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  #1  
Old 04-17-2017, 04:51 PM
pa38112 pa38112 is offline
 
Join Date: Mar 2008
Location: Clarksboro, NJ
Posts: 396
Default Prop Clocking data

This weekend I finally got around to collecting some real data on prop clocking (Sample size of 1):
Prop clocked 11:00 un-balanced = 0.36ips
Prop clocked 11:00 balanced = 0.20ips
Prop clocked 9:00 un-balanced = 0.12ips
Prop clocked 9:00 balanced = 0.016ips

O-360-A1A with Sensenich Aluminum FP.

If anyone in/near New Jersey wants to help expand the sample size I would be willing to do a free prop balancing (RV's only) at NJ25. We would take readings before, then balance, then re-clock, then balance again.
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  #2  
Old 04-17-2017, 08:10 PM
j-red j-red is offline
 
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Ooh, pick me! I've got a 6a with an o-360 and sensi fp too. I'm in Delaware just across from Cape May.
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  #3  
Old 04-17-2017, 08:36 PM
pa38112 pa38112 is offline
 
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Perfect. What are you doing Saturday morning?
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  #4  
Old 04-17-2017, 09:30 PM
Michael Henning Michael Henning is offline
 
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Location: Nashua, NH
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Out of curiosity, why are you collecting this data?
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  #5  
Old 04-18-2017, 06:58 AM
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Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
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Quote:
Originally Posted by pa38112 View Post
This weekend I finally got around to collecting some real data on prop clocking (Sample size of 1):
Prop clocked 11:00 un-balanced = 0.36ips
Prop clocked 11:00 balanced = 0.20ips
Prop clocked 9:00 un-balanced = 0.12ips
Prop clocked 9:00 balanced = 0.016ips

O-360-A1A with Sensenich Aluminum FP.
Are you saying that you were unable to improve the 11 oclock balance condition any better than .2 IPS and that is why you re-clocked?

Before and after spectral vibration plots would be more revealing than just prop freq. balance figures.
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Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
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  #6  
Old 04-18-2017, 07:10 AM
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Vlad Vlad is offline
 
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Location: NJ
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Hi Keith,
Would a three blade prop be a useful sampler?
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  #7  
Old 04-18-2017, 07:35 AM
jsharkey jsharkey is offline
 
Join Date: Nov 2006
Location: Bennington, Vermont USA
Posts: 1,261
Default Define Clocking

Apologies if this is a dumb question.

I too have an RV6 with an O360-A1A and a 72/85 Sensenich.

When facing the front of the aircraft my prop stops with the left (stb in aircraft axes) blade below horizontal. How does that compare with the 9 o'clock and 11 o'clock definition above?

I had initially set it up to stop with this blade high thinking that it would be easier to hand prop but it runs smoother as it is now. And besides I'm not brave or foolhardy enough to hand prop an O360.

How do these positions compare with the plane of the crank journals? I remember that the prop is vertical when I do the cylinder compression tests at TDC so that means that the prop is at 90 deg to the crank plane.

Jim Sharkey
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  #8  
Old 04-18-2017, 04:49 PM
pa38112 pa38112 is offline
 
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Location: Clarksboro, NJ
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Micheal, I am collecting this data because I feel it is beneficial to the RV community. There have been many post debating the theory of prop clocking and I would like to get real data.

Vlad, I don't know that a 3 blade will advance the topic any, but come over any time to balance it!

Walt, .02 was after one balance run. I could have trimmed it, but the phase angle was jumping around, which told me there was more than a balance issue. I was going to re-clock no matter what as an experiment. 0.016 was after one balance run, and the phase angle was holding consistent. This weekend I intend to re-do it a couple of times for verification. I'll try to plot the spectrum for you. I am filtering out 10hz and below because I am balancing on the ground and the plane is bouncing around on the landing gear.
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  #9  
Old 04-18-2017, 06:01 PM
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Kahuna Kahuna is offline
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Location: Gold Hill, NC25
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Not sure what theory your working. Are you trying to make the engine feel better or your Butt? IF it is the latter, This process will not help. Your butt feel takes into consideration the 'system'. From engine to your butt. You will need the transducer mounted near your butt. I did some clocking and butt tests years ago. Data and write up here.
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  #10  
Old 04-18-2017, 07:33 PM
pa38112 pa38112 is offline
 
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Location: Clarksboro, NJ
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Kahuna, I'm trying to minamize vibration on the airframe - my butt is fine. I read your write-up a couple of years ago and it was one of the reasons I started exploring this topic, but you too are a sample size of one. For every write-up like yours I also read another that said Prop clocking is snake oil. If I do 10 or 20 planes, all with the same equipment, operator, and process then I start to have proof if this works or not.
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