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Pin Style Prop Settings

DonFromTX

Well Known Member
I sent my Sensenich two blade prop back to Sensenich for upgrade to the new hub and settings. Essentially you are furnished a set of pins which you stick in a hole of the new hub, then rotate the blade until the newly installed pins installed by Sensenich contacts.
I cannot find anyone in the archives that has done this, and I was wondering how well this new method gets the blades equal with each other, and which pin others have found to result in the most favorable pitch.
 
I sent my Sensenich two blade prop back to Sensenich for upgrade to the new hub and settings. Essentially you are furnished a set of pins which you stick in a hole of the new hub, then rotate the blade until the newly installed pins installed by Sensenich contacts.
I cannot find anyone in the archives that has done this, and I was wondering how well this new method gets the blades equal with each other, and which pin others have found to result in the most favorable pitch.

Stretching my recollection a bit but I seem to remember starting with a number 3 pin. That only got me in the ballpark and I used a digital level and Van's fixture to fine tune it and get the blades pitched exactly the same.
 
That would be disappointing, I had hoped for all the bucks spent I could get it right on with the pins. I have the Sensenisch slip on the blade tool to check them with if necessary.
Stretching my recollection a bit but I seem to remember starting with a number 3 pin. That only got me in the ballpark and I used a digital level and Van's fixture to fine tune it and get the blades pitched exactly the same.
 
It has been discussed in the archives in the past.
As Tom mentioned, pin 3 is the recommended starting point.
The difference between each pin # is quite a bit so most people end up somewhere in between.
Since a smooth running engine requires blades to be pitched within .1 degrees of each other, you have to measure it. Neither the old style or new style hub gets the blade pitch relationship accurate enough.
 
The sheetmetal gauge from Van's, when used with a precision digital level, works very well to set blades within 0.1 degree pitch.

I have my blades set at 71.4 with the Rotax 912 engine. Performance matches Van's published figures and engine/prop run very smooth without need for dynamic balancing.
 
The sheetmetal gauge from Van's, when used with a precision digital level, works very well to set blades within 0.1 degree pitch.

I have my blades set at 71.4 with the Rotax 912 engine. Performance matches Van's published figures and engine/prop run very smooth without need for dynamic balancing.

I've tried different settings, but agree with Piper J3...71.4 works best (at least for me). Both blades dead on..is running super smooth! Digital level is easiest...as you set reference angle as per instructions.
 
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I run mine at 71. That gives me 4850 RPM WOT on the ground and 5540 RPM WOT at 7500' DA. Seems to work well here in Fl where our highest mountain is 315' :)
 
I run mine at 71. That gives me 4850 RPM WOT on the ground and 5540 RPM WOT at 7500' DA. Seems to work well here in Fl where our highest mountain is 315' :)
That's still a little course (over pitched).
Ideal WOT RPM, at your preferred cruise altitude, during straight and level flight, should be about 5650. That will also give you a little more RPM for your climbout.
 
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That's still a little course (over pitched).
Ideal WOT RPM, at your preferred cruise altitude, during straight and level flight, should be about 5650. That will also give you a little more RPM for your climbout.

I agree it sounds just a bit too course, but maybe Tom is cruising around down low at 125 kts and just not telling anyone;)
 
I agree it sounds just a bit too course, but maybe Tom is cruising around down low at 125 kts and just not telling anyone;)

Hi, I'm Doug in IL. In bound is hub replacement IAW theSeninich B revision exchange program. I bought my 12 built/used and it had a dynamic bal job 3 years ago. What to do now. I don't have dynamic balance capability nearby? Any suggestions opinions welcomed. I took the B hub off because of a 1.15 dif in blade angle and it's a b hub??
 
Thanks Scott, that is the info I needed. I was unable to get that from the archives, and supposed it was not a Vans option. Sensenish sold me on their idea that the old nylon button was not accurate, but that the new pins were to be totally accurate. I guess that is not the case. I have the Sensenish blade angle tool, guess I will have to fine tune the settings that way.
It has been discussed in the archives in the past.
As Tom mentioned, pin 3 is the recommended starting point.
The difference between each pin # is quite a bit so most people end up somewhere in between.
Since a smooth running engine requires blades to be pitched within .1 degrees of each other, you have to measure it. Neither the old style or new style hub gets the blade pitch relationship accurate enough.
 
Thanks Scott, that is the info I needed. I was unable to get that from the archives, and supposed it was not a Vans option. Sensenish sold me on their idea that the old nylon button was not accurate, but that the new pins were to be totally accurate. I guess that is not the case. I have the Sensenish blade angle tool, guess I will have to fine tune the settings that way.

The current Rev. KAI section for propeller installation mentions using pin 3 as the starting point.
 
I agree it sounds just a bit too course, but maybe Tom is cruising around down low at 125 kts and just not telling anyone;)

Hi, I'm Doug in IL. In bound is hub replacement IAW theSeninich B revision exchange program. I bought my 12 built/used and it had a dynamic bal job 3 years ago. What to do now. I don't have dynamic balance capability nearby? Any suggestions opinions welcomed. I took the B hub off because of a 1.15 dif in blade angle and it's a b hub??

From my experience, anytime a propeller is removed from an engine (Rotax, Lyc., etc.) and then reinstalled, it will have some level of influence on the overall balance and that rechecking the dynamic balance afterwards is typically warranted.

If that wont be possible, you can label all of the parts positions so that is gets reassembled with the blades and the spinner reinstalled in the exact same clocking positions on the crank shaft and see what happens. If it feels as smooth as it has previously then you could just leave it as is. If not, then finding someone to check the balance would be a good idea.

P.S. I am somewhat hesitant to recommend this because physical evaluation of smoothness is very subjective. The only truly accurate way to know is to measure it. Having engine vibration low in an aircraft has many benefits far beyond passenger comfort (airframe longevity, etc.), so knowing for sure that the vibration level is as low as possible is worth traveling to have it checked in my opinion.

Also keep in mind that a very close match in blade pitch has a major influence on smoothness. Doing a dynamic balance without confirming that the pitch of the blades is within .1 degrees of each other is a waste of time and money.
 
Sensenish sold me on their idea that the old nylon button was not accurate, but that the new pins were to be totally accurate. I guess that is not the case. I have the Sensenish blade angle tool, guess I will have to fine tune the settings that way.

I wouldn't even use Sensenich's blade angle tool. I would get the sheetmetal pitch gage from Van's. Very accurate and repeatable...
 
I don't think it can get any closer by the gage method

I know that there people that think that they can set the prop angle better with a pitch gage and maybe they can.
The pin setting method is in my view as close as 95% of the all the props set with a gage
The pin method is designed to change two inches of bite in one revolution .
If you want something in the middle you can turn down the larger pin to the one half the difference in the next smaller pin.
I have reviewed this possess add I don't think it can get any closer by the gage method
I went to Sensenich for a Factory tour on 09/06/17 for this same question.

FS_09_06_17_012.jpg


The story I posted on our chapter 1298 web page

http://eaa1298.com/Members/1298_FS_09_06_17.html

MY view

Joe Dallas
 
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I'm going to be pretty upset if the pin system is not accurate. I paid a premium for this prop over the Whirlwind GA, because this pitch pin system promises easy pitch adjustments.
 
1 tenth of a degree is .0017 in a inch.

Scott is dismal point on the wrong side of the 1 ?

1 tenth of a degree is .0017 in a inch.

Joe Dallas


 
From my experience, anytime a propeller is removed from an engine (Rotax, Lyc., etc.) and then reinstalled, it will have some level of influence on the overall balance and that rechecking the dynamic balance afterwards is typically warranted.

If that wont be possible, you can label all of the parts positions so that is gets reassembled with the blades and the spinner reinstalled in the exact same clocking positions on the crank shaft and see what happens. If it feels as smooth as it has previously then you could just leave it as is. If not, then finding someone to check the balance would be a good idea.

P.S. I am somewhat hesitant to recommend this because physical evaluation of smoothness is very subjective. The only truly accurate way to know is to measure it. Having engine vibration low in an aircraft has many benefits far beyond passenger comfort (airframe longevity, etc.), so knowing for sure that the vibration level is as low as possible is worth traveling to have it checked in my opinion.

Also keep in mind that a very close match in blade pitch has a major influence on smoothness. Doing a dynamic balance without confirming that the pitch of the blades is within .1 degrees of each other is a waste of time and money.

Thanks Scott, say do the slsa versions come off the line dynamic balanced?
 
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'm going to be pretty upset if the pin system is not accurate. I paid a premium for this prop over the Whirlwind GA, because this pitch pin system promises easy pitch adjustments.
 
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Scott is dismal point on the wrong side of the 1 ?

1 tenth of a degree is .0017 in a inch.

Joe Dallas

No, I meant 00.1 degrees

Your are of course welcome to your opinion if you think it doesn't matter.

I rarely provide info based on opinion (I try and use actual testing or in service experience).

I have seen, felt, and measured the vibration difference that more than .1 degrees of mismatch makes.

I have also measured the blade pitch differences that result from just using the pins on quite a few different props (Van's flight tested one of the early prototypes, and has sold more than a few S-LSA's so there is experience with a lot of different props.

The very first S-LSA's did not get the props Dyn. balanced, but they have been for a number of years now (not sure when exactly it was started).
 
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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.
 
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



Your are of course welcome to your opinion if you think it doesn't matter.
.
 
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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?
 
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?
I wouldn't even use Sensenich's blade angle tool. I would get the sheetmetal pitch gage from Van's. Very accurate and repeatable...
 
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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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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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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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.
 
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


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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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.
 
Thank you a pic is worth 10000 words to me I look forward to seeing what the standard 71.4 turns up with my configuration.
 
When I put my new Sensenich on they told me the pins were good for the ballpark, but preferred the blades get checked with a protractor to make sure and that they may even need some fine tuning to get my exact rpm I was looking for.
 
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