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I'm at this stage on my fuse too. I think this is what Bjorn is referring to:
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Originally posted by John Rheney View Post
Wow, these do look like they have potential. I had planned to use nutcerts inserted from the top, but a nut like this might do as well and provide some good dampening. Do you think they're positive enough? It ends up being only the rubber/ploymer or whatever it is as the backing material. How much can they be torqued before they spin? How easy to back off?
I talked to someone recently who commented that the upward force on the skylight is pretty substantial, and to lose it in flight would be catastrophic.
A t-nut like fastener might also make a good solution, if there was something appropriate to use on steel. It would be great if there was a saddle-shaped nut with wings that would wrap around the edges of the 3/8 tubing.
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I think those well nuts look great but you would have to countersink the skylight on the underside where every nut goes at least along the edges of the skylight so you could seal it.Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.Comment
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Found these stainless barrel nuts for 8-32 that seem like they would be a good low profile solution not requiring a crimped rivnut.
Last edited by Zzz; 02-17-2016, 04:56 PM.Comment
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Am I understanding it right? These well-nuts are pushed into the windshield and the screw in through the structure(the angle in the drawing) from the inside. That would leave the threaded end of the screw outside in the airstream? Maybe I am not looking at it right.
Doug
Scratch building Patrol #254Comment
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Well, I think the illustration is how to attach a motorcycle fairing. For installing a window / skylight, I would think the rubber bushing of the well-nut is pushed through a hole in the structure from the outside, then the lexan would sit directly on the rubber bushing's flange. The cap strip would go on next (visualize it where the L-shaped piece is in the illustration), then the screw goes in to expand the rubber bushing and hold everything in place. Pretty slick idea!Last edited by JimParker256; 02-12-2016, 08:08 AM.Jim Parker
Farmersville, TX (NE of Dallas)
RANS S-6ES (E-LSA) with Rotax 912ULS (100 HP)Comment
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OK That makes a little more sense.
DougScratch building Patrol #254Comment
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Ok well glad to hear I'm not totally on crack with this idea then. I'll grab a couple pics of how it goes on a motorcycle fairing later today just for reference, but Jim is basically correct - the well nut is pushed in from the outside, then the lexan is on top of that. A screw (usually with a thin plastic washer) is then threaded in through the lexan into the nut and as you tighten the screw it pulls the rubber up snug underneath. No countersinking is required, nor is any access from underneath - you just need a suitable hole to shove it through. One thing I'd be careful of though is sharp edges - all holes must be deburred and rounded so you don't shred the rubber. The screws meant for MC use are also usually low profile and smooth aerodynamically so that's another plus.Comment
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If you don't countersink the underside of the skylight and set it directly on top of the rubber flange then how do you make it air/water tight?Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.Comment
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Ah I see what you're saying, sorry I need to not Internet before my coffees. So you could countersink then, or could also maybe use a very thin rubber gasket/strip that fits flush around the flange circumferences. Even with countersinking you're going to need something else (flexible sealant, gasket, etc) between the lexan and the surface underneath to seal it airtight. If you're using sealant it may take up the gap anyway as the rubber flange on the well nut isn't very thick.
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Looks like an bi-annual maintenance issue primarily due to UV damage. A separate issue is hardening and shrinkage of the rubber. I use something similar on my ATV wind shields. They live outside less than 2 months a year...and are good for a couple years... If those fasteners had a metal back up to prevent pulling through the drill hole they were inserted into....just saying I don't like them on a part of the airplane that has negative pressure exerted...trying to pull it off the airplane.....Bad jewjew.
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I would agree with Mark on this. On a motorcycle, those fasteners are primarily in compression and some shear. On the airplane skylight, they are in tension, which I don't think is the intended application.Comment
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I am doing my skylight/top stringers and have to clear the fairlead for the trim. I would like to lower the stringers as much as I can. I have zero experience with fabric airplanes.
With the fuselage covered, how does the fabric lay between stringers? What i mean is if you put a straight edge between two stringers, does the fabric go straight across, or is there some billow down away from a straight line?
I don't want the fabric laying on the trim fairlead.Comment
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The fabric does not make a straight line. It concaves down some in a normal ceiling. MarkLast edited by Mark Goldberg; 09-20-2019, 07:19 AM.Comment
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