---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sun 03/16/08: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:37 AM - AW: Re: 912 with low RPM--- new vibration problem (Thom Riddle) 2. 09:55 PM - Vibration due prop irregular blades (Fergus Kyle) ________________________________ Message 1 _____________________________________ Time: 11:37:01 AM PST US Subject: RotaxEngines-List: AW: Re: 912 with low RPM--- new vibration problem From: "Thom Riddle" Gtblu, In answer to your question about vibration smoothing out at 5400 rpm, yes, it is possible. As the centrifugal forces increase with increasing rpm, the apparent out-of-trackness at places other than the tip could disappear. Do you know which blade is running out of track? You might consider removing the blades and comparing them to each other on a true flat surface in several directions. If one of them is measurably out of synch with the others that could be your problem and a blade replacement might resolve the issue. -------- Thom Riddle N221FA Allegro 2000 912UL N197BG FS1/447 -------------------- Believe nothing, no matter where you read it or who has said it, not even if I have said it, unless it agrees with your own reason and your own common sense. - Buddha Read this topic online here: http://forums.matronics.com/viewtopic.php?p=170197#170197 ________________________________ Message 2 _____________________________________ Time: 09:55:46 PM PST US From: "Fergus Kyle" Subject: RotaxEngines-List: Vibration due prop irregular blades I have read the considerable discussion regarding 912 and vibration, and the possibility of improper prop blade angles of pitch. I have a 914 with a Woodcomp CS prop which I put together after shipping. At one stage, the maker suggested I check the accurate duplication of pitch angle of each blade against a made-up stand and a common angle standard. I couldn't afford to make this, nor to transport it to someone who had the jig. I did have a number of paper clamps which slide onto small groups of printed 8.5x11inch sheets - and make them into a temporary booklet. You may have seen these OR have a source of small ID straws or alu tubing. I used these by marking a fixed distance inboard of the prop tips on all three blades, then covered one with release plastic film and made an composite mask around the blade. When it hardened, I checked to see that it sat in exactly the analogous site on each of the 3 blades. I then glued one of the above-described sighting tubes such that when viewed from one end, the straw sighted to exactly the same spot on the preceding blade trailing edge. If it does so, the prop blades must have the same pitch angle, whatever that may be. Thus, if you change the common pitch angle, you would have to repeat the fabrication of a new sighting tube to gauge its new commonality. Maybe that's not too clear. If someone wants, I'll post a photo or two, or a sketch. Ferg Europa 914 mono classic CS prop 90% done, 50% to go ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-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/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-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.