Intersection fairing layup issues

[sblack]

as my kid would say... "Noice"

[Cam7nut]

Thanks very much Dan.
I thought with the flox trailing edge that I would tape the T.E. together and apply a small flox fillet from the inside. Maybe even see if I can put a strip of light fibreglass over the flox.
I didn't think of doing it the way of digging the foam and floxing before the second 'glass layup.
Cutting away the inside of the wheelpant to match the fairing then fibreglassing the inside was something I had been considering, but was not sure whether it would be worthwhile. Thanks for removing any doubt and confirming that idea.
While I'm getting the other side wheelpant fairing up to the same stage, I thought people following this might like to see what I did for the outboard wheelpant attach fitting.
I laid some carbon cloth on foil, then wet it out before applying a second layer of carbon. I then covered the wet carbon with 0.4mm clear plastic and squeegeed out excess epoxy. I marked 4 squares to be cut from the carbon sandwich.



After cutting I removed the plastic and applied the carbon square to my wheelpant. (Foil still on at this stage). Then pushed the carbon to conform to the wheelpant. Removed the foil and covered the carbon with peel ply.





Removed peel ply, drilled rivet holes and countersunk, then riveted on bracket

[Cam7nut]

After separating the left fairing from the wheel pant and rough trimming, I thought I'd try fibreglassing the trailing edge.
Before doing this I added a few layers of masking tape with a cover of packing tape to the gear leg fairing to allow for Mylar wear tape strip that will eventually be applied after paint. Probably would have been a good idea to do this earlier on, but the split in the trailing edge of my intersection fairings allows this.



I used 2.5oz cloth cut on 45 deg and was able to get it to conform to the sharp corner. Used 4 layers and held the whole thing together with peel ply.





After drying, with peel ply removed, I'm pretty happy with the result. The rest of the trailing edge will be floxed and glassed as per Dan H's suggestion.



I got a bit carried away trimming the rh fairing and got a bit of a gap



Still, I don't think this is a big problem, the top part took the 2.5oz fibreglass ok and I think the trailing edge will be ok with the flox method to finish it off.

[Cam7nut]

Fairings trimmed and wheelpant cut to follow inside of fairing as per Dan H suggestion.



Then I glued fairings to wheelpant with epoxy/flox.



Flox fills inside lip joint so future layup will sit nicely.

[Cam7nut]

Fairing joint sanded to prepare for fibreglassing.



An inch wide strip of 6oz cloth on the joint and 2 full layers of 6oz over the whole surface of the lower aft fairing. Before peelply.



Before trimming the lower fibreglass I ran a bead of flox along the trailing edge.
This will be sanded down to match the upper surface profile and (hopefully) leave me with a nice strong trailing edge to lay the upper surface fibreglass across. Another great Dan H suggestion. Thanks!

[DanH]

Originally Posted by Cam7nut

Removed peel ply, drilled rivet holes and countersunk, then riveted on bracket

Can't do that Cam. Carbon in direct contact with aluminum is a no-no. It's a corrosion issue. That includes the rivets.

Not much reason to use carbon there anyway.

[Cam7nut]

Thanks again Dan. At this stage it's no problem to remove the brackets and replace the carbon with fibreglass... or maybe drill the holes bigger and fill them with flox, then drill the #30 holes for the bracket through the flox? What do you think?

[rv7charlie]

For reinforcement, on my 25 yr old RV-4's pants I epoxied patches of aluminum sheet at the screw insertion areas, using the same technique used to attach the hinge stock to the cowl. Fairly quick; no corrosion issues.

Charlie

[DanH]

Originally Posted by Cam7nut

Thanks again Dan. At this stage it's no problem to remove the brackets and replace the carbon with fibreglass... or maybe drill the holes bigger and fill them with flox, then drill the #30 holes for the bracket through the flox? What do you think?

Anything to isolate from direct contact will work. When the concern is simple surface contact, the usual prophylactic is a layer of glass between the carbon and the aluminum. However, that doesn't help with fasteners through the carbon.

Me? I'd remove the carbon, and patch 3 plies of glass because I'd want thickness under the rivet head. When cured, butter a little bit of epoxy/flox under the bracket tab and set the rivets while it is wet. Let the wet flox mix squeeze out to form a filet around the edge of the aluminum