Jerry,
Having been the US Dealer now for nearly six years and I have put blades
on everything from Rans, Vans, Kitfox, Highlander, Zenith, Ximango, and
every other in between using the Rotax 912, 912S and 914.
The best blade is more of a decision on how you want to fly and how much
maintenance you want to do. Each prop manufacturer tries to optimize
his prop for the 912S as it is the most common engine in the
experimental fleet. Back to my previous post, a light prop blade is
great until you hit something, fly through rain, sand and the like which
leave you grounded for months, tough blades last longer but are heavier
and weight is a penalty....
As the US Dealer for Airmaster and Europa, I test blades for Martin from
time to time for the Europa and other planes. Again, we have found the
best blades to be Whirlwind for speed, WD for toughness, Sensenich in
between. I don't do Bolly or Kiev. Max length for any WD is 67 inches
or the prop just makes noise, and 64 inch is tollerable provided the
blade has a wider tip. Same for Whirlwind. Sensenich is better on
float planes at 68 to 70 inches due to the tip shape, twist and chord
length.
As for length of the prop, I have tried a number. Don't get into that
trap of longer is always better. Look at your engine and torque or prop
power curve. The Rotax only turns at 2050 at cruise prop speed. So one
would think I need a longer prop, but to absorb the torque it would need
a narrower blade, have less area, and be twisted in a way where it is
stalled at some speeds or altitudes... The Sensenich doesn't really
perform (swept tip) until over 68 inches any better than the others
because the sweep of the tip lowers the pull from the tip (but it looks
cool). The Whirlwind is only average at the longer blade lengths but is
great at the short lengths due to the wide tip and generous mid chord.
Trust me, the 64-68 inch WD narrow chord sucks on the Europa and
anything else. Max length is 67 inches for the wider chord blades and
works fine for any of the 912S and 914 engines. I attain as much speed
with my 64 as a 67, on the Fascination or Europa, why, the blade is at a
higher angle and more of my prop is pulling due to the twist angle at
our speed range (over 130 KIAS). The 67 out accellerates from 70-100
the short blade is all that I have seen.
We have seen many claims about cooling, twist and static thrust.
Frankly the 64 inch for a 914 is the min diameter and 67 is the max
because of engine torque, or lack of it. The actual performance
difference is minimal. Ground clearance takes care of the prop ding
problem. The FAA mandates a min clearance and our Europa is at the min
clearance now.
I too like the KISS principle. I prefer to have folks fly, not tinker,
but that is the choice of each builder.
Call or email me anytime, and I can discuss further what we have seen as
a dealer...
Bud Yerly
----- Original Message -----
From: N6ZY<mailto:jffisher@gmail.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Tuesday, June 11, 2013 10:58 AM
Subject: Europa-List: Re: Woodcomp or Airmaster Prop
<jffisher@gmail.com<mailto:jffisher@gmail.com>>
Thanks to everyone who answered my original post, there was a lot of
information there. My end conclusion was much as when I posted, that
the Woodcomp prop blades are really good, but the combination of poor
quality control and lack of US support makes the Airmaster a better bet
for me. I dismissed the MT prop option as being expensive, and I know
---From previous experience that MT are not always responsive and they are
not troubled by excessive humility!
So I phoned Martin at Airmaster yesterday and we discussed the options
for 20 minutes. He gets his blades from various suppliers, and
basically agrees that it would be much better if he had blades with more
twist in them. He is looking into a number of options. This includes
using Whirlwind blades; although they are a competitor, they are now
willing to supply him. Another option is blades from either Helix or
Neuform in Germany. Finally he can use any of the Sensenich blades. He
suggested that I phone the various blade manufacturers to see what they
have for my application.
The other question we discussed was the prop diameter. I will fly 98%
of the time off hard runways, and cannot see that a 68" diameter prop
would be impractical even allowing for flat nosewheel tires (tyres? I
am a Brit living in the US) and my bad landings. That would open up the
number of blade options. I know that Frans has increased his clearance
using some form of nose gear spacer, but I would rather keep it simple
if I can. In addition using a 3 blade prop may make the use of smaller
diameter blades equivalent to larger 2 blades.
My end result is that I will delay the blade selection as long as
possible, but will go with the Airmaster prop, probably with 3 blades,
and possibly with Whirlwind blades. They appear from their website to
be well shaped with adequate blade twist.
Any reactions to the use of a larger diameter prop would be
appreciated. Thanks again for the interest and inputs.
Jerry
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