Lightning-List Digest Archive

Sun 01/23/11


Total Messages Posted: 7



Today's Message Index:
----------------------
 
     1. 01:50 AM - Re: Wheel shimmy - solutions? (selwyn)
     2. 07:27 AM - Re: Re: Wheel shimmy - solutions? (Bernard Melendez, Jr.)
     3. 07:55 AM - Re: Re: Wheel shimmy - solutions? (Maxim Voronin)
     4. 09:38 AM - Re: Re: Wheel shimmy - solutions? (Bernard Melendez, Jr.)
     5. 07:26 PM - Re: Re: Wheel shimmy - solutions? (N1BZRich@AOL.COM)
     6. 11:01 PM - Re: Wheel shimmy - solutions? (selwyn)
     7. 11:35 PM - Re: Re: Wheel shimmy - solutions? (James, Clive R)
 
 
 


Message 1


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    Time: 01:50:54 AM PST US
    Subject: Re: Wheel shimmy - solutions?
    From: "selwyn" <selwyn@ellisworks.com.au>
    Hi Bill, I'd have to agree, there are proponents of just about every combination. I have about 2 inches of toe out, measured as per build manual, standard tires, 28lb pressure and occasionally get a brief shimmy on roll out slowing through around 28 kt, a quick tap on the brakes stops it. It has never been a problem. I'm just in the process of fitting spats so that may be interesting in the light of earlier comments. My question to the group would be: does anyone with toe out set have significant shimmy problems? -------- Cheers, Selwyn Kit 66 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=327981#327981


    Message 2


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    Time: 07:27:46 AM PST US
    From: "Bernard Melendez, Jr." <n45bm@yahoo.com>
    Subject: Re: Wheel shimmy - solutions?
    Hi Selwyn, Most people would consider toe IN, rather than toe out, if any, to be benef icial. Not there yet on my project, so I'm interested in following this thr ead and see what results others are getting. Bernardo Melendez, Kit #`110, Corby Starlet n45bm --- On Sun, 1/23/11, selwyn <selwyn@ellisworks.com.au> wrote: From: selwyn <selwyn@ellisworks.com.au> Subject: Lightning-List: Re: Wheel shimmy - solutions? Hi Bill, I'd have to agree, there are proponents of just about every combination. I have about 2 inches of toe out, measured as per build manual, standard ti res, 28lb pressure and occasionally get a brief shimmy on roll out slowing through around 28 kt, a quick tap on the brakes stops it.- It has never b een a problem.- I'm just in the process of fitting spats so that may be i nteresting in the light of earlier comments. My question to the group would be: does anyone with toe out set have signif icant shimmy problems? -------- Cheers,- Selwyn Kit 66 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=327981#327981 le, List Admin.


    Message 3


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    Time: 07:55:40 AM PST US
    Subject: Re: Wheel shimmy - solutions?
    From: Maxim Voronin <voroninmax@gmail.com>
    1 degree toe out is the standard these days. I would either do that, or set them at 0. Max On Jan 23, 2011 10:29 AM, "Bernard Melendez, Jr." <n45bm@yahoo.com> wrote: Hi Selwyn, Most people would consider toe IN, rather than toe out, if any, to be beneficial. Not there yet on my project, so I'm interested in following this thread and see what results others are getting. Bernardo Melendez, Kit #`110, Corby Starlet n45bm --- On *Sun, 1/23/11, selwyn <selwyn@ellisworks.com.au>* wrote: From: selwyn <selwyn@ellisworks.com.au> Subject: Lightning-List: Re: Wheel shimmy - solutions? > > Hi Bill, > > I'd hav... http://www.matronics &nbs;--> <http://www.matronics.com/contribution>


    Message 4


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    Time: 09:38:57 AM PST US
    From: "Bernard Melendez, Jr." <n45bm@yahoo.com>
    Subject: Re: Wheel shimmy - solutions?
    Okee dokee. 0 degrees sound ok to me, but I'm still not convinced. Besides, doesn't the toe out increase as the landing gear is splayed out, when the plane is loaded, and especially at landing? I've always heard that putting 1 or 2 degrees toe IN makes an aircraft track more true, or straight. Food for thought. Bernardo --- On Sun, 1/23/11, Maxim Voronin <voroninmax@gmail.com> wrote: From: Maxim Voronin <voroninmax@gmail.com> Subject: Re: Lightning-List: Re: Wheel shimmy - solutions? 1 degree toe out is the standard these days. =0AI would either do that, or set them at 0.=0AMax=0AOn Jan 23, 2011 10:29 AM, "Bernard Melendez, Jr." <n45bm@yahoo.com> wrote: =0AHi Selwyn, Most people would consider toe IN, rather than toe out, if any, to be benef icial. Not there yet on my project, so I'm interested in following this thr ead and see what results others are getting. Bernardo Melendez, Kit #`110, Corby Starlet n45bm =0A --- On Sun, 1/23/11, selwyn <selwyn@ellisworks.com.au> wrote: =0A From: selwyn <selwyn@ellisworks.com.au> Subject: Lightning-List: Re: Wheel shimmy - solutions? =0ADate: Sunday, January 23, 2011, 3:48 AM =0A> > Hi Bill, > > I'd hav...http://www.matronics - - - - - - - - - - &n bs;--> =0A =0A=0A


    Message 5


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    Time: 07:26:57 PM PST US
    From: N1BZRich@AOL.COM
    Subject: Re: Wheel shimmy - solutions?
    Hey Bill, Right on, a bird in hand. I was not aware of that google feature, but as you said it does allow a type of search feature. Certainly better than nothing. I'll suggest the new newsletter editor, John Jenkins, put a note about it in an upcoming issue. After you switch to the 6 ply tires and balance them again, I think you will notice a big improvement. If you do decide to try the wood stiffeners, I might suggest buying an ax handle at Lowes or Home Depot. With some work on a band saw, then a table saw, and then a router, you can come up with some parts that fit pretty well. However, before you go to all that work, you might want to try an aluminum angle - again from Lowes or Home Depot. I think what I used was about 1/2 inch on each side of the angle and the length was cut to fit the gear leg. Just be sure the thickness of the angle is enough to provide some stiffness to the gear legs. I held them in place on the gear leg with two or three hose clamps. Done carefully, it will still fit under the fiberglass gear leg fairings. Buz In a message dated 1/22/2011 2:39:59 P.M. Eastern Standard Time, bill@gdsx.com writes: --> Lightning-List message posted by: "Bill Strahan" <bill@gdsx.com> 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 6


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    Time: 11:01:40 PM PST US
    Subject: Re: Wheel shimmy - solutions?
    From: "selwyn" <selwyn@ellisworks.com.au>
    Hi Guys, I didn't want to get into a debate about the merits of one or the other, that's been done to death already. I simply want to gather some data. Is there anyone who has had significant shimmy problems with definite toe out set? -------- Cheers, Selwyn Kit 66 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328179#328179


    Message 7


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    Time: 11:35:36 PM PST US
    Subject: Re: Wheel shimmy - solutions?
    From: "James, Clive R" <clive.james@uk.bp.com>
    Hi Selwyn, I haven't had any shimmy on the Esqual since I reset it and before nothing that would worry me it was more as I thought the tyres would wear. However, I did wrestle with alignment on the Esqual after my Jabiru, which was very carefully set as required, wore it's tyres out in 150 hrs. I reset the toe after 5 years (3 sets of tyres) with the plane fully fuelled but empty. Initially when rolling the Esqual over a painted hangar floor it squeaked. I rolled it over some newspaper and the twist showed it was toed out. I believe the recommended set was 2 degrees in? I obviously got it wrong or... Staring at the thing it looks to me like the aircraft would toe out the heavier it got. This from the angle of the legs (same as the Jab). I'd set the toe before it had the wings + engine on and was loaded. So I did it again full of fuel and with barrels or water in the seats to simulate 1 pilot. I set it as straight as I could get it, not in or out. Now it doesn't squeak. My thoughts on the shimmy. If it's out of toe when rolling surely the wheels will try and get further apart (toed out), further together (toed in). When the wheel rotates the rubber will flex and then release, flex then release, as it tries to steer the leg away from it opposite side leg (or towards it-toed in). Ideal to set up a shimmy? So my vote goes for parallel at middle weight which is why I did what I did. This at the risk of doing the subject to death a little more....sorry. My question is? How are people repeatedly changing the tracking? Surely you only get one shot and then you drill the holes, after they are drilled how do you make adjustments? Regards, Clive -----Original Message----- From: owner-lightning-list-server@matronics.com [mailto:owner-lightning-list-server@matronics.com] On Behalf Of selwyn Sent: 24 January 2011 06:59 Subject: Lightning-List: Re: Wheel shimmy - solutions? --> <selwyn@ellisworks.com.au> Hi Guys, I didn't want to get into a debate about the merits of one or the other, that's been done to death already. I simply want to gather some data. Is there anyone who has had significant shimmy problems with definite toe out set? -------- Cheers, Selwyn Kit 66 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328179#328179




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