There has been a recent conversation about these devices on Shadowrider's build log... thought I'd bring it back over here. Larry's comments, as well as the fact that Hal Stockman was involved means a lot to me, and is also why I decided to get one and hopefully do a little testing. The price is not unreasonable, and worth it to me if there is truly some advantage over a good dynamic balancing job. Regardless of the fact that Balance Masters says you should not dynamically balance before using it, and that any weights should be removed, that just doesn't make any sense in my mind. Here are some comments from a Pilots of America forum back in 2015, where they were discussing these devices. I believe these were not Rotax powered aircraft. I thought they might be interesting to this group. The comment about seeing "smooth operation throughout the operational range (after a dynamic balancing) if they show smooth on the ground" is consistent with my experience. There is generally a good improvement throughout the range. The one stating that "If I balance an engine say at 2400 RPM to .04 IPS and test again at 2000 RPM it is going to be way off" has not been my experience at all... I see it as best at the balanced RPM, but usually not "way off" at other speeds. Also, the "Seat-O-Pants Meter" comment was accurate, IMO -


"I balance props too using the DynaVibe. Thus I was interested in these things when I first heard about them. Reading about them over time, the most interesting and believable article was one in which a person adept at prop balancing compared using a Balance Master with the results of a conventional dynamic balance, on a prop/engine that had been deliberately put in an out-of-balance condition. The results as I recall were that the Balance Master improved the situation, rendering .11 -.13 IPS. With the Balance Master removed, the person with the balancing equipment was able to get it easily below .07. My take on them, just reading . . . all second hand . . . is that they can improve an out-of-balance condition, but will not improve it as well as a good dynamic balance job."



"But the dynamic balance is only good at a certain RPM, and on the ground. I am very interested to see if these work at all RPM ranges and pitch angle of the props.
I have a plane that I can get down to .07 IPS, but in the air it is still rough. I am leaning towards a constant speed prop issue rather than and out of balance issue. I'm hoping this gizmo will help.
I might be overly optimistic, but it will be fun to see."


"Where I'm going with this is once it is balanced, any excessive vibration is likely not a result of simple dynamics. Our engines generally operate in a fairly narrow RPM range so balancing it at a particular RPM is not a big deal."

"I'm curious about how many folks experience vibration problems after a dynamic balance? What I've seen is that the engine/prop are smooth throughout the operational range if they show smooth on the ground. Maybe not perfect throughout the operational range but pretty darn good."


"Balancing certainly makes a difference, but anyone that dynamically balances knows that the balance is only good at a certain RPM. If I balance an engine say at 2400 RPM to .04 IPS and test again at 2000 RPM it is going to be way off. I have seen it go to .15 IPS easily. This "constant balancer" should work at all RPM ranges."


"Do you think you're finding a harmonic? I don't think so. On certified equipment the RPM with that type of problem would be either "avoid" or prohibited.
I think you're seeing an engine problem which might be a simple thing like slightly fouled plugs or an intermittent plug wire failure.
Possibly harmonic, but in my experience all airplane engines with props seem to do this. This is why we balance to cruise RPM, or as high as we can get static.

The difference between .15 & .04 IPS to the pilot (seat-o-pants meter) is pretty small. They might not even be able to feel it depending on the airframe."