---------------------------------------------------------- Lightning-List Digest Archive --- Total Messages Posted Sat 01/22/11: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:39 AM - Re: Wheel shimmy - solutions? (Bill Strahan) 2. 11:52 AM - Re: Wheel shimmy - solutions? (Bill Strahan) ________________________________ Message 1 _____________________________________ Time: 11:39:34 AM PST US Subject: Lightning-List: Re: Wheel shimmy - solutions? From: "Bill Strahan" Buz: It's not a perfect solution, but bird in hand... Anyway, try this: Go to google.com and do a search that looks like this. shimmy site:flylightning.net You can replace the "flylightning.net" with any site that is hosting the newsletters. You'll get a list of pages, almost all of which will be PDF files from the newsletters, that have the word "shimmy" in them. You can hold down the shift key while clicking on the "quick view" link for the search results and it will open the PDF. You may then have to put the search term in the PDF viewer as well, but this will at least take you to newsletters with the words you're looking for. Trying "tire pressure site:flylightning.net" brought up a list of newsletters that talk about tire pressure. You get the idea. Again, not perfect, but it's pretty useful. Now, back to shimmy. I had already searched all the newsletters and I had also searched the Matronics list before I made my post. The info is all over the map, and most of it is a) stiffen gear legs, b) 6 ply tires, c) set toe in, or out, or neutral, and d) balance the wheel/tire assembly. I had already balanced my tires using a motorcycle wheel balancer. It could tell a difference in how smooth it rolled when it wasn't shimmying, but it didn't help the shimmy. So my real intention was to find out what was really working...I guess the best thing would be to take a poll. Poll one would be for people who never had shimmy. What is their setup, notably the tires and the toe in/out? Poll two would be to find out what you did to fix shimmy if you had it. What finally worked. Since I've balanced my tires I'm leaning towards getting 6-ply tires and balancing again and installing. It's the least work and least modification to the airframe. If that doesn't do it, I think I'll make some wooden stiffening pieces to glue to the front and back of the gear. The goal would be to get as much bending moment away from the center of the rod to raise the stiffness and perhaps get the resonant frequency above what is generated at the speed I see on the ground. I had also mentioned to Nick that it might be worthwhile to find someone who could machine some bar stock into a landing gear. Take a piece of aluminum the length of the current gear leg, as thick as the current gear, but about twice as wide. Machine the ends into the rod shape needed to fit in the spar box and in the axle weldment. Then machine the rest of the bar into a teardrop shape. Drill the teardrop part for the brake line, and now you don't need any type of landing gear leg fairing. The teardrop shape would start just outside the fuselage and would end just before the axle weldment, so simple fairings like I already have to fair that shape into the fuse and the wheelpants would be all you'd need. The leg would have almost the same flexibiltiy in landing, but would be much stiffer fore and aft due to the added material further away from the neutral line. I have no idea the cost of that process, perhaps Grove would give an estimate. But If the additional cost wasn't more than about $500 I think it would be slam-dunk considering you would save the cost and installation time of the gear leg fairings. And I'd be happy to beta test them for free! I will document my progress in addressing this issue for 7RW. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=327915#327915 ________________________________ Message 2 _____________________________________ Time: 11:52:47 AM PST US Subject: Lightning-List: Re: Wheel shimmy - solutions? From: "Bill Strahan" Okay, another quick question, hopefully someone is reading to the bottom of this thread. If I order Aero Classic 5.00 X 5 tires do I need to get matching tubes or can I reuse my old tubes? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=327919#327919 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message lightning-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Lightning-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/lightning-list Browse Digests http://www.matronics.com/digest/lightning-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.