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stug
 Post subject: 580 -8 Stiffener
PostPosted: Sat Oct 27, 2012 3:13 pm 
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I have been looking at the 580 -8 stiffener thats the external 5/8*1/8" fuselage stiffener running outside the skin around the cockpit at the main W42 longeron level. I noticed that on some T18's this stiffener is extended all the way forward to the firewall.
I'm curious to know why!

Standard T18 plans have this stiffener finishing a couple of rivets just forward of the dash frame, I haven't seen any revised plans for this area suggesting it needs to be extended forward.

Is this an S18 mod, needed with higher HP engines, is it "recommended" or just cosmetic. I would assume it would be of slightly more value is using the .025 side skins but If using .032 skins is more beef really needed in that area?
Stuart


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Bill Williams
 Post subject: Re: 580 -8 Stiffener
PostPosted: Sat Oct 27, 2012 3:43 pm 
No reason , just looks better when carried all the way to the cowl. Some do and some don't


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dan
 Post subject: Re: 580 -8 Stiffener
PostPosted: Sat Oct 27, 2012 9:32 pm 
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I asked the same question in regards the the stiffner that runs on WL 42 outside the Fuselage. The answer surprised me as this stiffner appears to be not really of any significance. This little stiffner causes the Fuse to surpass FAA standards for twist in the Fuselage. I was concerned about doing the airframe to print as I wanted it to ba as strong as it was intended to be so I asked a lot of questions. I still ask a lot of questions, This little Plane is built like a tank, there are a lot of standards it surpasses, whether it is a T or an S, we got a good airframe here guys, one of the best ever designed...Dan


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stug
 Post subject: Re: 580 -8 Stiffener
PostPosted: Sun Oct 28, 2012 5:45 am 
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Thanks guys, the extra length just for looks, adds, by my calculations about .2 lb extra weight.

I don't understand the engineering involved but based on Dan's comments there would presumably be some improvement in the strength/ twist rating of the structure if the stiffener was as lengthened.


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