Help with Closing the Elevator Tip

[Nihon_Ni]

Thanks Dan & Ron for your tips. I'm headed back to the airplane factory and will just round the corners of the counterweight and use it as a form for my fiberglass.

Rob

[Nihon_Ni]

I had a big day in the factory today and I'm happy with the results. As suggested, I removed some material from the corners of the Counterweights to follow the contour of the Counterbalance Skin, with an allowance for a few layers of fiberglass. I used the notch I cut off the flange of the elevator tip as a guide for how much material I needed to remove in order to make the new fiberglass cap flush with the counterbalance skin.



The right elevator is still a bit nose heavy, but the left elevator was a little under after today's nose job surgery, so I added a platenut to the inside of the E-703/704 web centered on the tooling hole, and used the lead I removed from the right Counterbalance to add more weight to the left side.

With a little luck, my fiberglass supplies will arrive from ACS tomorrow, and I'll finish the job.

Thanks for all the assistance!

[Ron RV8]

Looks good Rob...

A suggestion would be to taper back the gelcoat a little more, particularly on the inner edge, to a point where the glass is flush with the aluminum. Right now the glass is a little proud... There is a black mark on the aluminum close to where it seems to come flush...

You might also want to install some sort of fasteners to make sure that the tip is in it's final position and will not be pulled to a different shape when you install them later... Maybe clecos or a few temporary pop rivets?

Don't forget release agent or it will be there permanently!

[Nihon_Ni]

Ron,

I was wondering how far I should sand off the gelcoat, and wasn't sure how much I need for proper adhesion of the new glass to the old.

If you're looking at the black mark in the bottom right photo, that's the mark I had for the aft edge of the counterweight. I noticed the Vans tip is bulging a bit around the counterweight and I think it needs sanded on the inside to relieve a bit of outward pressure.

There's a bit of gap between the outer edge of the counterweight and the inside of the fiberglass tip. Should I fill this with flox when I cover the front, or leave the gap to aid in removing the finished product?

Your comment about fasteners -- I drilled the tips to #30 and installed clecos prior to shaping the tips, but took them off to check the balance when I took the lower two photos. I think that's what you mean, right?

[RV7A Flyer]

Originally Posted by Nihon_Ni

The left elevator is still a bit nose heavy, but the right elevator was a little under after today's nose job surgery, so I added a platenut to the inside of the E-703/704 web centered on the tooling hole, and used the lead I removed from the left Counterbalance to add more weight to the right side.

YMMV, but I found, as expected, that when the elevators are perfectly balanced during construction, they were unbalanced and required more weight (using the platenuts/bolts/washers) on both sides *after* painting.

Having those platenuts on both sides made final balancing straightforward...a stack of 4 or 5 large fender washers and a bolt on each side. Easy peasy and simple to check during each preflight...400+ hours and not a hint of loosening.

[Nihon_Ni]

Originally Posted by Ron RV8

A suggestion would be to taper back the gelcoat a little more, particularly on the inner edge, to a point where the glass is flush with the aluminum. Right now the glass is a little proud... There is a black mark on the aluminum close to where it seems to come flush...

How's this?





After closer examination this morning I decided not to sand it from the inside and just kept shaping the outside.

[DanH]

Simple rule Rob...if it's a structural bond, remove all the gelcoat, primer, etc. If it's merely cosmetic, gelcoat doesn't matter.

I consider this fairing to be structural, due to the potential for control jam. More of a mindset than an engineering truth.

How far back to remove gelcoat? No good rule, but it's hard to go wrong with more, as there is going to be a filler application later anyway.

BTW, if you're not going to do a floxed-core corner, I'd cut the original glass back to about where the black line is in the prior photos, then scarf. The new layups won't like being bent over the current edge.

The advantage to a cored corner is that it allows shaping the corner radius before laying down any glass fabric. Here the glass-to-glass scarf joints are primary, so micro would core for shape just as well. However, cored corners are not strictly necessary....lots of ways to skin a cat.

[NavyS3BNFO]

Any tips for shaping lead?

Just curious what you used to trim the lead. I'm at about the same stage and don't really like getting small pieces of lead shavings all over (I have small kids who like to see what I'm doing) so I hesitate using a file. I was thinking about using a sharp knife to shave larger pieces off but then the resulting surface would be fairly irregular.

[Ron RV8]

As Dan sugggested, tapering back the gelcoat a bit more is a good idea structurally. Dan also picked up on your latest pics that show too sharp a radius near the tip. Glass layup is reluctant to stick to a radius less than about 1/4", so you'd need to grind back more like you've done inboard.

If you want a sharper radius, that is where flox comes in handy cause it will conform to a sharp corner if that's what you want.

As Dan says, lotsa ways to skin a cat...

[Nihon_Ni]

Originally Posted by NavyS3BNFO

Any tips for shaping lead?

Just curious what you used to trim the lead. I'm at about the same stage and don't really like getting small pieces of lead shavings all over (I have small kids who like to see what I'm doing) so I hesitate using a file. I was thinking about using a sharp knife to shave larger pieces off but then the resulting surface would be fairly irregular.

I just used files to do the shaping work. I didn't try using a knife, so I can't speak to it.

MarineEA6BNFO