Flap Jointer wire box - lucky box?? How 2

[Paul Taylor]

Can someone please explain this to me. I will be adding flaps to my new scratch Cardinal and would like to make the jointer wire boxes?
I searched and searched but came up empty. I did find this on the main page but I need a little more info.
And what size wire should be used for flaps?

Thanks guys.
Paul 

[SteveMoon]

Paul that is commonly known as a 'lucky' box. Don't know where the name came
from. It's an easy way to get a perfectly aligned hole in the flap without having
to hand drill it. My brother and I use a very similar method, and it really is a good
and simple solution.

Generally flap horns are 1/8" music wire and elevator horns are 3/32" music wire.
Although, on smaller planes it is okay to uses 3/32" music wire for the flap horn.

Later, Steve

[Bill Little]

I don't mean to contradict Steve, but those are just *horn clips*. 

A *Lucky Box* is made so the horn wire can slide side to side like in a set up where there is a lot of forward sweep in the TE.  Eric Rule at RSM is the first person I saw bring out a product for this.

All you need, Paul, is the horn clips.  3/32nd wire should be fine for a Cardinal Profile.  Some will say 1/8th, but a lot of others will say 1/8th isn't necessary for that size plane.

Make the center ply piece out of 1/8th ply, bass, or spruce, and cap it with 1/32nd.  Wrap some CF veil around the cap to extend out on the balsa flap with CA. (usually the next larger size of wood is used compared to the wire diameter.)

[Larry Cunningham]

The horn clips are available from Brodaks. You can also make
them yourself, they are a simple, clever method.

L.

"The question of whether a computer can think is no more interesting than the
question of whether a submarine can swim." -E. W. Dijkstra

[Paul Taylor]

Larry,
Looked on Brodaks site and did a search. Did not find them.
Do you have a picture or link?

Paul 

[Steve Helmick]

Genuine "Lucky Box" kits are available from RSM, available in both 3/32" and 1/8" sizes. They were invented by the late Lucky Pyatt. Like Little Bill wrote, the Lucky Box allows for swept TE's, and allows removing the flaps and elevators, as they are a slip fit. Removable control surfaces makes finishing easier, and also allows experimenting with areas, "Servo Tabs" and such. I'm not sure the basswood clips per the sketch would allow removal...I'd think the basswood could wear and eventually make for a sloppy fit unless epoxied in. Still, clips would allow finishing the control surfaces separately, then assemble.  Steve

[Wynn Robins]

Paul,

Go to RSM web page - building guides.  the Lark building guide that I did for Eric has a picture of the lucky boxes in it.......I will send you the real pics tomorrow at when I am at work - send me a PM to remind me.

W

[Bill Little]

I'm not sure the basswood clips per the sketch would allow removal...I'd think the basswood could wear and eventually make for a sloppy fit unless epoxied in. Still, clips would allow finishing the control surfaces separately, then assemble.  Hoff Steve

Hi Steve, that is Randy Smith's normal method he shows on his plans.   Once everything is finished and you are ready for final assembly, you do epoxy the wire into them.  At first he suggested ply, but has switched to bass.  No problems, but they are not intended for removable flaps as far as I know.

[RandySmith]

Hi Steve, that is Randy Smith's normal method he shows on his plans.   Once everything is finished and you are ready for final assembly, you do epoxy the wire into them.  At first he suggested ply, but has switched to bass.  No problems, but they are not intended for removable flaps as far as I know.

Hello Steve  and Bill

The boxes can be used with or without glueing them to the wire, without much worry about them wearing out and getting sloppy, if the space is kept snug, they will last about a thousand flights before you get any slop in the clips.
I use them made of bass or ply, both work well.
You can make your flaps removable using this method with my clips by either un pinning your hinges or using a long piece of thin piano wire as the pins in the hinges. several people have done this before, it works well.

Also they can be used with swept flaps by keeping them snug top to bottom and wider side to side, same way people use "lucky boxes"

Regards
Randy

[Terry Bolin]

These are the ones I looked at using last time. Go to Brodak and search for a BH738 or 739. "Flap horn boxes. $2.??
Good luck!

[Paul Taylor]

Thanks Terry!!!