I tried o post on the one I found about the Lucky Boxes but was told by comuptor it was too old.  The King Sweep has qute a bit of sweep back on the trailing edge.  What I need to know is if I make the flap horn bends at the end of the flaps.  The horn is being installed ona peice of wood so it it will be straight across at the center section of the wing.  Someone stated using Phenolic material for the top and bottome surfaces.  What I can't remember is what is the angle of the flap horn arms at the flaps.  Or do I leave them going 90 degrees to the hinge point of the horn?  Spent today getting the bellcrank partially mounted.  Didn't think about how much bigger than the Sweet Sweep this is going to be.   

Hi Doc-
Bend the horns 90 degrees the same as any normal model as that is the usual practice. However, the horns could be at 90 degrees to the trailing edge just as well. The amount the end of the horn articulates as the flaps move is the same either way. 90 is just easier. I use 1/8 x1/4 brass tube for lucky boxes, works great with 3/32 horn wire. Just be sure the horn tips are real close to the outboard edge of the box when the flaps are at neutral as the ends will move toward the inboard edge as the flaps move up and down. I am not real thrilled about epoxying fiberglass sheet for lucky boxes as the epoxy doesn't adhere to the slick surface all that well.
Don

G-10 epoxy board material (sometimes called FR-4) works well for lucky boxes, and a lot of other stuff.  The secret is to rough up the surface of the epoxy-glass board and use JB Weld.

Floyd

Hey Floyd:  What you are describing is more commonly known as phenolic or micarta.  That is tought stuff, I use it for motor mount pads.  I have used it for horn pockets, but have changed to spruce or bass because it is much easier to sand and shape into flap tapered cross section.

Hey Floyd:  What you are describing is more commonly known as phenolic or micarta.  That is tought stuff, I use it for motor mount pads.  I have used it for horn pockets, but have changed to spruce or bass because it is much easier to sand and shape into flap tapered cross section.

I hate to disagree, but FR-4 is, indeed, an epoxy-glass laminate.  You can get phenolic circuit board material.  It's often used in really cheap consumer electronics because it's -- well -- cheap.  But epoxy-glass is quite common, and is to be found anywhere that the circuit board quality can make or break the product (I doubt that you'll find a phenolic circuit board inside of a PC, for instance).  Phenolic is used in things like cheap radios and electronic alarm clocks; it's mostly restricted to far east manufacture these days.  FR-4 is what you'll usually find as surplus copper-clad board in the US and probably Europe.

I hear you about your material choice -- I'm currently making my very first pair of lucky boxes for a V-tail; I'm using FR-4 because that's what I have around and I know that I won't have to worry about strength.  But I'm not looking forward to getting any exposed corners to look good.

I hate to disagree, but FR-4 is, indeed, an epoxy-glass laminate.  You can get phenolic circuit board material.  It's often used in really cheap consumer electronics because it's -- well -- cheap.  But epoxy-glass is quite common, and is to be found anywhere that the circuit board quality can make or break the product (I doubt that you'll find a phenolic circuit board inside of a PC, for instance).  Phenolic is used in things like cheap radios and electronic alarm clocks; it's mostly restricted to far east manufacture these days.  FR-4 is what you'll usually find as surplus copper-clad board in the US and probably Europe.

I hear you about your material choice -- I'm currently making my very first pair of lucky boxes for a V-tail; I'm using FR-4 because that's what I have around and I know that I won't have to worry about strength.  But I'm not looking forward to getting any exposed corners to look good.

My source for phenolic is McMaster Carr.  In there catalog they list G10 / FR4 as one of several grades of phenolic.  They also call it Garolite.

From the McMaster site:

"Grade G-10 Garolite: A glass-cloth laminate with epoxy resin binder offering excellent strength and low water absorption."

"Grade G-10/FR4 Garolite: A glass-cloth laminate with epoxy resin binder, this material is the flame-retardant version of standard G-10 Garolite. It offers excellent strength and low water absorption. "

They list it alongside phenolic/linen composites, but fiberglass isn't linen, and epoxy isn't phenolic.

I think phenolic has become a misnomer for pretty much all high pressure laminates, or is it just me ?  LOL
 

Instead of starting a new post, here is where I am at on the King Sweep.  Don't have picture of flap horn yet.  These are before I started sanding to get it look half way decent.

Made the flaps yesterday.  Plywood top and bottom.  Glued one side and then tested.  Hoged out for the flap horn arm sweep and glued other ply peice on.  Pictures later.