---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Mon 10/27/14: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:30 AM - Re: Re: ultrastar cuyuna prop shaft breakage (Richard Girard) 2. 05:37 PM - Re: Legal Twinstar (Shadow94) ________________________________ Message 1 _____________________________________ Time: 11:30:09 AM PST US Subject: Re: Kolb-List: Re: ultrastar cuyuna prop shaft breakage From: Richard Girard 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 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 > > > > > 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 _____________________________________ Time: 05:37:40 PM PST US Subject: Kolb-List: Re: Legal Twinstar From: "Shadow94" 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 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kolb-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kolb-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kolb-list Browse Digests http://www.matronics.com/digest/kolb-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.