Closing out the TE of the canard

[Phil Kriley]

This question was asked twice in the archives, but I could not find an answer:

 

I'm ready to skin the top of my canard and noticed a 1/8" joggle at the

trailing edge where the foam ends and the bottom skin continues. The

contour is very close to the F templet and I'm afraid to sand the foam

any further. My fix is to add small amount of wet flox, peel ply and let

cure before applying top skin. Does this sound ok?

 

And:

 

Builders,

 

I know Nat is on the road to the Big "O"....so I will ask for the other

expert opinions out there.

 

I'm getting ready to skin the top of the canard. I put 3/4" peel ply on the

trailing edge of the canard when I did the bottom layup. Not the 1" called

out in the plans because it removes too much foam. I figured this still

would give me a 3/4" glass-to-glass close out on the trailing edge.

 

When I flopped the canard over, cut the fishtail off, and pulled the peel

ply. It still pulled up too much foam. My question is what is the

recommended fill for the small void where the foam has been pulled out?

Flox?, Micro?....

 

It looks like the peel ply made a perfect flox corner and I will still be

able to get a 3/4" glass-to-glass trailing edge that I will put micro over

to match the template.

 

The instructions are vague on how to close out the trailing edge. I assume

we close the canard out like the elevators that Nat shows in fig. 12, CH. 11

page 5.

 

So what is the answer? Do we make a flox corner or use micro or...?

 

Thanks for your help!

[Lynn Erickson]

This question was asked twice in the archives, but I could not find an answer:

 

I'm ready to skin the top of my canard and noticed a 1/8" joggle at the

trailing edge where the foam ends and the bottom skin continues. The

contour is very close to the F templet and I'm afraid to sand the foam

any further. My fix is to add small amount of wet flox, peel ply and let

cure before applying top skin. Does this sound ok?

 

And:

 

Builders,

 

I know Nat is on the road to the Big "O"....so I will ask for the other

expert opinions out there.

 

I'm getting ready to skin the top of the canard. I put 3/4" peel ply on the

trailing edge of the canard when I did the bottom layup. Not the 1" called

out in the plans because it removes too much foam. I figured this still

would give me a 3/4" glass-to-glass close out on the trailing edge.

 

When I flopped the canard over, cut the fishtail off, and pulled the peel

ply. It still pulled up too much foam. My question is what is the

recommended fill for the small void where the foam has been pulled out?

Flox?, Micro?....

 

It looks like the peel ply made a perfect flox corner and I will still be

able to get a 3/4" glass-to-glass trailing edge that I will put micro over

to match the template.

 

The instructions are vague on how to close out the trailing edge. I assume

we close the canard out like the elevators that Nat shows in fig. 12, CH. 11

page 5.

 

So what is the answer? Do we make a flox corner or use micro or...?

 

Thanks for your help!

I would use Micro, it is the same weight as the foam. the void can be filled like any other depression in the foam. add the micro just before the layup is done , same time as the foam cells are filled with micro. just keep it off the glass to glass area.

[jpolenek]

I'm ready to skin the top of my canard and noticed a 1/8" joggle at the

trailing edge where the foam ends and the bottom skin continues. The

contour is very close to the F templet and I'm afraid to sand the foam

any further. My fix is to add small amount of wet flox, peel ply and let

cure before applying top skin. Does this sound ok?

 

Are you talking about the same thing that's shown in the attched photo?

(I'm not there yet, but here's my 2 cents worth...)

 

Since the glass-to-glass bond at the trialing edge is critical to the torsional strength of the wing, I would ensure that the top skin meets the bottom skin for a good strong glass-to-glass bond. My plan is to sand the foam near the trailing edge so it smoothly transitions down and provides for plenty of direct contact between the top and bottom skins. Afterwards, the resulting joggle can be filled ON TOP of the skin.

 

Joe Polenek

[Phil Kriley]

Hi Joe - actually, the "gap" is created when you remove the peel ply that's between the bottom skin and the foam. Some foam gets removed along with the peel ply. This leaves the bare glass of the bottom skin ready for mating with the top skin, BUT it leaves a rather large "joggle" where the foam gets ripped up by the removal of the peel ply. If you try to lay the top skin over this, you will get the glass-to-glass bond you desire, except that there will be a large joggle on the top skin at the aft portion, starting at the T/E and going inboard about an inch.

 

I think it might even be difficult to get the cloth to lay down unless you either radius the foam or, as Lynn suggests, fill with some micro. You will still have at least 3/4" glass-to-glass, but w/o the joggle. I'm leaning towards wet flox, peel ply, cure, and then add the top skin. It will be stonger and since it is only a small amount it shouldn't add much to the weight. I want the top skin to have a smooth, uninterrupted airfoil shape that matches the "F" template when I'm done. I don't want to have to add filler on top of the skin.

[TMann]

In the Berkut construction videos, they fill these areas of discrepancy with flox and follow it right away with your skin layers.

 

Seems like a pretty good source.