10 minute flap -Zone 2

LAST EDITED ON Nov-28-04 AT 10:48 AM (CST)
 
This is my method for building a flap. It takes about 10 minutes. All parts are lazer cut and my design.

The flap is made in two parts. The core is laser cut 3/16".
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1/8" ID Aluminum tube is added to the slot for the controls.
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Both sides are soaked in thin CA and sealed with two layers of 3/4 oz glass.

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Core joined and ready for sheeting.

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Sheeting added to one side.

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Done.
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The only thing left is the triangle stock added to the leading edge. I will show that later.

>This is my method for building a flap. It takes about 10
>minutes. All parts are lazer cut and my design.

Finished sanded how much does it weigh?

>>This is my method for building a flap. It takes about 10
>>minutes. All parts are lazer cut and my design.
>
>Finished sanded how much does it weigh?

3/4 OZ.

>>>This is my method for building a flap. It takes about 10
>>>minutes. All parts are lazer cut and my design.
>>
>>Finished sanded how much does it weigh?
>
>3/4 OZ.

Thanks

Hey Zilla,

Why two parts? Stock balsa sizes?

Since I don't lazer cut, would a glued up core section work as well? Perhaps a tad heavier for the glue joints, but since the ribs would be stiffer since they're not short grain, a lighter grade of balsa could be used to offset?

Tools

>Hey Zilla,
>
>Why two parts? Stock balsa sizes?

The lazer will only cut 24" stock. All of my designs take this into consideration.

>Since I don't lazer cut, would a glued up core section work
>as well? Perhaps a tad heavier for the glue joints, but
>since the ribs would be stiffer since they're not short
>grain, a lighter grade of balsa could be used to offset?

I made new flaps for the Dr. Jekyll. I made my own cores by hand. I cut the outline in 3/16" balsa and then made a 3/8" border of balsa. I even cut the slot for the controls the same way as the laser cut version. I used 3/16" square former sticks every two inches. It came out within .1 oz of the original.

Timely subject, Brad- thanks.
Do you consider this construction to be strong enough to "tweak" the flaps without using external clamping blocks?
1/8 OD horn wire running in 1/8 ID tubing leaves zero tolerance for mis-alignment or flex in the system. How do you handle these issues?
How do you rate the torsional stiffness of your flap construction: very stiff, not bad, at least both sides deflect the same?
Derek Moran

Yii! You're able to tweak 1/8" control horn wires? At all?

I thought you pretty well gave that up unless 3/32" wire horns are used.

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"Money will buy you a fine dog, but only love can make it wag its tail." -Richard Friedman

>Timely subject, Brad- thanks.
>Do you consider this construction to be strong enough to
>"tweak" the flaps without using external clamping blocks?

They are made to tweak. The area is very strong due to the glass and CA. The key is to soak the endgrain to the tube with thin CA. I use Bob Geiseke "tweakers" which is full stick of Prather lead weights bent in a 180 degree "U"" (leave the foam on the stick). This is adequate for tweaking if the horns are annealed correctly. I ask Tom Morris to "extra" anneal the wire to make sure it will move.

>1/8 OD horn wire running in 1/8 ID tubing leaves zero
>tolerance for mis-alignment or flex in the system. How do
>you handle these issues?

No flex is good right? That has always been my view. As far as misalignment, I align the elevators before assembly. Since the surfaces are flat, simply lay both elevators on a flat surface joined with the horn wire. Tweak until both lay dead flat on the table. Same with the flaps.

>How do you rate the torsional stiffness of your flap
>construction: very stiff, not bad, at least both sides
>deflect the same?

Depends on what you want them to weigh. My Solace flaps are super stiff. I simply used 8-10 lb C-grain sheeting on the same core and covered in OZCOver. They are the stiffest flaps I have ever made by far. In fact, these are much stiffer than flaps that I have made with lighter wood and covered in various materials (glass, carbon, PC and silkspan). I would suggest if you want SUPER stiff flaps simply use heavier, stronger sheeting, and do not use any special finishing methods.

My stuff is stiff. Plenty stiff. I went to the 3/8" stab because additional thickness for rigidity is not necessary. The entire plane is sheeted.

Zilla,

Do you have the flap cores drawn in AutoCAD and would you be willing to share the file? With the file they could be scaled and tips reshaped to work with anything..

>Zilla,
>
>Do you have the flap cores drawn in AutoCAD and would you be
>willing to share the file? With the file they could be
>scaled and tips reshaped to work with anything..

I e-mailed the file.

Do you not taper the thickness of your flaps?

>Do you not taper the thickness of your flaps?

No. I see no advantage to tapered surfaces. Flat surfaces build better and are stronger and more predictable (for me).

Everything is flat on my planes. Stab, elevators, flaps, rudder, etc.

>>Do you not taper the thickness of your flaps?
>
>No. I see no advantage to tapered surfaces. Flat surfaces
>build better and are stronger and more predictable (for me).
>
>Everything is flat on my planes. Stab, elevators, flaps,
>rudder, etc.

Better and better. I like flat too. Hopefully we'll see this flap construction, along with the awesome fuse construction, when the Zone becomes a UHP kit!

Hopefully we'll see
>this flap construction, along with the awesome fuse
>construction, when the Zone becomes a UHP kit!

You could order a Zone 2 from Kyle at Tanks Hangar. Then all you would need is some select 4" x 1/16" sheeting from your favorite source. The foam core is a Time Machine 60 and is available from Dixon. The control hardware is avialable from Tom Morris (he has all the specifications in my file).

>>Do you not taper the thickness of your flaps?
>
>No. I see no advantage to tapered surfaces. Flat surfaces
>build better and are stronger and more predictable (for me).
>
>Everything is flat on my planes. Stab, elevators, flaps,
>rudder, etc.

You may be right, but I sure like to taper flaps and elevators.. However, I've been thinking - again (?). Suppose I pre-tapered my center laminate sheet stock (sanded, using steel rods on edges for guides). THEN I get the sheets laser cut!

Whaddya think? Just a minor readjustment in the order of machining.. I might have to square up external edges slightly with a sanding block, but that's no big deal. You always need some way to hold more fragile parts for sanding.

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"If a little dreaming is dangerous, the cure for it is not to dream less but to dream more, to dream all the time." -Marcel Proust

Larry,
The only drawback to pre-taper before laser cutting would be that this would result in angular laser cuts. I guess that if you were careful you could taper the core after laser cutting.

>You may be right, but I sure like to taper flaps and
>elevators.. However, I've been thinking - again (?). Suppose
>I pre-tapered my center laminate sheet stock (sanded, using
>steel rods on edges for guides). THEN I get the sheets laser
>cut!

No. I would PARTIALLY cut the holes. Leave a 1/4" uncut portion on each bay. Then sand the entire core, and THEN remove the bays afterward.