BIG SNIP

My 2 cents worth on the subject - I have not seen the so called high

twist version of the

Ivo prop
but the flat 2 bolt mounting does not preclude having  a steeper angle

near the hub. This is

no
different than the flat area on either awodd or metal fixed pitch prop,

so he could set this

area
at a good compromise angle if he invested in the tooling to do so. My

main concern withe the

Ivo is in making making it torsionally flexible enough to be twisted with

that small rod, it

now concerns me about flutter. The 2 bolt mounting also worries me, and

even he advises

against the use on engines with high pulsing loads such as the big

fours.. A contollable

prop
is relatively easy to design, and not that hard to fabricate - but

sphincter tightening bear

to prove.
I am building a 3 blade variable system, but intend it for use as a sort

of ground based

air dynomometer for a long time before even considering fitting it with

flight worthy

blades.
Vance

  I'll go with Vance on this one.  Props are a bit scary to design since the
actual loads
are relatively poorly known, esp. the vibration portion.  Generous
overdesign and
thorough testing on the ground are very important.   It is *extremely* ugly
when you lose
all or part of a blade in flight.   I strongly suggest that anyone using a
non-wood prop
have a very substantial steel cable attaching the engine to the main
structure of
the airframe to at least have a fighting chance on a controllable dead-stick
after the
engine is instantly ripped off the airframe in a loss of blade accident.
Composite
airframes have a significantly better track record on this than aluminum,
but I'd not
care to run without a cable with any multi-piece experimental prop.  The
stories seem
to indicate that this is one of the most 'interesting' flight incidents you
can have.
Probably nicer than a fire, tho.

Bill
Long EZ builder & pilot
BSME, MSME

 
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