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Allegro 80 HP Woodcomp Pitch setting

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tcmoses(at)earthlink.net
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Posted: Tue Oct 30, 2007 4:11 pm Post subject: Allegro 80 HP Woodcomp Pitch setting

What would be a good pitch setting for climb on an  Allegro with the 80 HP Rotax and the Woodcomp prop?  The previously  reccomended pitch of 23.5 degrees at 7.875" from the tip seems like it is way  too much.

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Tue Oct 30, 2007 4:35 pm Post subject: Allegro 80 HP Woodcomp Pitch setting

Tim:  

I agree, the 23.5 degrees is too much. I went through a series of emails on the rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com) back in October 2006 on this same subject. Go to that forum and look at the archived emails on the subject. I finally settled at 15 degrees which gave me 5100 rpm (static). If you ask Fantasy Air USA (Matt Smith) he will tell you they set all their props at 14 degrees. You will get various opinions on this subject, but 23.5 degres is certainly too much, and I believe every one will agree on that. At least I hope so!! 

  

Hugh McKay in NC 

Allegro 2000 

Rotax 912 UL 

WoodComp Three Blade (Klassic 160/3/R 

N661WW

  	  Quote: 	
		  -------------- Original message from "TIM MOSES" <tcmoses(at)earthlink.net>: -------------- 



    What would be a good pitch setting for climb on an Allegro with the 80 HP Rotax and the Woodcomp prop?  The previously reccomended pitch of 23.5 degrees at 7.875" from the tip seems like it is way too much.

 	  Quote: 	
		  

	
	
      [quote][b]

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tcmoses(at)earthlink.net
Guest

Posted: Wed Oct 31, 2007 6:02 am Post subject: Allegro 80 HP Woodcomp Pitch setting

Hugh,

 I just got an email from the Australian  Allegro/Woodcomp dealer and he said that the blade pitch is measured at "1/3 of  the blade length from the tip".  I thought it was customary to use the 75%  blade span (ie. 1/4 of the blade length from the tip).  So my question is  what distance is this 14 or 15 degrees measured at?

  

 The following is the adjustment message I recieved  from Michael Coats:

  

 setting up the propeller is no big deal but it must be done properly.  

forget the recommendations above, there is only one way to set the  

propeller and the instructions follow.  Please note I am the Woodcomp  

certified service centre from Australia and New Zealand so I can tell  

you with certainty that the following information is correct.



The  correct distance the setting the blade measurement with just about 

every  propeller ever manufactured is ***one third*** of the blade length in 

from  the blade tip.  You will see in the attached photographs I have 

made a  very small T square which on the propeller I am using is 180 mm 

long, yours  will be similar.



In a pictures shown I am using a warp drive propeller  protract which is 

probably the most common unit out there, is extremely  cheap (approximate 

we $20) and will last a lifetime of normal use provided  you don't drop 

it and break it.



Step one, make sure the propeller  blade is horizontal, if it is not 

horizontal get it is close to horizontal  is you can and using a piece of 

wood or a broomstick or something like that  marked the distance from the 

propeller leading edge to the ground and make  sure that all of the other 

adjustments are made in this exact same position  otherwise you will get 

varying blade angles.  So firstly to set the  propeller horizontal and 

then using the little T square position the  propeller protract one third 

of the way up the propeller and take your  adjustment.  We mainly have 

cruise settings on our propeller and these  follow below....



80hp 18 degrees



100 hp 21 degrees



   If you want to get a bit more climb performance out of it I would 

suggest  initially going approximately 1 1/2 degrees finer pitch, so for 

example on  the 80 hp engine I would start at about 16.5° or thereabouts 

than it is a  simple matter of adjusting each of the three blades on the 

propeller to get  them all identical.  Tighten up all the bolts and 

recheck after  everything has been tightened just to make sure that 

nothing has  moved.  You can leave the propeller spinner off if you wish 

and go for  a fly making sure that the performance and blade angles suit 

your  needs.  If you find your engine is over revving or you are using 

too  many revs to your desired cruise speed simply course in the 

propeller up so  go from 16.5° to approximately 17.5° and so on.



On most of these  propellers 1° of blade movement makes approximately 200 

rpm difference as a  general rule of thumb so if your aircraft is 

readying 400 rpm too high then  you can make a adjustment of 2° to bring 

it back to the desired rpm.   Please let me know if you have any 

additional questions, kind regards  Michael



Note: To protect against computer viruses, e-mail  programs may prevent

sending or receiving certain types of file attachments.  Check your

e-mail security settings to determine how attachments are  handled.



-- 

With regards,    Michael Coates

Company  Director X-Air Australia

Gold Coast, Australia.



 Tim

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Wed Oct 31, 2007 6:46 pm Post subject: Allegro 80 HP Woodcomp Pitch setting

Tim: 

  

Who am I to question the Australian Authorized WoodComp Service Center! It is interesting however to note that the Woodcomp Manual (at least the one I have) shows that the pitch angle should be measured 60 mm from the blade tip. For a 1600 mm diameter propeller (800 mm blade length from center of hub) this is 92.5% of the blade length. The little diagram shows that the blade pitch at this point can vary from 6 degrees to 17 degrees. All this is meaningless! Remember, the blade twist changes through out the length of the blade. I do not know why most prop manufacturers use the 75% length, and neither do I know why Mr. Coats uses 60% of the blade length (i.e 30% in from the blade tip). His procedure for setting the pitch is correct and I fully agree with it, but why 30% in from the tip vs. 25% in , I haven't a clue! Use either one, and then do your static test runs and adjust the pitch to get the max static rpm you desire without exceeding the Rotax limit. 

  

I do know this, you will have to choose what pitch you want for the engine performance you desire. Pitch angle is a trade off between high performance on climb out vs. most efficient cruise speed in horizontal flight. You will have to decide what you want, and set the pitch, do the static tests, and then fly the plane and find out if it performs the way you want it to. In the air check the cruise rpm at WOT. Hopefully you will be around 5500 rpm at WOT. If not come back, land and adjust the prop pitch accordingly (lower pitch angle = better climb out performance, higher pitch angle = better rpm cruise speed. 

  

I will note that I had a difficult time adjusting the pitch on my Allegro (I used the same method Mr. Coats described with the prop on the airplane). The blades would not rotate smoothly in the hub with the bolts loosened. They would slip and seize making it very difficult to get the bubble in the Warp drive protractor exactly in the middle. Hope you don't have the same dificulty. I would love to have a jig to do this on a level table rather than on the plane. Good Luck. 

  

Hugh McKay

 [quote]-------------- Original message from "TIM MOSES" <tcmoses(at)earthlink.net>: -------------- 



  Hugh,

 I just got an email from the Australian Allegro/Woodcomp dealer and he said that the blade pitch is measured at "1/3 of the blade length from the tip".  I thought it was customary to use the 75% blade span (ie. 1/4 of the blade length from the tip).  So my question is what distance is this 14 or 15 degrees measured at?

  

 The following is the adjustment message I recieved from Michael Coats:

  

 setting up the propeller is no big deal but it must be done properly. 

forget the recommendations above, there is only one way to set the 

propeller and the instructions follow.  Please note I am the Woodcomp 

certified service centre from Australia and New Zealand so I can tell 

you with certainty that the following information is correct.



The correct distance the setting the blade measurement with just about 

every propeller ever manufactured is ***one third*** of the blade length in 

from the blade tip.  You will see in the attached photographs I have 

made a very small T square which on the propeller I am using is 180 mm 

long, yours will be similar.



In a pictures shown I am using a warp drive propeller protract which is 

probably the most common unit out there, is extremely cheap (approximate 

we $20) and will last a lifetime of normal use provided you don't drop 

it and break it.



Step one, make sure th  e prop eller blade is horizontal, if it is not 

horizontal get it is close to horizontal is you can and using a piece of 

wood or a broomstick or something like that marked the distance from the 

propeller leading edge to the ground and make sure that all of the other 

adjustments are made in this exact same position otherwise you will get 

varying blade angles.  So firstly to set the propeller horizontal and 

then using the little T square position the propeller protract one third 

of the way up the propeller and take your adjustment.  We mainly have 

cruise settings on our propeller and these follow below....



80hp 18 degrees



100 hp 21 degrees



  If you want to get a bit more climb performance out of it I would 

suggest initially going approximately 1 1/2 degrees finer pitch, so for 

example on the 80 hp engine I would start at about 16.5° or thereabouts 

than it is a simple matter of adjusting each of the three bl  ades o  rtain  Tim

 [quote] ---

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tcmoses(at)earthlink.net
Guest

Posted: Thu Nov 01, 2007 3:35 am Post subject: Allegro 80 HP Woodcomp Pitch setting

Hugh,

 I saw the Woodcomp adjustment instructions (mine  said 50mm) and was also surprised with their adjustment instructions.  It  looks like this adjustment is not going to be a one shot deal.  Also in  practice the 16.2 ft/lbs of torque recommended by the Woodcomp manual on  the M8 bolts closes the hub gap completely and seems excessive.

 Tim

 [quote]   ---

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Thu Nov 01, 2007 4:48 am Post subject: Allegro 80 HP Woodcomp Pitch setting

Tim: 

  

You are right, the adjustment will not be a one shot deal, unless you are very lucky. My prop adjustments were three in number. I started out with 17.5 degrees which gave me 4600 rpm (Static) at WOT. The second adjustment was 16.5 degrees which gave me 4900 rpm (static) at WOT. The third adjustment was 15 degrees, which gave me 5100 rpm (static) at WOT. That is where I chose to leave it. My choice. Don't forget to track your prop before the static tests. 

  

Hugh McKay

 [quote]-------------- Original message from "TIM MOSES" <tcmoses(at)earthlink.net>: -------------- 



  Hugh,

 I saw the Woodcomp adjustment instructions (mine said 50mm) and was also surprised with their adjustment instructions.  It looks like this adjustment is not going to be a one shot deal.  Also in practice the 16.2 ft/lbs of torque recommended by the Woodcomp manual on the M8 bolts closes the hub gap completely and seems excessive.

 Tim

 [quote] ---

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