Anyone try prop Balance Master?

Wondering if anyone here has experience with a mercury auto-balancing accessory for prop vibration reduction on their self-launcher, ultralight, etc.
www.balancemasters.com/ultralights

At 17:40 23 June 2013, Soartech wrote:
Wondering if anyone here has experience with a mercury auto-balancing
accessory for prop vibration reduction on their self-launcher,
ultralight,
etc.
www.balancemasters.com/ultralights

I achieved a considerable improvement in vibration after using
a double straight edge and a central spindle.
The prop overhauled by a prop shop was 4 gm (at the tip)
out of balance.

JMF

On Sunday, June 23, 2013 1:40:15 PM UTC-4, Soartech wrote:
Wondering if anyone here has experience with a mercury auto-balancing accessory for prop vibration reduction on their self-launcher, ultralight, etc.

www.balancemasters.com/ultralights

Thanks. Can you please email me with details of "double straight edge" and
which prop shop you used?

(I am not liking this new Google Groups interface.)


I achieved a considerable improvement in vibration after using

a double straight edge and a central spindle.

The prop overhauled by a prop shop was 4 gm (at the tip)

out of balance.



JMF

On Sunday, June 23, 2013 10:40:15 AM UTC-7, Soartech wrote:
Wondering if anyone here has experience with a mercury auto-balancing accessory for prop vibration reduction on their self-launcher, ultralight, etc..

www.balancemasters.com/ultralights

I don't know how or if the "self-adjusting" centrifugal balancers work. It defies whatever logic I might have, as I'd think the weight would migrate to the heavy side (g).

Dynamic computer balancers work very well and are pretty much the industry standard for prop, turbine, and rotor blade balancing. They have the advantage of balancing the entire rotating mass at speed.

Static balancers usually require prop removal, but they do okay for blade imbalance. I think they'd have a harder time correcting for an imbalance at 90 degrees to the blade axis. My 26E had such a lateral imbalance when delivered and it took a fair amount of weight to correct (partly because the weights had to go on the prop mounting bolts).

"Double straight edge" I believe refers to setting up two lever straight edges. A close fitting bushing is used through the prop hub and to mount the prop with a small diameter center pin that spans between the two straight edges. When mounted such, the prop should stay horizontal, as a heavy blade will rotate downward. Works similar to a motorcycle wheel balancer.

bumper

On Wednesday, July 3, 2013 4:58:15 PM UTC-7, bumper wrote:
On Sunday, June 23, 2013 10:40:15 AM UTC-7, Soartech wrote:

Wondering if anyone here has experience with a mercury auto-balancing accessory for prop vibration reduction on their self-launcher, ultralight, etc.



www.balancemasters.com/ultralights



I don't know how or if the "self-adjusting" centrifugal balancers work. It defies whatever logic I might have, as I'd think the weight would migrate to the heavy side (g).



Dynamic computer balancers work very well and are pretty much the industry standard for prop, turbine, and rotor blade balancing. They have the advantage of balancing the entire rotating mass at speed.



Static balancers usually require prop removal, but they do okay for blade imbalance. I think they'd have a harder time correcting for an imbalance at 90 degrees to the blade axis. My 26E had such a lateral imbalance when delivered and it took a fair amount of weight to correct (partly because the weights had to go on the prop mounting bolts).



"Double straight edge" I believe refers to setting up two lever straight edges. A close fitting bushing is used through the prop hub and to mount the prop with a small diameter center pin that spans between the two straight edges. When mounted such, the prop should stay horizontal, as a heavy blade will rotate downward. Works similar to a motorcycle wheel balancer.



bumper

Bumper,

Self adjusting balancers do work, though the physics is not very intuitive. Think of an imbalanced wheel spinning in space: it will rotate about its center of gravity, that is, the axle center will describe a circle opposite the heavy side since the CG is displaced towards the heavy side. It is therefore the light side rim making the largest radius, not the heavy side as is commonly thought. The weights migrate towards the largest radius until balance is achieved relative to the balance weight track (which is concentric with the axle by design). Constraining the wheel to rotate about the axle does not change the physics - unless the axle and its mountings are infinitely rigid, in which case you would feel no vibration. The vibration felt is the extent to which the axle orbits just as the wheel would in free space, limited only by the stiffness of its mountings.

On Wednesday, July 3, 2013 5:55:22 PM UTC-7, jfitch wrote:

Self adjusting balancers do work, though the physics is not very intuitive. Think of an imbalanced wheel spinning in space:


Jon,

Got it! Clearly I wasn't thinking that one through well (grin).

bumper