2nd nose rib jpg

Lazair Parts for sale

Postby fltofancy » Wed Jun 09, 2004 10:37 am

Here is the 2nd nose rib jpg.
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Postby JPXman » Wed Jun 09, 2004 11:06 pm

how much? and are you building ribs for each of the outboard ribs... as they're all different that'd be a lot of tooling...

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Postby fltofancy » Thu Jun 10, 2004 7:09 am

Price looks like $20.00 US ea. These are nose ribs only. They will replace the foam ribs in the constant section of the leading edge (they are all the same). I may be able to offer a discount if someone wanted to get a complete set for both wings.
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Postby Guest » Thu Jun 10, 2004 12:50 pm

How many ribs of the same size are in the Lazair wing before it tapers down ??

Postby Guest » Thu Jun 10, 2004 8:30 pm

Something like 35-37 in the long constant thickness portion of one wing. You do the math.

Postby fltofancy » Fri Jun 11, 2004 12:08 pm

The ribs can be purchased individually @ $20.00 ea. One kit to modify one wing (left or right) consists of 12 ribs and necessary rivets. A complete kit is $225.00 USD, a 10% discount from the individual cost. I will give a 10% discount for two complete kits at $432.00 USD.
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Postby xgary » Mon Dec 06, 2004 1:34 pm

fito how r those nose ribs selling ?

20$ pretty steep considering foam ribs can justbe hotwired in place.

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Postby rayjb60 » Mon Dec 06, 2004 3:17 pm

I agree shorty, plus all those rivets and such in the skin will be creating places for cracks to start, and add a good deal of weight.

Totally overkill in my opinion.

I think the best option is to Hotwire the hardest 2" foam you can get and glue them in place with a water based contact cement.

No holes in the pretty skin, likely to never collapse except in a crash, forgiving of dimensions due to the compressable nature of the foam, cost less than $100, is easy, quick and provides incredible support for the skin without creating any sharp stress points.
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Postby Guest » Mon Dec 06, 2004 8:12 pm

Nose ribs are more likely to break loose and fall over if they are not tight inside the skin, as in the early Series 1 models, but can occur in any Lazair that's been around awhile. Engine vibration causes them to vibrate back and forth. Originally, epoxy glue was used to attach the foam ribs into the aluminum U channel that's riveted to the spar web. When the rib moves, it stresses the foam at the edge of the glue line. The epoxy is much stronger than the foam, so the foam breaks, or shears, right along the glue line.

I did some tests way back in 1980 where I tried gluing foam ribs using different adhesives. The two extremes were epoxy and (adhesive type) RTV. When the rib that was rigidly glued in place with epoxy was pushed to the side, it would quickly fail along the glue line with not much force. When the same test was performed, this time glued with RTV adhesive, the rib could be pushed much harder - with so much deflection that the rib would flex over it's length quite a bit before the rib would begin to fail along the glue line. Because of my tests, the factory changed from epoxy glue to a somewhat flexible adhesive similar to (exactly like?) Liquid Nails Panel Adhesive. Dale Kramer thought it solved the epoxy problem at a much cheaper cost than RTV. I prefer the RTV, as the panel adhesive continues to harden over time until it's almost as hard as epoxy, but that's my opinion. The loads on the adhesive are low, as the strength of the foam is very low in shear and is the limiting factor.

A good fix that will keep stock ribs from working loose is to open the bottom of the spar, lift the skin up a couple of inches, and add a couple inch bead of RTV along the bottom of each rib, then close up the wing again. If the ribs don't move, they won't fail and fall over. If you ever have to open the wing up for repairs in the future, open it from the top. Obviously, the best time to do this is when you are doing a recover job.

On my Series 1, I just snapped each rid out of the channel by pushing it to the side, then re-glued it right back in. I then added the glue bead along the bottom of the ribs and closed up the spar. I've never had another rib failure in these wings in almost 25 years.


Postby ozzie » Tue Dec 07, 2004 2:09 am

another material to try for substituting the blue foam is duracore that is used in the fiberglassing industries much stiffer and wont break.
on my mk1 wings the skin did not touch the ribs i removed the top row of rivits and ran a bead of expanding single pak foam around all the ribs and quickly closed it up worked a treat. the later wings of which one is almost finished i made all new ribs from alclad and used an epoxy that is used to glue helicopter blades and wing skins on the gruman cheetah i removed the channel and picked up the holes and put a bead of epoxydown before riviting a bit of work but the spar is really stiff now no rivets on the leading edge skin to spoil the looks. if you are looking to make stronger wings and are putting in the beef up mods then think of going down this road. for the tapered ribs i just traced around the old foam rib onto some hardwood and cut that out and formed the new metal ribs to the timber shape new metal ribs were made in a day from scratch. i went down this road after trying to refit broken ribs by regluing them the only glue that came close was like what chappy used called here liquid nails. no matter how careful i was they just kept rebreaking in the end the metal ones were less time consuming less frustrating,and did a much better job.
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