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Thread: Balance Master

  1. #21
    Senior Member Dave S's Avatar
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    Default Re: Balance Master

    John,

    It's great to see some empirical data on this.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  2. #22
    rdooley79's Avatar
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    Default Re: Balance Master

    Quote Originally Posted by rv9ralph View Post
    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.



    Last edited by rdooley79; 01-19-2020 at 08:57 AM.
    Kitfox IV - 1200 (1994) #1830
    Rotax 670 (90+hp)
    C-Box 3:1
    Warp Drive 3 Blade 72"
    Grove Gear, Wheels, Brakes
    22" Desser Tundra Tires

  3. #23
    Senior Member Dorsal's Avatar
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    Default Re: Balance Master

    Quote Originally Posted by jrevens View Post
    Attachment 23899Attachment 23901Attachment 23898Attachment 23900
    I flew for 1.5 hours on 1/16/20 with the Balance Master installed. The airplane didn't feel as smooth as before, but definitely smoothed out more after full throttle run-up. Today I installed my balancing equipment to get some real numbers. After warm-up, I advanced to 5000 rpm, took a vibration reading, then did the same thing at 4000, 3000 & 2000 rpm. I then went back up in 1000 rpm steps to 5000. I then removed the Balance Master and performed the same exercise again. I had previously dynamically balanced the assembly to 0.02 to 0.03 ips at full-throttle static of approximately 5100 rpm. Here are my results and observations -

    With Balance Master - Starting at 5000 rpm - 0.04, 4000 - 0.04, 3000 - 0.12, 2000 - 0.02 Starting at 2000 - 0.03, 3000 - 0.07, 4000 - 0.03, 5000 - 0.10

    Without BM - Starting at 5000 rpm - 0.02, 4000 - 0.02, 3000 - 0.01, 2000 - 0.02 Starting at 2000 - 0.02, 3000 - 0.02, 4000 - 0.03, 5000 - 0.03

    I allowed time for things to "settle down" before each reading, and observed that with the BM it took a minimum of 30 sec. to 1 min. (sometimes considerably longer) to reach the best balance condition. There was no delay without the BM. I'm not certain why the spike at 5000 rpm when going from 4000 to 5000 with the BM as compared with starting at 5000. Hysteresis in the throttle cable when pushing as opposed to pulling on the throttle arm (I don't have the throttle springs) creating a little carb imbalance may be a factor, but I don't see the same thing without the BM.

    So, my experience is smoother operation without the Balance Master, and much smoother during the transition "settling down" periods. I think that the Balance Master would potentially offer a good improvement/option for an out-of-balance condition if dynamic balancing was not easily accomplished, such as when a small "skull-cap" spinner is used on a Rotax. For me, there is no doubt that my situation is better with a good dynamic balance job alone. Your mileage may vary.
    Just the experiment I was planning on running, might still to verify results.Quality work as always John, thanks.
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

  4. #24

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    Default Re: Balance Master

    Quote Originally Posted by Dorsal View Post
    Just the experiment I was planning on running, might still to verify results.Quality work as always John, thanks.
    It will be interesting to see if you have the same results...

    Clark

  5. #25
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    Default Re: Balance Master

    John I questions your numbers. Did you get confused and balance a turbine? That’s some smooth readings. Wonder if you tried the BM with dynamic balanced weights or without weights? Curious if it’s true its better without weights. I put my weights back on to try flying with the BM and balance weights that had me at .05
    Dustin Dickerson

    Building 7ss STI x 2
    Oratex
    29" shock monster
    EP912STI 155hp
    Garmin
    N33TF......FLYING!
    N53TF......Building

  6. #26
    Senior Member jrevens's Avatar
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    Default Re: Balance Master

    Quote Originally Posted by Shadowrider View Post
    John I questions your numbers. Did you get confused and balance a turbine? That’s some smooth readings. Wonder if you tried the BM with dynamic balanced weights or without weights? Curious if it’s true its better without weights. I put my weights back on to try flying with the BM and balance weights that had me at .05
    Hi Dustin,

    I never removed the weight that I had installed during dynamically balancing it. I know that Balance Masters says you should remove any balance weights, but I still don't buy that. As I've said previously, I think it might be a marketing strategy on their part. The Balance Master device has no way of knowing that there is a small weight that is making the propeller well-balanced to begin with, and if a well-balanced assembly is not as well balanced after installation of the Balance Master... well, what can I say? These are just my observations and experience... I'm open to any discussion or disagreement. I found out a long time ago that what I believe is not always right. As far as the smoothness goes, yes - I do have a very well-balanced propeller assembly. Anyone who has done a lot of them, like I have, can tell you that there is just a little bit of "art" involved, even with the modern balancing devices. I do think that the ACES machine is a little easier to use than the Dyna-Vibe that I saw a few years ago. My ACES unit is an older one - the mod. 1000.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE

  7. #27
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    Default Re: Balance Master

    Nice! Sorry I hope you know I was being sarcastic because of your very smooth readings. You defiantly have a smooth readings. Best I could get was .05 only at 5000rpms. Everywhere else it was all over the place. Yeah I took the weights off because of BM recommendations. Bm explanations made sense to me but I can see it both ways. I figured I would listen to him since he has more experience than myself. I am curious though if running weights or no weights is smoother or how it effects balance with BM. I put another hour on mine and as far as mine goes it’s defiantly smoother, in the air. What kind of prop are you running? Mine defiantly feels smoother in a steep climb with high AOA with BM. I am running a NR prop that is carbon. I noticed it has flex in it and I can see the tracking changing (in my mind) at different AOAs when p factor comes into play. When this happens vibrations happens that the BM is overcoming. Just a couple thoughts I had why we had different results. I was going to buy a balancer and was looking at getting the aces to balance my prop yearly. I know it doesn’t take much to effect balance. Ultimately it came down to my prop was very difficult to balance, partly because the setup was initially wrong on the G3X but maybe these props are just harder to balance. On 53TF we are just putting on a BM and skipping balancing it.
    Last edited by Shadowrider; 01-22-2020 at 06:56 AM.
    Dustin Dickerson

    Building 7ss STI x 2
    Oratex
    29" shock monster
    EP912STI 155hp
    Garmin
    N33TF......FLYING!
    N53TF......Building

  8. #28

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    Default Re: Balance Master

    Dustin, it will be interesting to see how the other prop balances. It seems like you guys pretty much built a carbon copy of your plane. I wonder if you'll encounter the same issues with this one?

    Clark

  9. #29
    Senior Member jrevens's Avatar
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    Default Re: Balance Master

    Quote Originally Posted by Shadowrider View Post
    Nice! Sorry I hope you know I was being sarcastic because of your very smooth readings. You defiantly have a smooth readings...
    Dustin,
    Nope... I understood, and your comment was appreciated! My prop is a 70” 3-blade Whirlwind. Every combination of engine, prop, & spinner can be different in how easily and well they can be balanced. I think I got lucky with what I have. I’m really glad the Balance Master works so well for you, Larry, & others! To further the conversation a little, when you conventionally balance a prop assembly it needs to be realized that it is only that individual assembly that is considered. Especially with a Rotax, having a PSRU between that and the engine since they are not fully “in-synch” the same way with every revolution of the propeller. I’m not familiar enough with Dyna-Vibe, but with my balancer “random” vibration events that may occur other than every 180 & 360 degrees are “filtered out” when the machine calculates the solution of necessary weight & position. This makes sense since a fixed balance weight on the propeller is not going to necessarily balance anything that may be causing vibration in the engine or gear box. An additional Balance Master on the engine sounds interesting. Again though, my situation tested better not only according to my balancer, but also “feel” on the ground & in the air.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE

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