Today's Message Index:
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1. 11:30 AM - Re: Re: ultrastar cuyuna prop shaft breakage (Richard Girard)
2. 05:37 PM - Re: Legal Twinstar (Shadow94)
Message 1
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| Subject: | Re: ultrastar cuyuna prop shaft breakage |
The Ultrastar and Cuyuna weren't the only aircraft to suffer from prop
shaft breakage. The Kasperwing had problems with the 250 Honda ATV engine
they started out with and again with the Zenoah G25. It was neither engine
nor airframe, but a failure to understand the stresses put on the shaft by
resonance of the prop as it rotated. In the Kasperwing's case, the original
shaft was annealed 1" diameter 4130 tube with a .188" wall thickness. Then
a 5/8" grade 8 bolt was put through the center. When the tube still cracked
it was ditched for solid bar stock and no cracks were reported but that may
have been because the company died and the aircraft were either destroyed
in crashes or simply retired to garages and never emerged.
Rotax uses hollow prop shafts in their gearboxes but they are hardened and
the bearing surfaces are ground to fit the carrier bearings. The material
is stronger and there's no slop for the propeller oscillations to begin
working up cracks.
Rick Girard
do not archive
On Sat, Oct 25, 2014 at 10:27 PM, John Hauck <jhauck@elmore.rr.com> wrote:
>
> Do you know when the US kit was purchased? I bought mine
> Feb 1984, one of the first US kits to be shipped with
> factory welded fuselage and components. Earlier versions
> were shipped as material kits with builder required welding.
> Don't know when the ULII02 replaced the 430, but may have
> been a factor in possible crank shaft failures.
>
> john h
> mkIII
> Titus, Alabama
>
>
> <bobg379@yahoo.com>
>
> I agree but....
> In my ultra stars documents is a hand written letter by
> homer himself talking about the prop shaft failures. He
> stated there was a fix and most we're upgraded but I'm
> looking for some details here to decide whether I need to
> address mine. It sure looks beefy tho...
>
> A shaft failure of a pusher would be bad indeed.
>
> He also states that eventually the cuyuna cranks will break
> from belt tension. Looking for some info on this as well.
>
> --------
> 1984 kolb ultrstar
> Former 1997 kolb firestat
>
>
--
Believe those who are seeking the truth, doubt those who find it.
-Andre Gide
Message 2
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| Subject: | Re: Legal Twinstar |
Thank you all for your input. The replies were interesting and very informative.
I spent an hour on the phone the other day with an EAA representative. My
membership has already paid off. He was able to offer more insight into the
experimental and experimental exhibition. It really does look like the exhibition
just might be my best path forward. It will take some more research into
all the steps needed to complete the process.
It would allow me to get my Twinstar registered and the restrictions would fit
into the flying I want to do with the plane.
This forum as well as the Kolb Facebook page are great sources of info and Kolb
sense.
--------
Mark
Twinstar MKII
Great Bend, PA
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=432384#432384
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