Take a look at the data in my writeup.
It is hard to argue with.
Had a look thank you. Your own conclusions go hand in hand in demonstrating how difficult a reduction in total vibrations is.
On my ship the on ground balancing measure was just conducted as an exercise, as the running was, and still is pretty smooth. I was just curious really.
A 2 bladed metal RV-7 prop friend had his prop balanced right before mine, and having added some weights in the right positions there was some major improvements in the readings, and the vibes as felt… subsequent in flight reports, no instrument measurements, confirmed the improvement by said owner/builder/pilot.
I will continue to believe that dynamic prop balancing is not the miracle solution for an antiquated airplane with worn out Lord mounts, asymmetrical injection, etc, etc, but can only be beneficial if weights can/are added in the right location(s).
Prop balancing is to balance… the prop/spinner/flange assy, on its own. An overall reduction in airborne vibrations is difficult to achieve, but lessening one cause should not be detrimental, but for a very rare counter harmonic reaction.
My experience is that balancing a prop on the ground is much harder than it looks – changing the RPMs by a few hundred changes the numbers substantially. Here are my numbers – I think doing it in flight would be much more interesting.
Not to mention in an over-powered taildragger it’s pretty scary to run these kinds of power settings with the aircraft tied down to my car.
(Hartzell 2-blade aluminum prop, IO-360)
eurogaguest1980 wrote:
changing the RPMs by a few hundred changes the numbers substantially
and of no use… as you state, the numbers change with any different RPM, let’s call it a demonstration of kinetic energy. And this why for instance in my case, the measurement was done with the commonly used cruise RPM, e.g. 2034 (2050 is what I normally use) and 2278 (2300 is my normal higher cruise setting).
Again, everything in aviation is compromise 
An airborne prop balancing is of no use since any vibrations measured will only be the cumulative sum of the other sources.
Logically (well, according my humble logic), if the prop assy is statically and dynamically balanced on the ground, there’s no good reason for the same assy to suddenly become unbalanced when flying…
PS
For info, my ship is far from overpowered (yet to see an “overpowered” SEP 
) but using chocks and applying the brakes whilst holding the stick fully back permits the application of 2300RPM… more and the tail starts to lift. Of course, I would not perform this on my own, one operates the aircraft, the other the reading equipment.
Peter wrote:
It is more placebo…
It seems to be very installation-dependant. I could feel no discernible vibs difference on our former 4-cyl , 2-crank dampers, 2-blade, dynafocal mount C177RG with a reading of .5 vs .05 ips.
On our current 6-cyl, 4-crank dampers (4th, 5th and 6th order weights) , 3-blade, lower-mount P210N, I can feel a clear difference between .13 and .03 ips, especially when going off-nominal (balanced) RPM, to the point I would not run the engine at those off-nominal RPM in the former case. In theory .13 ips should be nothing to make fuzz about…
From the ACES system balancing guide:
eurogaguest1980 wrote:
changing the RPMs by a few hundred changes the numbers substantially
You should balance it at your critical RPM, typically the one you use for cruise. The only reason to use a different setting for balance is if you have a concern about specific vibration levels being too high at some other specific setting that you need to use often (climb or descent or whatever).
But you are right: the dynamics of a propeller airplane’s vibration are way too complex, even more when on the ground. One thing you know for sure, though, is that if ips is lowered in a certain configuration on the ground, same RPM in flight will have less excitation and hence vibs than if otherwise.
If in Germany – I do this. Http://wisniewski.aero
I have been toying with getting a balancing machine and adding the service to our list of services but am unsure if there is the demand to pay for the kit.
Looking above there are others in the game and despite the company name I would have no hesitation recommending Kerry Ashcroft KrAsh aviation.
FWIW bought a dynavibe classic a couple of years ago( + an android app-triangle calculator, scales and some washers, nuts and bolts)
We have done a couple of aircraft(lyc 360) and had good results with subjectively significantly smoother running. Numbers were 0.4 to 0.04 ips typically in 3 runs.
I can do this in Germany, EDLB if someone is asking.
https://www.wisniewski.aero/
