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DynaVibe

initial impression

Well, it appears no one else has seen one of these??
We used ours (RAA Brampton)for the first time last week and it seems like it works well. Had to fashion a bracket to attach the little light unit to the top of the engine but it was easy to attach and seemed to stay secure while the test runs were accomplished. We used bolts and washers attached to the flywheel to make weight adjustments but managed to balance everything after about 12 runs ... it gets tougher as you get closer to being perfectly balanced but the vibration definitely decreases.
The unit is easy to read and seems quite consistant.
This was our first experience with this unit, it will get easier/faster with more practice.
Incidently, this prop was perfectly balanced prior to mounting.
I will try to post some pics the next time it is used.

Cheers
 
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Dynavibe

Dave,

Thanks for the report. Our local EAA chapter is considering the purchase of one of these balancers. What IPS number did you find initally and how low were you able to get it?

Thanks,
John Roberts
 
Thanks Randy, the devices look very similar. Can you give us and advice re the procedure your group uses to add weight? Thanks.

John, I spoke to the guys yesterday and apparently, after I left, they ran out of time and daylight and did not get the IPS number down below .09. another attempt is in the works. Still not bad for a first experience with this unit.

Dave
 
Thanks Randy, the devices look very similar. Can you give us and advice re the procedure your group uses to add weight? Thanks.
Dave
We have a lot of RVs in our chapter so most of what we do are Lycomings. Virtually all Lycomings have holes in the starter ring spaced every 30 degrees. We put AN4 bolts/washers/nuts in those holes. There's a lot more to it than that but that's where the weights go.
 
second try

It seems on the second attempt (same aircraft) they got down to the same reading, about .10 IPS... not sure how many attempts they made at fine tuning to eliminate the final .1 Perhaps this is the trickiest part of the process.
I plan to try my RV4, 0-360 later this month.
 
followup

Did mine today with lots of help....
started out about .41 IPS. Took about 6 or 7 runs but got it down to .05
Seems smoother too.

Cheers
 
Thanks for the report, I was looking at purchasing one of these. So is it like a tire balancer, it tells you where to place the weight?
 
Has anyone used the Dynavibe unit? I still would like 1st hand experience before I make a decision to buy.

Anyone?
 
Has anyone used the Dynavibe unit? I still would like 1st hand experience before I make a decision to buy.

Anyone?

Our chapter recently purchased a DynaVibe balancer and we are very happy with it. Balancing only takes an hour or so, but it will take more time to make a bracket to hold the unit on top of the engine or to correct a propeller tracking problem. One person can do the whole operation alone because the display device can be brought into the cockpit and the unit has an LED that shines light at reflective tape on the prop. My prop imbalance started out at 0.32 in/second and finished below 0.07 in/sec, where anything below 0.15 in/sec is considered acceptable. Mine required two 1/4" bolts through the flywheel. Cruising is definitely smoother, although my 3-blade was already pretty good. When using the unit, chock your wheels securely and use tie wraps and duct tape to hold down the cables.

Before balancing, I checked the propeller tracking and found it to be off. According to Craig Catto, his props should be checked on the leading edge some 3" back from the tip. Mine started out with a tracking error of 0.11". A 0.007" thick spacer under one side of the prop hub reduced the error to 0.025". Craig usually tracks his prop blades to within 0.03" of one another. Compression of the hubs over time can change tracking.
Leland
RV9A
385 hours tach time
 
Likewise... I bought a DynaVibe unit and did two planes so far... the unit is very easy to use and the whole process is pretty straightforward. Only wish they supplied the bracket.. but it wasn't a big deal to make one..

PS.. (shameless plug) If you're in Charlotte, NC area -- I am offering this service to experimental crowd.
 
Likewise... I bought a DynaVibe unit and did two planes so far... the unit is very easy to use and the whole process is pretty straightforward. Only wish they supplied the bracket.. but it wasn't a big deal to make one..

PS.. (shameless plug) If you're in Charlotte, NC area -- I am offering this service to experimental crowd.

Do you guys that have one use a scale to measure the weights? If so what scale do you recommend? What accuracy range?
 
Do you guys that have one use a scale to measure the weights? If so what scale do you recommend? What accuracy range?

Ours does not have a scale and I did not need one. It would probably require a gram-scale to measure low enough weights.
Leland
 
Supposidly ACES is coming out with a $1,000 prop balancer. I'll hold off buying one for a month or so. I like the idea of having the customer support of ACES without the $5K price tag.
 
I bought a Dynavibe about 5 years ago and have done about 20 planes. Many RV owners have told me "It is like getting a new plane" Recently, I had two planes in a row give me "weird" readings that required a large amount of weight. 70+ grams each where a usual balance takes 1-30 grams.

After calling Walt and discussing (Thanks Walt!) I decided to send the unit back in for calibration and a check up. The unit came back with a clean bill of health and no calibration was needed. It was just a weird coincidence that both planes needed so much weight, but now I can tell the owners I am confident the balance job was done right. Go fly the plane! I wanted to make sure the unit was working properly because one plane needed to have the cowl & baffling modified to allow the weights. I certainly didn't want them cutting into the cowl until I was 100% satisfied the machine worked correctly, and it did.

I do want to thank Steve at Dynavibe for all of the help and promptness in getting this machine checked. They kept me informed all the way through the process so I could keep the plane owners up to date.
These machines are worth every penny, IMHO.

I'm not associated with them at all, just wanted to let anyone know if you are looking at a DynaVibe these guys make and service a great product that performs as advertised.
 
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I wanted to make sure the unit was working properly because one plane needed to have the cowl & baffling modified to allow the weights.

Where were the weights being added that required modification of the cowl and baffling?

-Dj
 
My experience balancing props on experimentals with an ACES balancer would also raise concern for needing 70+ grams for balance solution, especially if the cowl and baffling needed modifying. Based on the factory recalibration of the unit and still needing that much weight you might suspect something internal or other problems may exist. I would suggest further investigation. Especially if the engine had been running prior without excessive vibration. My two cents worth.
 
I get good results with with my DynaVibe... after I got thru the learning curve.
I usually target 0.03 IPS but have settled for 0.05 IPS on some jobs. Even at 0.05, the owners rave about the difference in feel from their props. The process I follow is:
1/ Do your runs at a consistant RPM that is leaned for smoothest operation.
2/ Do your run ups in an OPEN AREA, do not try to do the balancing in between buildings, I found that harmonics echoing back off close buildings screw with getting good or consistant results.
3/ First run up- find the heavy spot & note the RPM, degree position & IPS reading. I install what I figure is too much weight opposite the heavy spot, on next run heavy reading will shift 180 degrees from original reading.
4/ On progressive runs- I reduce the installed weight in small increments till I achieve lowest IPS reading before the readings begin to swing towards a different degree angle- This is usually my best result point.
Some engine/prop combos will produce vibrations that you just can't balance out, variables being: baffles, spinner(!), exhaust, uneven compression, uneven engine mounts, or what ever.
The brackets required will vary with each different engine, I fabricate them out of 1'X1"x1/8 steel angle about 4" long.
 
Love it!!!!!

I have both the old one and the new one. Incredible customer service, they always work well. I stand behind them 100%.
 
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