Here is my new trim tab sitting next to the first one. I will keep the original as a backup in case I totally screw up the new one. The original is just fine to use if needed. But, the fact remains, I am kind of really going EXPERIMENTAL with this new design. I'm not positive this has ever been done before (although I imagine it has...there are some clever builders out there for sure).
The first task was to cut up my new $18 skin. Seemed a little crazy to me at first and I really was hesitant to get started. But, eventually I dove right in. You can see where I cut off the bend tabs since my new design wouldnt use them...consequently, they weren't needed where I was going.
I used the dremel tool with a cutoff wheel, this really is a great tool for cutting aluminum. Goes through it like butter. Much better than using snips in my opinion.
So, here is my idea, I am adding fiberglass endcap ribs to the trim tab and elevator. I researched bonding fiberglass to aluminum and was told it works just fine. I just acid etched the aluminum and scuffed it up so the epoxy had a surface to bite into. On top of the fact, these end pieces are not key structural components since there are spars that would keep the structure intact if these failed or delaminated. I have seen people creating their own custom aluminum end ribs here and I considered doing that. The reason I wanted to do it this way is the superior aerodymanics of this design. It will seal the endcaps off nice and smooth. Not only will it look nice when done, but it will have less drag.
Here it is with my homemade fiberglass endcap. I cut it to fit on the band saw and fine tuned it with the belt sander.
Here is a picture of the foam core laminated with fiberglass. After the epoxy cures, you just mark out your rib and cut it to size. Works slick, finally found something that my bandsaw is useful for.
And here it is after cutting and shaping, ready for install.
This is another idea I read about and decided to implement. I sprayed in some contractor foam in the center of my trim tab. This will serve as an vibration dampener and also add a little structure to the center where there is no ribs. This acts as a foam rib of sorts. Notice I primered the inside of the skin since I was concerned with water/moisture causing corrosion from the inside.
Also notice how I made sure not to go all the way to the trailing edge here. The reason being is, once again, water. I dont want water getting trapped inside there so I left a path for drainage if water does enter the trim tab assembly.
Here you can see after the first coating of flox was applied. I used liberal amounts of flox to basically glue this puppy in place. I am liking the look of this so far, nice clean edge and it will only get better as I fine tune it.
This is after I applied the second coat. The rust colored epoxy has West System 407 fairing mixture designed expressly for thin coats like this. It is also lightweight, so very suitable for aerospace applications.
In this view, you can see the buildup of this layer. I didnt get my mixture quite thick enough for this. It should be peanut butter consistency, but I was a little closer to mayonaise. Lesson learned, but it came out ok when it set up as you'll see.
This is just a teaser of how nice this 'reveal' is going to be with this design. I will fine tune this by adding more fairing mix and sanding/shaping until I have it exactly how I want it. Since there are no rivets (as with the original design) to interfere with each other, I can really close up this gap nicely.
No comments:
Post a Comment