On 02/07/2013 02:32 PM, Europaul383 wrote:
> I am also going for the SR3000/3 - again, unless somebody tells me I
> simply *must* have the 3000/3W.
I would go for the /W, because for the Europa cruise speed the inner
portion of the blades has a much better profile. It increases
efficiency, speed, and cooling. (The latter because the inner portion of
the blades throws more air into the cooling system). I'm unaware of any
advantage of the "normal" version over the /W version. The /W version is
simply a prop better suited for the speed range of the Europa airplane.
Also I would go for the 2-blade version. This for the same reason as why
for a fast airplane a single plane wing is better than a bi-plane. With
two blades instead of three you cut down 33% of the leading edge,
blade-tip vortexes, weight, etc. The result is higher efficiency and
higher speed, lower gyroscopic effects, better glide ratio, etc. The /2W
prop has more than enough area to fully utilize the power of the Rotax
engine; you don't need more blades for this amount of power.
I have the SR3000/2W on my 914 powered Europa, and I'm very satisfied
with the performance to say the least. The only drawback of a 2-blade
prop is that it is a bit more prone to vibrations, but with the prop
properly balanced and the carburators properly tuned there are no
significant vibrations. I see it as an advantage that I immediately feel
it when the carbs are unbalanced, inviting me to investigate, rather
than to hide the imbalance to me until more serious problems develop.
Avoid the scimitar blades. They offer no advantage over the normal
blades, it is just for the looks (if it is your taste after all), but
they are asymmetrical on the variable pitch system and create strain
both mechanically as electronically.
Frans
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