----------------------------------------------------------
                           RotaxEngines-List Digest Archive
                                      ---
                     Total Messages Posted Wed 10/25/06: 1
           ----------------------------------------------------------
 
 
Today's Message Index:
----------------------
 
     1. 06:44 AM - Re: Rotax 912UL/Woodcomp 3 Blade, Klassic 160 (63")  (JC Propellerdesign)
 
 
 
________________________________  Message 1  _____________________________________


Time: 06:44:04 AM PST US
From: "JC Propellerdesign" <propellerdesign@tele2.se>
Subject: Re: RotaxEngines-List: Rotax 912UL/Woodcomp 3 Blade, Klassic 160 (63")

Hi

You are supposed to climb at Vy with WOT without over revving.

Best speed is achieved if you prop it for 5800 at WOT horizontal flight, 
at your normal cruising alt.

Some over-reeve for better climb.

or to 5500 at 7500=B4 WOT for max cruise.

Jan Carlsson
www.jcpropellerdesign.com

  ----- Original Message ----- 
  From: Hugh McKay III 
  To: rotaxengines-list@matronics.com 
  Sent: Wednesday, October 25, 2006 1:43 AM
  Subject: RotaxEngines-List: Rotax 912UL/Woodcomp 3 Blade, Klassic 160 
(63")


  Gentlemen:

   

  I am getting all types of input concerning setting the prop pitch for 
my Allegro 2000, which has a 912 UL engine and a Woodcomp, 3 blade, 
Klassic 160 (63") prop. I have gotten recommendations everywhere from 
14=B0 to 20=B0. This is quite a variation for prop pitch. I have tested 
the engine (Static Test) for two pitch settings and the rpm results as 
indicated by the engine tach are as follows:

   

  17.5=B0 Pitch = 4600 engine rpm  = 65 engine hp* = 40 propeller 
hp*

   

  16.5=B0 Pitch = 4900 engine rpm = 70 engine hp* = 47.5 propeller 
hp*

   

    a.. *see graph on page 10-3 of the Rotax Operator's Manual 
   

  These numbers don't appear to reflect an efficient use of engine 
horsepower to prop horsepower. Seems to me that the higher the static 
rpm (up to 5800 rpm) the more efficient use of the engine/propeller 
combination. Therefore, one would think that setting the Prop pitch to 
obtain a static max rpm of 5700 rpm would be the best choice. To do this 
the pitch would have to be reduced below 16.5=B0 (in my case). It is 
interesting to note that the tech at Fantasy Air USA (Distributor for 
the Allegro) tells me they set all of their props at 14=B0 pitch. I am 
going to reduce my pitch to 14.5=B0 and conduct another static test to 
see what rpm I get on the engine at max throttle. Any comments or 
suggestions concerning this?

   

  Hugh McKay

  Allegro 2000

  912UL

  N661WW