Dynamic Prop Balancing

[corbinace]

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?

[Bob Axsom]

Originally Posted by corbinace

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?

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

[RV8R999]

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.

[jlk]

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.

[Geico266]

Originally Posted by jlk

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.

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.

[corbinace]

Originally Posted by Bob Axsom

What RPM(s) did they balance your prop at?

Bob Axsom

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

[Flying Scotsman]

Originally Posted by Geico266

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.

Bob Axsom will be able to relate to this...sounds like a much-faster-operating version of something called a nutation damper...

[pierre smith]

Originally Posted by rvmills

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

Cheers,
Bob

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,

[doug_rv7]

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

[MikeS]

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