I have near perfect, "suberb" glider wings. Lots of time and a unique tool,
a snow picket, made it possible.
Snow pickets are extruded aluminum "T" bars either 2 or 3 feet in length.
They are pounded into snow to protect snow and ice climbers so they're
light-weight and extremely sturdy because climbers trust their life to them.
Snow pickets are also perfectly straight, making them the perfect sanding
block. I glued ever finer sanding paper to the bottoms. I used the
three-foot T-bar mostly so I'd get not waves. When I got done there were no
imperfections. I checked the wings often in the dark using a flashlight or
a laser beam to determine the "light-rise" was consistent. As you lift the
light source up over an edge, the light-to-shadow line will show all
imperfections. The laser lifted over an edge will give the final
inspection.
It takes lots of time and patience.
Watch the "spindrift" (let's keep the snow picket comfortable with a
compatible vocabulary because you've got to make friends with this tool
because you'll be using it a lot) as you work the snow picket. You'll see
where the low points are by the absence of "spindrift" as the snow picket
slides back and forth going from front to back of the wing sweeping at a 45
degree angle. Move your grip from edge to middle to other edge on the snow
fence as you sand. This will allow the power of random numbers "float" the
snow picket making the surface superbly smooth. Hours of concentration
watching the "spindrift" was the most challenging task I had in the entire
build. I took it as a challenge to mental discipline to keep full, alert
attention without lapses for hour upon hour. It's hard to believe but once
you get clear into it it becomes very satisfying to see such a suburb finish
produced by hand.
I had trouble not seeking perfection on my build. I sometimes put a
"moustache on the Mona Lisa" by trying to make the "excellent" into
"perfect." Perfection is nearly always demonic. I finally settled on
"superb" and operationally defined it as every station on N128HW has to be
within 1/2 of a centimeter of where it theoretically belonged or I'd rebuild
or modify. But when it came to the wing surface I went all out: The
three-foot snow picket and lots of elbow-grease will give you a finish that
is beyond what you could even hope for...damn near perfection.
Snow pickets can be bought at
http://store.thebackcountry.net/cart/product.php?productid=18174
for $18 or $20 US for the two or three footer respectively.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Jack Hilditch
Sent: Tuesday, November 21, 2006 5:01 AM
Subject: RE: Europa-List: To Those That Have Sanded Before Me... :)
Fred,
The serration direction is immaterial as it will eventually be faired in by
a thin, flat, surfacing coat. This resin/filler application technique is
used to visually identify low areas during initial filling and sanding
steps. As I mentioned, it also provide a better keying surface for
succeeding coats. Using a 'long board', rather than a block sander, for
initial fairing helps to prevent the creation of additional low areas
through spot sanding. It spans existing low spots by resting on higher
surfaces around the depression thereby bringing the low spot into fair.
Regards,
Jack
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Fred Klein
Sent: Monday, November 20, 2006 3:19 PM
Subject: Re: Europa-List: To Those That Have Sanded Before Me... :)
Jack,
As I visualize this technique, I take it that the strokes of the
serrated screed are chordwise (rather than spanwise) in order to
facilitate the maintaining of the airfoil.
Please confirm.
Fred
A194
> Jack Hilditch wrote:
>
>> Composite racing sailboat builders use a technique that produces a
>> fair surface, without bumps or valleys, while minimizing weight or
>> extra filler. They screed the filler/resin mix onto the surface using
>> a small-toothed, serrated plastic trowel (the same kind used to apply
>> ceramic tile cement to walls).
--
9:20 PM
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