Conference vmszoo::rc

    When I make ribs for a constant cord wing the first thing I do is
    make two accurate templates of the rib, usually from aluminium or
    1/8" plywood. I then stack my rib stock between the templates, saw
    and sand the whole stack at once, and Ive got a bunch of identicle
    ribs.
    Wayne

>>>	I then stack my rib stock between the templates, saw
>>>    	and sand the whole stack at once, and Ive got a bunch of identicle
>>>    	ribs.

How do you clamp the rib stock between the templates??

mjv

        Possibilities are T pins, small holes and dowels, contact cement,
        3M "77", white glue, masking tape, white glue, ... use whatever
        works for you. If you are making a tapered wing, do the same as in
        -1, but you have 2 different rib patterns. After sanding, the
        angle in the ribs will be a bit too steep, and each rib will need
        a bit of cleanup with a sanding block, but it still gets a pile of
        ribs faster than cutting them all out by hand. Reverse the order
        of the root and tip templates for the other side. 
        
        If the problem becomes making hundreds of ribs (you crash a lot,
        are kitting something yourself, or for a club project) you can
        even die cut the ribs. To make a die, cut the shape out of thick
        wood instead of the aluminum or plywood used in -1. Something like
        a scrap of 1x2 works fine. Drill a couple holes in the middle of
        the pattern, to use to knock out the cut ribs. Next put on some
        work gloves and eye protection. Break in half a bunch of single
        edge razor blades and fasten them around the perimeter of the wood
        pattern. This can be tacked in place with CYA, and then beefed up
        with epoxy. The razor blade is flexible enough to conform to the
        gentle curves of an airfoil, except for the rounded LE. This can
        be made from a sharpened section of brass tube. Once this is done,
        a tap with a mallet or another scrap of wood will cut a complete
        rib. 

    
    	I've tried method #1 and one mistake means you have a stack
    of bad ribs instead of good ribs.
    
    	I typically lay out the pattern of the rib including spare
    locations on a piece of 1/8" aircraft grade plywood. This is then
    cut out and sanded to match the airfoil. Then I cut two scrap
    pieces of ply app 1/2 x 1. These are laminated to the top side
    of the template. Now get two good sized buildin pins and cut the
    heads off. From the top of the template drive these thru the laminated
    section so that they extend thru the bottom of the template the
    same length as the thickness of the rib material. Lay this template
    on the rib stock and it will not move around on you. Using a pointed
    tip exacto knife you then cut out the ribs. Don't skimp on the blades.
    Sharp blades always work better. I find that I change blades every
    five or six ribs. Same the blades they're still ok for all the other
    chores you use them for. When you cut the ribs out make sure the
    knife is kept at right angles to the rib material. I find that I
    can cut out an entire constant cord wing 60" in span including the
    template in about 1.5 hrs. First time it may take you a little longer.
    
    
    						Tom

I cut out two templates from 1/8 inch ply.  Then I cut out a
bunch of rectangular balsa for rib blanks.  Using a drill press
(the holes must be straight), I drill the templates at about the
20% and 70% positions.  Then I lay one of the templates on the
stack of blanks, mark it, and holding the stack of blanks
tightly, run the drill down the stack.  It doesn't matter if the
blanks are slightly askew; just as long as they're larger than
the rib.  Now, I run a 6/32 x 3" screw through each hole.  The
screws are flat head, and one template is countersunk.

The hard part is over.  I use my Dremel jig saw to rough cut the
stack.  Do not cut the spar grooves yet, or any other recesses in
the rib.  Just get the gross outline.  Now I take my #50 sanding
block and sand everything to shape across the templates.  Then I
use a razor saw to cut the spar grooves, taking care to use a
square to mark lines across the stack.  If there are other
recesses, such as a "v" in the leading edge, I'll use the razor
saw, or a knife, or a sanding block, depending on the size of the
recess.  Now I finish it all off with #120 on a sanding block.
It's amazing how neat and true the ribs come out.  The only way
to go!

Be careful of that scratch building, its addictive.

I know of another method of duplicating ribs (or just about any other 
piece used in constuction, for that matter), but it requires a router 
and router table.  The method is also really expensive from the 
standpoint of the amount of time and effort to set up for it, so it is 
not really the best method to use if you are building a single plane - 
unless the plane has a constant chord wing (meaning all ribs are the 
same) or you are just a real picky builder like me.  If anyone is 
interested, reply in a following note and I will try to find time to 
enter the method here.

There are two types of R/C modelers:

	1 - The Scratch Builders
	2 - those "other" guys

P.S. - I usually only get to read this Notes file about twice a month, 
so if someone wants to see this method understand that it may be a week 
or two before I can reply.

Just thought I'd mention this.

I put together a couple of tools that I think are very useful for
scratchbuilding.  The first is a small circular saw, using a
dremel tool and the 1" saw blade.  I rigged it up with a table so
I could get accurate straight cuts.  It is incredible; far better
than trying to strip out wood with a blade and ruler; especially
on 1/16 and 1/8 stuff.  I would like to build another one, this
time using a 2" blade that I saw in the hardware store and a
fractional horsepower motor.  The one I have now uses an old
dremel tool and boggs down quickly past 3/16 balsa. The next one
will do better.  Burned a lot of midnight oil figuring out how to
get everything straight and true!

The other tool is going to be the basis for the new saw above.
Right now its a 1/12 horsepower motor with a 5" sanding disk on
the front.  Again, I'm taking great pains to be sure that the
disk and table are at exact right angles to another, and that
its all true.  Later, I'll build the table saw above the motor
with the blade running off a pulley on the disk shaft.

I haven't used the disk sander yet, but it will be great for
fitting pieces, such as making the sides of bulkheads perfectly
true and square (the real secret of making a square fuse).  Also,
for fitting stick and stringer construction for old timers and
the small models that I dearly love.  The disk sander, if I
succeed in making it as true as I want, will also sand the stack
of ribs as i described earlier.

These things make prekitting a model a lot easier, and, I think,
really make the process of scratchbuilding very comparable to
doing a kit.

Of course, all models REkit in the same fashion...

    
    Does anyone have a formula for determining the Volume of a wing,
    any wing?  Something generic that can be used to corellate one
    wings size with a larger or smaller wing?
    
    
    Thank's in advance...
    
    
    Tom

    (The surface area of the root chord + the surface area of the tip chord) 
    divided by 2 times the wingspan.
    
    This is the same as finding the volume of a cylinder or conic section.
    The real problem is calculating the area of the chords.
    
    I would think that most of the interesting effects of the wing would
    deal with the maximum thickness (which affects drag) and the surface
    area (which affects wing loading). The areas of these sections end up
    being rectangles (or trapizoids in the worst case)
    
    (large end + small end) / 2 * overall length gives you the area of each

You say you weren't too busy yesterday afternoon Kay?

Francis Reynolds in Model Builder's Model Design and Technical
Stuff column is a big proponent of wing volume as a model design
tool.  His first articles, about a year and a half ago, addressed
the topic, which has been making its rounds among the various
columnists since.  The formulas given and the method of
calculating wing volume were quite a bit simpler than the ones in
the previous notes.  Anyway, check into these back issues for
some more info.

    The disk hates it when Kay gets bored ;^)
    
    If it is truely simpler that previous stated, it would be worthwhile
    posting it here once somebody finds the appropriate issue. It wouldn't
    be hard to write a little .com file that prompts for parameters and
    spits out a value...

>>Ohhhhhhhhhhh 1 bottles of beer in the wing 
>>             1 bottles of beer
>>             take one down and pass it around
>>             0 bottles of beer
>>
>>Bet you didn't think I would go all the way.

Bet'cha didn't fig-gur I'd wanna keep tabs on my boozed out fren's, huh?

Ah' don' dwink beer, but ah knows its "1 bottle of beer" and not "1 bottleS..."
But ya wuz drunk to excess, but ah'll forgive ya, since the Good Lord,
who is the biggest name in the forgiving business worldwide, hath said it is
a good idea.

I don't post 517 line notes - at least not computer generated prose.

:-)

>>Here's wishing Al Casey well tomorrow in the eye surgery.
>>Kay R. Fisher  |

Heyy! Now there's a sober thought! A toast to Al's future X-ray  vision,
folks...

ajai