Balancing the Prop on my Experimental airplane. What I used and how I did it.
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Capt. Geoffrey Thorpe
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Light and Sporty Guy
Let us know how much difference it made!
Geico266
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That will get the prop close, but you still need to have it dynamically balanced so the engine and prop are balanced as a unit at the RPM you cruise at, or the static RPM you can reach on the ground.
1600vw
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It has to be better then what I had. I called and complained that I thought this prop was out of balance. I wanted to send it back. I was told it was in balance. As you can see from the video I was having smoke blown up my as# by this person. I proved he was blowing smoke in this video.
How does one balance a prop to the engine? The only way I know to do this is how the helicopter guys and gals do it. But that takes equipment most do not have. If there is another way, do not keep it to yourself but share this for others.
Tony
Geico266
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Dynamically balance is done with the same type of equipment used on helos. Many A&Ps have them and charge around $150 -$200 for a balance job. Some EAA chapters have them available for a smaller fee if you are a member.
Out of balance is measured in IPS (inches per seconds) anything above .7 IPS is rough and dangerous to the aircraft. Getting it down to .07 IPS by adding weights is a good thing. I usually get it down to .04 IPS or less.
Dynamic balancing cannot overcome a poor running engine, bad mags, plugs or wires, bad cylinders, clogged injectors, etc. The engine must be in good running condition.
Use the search function and you can find many threads about dynamic balancing.
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1600vw
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I did all sorts of searching on this subject. The only thing I found was this thing called a Buzz master and a couple other things people used to balance a prop.
My engine is new as is every part on her. She always ran without any vibration. Then one day she started vibrating. I found this one the prop. I thought it was cracked. But was told it was a scratch.
She has never ran the same since. I will find out later how this works. The prop is going back on today and will be flown later weather permitting.
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Geico266
Touchdown! Greaser!
Even brand new engines are build within "tolerances". The "out of balance" specs can and are certainly smooth, but add a prop and swing it at 2700 RPM and there is no way it can be as smooth as dynamically balancing it. The human body cannot detect anything below .07 IPS, but your airframe certainly can.
The degree of smoothness you want is up to you. Static balancing like you did is one step in the balancing process. If you want it smoother you will need to dynamically balance it.
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... Great advice...
retpd2001
Line Up and Wait
I had my prop balanced after about 3 months of flying my new RV. I was skeptical as I thought the prop was fine out of the factory (Catto 3 blade) but was amazed at the difference, and in the end you can see the weights that were added. In my situation, there is a guy who has the balancer in the Phoenix area. The info is in my logbook in my hangar but if need be, I will get it out for the brand name of the unit if anyone wants it.
N2124v
Line Up and Wait
A second vote for getting the prop dynamically balanced. I bought my Mooney last September and went in January and had the prop dynamically balanced, the plane felt completely different. I went from 0.484 in/s to 0.06 in/s. Could really tell a difference.
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1600vw
Pattern Altitude
I did this before I ever called the man about the issue or vibration.
As to the dimple, I have no idea and when I asked about this he said it was nothing.
You can see what he did to the back side of the prop in this pic. Before he did this my prop would get covered in bugs. Not anymore. It gets a few streaks on the back side but nothing as before. The leading edge is also cleaner after a flight.
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timwinters
Ejection Handle Pulled
Don't some engines require the prop to be indexed...clocked...a certain way? Like pointing at 8 & 2 when #1 is at TDC? Or is this just for ease of hand propping since it should supposedly shut down at 10 & 4 when indexed this way?
(At least that's what I've been told)
Tom-D
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These light weight, short wooden props do not do much to vibrations, there is some thing else going on here.
Balance to engine. They can create excessive vibration if not properly installed.
Tom-D
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Yes, see the C-170 service notes.
The Warner 165 has a master spline. as do many others.
Tom-D
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Only on engines with counter weighted cranks.
Picky aren't we?
upstateny
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Excuse this possibly-dumb question from someone who has never had to deal with wooden props, but how can one be sure the center hole used for balancing is exactly in the center of the bolt circle?
Is there a plate in the hub that the cones seat on or just the wooden hole?
Is there a plate in the hub that the cones seat on or just the wooden hole?
1600vw
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The hub can be off. This happens every so often. If not caught the customer is left to deal with it. When this happens and you do not recognize this, you will never get the prop to balance. I was worried about this. But as you see in the video, I was able to get the prop to balance with just a couple pieces of tape out on a tip. If the hub was off the weight would have to be added to the hub, and then you are only covering up a bad prop by balancing the hub. You see this alot in the RC airplane world. The props are not always drilled center.
1600vw
Pattern Altitude
Something like this?
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Geico266
Touchdown! Greaser!
Again, the human body cannot feel anything under .07 IPS. Balancing an aircraft by the seat-o-pants meter is unreliable at best.
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Tom-D
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Tom-D
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NO, maybe not, but you can find the one that bothers you least, and start from there.
1600vw
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It made a huge difference. I was having needles on a couple gauges vibrating so bad you could not see the needle. Not anymore. Now they are all steady.
I should have done this 20 hrs ago.
Tony
Tom-D
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Most are carved on CNC machines after the center hole is bored. IOWs the center hole is the reference for the whole carving.
Geico266
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Why not do it right and dynamically balance it?
Vibration, aluminum, and avionics don't play well together.
Tom-D
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Why balance it at the worst possible position?
1600vw
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Why not do it right and dynamically balance it?
Vibration, aluminum, and avionics don't play well together.
Just where do I find the equipment to dynamically balance my prop? I had a hard enough time finding the equipment to balance it the way I did.
Tom-D
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Prop shop or some A&Ps
MikeS
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http://www.rpxtech.com/DynavibeClassicPropBalancer.html
Is one place. A couple of the other outfits that used to sell their analogue balancers for many thousands of dollars have come out with digital models to compete with the Dynavibe product. I'm sure they all work fine. Certainly the Dynavibe does. I've had mine since they first hit the market in 2007 and have found it very useful . . . not just for helping others with their vibration problems but every time you make any change at all to your spinner, prop, backplate . . . anything that rotates, you can re-do your balance without spending more money. Just seasonal changes of humidity can cause, wooden props at least, an imbalance in a formerly balanced prop. The Dynavibe was/is $1500 last I looked and sometimes can be found on the used market now that they've been out for quite a while.
Essential hangar tool once you get used to having one.
************
Forgot to include the thought that with your own balancer you'll take as much time as you want to get it just right. A&P's or others who do prop balancing as a "job" will want to get the job done so they can get on with whatever else is on their list of things to do that day. They also may not give as much attention to what the wind is doing as you will want to when doing your own plane. Good balance jobs are done in no wind conditions.
Is one place. A couple of the other outfits that used to sell their analogue balancers for many thousands of dollars have come out with digital models to compete with the Dynavibe product. I'm sure they all work fine. Certainly the Dynavibe does. I've had mine since they first hit the market in 2007 and have found it very useful . . . not just for helping others with their vibration problems but every time you make any change at all to your spinner, prop, backplate . . . anything that rotates, you can re-do your balance without spending more money. Just seasonal changes of humidity can cause, wooden props at least, an imbalance in a formerly balanced prop. The Dynavibe was/is $1500 last I looked and sometimes can be found on the used market now that they've been out for quite a while.
Essential hangar tool once you get used to having one.
************
Forgot to include the thought that with your own balancer you'll take as much time as you want to get it just right. A&P's or others who do prop balancing as a "job" will want to get the job done so they can get on with whatever else is on their list of things to do that day. They also may not give as much attention to what the wind is doing as you will want to when doing your own plane. Good balance jobs are done in no wind conditions.
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