a coaxial shaft. You have a front shaft with a big hollow space in it, and then you’ve got a smaller shaft that sticks through it to the rear prop. They turn in opposite directions. The marine [airboat] guys call it a counter rotator. The aircraft guys call them contra rotating.”
Boser’s engineering team already had a DynaVibe GX for use as an engineering tool with spectral analysis. “Also, to help us in refining procedures for static balance,” says Boser.
Sensenich agreed to send Boser, along with the DynaVibe GX, to help troubleshoot this contra-rotating 16-bladed 850-HP power plant. This power plant can propel the large airboat across the water at up to 80 MPH. However, before this high-performance airboat could be delivered, the vibration issues had to be tamed.
Boser made some initial measurements with the GX, but there wasn’t an application note for this unique setup, so he ended up contacting Steve Sennett at RPX, the makers of DynaVibe. “I reached out to Steve,” says Boser. “and after about 20 minutes I had it all figured out.”
Because of the design of the counter-rotating prop assembly, the rear prop could be removed but it was not practical to remove the front prop. Therefore, Boser first balanced the front prop with the rear prop removed and then balanced the rear prop with the now-balanced front prop in place. In this counter-rotating setup, the props are mechanically locked 1:1 in rotations, so Boser did not have to move the optical tach to balance either prop.
“Half of it was getting into the routine of removing and adding weights,” says Boser. Sensenich Saber Blades are designed to mount on a Warp Drive hub. “There are four bolts that hold each blade into a plate hub. It’s like two aluminum plates that sandwich the blade pitch blocks. Once I got into the routine of getting them apart and adding the weights it went pretty fast.”
“I’d get it up to cruising RPM because that’s where I wanted to ensure it was going to be nice and smooth,” says Boser. “They don’t go full throttle for a long period of time. It’s just like an aircraft, you’re going to be trucking around at cruise RPM. It was 1,100 RPM on the prop or so. It was around 3,000 RPM on the engine with a 2.68 reduction.”
“I think I got the front prop in about three runs” says Boser, “and I got the rear prop in two runs. I ended up with a 0.04 IPS on it. Went very fast.”
The core business of RPX is aviation -- its passion is making anything with a prop spin more smoothly to minimize damaging and uncomfortable vibrations. Whether you’re piloting an experimental canard pusher, a traditional tractor-design aircraft that pulls itself through the air, or even a Skymaster that pushes and pulls, RPX can help. Even if you are skimming around the bayou, or navigating flood waters in water-rescue operations -- DynaVibe can balance your airboat prop too. If it’s got a prop and it rotates, contact RPX to let us help you smooth out your ride and find out which DynaVibe is right for you.