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Dynamic Prop Balancing

Webb

Webb

Well Known Member
Sponsor
I thought mine was smooth....until after I had it dynamically balanced ....... oohhh what a difference.

Heard the best explaination from the Jim Jeffries that did it.....It's like buying a new set of tires and not balancing them. Anytime you marry a prop to an engine, it should be done...... And he's right.

He took it from a 0.5 to a 0.025 - check out the graph.

propv.jpg
 
$300 - The guy lives in Brandon MS and covers a pretty large area.

Most impressive were as the awesome planes he has balanced.
 
equipment used

Do you recall the name of the system used? I had my Whirlwind RV200 balanced after I installed and the name of the equipment was Chadwick Helmuth Vibrex 2000. I was just curious if this is still considered the "lastest" and very reliable equipment to balance props.
Thanks
Kenny Gene
 
Does anybody have any experience with the Dynavibe units? I see they are listed for $1495, it seems like it might be a good investment for a couple of owners. It seems like a pretty simple process, with lots of benefits.
 
I also thought I had a real smooth engine until I had my prop balanced. Very noticeable difference. Cost me $180 well worth it. I don't know about getting a balancer and doing it yourself as there is an art to it as well as the machine. Don
 
How it's done

For those that are wondering how it is done.

A vibration sensor is bolted to top of the engine. Reflective tape placed on each prop blade in strategic locations. Now comes the part you can't do by yourself. YOU sit in the plane and do a static runnup to 2,400 rpm while the technician uses a strobe light in front of the plane.

You then shut it down, and the tech using bolts and washers adds weight to the starter ring.

Repeat until balanced.
 
surprise benefit...

The surprise benefit to having a smooth running airplane is that you can greatly reduce your mx costs due to instruments zoning out... and cracks in sheet metal not to mention all the rivets that will have a longer life. I cannot vouch for this enough! I may go ahead and buy one since I send all my customers to another airport to get it done..... :)
Best
Brian Wallis

ps... track affects balance but balance does not affect track.
 
One important thing when balancing also is to find the right RPM you want to balance at. For example, I like to cruise at 2450 RPM, so that's where I ran up to on the ground with the balancer on the plane.

My vibration at that RPM? 0.01IPS. AWESOME! I didn't have to add any weights or anything. Needless to say when I got back home I pulled the spinner and marked the prop against the flywheel to make sure that I always align them the same way.

I always get comments from other pilots about the smoothness of my prop at cruise.

I have flown an $$$ MT $$$$ prop on my plane (of course we didn't balance it). The MT was definitely smoother during take-off but during cruise I think my Hartzell gave the MT a run for it's money in cruise flight. In fact, I believe my Hartzell was just a bit smoother (again, we didn't balance the MT).
 
Webb said:
For those that are wondering how it is done.

A vibration sensor is bolted to top of the engine. Reflective tape placed on each prop blade in strategic locations. Now comes the part you can't do by yourself. YOU sit in the plane and do a static runnup to 2,400 rpm while the technician uses a strobe light in front of the plane.

You then shut it down, and the tech using bolts and washers adds weight to the starter ring.

Repeat until balanced.
Click to expand...

Everything the same when mine was done, except I specified the rpm I was interested in and no one out the front and no strobe light.

Fin
9A
 
Definitely

WW 200 RV and ECI IO360. This balanced to a 0.00. The guy has never had a perfect balance before. Extremely smooth!! $150. He's based out of Falcon Field in Mesa AZ (KFFZ).
 
Jim Jeffries was at my home base balancing a AirTractor for a friend. I was visiting with him after I landed and he asked if I wanted my RV8 balanced and I told him it already had been dynamically balanced. He said he would check it and if he couldn't improve it I wouldn't owe him a cent.
I could almost see what was coming and boy was I wrong.
He checked it and said he couldn't improve it a bit, so I got a free check and a coffee cup.

Jim is a gentleman and honest. He travels to your site if you are interested his number is 985-507-9981. I just read it off my coffee cup.
 
Jamie said:
My vibration at that RPM? 0.01IPS. AWESOME! I didn't have to add any weights or anything. Needless to say when I got back home I pulled the spinner and marked the prop against the flywheel to make sure that I always align them the same way.
Click to expand...
Jamie, if you ever remove your prop your balance solution is out the window. Just the few thousands of an inch that the prop can move on the bolts will change it so technically it needs to be rebalanced every time the prop is installed. I have not tested what the error range is for bolt slop placement only but it will be measurable.
 
randylervold said:
Jamie, if you ever remove your prop your balance solution is out the window. Just the few thousands of an inch that the prop can move on the bolts will change it so technically it needs to be rebalanced every time the prop is installed. I have not tested what the error range is for bolt slop placement only but it will be measurable.
Click to expand...

Randy,
I also have never done a retest after the removal and (properly re-indexed) re-installation of a prop (so I can't say for sure) but I don't think it can move enough to make a measurable difference. The drive lugs on the prop flange are a pretty close fit in the counter bores of the prop hub.
What I have found with testing, is that there can be enough slop in the spinner mounting screws to allow the spinner to be positioned slightly different. I have seen this account for a .02-.03 IPS difference.
 
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rvbuilder2002 said:
Randy,
I also have never done a retest after the removal and (properly re-indexed) re-installation of a prop (so I can't say for sure) but I don't think it can move enough to make a measurable difference. The drive lugs on the prop flange are a pretty close fit in the counter bores of the prop hub.
What I have found with testing, is that there can be enough slop in the spinner mounting screws to allow the spinner to be positioned slightly different. I have seen this account for a .02-.03 IPS difference.
Click to expand...
When I went through the DSS factory training they told us that remounting the prop in the same place would make a measureable difference though they didn't say how much. I haven't tested that though.
 
DynaVibe Service avaiable soon!

I just ordered my DynaVibe and will be providing Dynamic Balancing Service by the end of Sept.

I am based at KHVC Hopkinsville, KY and will do the work at my airport or yours. I plan on offering a group deal also.

If you've been thinking about getting yours done and live near my area let me know!

I'll let everyone know when I am ready to start.

I am a A&P mechanic and I purchased the unit with the calibration certification so I'll be able to do certified aircraft also.
 
Another data point. We had to take our Sensenich prop off to do the S/B for the hollow crank pitting. After remounting it, we had the balance checked and it was still .02 so we left it alone.
 
randylervold said:
When I went through the DSS factory training they told us that remounting the prop in the same place would make a measureable difference though they didn't say how much. I haven't tested that though.
Click to expand...

When I had my Whirlwind 200RV inspected at 650 hours I asked if it needed to be re-balanced. According to them, NO.
 
Dynamic balancing

ronschreck said:
When I had my Whirlwind 200RV inspected at 650 hours I asked if it needed to be re-balanced. According to them, NO.
Click to expand...

Ron, I'm not so sure that what you are really doing is unbalancing the prop to balance the engine!:) At least that's the way the guy that did mine explained it to me. That you are really balancing the entire package of prop and engine combined. So that any unbalance inside your engine is compensated for by the weights added to the prop spinner. Of course, any unbalance in the prop is also being compensated. He was telling me that any prop work or major engine work (a cylinder change, for example) would be reason to re-balance.

Part of his sales pitch was extended avionics life, engine and airframe life, even the light bulbs will last longer. Made a big difference for me. I was amazed by the improvement in vibration level--very noticeable.
 
Webb, bit confused from the thread. Does he balance the prop on the plane or is the prop detached and balanced on a machine? How can we contact the fellow in MS that does the work so we can hire his services? Best regards, Bill
 
Bill Phillips said:
Webb, bit confused from the thread. Does he balance the prop on the plane or is the prop detached and balanced on a machine? How can we contact the fellow in MS that does the work so we can hire his services? Best regards, Bill
Click to expand...

I'm not Webb but I'll try to answer your question. It's called "dynamic balancing" because it is done on the plane with the prop in motion. In my case, they take off the top cowl and mount a vibration sensor on the top forward most case bolt on the engine. Next, a strobe sensor is mounted (taped) on the side of the bottom cowl pointed at the prop, about mid-blade. A reflective tape is placed on the back side of the prop blade aligned with the strobe/sensor. These two inputs are connected to a processor and the technician gives the thumbs up to start the engine. In my case, he wanted 2150 rpm and then he wanted me to dial the prop back to 2100 rpm so that the governor was controlling the prop and not the low-pitch stop. He then reads the vibration level and gets an approximate weight and coordinates for a correction. The correction is just a few grams of AN washers that are bolted to the back plate of the spinner at a certain angle and distance from the center of the crank. There is a bit of trial and error involved and he may want you to repeat the run and adjusts the weight until he gets most of the vibration out. The resulting AN washers are then permanently bolted to the spinner back plate. Put the spinner and top cowl back on and you are done. I think you can plan on spending anywhere from $150 to $300 or so. There are plenty of folks around who do the work and you should be able to find someone in your local area or nearby. It might help to get a group together if you need to bring someone in to do it.
 
Bill, if you come to the Charlotte area let me know.. I have the instrument and I can do it for you... I charge $150..
 
DynaVibe Service Now Avaiable!

I am now offering DynaVibe - Dynamic Prop Balancing Service! I just did my aircraft last week. Went from .48 ips to .06 ips with just a couple adjustments. I may fiddle with it later to get it even better but that made a big differance with the vibrations.

You can read about it on my web site:
http://home.newwavecomm.net/bobbyhester/2009AugDecFlying.htm
 
Good Information here -need more

As hard as it is to believe perhaps I have never had a prop dynamically balanced. Recently I replaced a Hartzell C/S with 7666 blades with one with F7496 blades. It is faster by 3 kts as advertized but it is noticeably roughter in vibration. After a few flights it seems fine and I'm interested in speed mainly but I'm thinking I may be able to get a fraction of a knot by getting the dynamic balance done at 2700+ rpm. Any experience in this in this frame of reference?

Bob Axsom
 
Bob,

We balanced my Hartzell 80" D-twist 2-bladed prop at 2300 RPM, and brought it down from about .5 to about .03 IPS. Felt to me like a noticible difference...not super-dramatic, but noticible.

The most interesting result was that after the balance, 2750 (max) RPM feels to me like the smoothest RPM, and the vibes increase as I slow the prop, peaking at 2300 (go figure, that's where we balanced it!), and then smoothing a little as I back it off further.

That doesn't really answer your question about balancing it at max RPM, but I thought you might find it interesting. The prop guy (Golden State Propellor) is a friend, so I'll ask him what he thinks about your question.

On another note, I have had the prop off once since the DB (crank sensor install on the Electroair EI), and have wondered if doing so marginalized the previous balance. Interesting to revisit this thread to see what others have said (little of both, yea and nay). I'm pondering a Hartzell BA as well, so a new DB may have to wait till that decision is made. ;)

Will let ya know what I hear from Eric at GSP.

Cheers,
Bob
 
rvmills said:
Bob,

...

Will let ya know what I hear from Eric at GSP.

Cheers,
Bob
Click to expand...

Looking forward to that information. It may be that there is no experience out there but if there is a benefit I find that hard to believe with all of the racers out there.

Bob Axsom
 
Pat Hatch said:
Put the spinner and top cowl back on and you are done. I think you can plan on spending anywhere from $150 to $300 or so. There are plenty of folks around who do the work and you should be able to find someone in your local area or nearby. It might help to get a group together if you need to bring someone in to do it.
Click to expand...

Pat, are you saying that the balance was done with the spinner off. I would imagine that a spinner itself (and particularly a Vans spinner) could be considerably out of balance.

I think I'd want the balancing done with the spinner installed.
 
DAllas Area Balancing

Can anyone tell me who does this in the Dallas area.

Thanks,
Boomer
 
spinner on

Captain Avgas said:
Pat, are you saying that the balance was done with the spinner off. I would imagine that a spinner itself (and particularly a Vans spinner) could be considerably out of balance.

I think I'd want the balancing done with the spinner installed.
Click to expand...

Just had my -4 done yesterday, left the spinner on and used the holes in the flywheel to attach weights (holes are spaced every 30 degrees). This worked great and now is very smooth!
 
question

D-B my prop at 2150 (max static rpm), what can I expect the balance to be when turning 2500=2600 in cruise? And how would you account for this if there is a noticeable change? Any thoughts would be appreciated.
 
Byam

Byam Propeller at Meacham in Fort Worth is the main prop service in this part of the world. My recollection is that their balancing services are reasonably priced.
 
I'll rent you mine

I have a brand new Dyna Vibe balancer that I'll rent out (DFW) for $100 DIY. PM me.
 
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Bob Axsom said:
As hard as it is to believe perhaps I have never had a prop dynamically balanced. Recently I replaced a Hartzell C/S with 7666 blades with one with F7496 blades. It is faster by 3 kts as advertized but it is noticeably roughter in vibration. After a few flights it seems fine and I'm interested in speed mainly but I'm thinking I may be able to get a fraction of a knot by getting the dynamic balance done at 2700+ rpm. Any experience in this in this frame of reference?

Bob Axsom
Click to expand...

rvmills said:
Will let ya know what I hear from Eric at GSP.

Cheers,
Bob
Click to expand...

Bob,

Sorry this took so long, but I finally talked with both Eric at Golden State Propellor, and John at American Air Racing. Both concurred that balancing at max RPM will not make you faster. In fact, given that you are running pretty smooth to start, a DB will probably have no perceptable impact on speed. Not sure if it would if you were running rough...unless you were a dern rattle-trap due to the prop...which of course you are not.

John explained that they do the DB at a mid-range RPM, one that "loads" the propellor (it's on the low-pitch stop, and creating thrust...thus bending forward a bit). He said if you went to a higher RPM, the prop would still be on the low pitch stop, and the increased thrust (bending moment) and speed/centifugal force would not make a significant difference in the dynamic balance...especially if the blades are well matched (they should be) and the prop was in good static balance. They both felt that the difference between 2300 RPM (for instance) and 2700 RPM would not be measurable. They both also chuckled when they said "and if you could keep the airplane on the ground...and find someone that was willing to stand in front of it!" :eek:

However, they both agreed that doing the DB will have a positive impact on the overall smoothness (albeit somewhat subjective). John added that even if your prop feels good now, a DB is well worth it, as there are vibes at frequencies you can't readily feel that may negatively impact the wear on the entire engine, engine mount, propellor system.

All FWIW of course...I personally think you'll get a knot or two out of it! ;) And I wasn't paid to say that :D

Cheers,
Bob
 
Thanks for the information Bob

Thanks for the information Bob I really appreciate your time and effort to get it and pass it along. I may do it at Hartzell some time in the future but not before the first race at Taylor, TX on 4-10-10. I fitted the second semi-flat wing tip yesterday and drilled the pilot mounting holes (#30). Some time today I will continue on with that effort. In the process I have been thinking of a way to cover the outboard aileron mounting brackets and associated openings. I still have to do the annual condition inspection so time is getting squeezed.

Bob Axsom
 
Placebo or science?

I have watched all the interest in dynamic balancing and I have had my Grumman Tiger balanced years ago, I am sure the equipment today is far superior to then.

What I bring up is the small weight differences in the balance process vs. the constant changes in the power systems of our planes. We use our planes. All props that are flown from pavement get stone dings. Metal props the dings are filed out and the prop touched up or repainted. We replace accessories, adjust timing and you get the idea do maintenance.

All these things change the balance of the rotating mass we call our engine and propeller. Constant speed props, the differential of the angle between blades while moving can cause changes in the vibration patterns; do we think our props move with absolute precision when changing pitch? Add to that, all this changes with RPM.

All this being said, I cannot see how balancing our power systems can have any long term affect, in the moment, at the rpm it was balanced, it is balanced. For how long and what about at other RPM. I propose that this is more placebo affect than actual science. You paid to have something done so you are invested in it, someone shows you a positive statistical result and you feel better about your plane.

I am not an engineer, I only try to present a logical arguement. I would like the engineering types to please put some more science in the discussion, one way or the other.
 
This placebo feels real good!!!

I think your idea of an everlasting balance is correct. But, for the time it is balanced it will provide measurable results.

I raced the Formula One class in Reno and we always had our props balanced for free at the venue. I didn't buy anything that I needed to justify and I gained sometimes as much as 50 RPM static. This gain may not coincide directly with the RV application, as I had a long prop extension and wooden prop and less power. Smoothness of my O200 with fixed wood prop was noticably improved.

That said I always figured that a prop/spinner R&R degraded that performance ever so slightly, though I cannot prove same.

I would like to have a balancer of my own but just cannot justify the cost as yet. Previously a poster said that there was an art to balancing, with this I might agree a tiny bit but everyone that uses one today started somewhere. If you had your own balancer you would be doing a lot of honing of that art. After having mine balances numerous times I wouldn't hesitate a second to create my own masterpiece.

$1500 = About $175 in our area, so about 9 balances = my own machine = part of a glass panel = 300 gal of fuel. Why can't we have it all?
 
First correlation with performance improvement

corbinace said:
I think your idea of an everlasting balance is correct. But, for the time it is balanced it will provide measurable results.

I raced the Formula One class in Reno and we always had our props balanced for free at the venue. I didn't buy anything that I needed to justify and I gained sometimes as much as 50 RPM static. This gain may not coincide directly with the RV application, as I had a long prop extension and wooden prop and less power. Smoothness of my O200 with fixed wood prop was noticably improved.

That said I always figured that a prop/spinner R&R degraded that performance ever so slightly, though I cannot prove same.

I would like to have a balancer of my own but just cannot justify the cost as yet. Previously a poster said that there was an art to balancing, with this I might agree a tiny bit but everyone that uses one today started somewhere. If you had your own balancer you would be doing a lot of honing of that art. After having mine balances numerous times I wouldn't hesitate a second to create my own masterpiece.

$1500 = About $175 in our area, so about 9 balances = my own machine = part of a glass panel = 300 gal of fuel. Why can't we have it all?
Click to expand...

I can relate this response directly to an increase in speed from dynamic balancing. A 50 RPM gain is hard evidence that some performance is being lost by the propulsion system to vibration. This is the very first direct connection I have seen. This relationship is either true or it is not and it does not matter whether the prop is constant speed or not. I can certainly understand the desire to have your own equipment to maintain the optimum performance in this area and learn the art. I received an input from a highly respected cross country race pilot with C/S that said he and a friend (another Rocket pilot/racer who is even faster) flew directly to Hartzell in Ohio to get their props dynamically balanced. That is what I would like to do whenever I can work it in - I figure they understand the "art" of the task on their props. What RPM(s) did they balance your prop at?

Bob Axsom
 
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it is not unreasonable to theorize some USEFUL power increase due to a reduction in vibration. The energy provided by the combustion process has to go somewhere (neither created nor destroyed....) most of it goes to heat, some to developing thrust, sound, and vibrations. Reduce the vibrations and that energy has to go somewhere else and it seems reasonable it would manifest in increased RPM.
 
Racing

is certainly a good application for balancing. I do agree that balancing itself does occur and I can understand that the reduction of energy spent in vibration would go to the prop in RPM. A cutting edge racer would probably want to be balanced the morning of the race to maximize his energy conversion. I just question the long term benefits for a regularly flown sport aircraft unless money is spent to balance very regularly and at the most used power settings. After all, filling out one prop ding on a 70 inch prop at say a station 25 inch from the center will make more change in balance than 5-10 grams inside the spinner.

Maybe someone will design a dynamic unit that would have a ring of contolled sliding weights or valved fluid that would continuously balance our engine/prop as we fly. Maybe just a button on the panel that you could push when you reached cruise that would rebalance. I would invest in one if it was shown to work well.
 
jlk said:
Maybe someone will design a dynamic unit that would have a ring of contolled sliding weights or valved fluid that would continuously balance our engine/prop as we fly. Maybe just a button on the panel that you could push when you reached cruise that would rebalance. I would invest in one if it was shown to work well.
Click to expand...

Interesting you should say that. I've used ceramic beads in my vehicle tires for nearly a decade with excellent results. When I mount have new tires put on I don't balance the tires, just add the ceramic beads to the tires. They balance themselves every time I drive. They work great. I could see a tube filled with 1-2 ozs of ceramic beads mounted on the spinner bulkhead.

http://www.innovativebalancing.com/index.html

http://www.youtube.com/watch?v=-pdjsfruQjI

The same principle could be added to aircraft spinners. I think.
 
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Bob Axsom said:
What RPM(s) did they balance your prop at?

Bob Axsom
Click to expand...

Unfortunately, I do not have that info in my cranial data base, it may however be available in some old notes at the hangar. What I do know is that it was at WOT, full rich, with temps as near as possible to operating range.

Tim
 
Geico266 said:
Interesting you should say that. I've used ceramic beads in my vehicle tires for nearly a decade with excellent results. When I mount have new tires put on I don't balance the tires, just add the ceramic beads to the tires. They balance themselves every time I drive. They work great. I could see a tube filled with 1-2 ozs of ceramic beads mounted on the spinner bulkhead.

http://www.innovativebalancing.com/index.html

http://www.youtube.com/watch?v=-pdjsfruQjI

The same principle could be added to aircraft spinners. I think.
Click to expand...

Bob Axsom will be able to relate to this...sounds like a much-faster-operating version of something called a nutation damper...
 
It has a greater impact than you think!

rvmills said:
as there are vibes at frequencies you can't readily feel that may negatively impact the wear on the entire engine, engine mount, propellor system.

All FWIW of course...I personally think you'll get a knot or two out of it! ;) And I wasn't paid to say that :D

Cheers,
Bob
Click to expand...

Last year, my Air Tractor's prop was so badly imbalanced from an outfit in the Florida panhandle, after overhaul, that it was not really legal to fly...even the elevators would be shaking up and down at idle (on a PT-6 Turbine) with the stick dancing as well. In flight it was smooth but by the next annual, my exhaust duct was cracked badly, the engine split and the assembly sent off for repair....very expensive! I had a guy come by and it was 1.5" IPS!!...way off but we weighted it until it was liveable for the season.

Last spring, I flew up to Gainesville, Ga. and Sensenich Propeller service had to bend a blade to make it track and another was off in pitch. After statically balancing in the shop, it was incredibly smooth on the first run. They kept on tweaking and after the third run, was down to .03 something IPS, so smooth, it feels like sitting at my desk! Those older, graying gentleman are the best.

Your accessories, exhaust, mufflers and many other components will live a lot longer as well. If you trim or file your prop, I'd do a balance at the next condition inspection.

Best,
 
DynaVibe Dynamic Prop Balancer

I'm considering purchasing the DynaVibe Dynamic Prop Balancer (by RPX Technologies) for our Chapter Tool Box. I would like some feedback from people who have used this particular Balancer.

Doug
RV-7
Fuselage
 
I've been using the Dynavibe for two+ years . . . was one of the first buyers when it came out. It's excellent, to put it in two words.

Most of my balance jobs I've done for free in the last two years. I currently charge $135 at my hangar (KSEE) and fly to any location in SoCal for $50. Anybody in this area PM me if interested. Free re-balance anytime within 5 years.

If buying your own, you can't go wrong with a Dynavibe. It's new technology and more accurate and easier to use than the older generation equipment which most of the shops still use.

To learn about prop balancing, reference this:

http://www.acessystems.com/downloads/manual-gpb/gpb.pdf

Mike
 
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