Prop balance, 0.01 IPS, lucky?

[JamesClarkIV]

Did our prop balance recently, it took 12 iterations but we got to 0.01 in averaging mode on the DynaVibe balancer. Is this luck? Did we do it at too low an RPM: 2100?

We were tied to the car for safety and braking and trying not to pull the rope taught @ 2100...is it safe to go higher? Tie or chock, or other?

Blog writeup is here:

N997CZ — Dynamic Prop Balancing: 0.57 IPS Down to 0.01

After the first five flights it was clear that N997CZ was sitting on more vibration than I wanted. The most visible symptom was the ADAHRS percent-deviation values logged by the G3X — they were chr…

jamessclarkiv.com

 

[Richard Connell]

Did our prop balance recently, it took 12 iterations but we got to 0.01 in averaging mode on the DynaVibe balancer. Is this luck? Did we do it at too low an RPM: 2100?

We were tied to the car for safety and braking and trying not to pull the rope taught @ 2100...is it safe to go higher? Tie or chock, or other?

Blog writeup is here:

N997CZ — Dynamic Prop Balancing: 0.57 IPS Down to 0.01

After the first five flights it was clear that N997CZ was sitting on more vibration than I wanted. The most visible symptom was the ADAHRS percent-deviation values logged by the G3X — they were chr…

jamessclarkiv.com

View attachment 118425

I dynamically balanced a few weeks ago after installing a new spinner.
We went from 0.7 down to 0.05 in 3 runs and called it a day.
We did that at 2400-2450 RPM and had the airplane tied down.

I see you are still chasing AHRS deviations. Where are your GSU25s mounted? On the sub panel?

 

[JamesClarkIV]

I dynamically balanced a few weeks ago after installing a new spinner.
We went from 0.7 down to 0.05 in 3 runs and called it a day.
We did that at 2400-2450 RPM and had the airplane tied down.

I see you are still chasing AHRS deviations. Where are your GSU25s mounted? On the sub panel?

Yep, still on the sub panel for the ADAHRS1 and 2. Panel for the SFD G5. Rewired entire CAN at Garmin request, fixed bus errors, and prop balance helped with smoothness, but AHRS1 tumbles still persist. Replumbed the pitot/static/aoa feeding the ADAHRS for support. Still searching.

 

[JamesClarkIV]

I dynamically balanced a few weeks ago after installing a new spinner.
We went from 0.7 down to 0.05 in 3 runs and called it a day.
We did that at 2400-2450 RPM and had the airplane tied down.

I see you are still chasing AHRS deviations. Where are your GSU25s mounted? On the sub panel?

Can you tell me a bit about how you tie the airplane safely? Just a tail ring?, tail, and wing tiedows?

 

[Richard Connell]

Yep, still on the sub panel for the ADAHRS1 and 2. Panel for the SFD G5. Rewired entire CAN at Garmin request, fixed bus errors, and prop balance helped with smoothness, but AHRS1 tumbles still persist. Replumbed the pitot/static/aoa feeding the ADAHRS for support. Still searching.

A well worn path...
Just move them to the back of the GDUs. that will solve all your problems. I promise. Don't spend the months I did messing about.

Yes just tied it by the tailring, chocked it and stood on the brakes.

 

[RV7 To Go]

Just did a dynamic balance the other day. Went from .6 down to .04 in 5 runs at 2400 rpm. Will be interested to see if I can notice a difference when I get to fly next.

 

[Richard Connell]

To answer your other question though, I’d be more inclined to mass balance at the RPM you expect to spend most of your time. So most likely 2400 or more.
Also, mass imbalance results in IPS to the 3rd power of velocity so 0.01 IPS at 2100 will be a significantly higher IPS at 2400 fwiw.

 

[Nova RV]

You want to balance at your typical cruise RPM according to the guy that did my balance since you spend the most time at that setting.

 

[Walt]

A well worn path...
Just move them to the back of the GDUs. that will solve all your problems. I promise. Don't spend the months I did messing about.

I've never mounted AHRS on the screen and never had any issues. Also not recommended by Garmin;

Also, mass imbalance results in IPS to the 3rd power of velocity so 0.01 IPS at 2100 will be a significantly higher IPS at 2400 fwiw.

"FWIW"; Having balanced hundreds of props, this may be true in theory, but certainly not in reality.

And for those of you interested, the DVib is what I consider a "hobby" balancer, I pretty much guarantee those low numbers y'all see won't be the same on my machine (Microvib II).

 

[skirting_virga]

I've never mounted AHRS on the screen and never had any issues. Also not recommended by Garmin;

What's your preferred mounting location in an 8?

 

[Walt]

What's your preferred mounting location in an 8?

Subpanel on every RV.

 

[pazmanyflyer]

.09 to .01 in 3 cycles.

 

[Richard Connell]

Subpanel on every RV.

Well theres been plenty of evidence to suggest that this is suboptimal in RV10s.
And yes I’m aware that Garmin specifically says not to mount it on the back of the GDU - I’ve written about the poor wording of this constraint several times over the years.

Im confident the OP will no doubt come to the same conclusion after frustratingly trying all other “solutions” to no avail.

 

[Philz7A]

Did our prop balance recently, it took 12 iterations but we got to 0.01 in averaging mode on the DynaVibe balancer. Is this luck? Did we do it at too low an RPM: 2100?

We were tied to the car for safety and braking and trying not to pull the rope taught @ 2100...is it safe to go higher? Tie or chock, or other?

Blog writeup is here:

N997CZ — Dynamic Prop Balancing: 0.57 IPS Down to 0.01

After the first five flights it was clear that N997CZ was sitting on more vibration than I wanted. The most visible symptom was the ADAHRS percent-deviation values logged by the G3X — they were chr…

jamessclarkiv.com

View attachment 118425

Recently had my prop balanced. It came out to .005 ips which the A&P said was better than usual (initially .06). Also, .005 ips is not a typo. I read it off the computer screen. Had it done at KTTD by Dash Air. His balancing tool was a Micro Vib II which he gives credit to for the near perfect balance number. Balanced at 2400 RPM.
Almost forgot, it runs a lot smoother!