Fibre glassing the tips

[RV6AussieNick]

I've been searching for what most builders are using to fair their glass tips, the only thing I can find is epoxy mixed with some sort of light filler.

How does this hold up over time, does it crack at the join line spoiling the paint finish?

What is your thoughts on the best thing to use..

Cheers,

[Sig600]

I did it to the empennage tips, using a method I found here on someones build log. Essentially using filler over the gap and rivets, sand, run 1/2" .003 fiberglass tape over that joint. Glass in, sand, then use super-fil to fill that in. The results came out better than expected, but for the amount of work it took I won't be doing it again. It was a little over 2 weeks, and looking at other planes around my field, the look just as nice with the traditional method.

To each their own, I think it'll look good after paint but all those hours would have been better spent getting it closer to flying IMO. YMMV.

[DanH]

Four general schools of thought.....

Open seam, exposed pop rivets (std)

Open seam, nutplates and screws (many do this for the rudder bottom only)

Filled seam, epoxy/micro

Filled seam, epoxy/micro, then thin glass fabric, then more fill.

How does this hold up over time, does it crack at the join line spoiling the paint finish? What is your thoughts on the best thing to use.

I don't think anybody knows for sure. I've not seen a lot of cracking in the field, but there are a lot of variables. It's not just the fill method or material. Logic says cracking would be the result of relative movement between tip and metal skin.

My own (experimental) approach was to scuff and clean the inside of the aluminum flange, scuff the surface of the glass flange, then apply an epoxy adhesive to the surfaces and rivet while wet. The idea is to adhere the tip to the aluminum and reduce/eliminate relative movement. I did some with ordinary West and some with Hysol. Subsequent surface fill is epoxy/micro, no glass fabric. No cracks so far. If the light is just right I can see the seam, but the pearl paint I'm using highlights everything.

Your mileage may vary.

[RV6AussieNick]

Hi Dan and Sig600,

Thanks for your tips and what you have experienced, much appreciated, Dan, what sort of Hysol did you use?

I have pop riveted my tips on with epoxy, Think i'll try the scuff, alodine and fill method as i dont have much miss match between the skins and fairings.

My main concern is bond strength of the fill..

Cheers,

[rockwoodrv9]

I have built several boats with West Systems Epoxy. It forms a very hard surface that I never had any cracking problems. As long as you make the "bond" first with fiberglass tape, thin coat epoxy, it will easily be as strong as the .032 skin. They have microballoons that are very light - don't sneeze around them or they are everywhere for filling. To do the rough sanding, I always used sanding belts cut and put on a sanding board. The stuff is HARD. The only possible question would be if because it is so hard, would the flexing of the aluminum be an issue. It wasn't on boats, but all the materials were similar.

Anyone here use West Systems?

[Sig600]

Originally Posted by rockwoodrv9

I have built several boats with West Systems Epoxy. It forms a very hard surface that I never had any cracking problems. As long as you make the "bond" first with fiberglass tape, thin coat epoxy, it will easily be as strong as the .032 skin. They have microballoons that are very light - don't sneeze around them or they are everywhere for filling. To do the rough sanding, I always used sanding belts cut and put on a sanding board. The stuff is HARD. The only possible question would be if because it is so hard, would the flexing of the aluminum be an issue. It wasn't on boats, but all the materials were similar.

Anyone here use West Systems?

Yup, used the stuff on the aformentioned tips. So long as you give the aluminum a good scuff with some 50-80 grit, and clean it with MEK or acetone that stuff grips like a cat on carpet. You're not kidding either, it's indestructible.

[DanH]

Originally Posted by RV6AussieNick

Dan, what sort of Hysol did you use?

Probably 9410....I'd have to look when I go down to the shop.

[RV Jerry]

If you bond your tips on as well as riveting it will reduce the likely hood of cracking considerably. Jerry

[Bill.Peyton]

I bonded all my tips except the lower rudder, which I used nutplates. My bonding cosisted of ruffing everything up with 100 grit then using one strip of 9 oz. tape applied with the west system 105 epoxy. The body work was done with Bondo fiber reinforced filler. I have not painted yet, but am hoping this is sufficient. After looking at a friends RV8 tips, which were done with rivets, I would not do it again. It was not worth the improvement in looks verses time it took to do the body work.

[sglynn]

I'm just now doing my fiber glass tips and am posting photos on my construction site www.mykitlog.com/sglynn.

http://www.mykitlog.com/users/catego...&category=3657

I'm doing as previously explained, by others. First putting a small amount of Rage Gold filler with micro balloons or glass flex, in the crack to fill it smooth. Then putting a 3/4 strip of glass over the crack using West Marine System Epoy Resin. I'm using glass strips that are the random angle threads, not the material looking stuff with orthogonal threads. Then finishing it off with more Rage Gold filler. I'm sanding it smooth and flat. I too am hoping it won't crack later. A super expert Corvette builder is looking at what I'm doing and he says it will crack because parts of different materials like aluminum and plastic have different expansion charactoristics. But others on this site have done the same with no reported cracking. I think if you scratch up the aluminum and clean it good, that the fiber glass and West System Epoxy are strong and won't let it crack.

I look at the RVs at Oshkosh and I like the smooth, no crack look. And it doesn't really take very long. At painting time, I'll spend a little more time with mud, sanding, and primer.