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  #21  
Old 09-22-2017, 08:15 PM
smithflys23 smithflys23 is offline
 
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Location: Jupiter
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Quote:
Originally Posted by DonFromTX View Post
Me too. I chose to spend the bucks because my EAB 12 has so many differences than an ELSA, I figured I would be playing with the pitch a lot getting it all dialed in where I wanted it, and wanted the quick and easy method.
The ferry pilot (Bob Bogash) who brought my ELSA down reported it was pitched far too coarse, but I think that I will like it that way. Fuel economy was very nice and so was the ground speed. It has the old Nylon button system.
I just ordered mine. It should ship shortly. I assume it will have the new hub.
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  #22  
Old 09-23-2017, 07:33 AM
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joedallas joedallas is offline
 
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Default The closer the better

Scott
I never said that it doesn't matter.

The closer you can get to the same pitch of each blade the better it is.

I Said ( The pin setting method is in my view is as close as 95% of the all the props set with a gage ).

I also rarely provide info based on opinion ( I use the experience of over 50 years of working with tolerances of less then.0005 Thousands of a inch ).

A one piece propeller is not within 1 tenth of a degree, they are all hand sanded to the final finish.

Fact 1. degree = .01745 thousands of a inch, .1 is ten times less .001745.

You may be able to set a propeller better than 95% of the propellers flying.

Most test equipment and propeller blade rotation and test location placement is not that close. ( they all have some tolerance )
And the blade itself will have some tolerance across the changing pitch curve.
The end of the blade moves thru the air almost 3 times faster than at the hub.
The pitch gets less as it move out to the end of the prop.

If using the pins to set the prop then test with a gauge and report the results.

I also think that dynamic balancing is a good idea.



My View

Joe Dallas



Quote:
Originally Posted by rvbuilder2002 View Post
Your are of course welcome to your opinion if you think it doesn't matter.
.
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Last edited by joedallas : 09-23-2017 at 04:14 PM.
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  #23  
Old 09-23-2017, 09:43 AM
AirHound AirHound is offline
 
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Wow, achieving .1 sounds like another challenge for us less experienced folk. I guess that final tiny movement will be on fairly snugged clamp bolts. Boy I can see it changing with just torquing them up, or am I being overly concerned?
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  #24  
Old 09-23-2017, 10:31 AM
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DonFromTX DonFromTX is offline
 
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I never thought much about it, but supposed that Sensenich had refined that tool pretty well. What are you basing your disapproval of it on Jim?
Quote:
Originally Posted by Piper J3 View Post
I wouldn't even use Sensenich's blade angle tool. I would get the sheetmetal pitch gage from Van's. Very accurate and repeatable...
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  #25  
Old 09-23-2017, 11:00 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by AirHound View Post
Wow, achieving .1 sounds like another challenge for us less experienced folk. I guess that final tiny movement will be on fairly snugged clamp bolts. Boy I can see it changing with just torquing them up, or am I being overly concerned?
It is not difficult but is not necessarily done in 5 minutes.

I would say that 95% of the props on RV-12's where the owner has experienced and learned the smoothness difference are set within .1 degrees (many here in the forum have mentioned it in the past).

Will the engine run ok with a difference of .3-.4 (fairly common if just using the barrel or pin indexing system)? Sure. But it is not worth compromising when dealing with airplanes.

All of my TeenFlight students learn my mantra very early on......

Good enough is not a word phrase used in our shop vocabulary......

Why compromise when with just a bit more effort you can make it better?
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Last edited by rvbuilder2002 : 09-23-2017 at 11:08 AM.
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  #26  
Old 09-23-2017, 11:27 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by joedallas View Post

A one piece propeller is not within 1 tenth of a degree, they are all hand sanded to the final finish.

Fact 1. degree = .01745 thousands of a inch, .1 is ten times less .001745.
We are not talking about 1 piece propellers... we are talking about what in service experience has shown regarding the dynamic effects of blade pitch difference on the Sensenich ground adjustable propeller for the Rotax 912.

I didn't check you math but will assume that your value per degree is correct.
That value means that Sensenich only has to miss-locate the indexing pin by less than four thousandths of an inch and it will already be inducing a blade pitch difference of .2 degrees. (for the record, I have seen them all over the place... some set the blade angles close to the same and others are off by up to .5 degrees)
Compound that with the tolerance that the digital levels typically used have... and the fact that even when your digital level says the numbers match you could be only .01 degrees away from the display changing to the next tenth of a degree, and we can see how the tolerances begin to drift the result a lot.

That is why I shoot for the exact same value, but realistically accept that even then it is probably off by .1 or so. I personally accept a difference of .1 and figure the difference is at least less than .2 degrees.


BTW, I know your airplane is still under construction and (I think) doesn't have an engine mounted on it yet........ do you have a lot of experience with the Sensenich propeller on other aircraft?
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Last edited by rvbuilder2002 : 09-23-2017 at 11:30 AM.
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  #27  
Old 09-23-2017, 11:36 AM
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Piper J3 Piper J3 is online now
 
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Quote:
Originally Posted by DonFromTX View Post
I never thought much about it, but supposed that Sensenich had refined that tool pretty well. What are you basing your disapproval of it on Jim?
Not so much disapproval of Sensenich gage as recognizing superior design of Van's sheetmetal gage. Van's gage automatically hangs square and straight to the blade. Very accurate setup and very repeatable. Not difficult to get 0.1 degree setting - just takes patience. Snug bolts and keep checking both blades alternately as you torque. Tightening bolts doesn't affect blade setting like you would imagine. Work slowly and keep rechecking pitch until you're satisfied that both blades are exact same angle.

My prop is pitched at 71.4. Plane is based at 900' field elevation and I typically fly 3,000-7,000 MSL. Performance is splendid...
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Last edited by Piper J3 : 09-23-2017 at 11:39 AM.
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  #28  
Old 09-23-2017, 12:55 PM
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Quote:
Originally Posted by DonFromTX View Post
I never thought much about it, but supposed that Sensenich had refined that tool pretty well. What are you basing your disapproval of it on Jim?
The Sensenich tool that came with my prop was a piece of plywood cut to fit over the prop blade. It seemed to work OK but was difficult to achieve repeatability because there was no mechanism to assure it wasn't tipped slightly sideways when taking the measurement. The Van's tool always aligns itself with the back edge as well as the back surface of the blade and stabilizes in both dimensions.
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  #29  
Old 09-23-2017, 04:57 PM
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joedallas joedallas is offline
 
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Default There is now question you have more experience with Rotax 912 and Sensenich

Scott
There is now question you have more experience with Rotax 912 and Sensenich

I was in no way saying that it could not be better with good equipment.

I have used Precision Machinist levels and Joe blocks to set angles to less than 30 seconds.

I have no experience with the Rotax Engine and never plan to.

The post was about a Viking engine at the start, and I think that the new Sensenich system is as good as what is in this video, and I was referring to the way I have seen it accomplished and the equipment used

https://www.youtube.com/watch?v=pT0rec0krq0

I don't think you can get to 0° 6' 0" with this method

My View


Quote:
Originally Posted by rvbuilder2002 View Post
We are not talking about 1 piece propellers... we are talking about what in service experience has shown regarding the dynamic effects of blade pitch difference on the Sensenich ground adjustable propeller for the Rotax 912.
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Last edited by joedallas : 09-23-2017 at 05:32 PM.
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  #30  
Old 09-23-2017, 05:26 PM
smithflys23 smithflys23 is offline
 
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Quote:
Originally Posted by Piper J3 View Post
Not so much disapproval of Sensenich gage as recognizing superior design of Van's sheetmetal gage. Van's gage automatically hangs square and straight to the blade. Very accurate setup and very repeatable. Not difficult to get 0.1 degree setting - just takes patience. Snug bolts and keep checking both blades alternately as you torque. Tightening bolts doesn't affect blade setting like you would imagine. Work slowly and keep rechecking pitch until you're satisfied that both blades are exact same angle.

My prop is pitched at 71.4. Plane is based at 900' field elevation and I typically fly 3,000-7,000 MSL. Performance is splendid...
Can you post a link for the Vans tool? I was unable to find it on their website.
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