Hi Fred and Andrew,
I hope you do not mind my combined reply. My plane is an XS monowheel.
Regarding the 66" diameter. Yes, that is larger than normal. For all
normal handling there is no problem. However, if one has a very heavy
landing, there is the risk of a prop strike. I believe there is also a
risk even with the standard diameter prop. I do not have any good
comparison on noise so cannot comment. It is important to balance the
prop to get smoothness.
Regarding modification to the oil system, this is a standard
modification to the 912/912S/914 engines and the components are all
Rotax supplied parts which are best installed by a Rotax dealer. The
governor is basically a high pressure oil pump which supplies a control
pressure to a piston in the prop hub. For example, on take off, the prop
is fully fine at 5,800 rpm. As airspeed increases the prop speed would
tend to increase since the blades get a smaller bite on the air. The
governor alters the supply pressure which coarsens the blade pitch, and
the thrust and load increase to maintain 5,800 rpm. All this is
instantaneous and requires no attention from the pilot. The prop is
truly a constant speed design. One small plus is that on approach, the
prop is normally set at fully fine for a possible go-around. If one
chooses to close the throttle fully, the prop acts as a fairly effective
air brake disc with consequent steep glide slope.
I am a little puzzled with the reference to an electric governor. I
think this would require a complete redesign of the Whirlwind hub so
that an electric motor could be included with the usual slip rings
required by electric VP propeller designs. The weight of this prop would
probably be quite a lot higher.
Cheers, John
N262WF, mono XS, 912S
Mooresville, North Carolina
ORIGINAL MESSAGES :-
Subject: Re: Europa-List: Propeller choice - Whirlwind?
From: Fred Klein <fklein@orcasonline.com>
John...thank you for putting your oar in. I note the Whirlwind series 100 is 66"
diameter...How do you feel about that size?...Are you mono or trigear?...How
do you rate the WW noise level? Fred
From: Andrew Sarangan <asarangan@YAHOO.COM>
Thanks for that information. Whirl Wind is local for me (Ohio), and I
had not realized that their 100-series prop was designed for theEuropa.
It looks like the photo on their website is also that of the Europa. But
I am a bit uneasy about modifying the 914's oil system, and also about
losing the auxilary pad (which I had planned for a secondalternator). I
spoke to Whirl Wind and they said an electric governor is a possibility,
but I did not press him for details.
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