Wing to Fuselage Fairing

[rodsmith]

This fairing, especially where it wraps around the leading edge is giving me fits. As you can see in the pictures, there is quite a gap on the wing side. Material is .020 2024T3, probably should have gone with a softer alloy. I used a Lancaster shrinker in that area but was way too much of a gap to shrink. You can see puckers between clecos on the top of the wing that I was able to successfully shrink. When I installed the windshield I did my best to align the wing root area of the windshield up with the wings, but the windshield was larger, I tried to split the difference top and bottom. I've run out of ideas of how to fix this. I think I will have to layup fiberglass or carbon for this part of the fairing, I really don't want to go that route.

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[Utah-Jay]

I have not yet tackled this project, but I have given it some thought in preparation. If you laid your fairing out flat, is/was it straight? I have been thinking it will not be straight for a proper fit.

Edited to add, for the left wing laying flat it seems to my simple mind that when laid flat the mid-point (leading edge of the wing) will be slightly left of the two trailing edges.

But I am often WRONG!

[TrueAirSpeed]

Rod, I experienced the same, and went with fiberglass.

Terry

[Bcone1381]

Rod, I'm going Fiberglass too. I'm very interested in this aspect as I'll be starting these items in the next few weeks.

[Chewie]

If it helps I can shoot a couple photos your way showing how they did it on my C-140. Basically two wrap-around strips per wing with edge protection strips, screwed into tinnerman nuts that are attached to the wing skin. The edge protector strips probably help to take up the gap.

[spinningwrench]

This is a job that really goes much easier in fiberglass as it is a real 3D challenge. I was resistant at first but after taking the EAA fiberglass course it was pretty straightforward. I’ll dig up some pictures.

[Steve W]

When I built my wings, I left a bit of .032 material beyond the root rib for what ever plan I came up with later on for the fairings. I installed anchor nuts in the roof rib flange. I sandwiched several strips of aluminum into the fairing to slide over/under the extra material at the wing root. On the bottom, I bent an angle on the fairing and shrink/stretched it to fit the contour of the wing cord. The bottom fairing was held on with #4 sheet metal screws. Fiberglass makes such a clean and sealed fairing. It’s a pain but makes for some decent finishes.

[alaskabearhawk]

Hey Rod, I don't know what access you have to materials, but 2024T3 is the wrong AL to try to work. Being heat treated it will crack like crazy and absolutely doesn't like to be (and shouldn't be) worked. If you want to continue to go the AL route, use 5052. It can be easily welded and worked. If it work hardens, just smoke it with a torch for a temp indicator and anneal it to get it back into workable condition. Even 3003 would work better, but I can't find any in Alaska so I never use it. Make a paper template first because there are some different curves but it should come out fine. Just FYI...I bought a set of these stippled jaws for my shrinker and stretcher. They are much easier to polish out that those long stress risers the standard jaws leave in the metal. Fiberglass and I don't get along. I can do it successfully, but it sure is messy. West Systems epoxy is the stuff to use if you go that route.

https://www.tinmantech.com/products/forming-machines/shrinker-stretchers/lancaster-shrinker-stretchers/lancaster-shrinker-stretcher-modified-jaws.php

[Steve W]

Thanks for the link to the stipple jaws. I knew they were out there years ago but for the life of me, I couldn’t find them. Always wanted a set!

[Steve W]

Just for an alternate, here in Canada, I found the West Systems hard to get locally and shipping with Spruce was unbearable. I used Smooth-On products that were available in Edmonton, were less expensive and extremely easy to sand and shape.

[BradW1062]

As an alternative, cheap and easy way (which is usually the way I end up going… ) you can glue/epoxy some 180 grit aluminum oxide cloth to the face of the jaws. You can get this as “emery cloth” or “plumbers sandcloth” at just about any hardware or big-box building supply. This will accomplish the same effect of gripping without the cuts the jaws normally make as tinman’s special jaws do (this is likely where he got the idea). Fairly easy to grind off and replace as needed with 5-minute epoxy. I used the Stewart Systems green glue for one small project and it worked fine, didn’t last forever but still works. Of course the tinman’s jaws are nice, and I may get some one day, but when you need a fast solution this may help.

I work with a fella some that can make these type of fairings out of aluminum so beautiful that you would never want to use fiberglass again. But he ain’t cheap - he makes parts for vintage aircraft. I am hoping to learn enough from him to bang out some simple things - it would take me many years to even approach his skill level. From being around him, I agree with alaskabearhawk - you have to use 5052 or 3003 to make anything with stretch in it, or even aggressive bends really. It can be done to some extent with 2024, but it has to be 2024-O to start with and then heat-treated in an oven for a specified program to bring it to T3 condition. And even then it’s a pain to work with because it work hardens quickly. This fella I’m talking about made four Lockheed 12 cowlings from scratch, and they were 24ST originally, now that is 2024T3 - so I got to see how hard that was in person, of course it was second hand since I was just the helper.

A couple of suggestions to try rodsmith: it looks like this may be a bit of a conical section, wider radius at the windshield than at the wing, so it would need to be curved a bit in plan (when flat on the bench), then when you bend it it would flare out some from the wing to the windshield. Use cardboard like from cereal boxes to mock up the basic shape first. Also, once you have the basic shape, a break inward along the edge at the wing will make it smoother and take the bulging out. One of those two-bearings side-by-side on a stick things made for making a slight 1/4” break along an edge is what I am talking about. Shrinking the edge will roll it in, but it probably won’t really lay down tight and smooth without a lot of hand-work and adjusting. You may not need to shrink it at all if you get the radii right.

[rodsmith]

Thanks for all the suggestions. I know I can make nice composite fairings, just have been hesitant due to all the masking it would require, not to mention the finish work. The weather hasn't been conducive for composite work in an unheated hangar. Even on the top of the wing I had some puckering that I needed to shrink out. This was because my 1/8th thick skylight prevents the fairing from laying flat from the wing to fuselage. Steve W, nice fiberglass work!

[spinningwrench]

Here is my windshield to wing fairing. Two layers of carbon fiber and three of fiberglass. First fiberglass project it went well once I dove in.

[RickG]

Nice job on the fairing, did you make a mold from it after you got the shape you wanted? You could probably sell parts

[spinningwrench]

You will find that no two wing to windshield match ups are the same so a custom fit is required for each builder. Some of this has to do with fitting the windshield but for a perfect fit a mold would not work.