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Re: [TowerTalk] Analysis of mast slippage in rotor

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Analysis of mast slippage in rotor
From: John Becker <johnb3030@comcast.net>
Date: Sun, 06 Oct 2013 12:14:38 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Thanks to all who responded on this issue.

It appears that there is no perfect solution. The weak link for the HAM-III and related rotors is the limited strength of a 1/4-20 U-bolt.

I'm reluctant to drill out the holes to accommodate a 5/16-18 U-bolt, but in looking at my test setup again, I came up with another idea. I could leave the existing U-bolts and backing plate just as they are and add a third larger U-bolt with a saddle (such as a muffler clamp but stainless) around the entire assembly midway between the original U-bolts. A U-bolt with a 3.5" ID should fit. This would add considerable pressure to the mast clamping action without modifying the rotor. Do any of you see a downside to this approach that isn't apparent to me?

One other thought comes to mind. The original design includes a bolt threaded through the center of the backing plate which is intended to be screwed down against the mast. I'm thinking that this actually may be counterproductive, because any force applied at this point would reduce the pressure between the mast and backing plate along the two 4.5" lines where they are in contact. Therefore, I'm considering the removal of this bolt. Your thoughts?

73,

John, K9MM






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