Balance Master

[Shadowrider]

Thanks John. Curious to see your results. Also I am going to put the weights back on mine that had me down to .05 and see if what it feels like with the BM and I will report back. Sorry no official data will be recorded other than seat of my pants.

[Dorsal]

Mine just arrived today, the comments that it may smooth out some of the transition rpms is what convinced me to try it. Will report measured results (ips/rpm) when my traveling Dynavibe is back home.

[PapuaPilot]

Does anybody know if they make one that fits on the Continental IO-240? I like the idea of having your prop & engine in balance at all RPMs.

[Av8r3400]

If you follow the link to ACS, you’ll see they do. John and others have stated they weren’t happy with the results on a direct drive engine. I would hypothesize that the harmonic pulses in a direct drive situation may negate some of the balancing properties.

[rdooley79]

I’m finishing a 912 install on my 4. Hal did the build of the engine for me and he recommended using two balance masters. One on the mag end and on the prop as well so I put them on my 912. Probably a couple weeks from first run up and no pirep yet. Hal recommended it highly so there’s that...

[littlecricket]

Two??? I was looking at getting one... now, I have to look at getting two... 😜

[rv9ralph]

Two??? I was looking at getting one... now, I have to look at getting two... 😜

So here is something to think about. In the Rotax 912/14/15 series there are two centers of rotation. The prop hub at the top of the gearbox, and the Crankshaft (I know the camshaft is also a different center of rotation but we will leave that one for now). These are separated by 4-6 incise. The prop and it's rotational forces are turning at 2.27 or 2.43 times slower than the crank's rotational forces. When trying to balance this, you have to consider both of these sources of acceleration.

To this, the suggestion of two balance masters does make sense.

Ralph

ps - I am not an engineer nor do I claim to be.

[rdooley79]

So here is something to think about. In the Rotax 912/14/15 series there are two centers of rotation. The prop hub at the top of the gearbox, and the Crankshaft (I know the camshaft is also a different center of rotation but we will leave that one for now). These are separated by 4-6 incise. The prop and it's rotational forces are turning at 2.27 or 2.43 times slower than the crank's rotational forces. When trying to balance this, you have to consider both of these sources of acceleration.

To this, the suggestion of two balance masters does make sense.

Ralph

ps - I am not an engineer nor do I claim to be.

I was thinking of this as well. The Balance Master on both rotational masses makes a lot of sense. Being able to balance both masses would stand to reason to smooth the running of the engine. I'm not sure but it seems that any change in resonances might effect that also. The active balancing effect of mercury in the ring of tha balance master plate would be constantly changing to accomidate any differences. Also as an engine breaks in over time things will change and might effect the balance ever so slightly (might be total bs here....) but with the active balancer on both masses those slight variations would be addressed by the balance master.
The weight of the balance master is very negligable. It seems that any weight addidtion would be negated by the theoretical longevity of the engine/wear/carb balancing due to vibration as well as enjoying a nice smooth running engine.

Being that I have a freshly built zipper 105hp engine the access was easy and installing the plate on the rear of the engine was quick. Looks like it could still be done with the engine on the plane but it's a lot tighter and may need to move the oil tank. dont forget to use a crank locking pin and that it's seated in the groove of the crank before using the breaker bar/torque wrench.

haha, I made a couple videos of the install months ago and forgot that they are already uploaded to YouTube.

[rv9ralph]

I used a Dynavibe to balance my prop. It worked and I may even swap to the balance master regardless.

Eddie, didn’t you report you only had a small vibration that popped up at certain times... could it be a multiple of the reduction ratio? Just a thought.

Ralph