Today's Message Index:
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1. 04:45 PM - Rotax 912UL/Woodcomp 3 Blade, Klassic 160 (63") (Hugh McKay III)
2. 04:55 PM - Re: Rotax 912UL/Woodcomp 3 Blade, Klassic 160 (63") (Dave Austin)
Message 1
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| Subject: | 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 to 20. 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 Pitch = 4600 engine rpm = 65 engine hp* = 40 propeller hp*
16.5 Pitch = 4900 engine rpm = 70 engine hp* = 47.5 propeller hp*
* *see graph on page 10-3 of the Rotax Operators Manual
These numbers dont 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 (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 pitch. I am going to reduce my pitch to 14.5 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
Message 2
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| Subject: | Re: Rotax 912UL/Woodcomp 3 Blade, Klassic 160 (63") |
Hugh,
I'd recommend you set the prop to get 5000 rpm static. With that you
will find that you still have to keep an eye on the rev counter as you
climb out so as not to exceed the 5800.
IMHO that is a good setting to start. You will probably want to coursen
up a couple of degrees to get good cruise later.
Dave Austin 601HDS - 912, Spitfire Mk VIII
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