Bud,
Thanks for the update. Sounds like some interesting developments on the prop
front.
I'm looking forward to our trip East for lots of reasons.
Check six,
Bob Borger
http://www.europaowners.org/N914XL
Europa XS, Short Wing, Intercooled Rotax 914
rlborger@mac.com
Cel: 817-992-1117
On Aug 19, 2010, at 5:17 PM, Bud Yerly wrote:
> Bud is up to his neck in a poop full of testing.
> Right now I have the AP332 and 420 in build up in the shop and will be
> starting
side by side testing. LSA testing is in write up. I figure by Rough River
I may have some data and the new 420 hanging on the front of my test mule 12AY.
So far on the slower planes like the Rans S-6, the 420 is ten knots faster
at the 72 inch length and the performance of the AP420 is better only on the
top end vs. the AP332. It appears the AP420 will tend to have a top end more
like the Whirlwind prop or a little faster. However, the prop pulses across
the windscreen on the Rans are very noisy at the 72 inch lengths. You can see
the windscreen move. It is quite a stump climber. Hopefully, it is not as noisy
with our shorter 64 inch prop.
> The AP420 Prop weighs about 20 lbs. Sensenich is a light prop blade by some
standards, but others are still lighter such as the Kiev, Neuform and other
recent
designs from the old Soviet Block. They are much lighter and flexible blades,
which means a potential for harmonic problems. Martin has accumulated quite
a stack of test blades and is methodically going through them.
> It is a work in progress as we are adding the AP430 which is a 3 blade, large
ferrule bore hole for the newer hollow core blades.
>
> Warp Drive was not interested in a wider chord blade or a more refined blade
for the shorter lengths. The problem is the initial inertia on start up with
the solid blades. A Wider blade for them means more torque on the sprag clutch
and possibly very expensive engine repairs. A hollow blade is the way to go,
but the Warp Drive is still the toughest prop. Airplanes are 20,000 compromises
flying in close formation and we really try not to disappoint customers so
the testing continues...
>
> More to follow.
>
> Bud
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