Schweizer 1-26E ~ 1/2.5-scale Kit by Peter Goldsmith (Build thread by JimD)

[JimD]

The fuselage is constant width from former F3 through former F6.

We begin the fuselage construction by gluing formers F3, F4, F5, and F6 perpendicular to one of the fuselage sides.







Here you go TJ, the anti-rotation dowel was used to center the F24 plywood reinforcing ring over the hole in the fuselage side.

[JimD]

We opted for the use of a slow set epoxy to glue these formers in place. Once the epoxy had cured, it was time to add the other side. We placed side two on the workbench surface and brought side one with its attached formers F3, F4, F5, and F6 down against side two. Again, triangles were used to check for perpendicular aligned of the formers with the fuselage sides.



The fuselage tapers aft of former F6 and forward of former F3. These formers tend to bend when you pull the fuselage sides together, so sections of the 1/4" x 3/8" spruce stick were added in front of former F6 and reinforcing ring F24 was added using the dowel rod for centering the holes.



With the fuselage side against the bench, we dropped the wing rod tube through the fuselage and marked it. With the point of the pen at the surface, we simple spin the tube and get a nice line drawn around it.





We used thin CA to harden the cardboard tube before cutting it to length.



A good way to get a straight cut through the tube is to start the cut and then rotate the tube through the blade.



And now the wing tube is ready to install.

[JimD]

Diagonal braces are added to the interior cockpit area. WE also added a piece of scrap wood as a support for the rudder servo tray assembly. Makes it easier to position when gluing servo tray into the fuselage.



Plywood servo tray parts are laminated together.



We want to use a Spektrum A6265 servo for the rudder, so the hole in the tray needed to be enlarged.









Tray mounted into fuselage.

[JimD]

Two other sub-assemblies need to be made before pulling the fuselage sides together in the front and back.



The F19 pieces need to be laminated together and the elevator servo tray needs to be assembled.



The holes in F19 need to be enlarged to 7/32" so the 8-32 T-nuts will press in.



I like to use my smal vise to press the T-nuts into the wood.





Epoxy with West Systems 404 filler is applied to keep the T-nuts secure in place.



The elevator servo tray is installed while it is easy to access the inside of the fuselage side.

[JimD]

Several other things need to be done before proceeding with installing the rest of the bulkheads.

Because of the fairly severe curve of the fuselage nose, cuts are made in the spruce stringers to ease the ability to bend. We made cuts every 1-1/2" between F3 and F2 and then every inch between F2 and F1.



As we mentioned earlier, F2 is under stress caused by the bending of the fuselage sides around this former. 1/4" x 3/8" spruce cross members were added to strengthen it.





The rear of the fuselage sides needs to have the spruce stringers tapered so as to allow the sides to come together to match the width of part F20.

[JimD]

We made a fuselage building stand with bricks and sticks. Then we dry fit parts and checked to straight and level before gluing anything.

[JimD]

The stab mounting plate F19 is located between F12 and F13. It fits between these two formers and the fuselage sides in a way that helps align things. We did a dry fit and clamped the aft fuselage parts together until we were sure that the fuselage was straight down the midline.

The fin mounting plate F21 is located between F11 and F12 and sits on top of the fuselage sides. There is a slot in the back of F21 that the fin tail post goes down through. There is another slotted plate, F22, that fits underneath this top one and it fits up against F12.



We added a stick across the fuselage behind F11 to support the front edge of the fin mounting plate F21.





With these mounting plate in place, the shape of the fuselage is now set. The rest of the formers between F6 and F11 were added.



Three stringers run from F3 to F11. The top stringer is 1/4" x 3/8" and is just long enough to reach all the way from front to back. The two side stringers are 1/4" x 1/4" and are just about an inch too short to reach. There is a change is contour at F5, so we elected to place our scarf joint at this position.

[JimD]

With the top stringers added, we checked to see that our fuselage was still level front and back (no twist).









Weights and clamps are placed to hold everything straight and level while the glue sets.

[Vic Shaw]

Are you removing the charring from the laser cutting before glueing joints?

[JimD]

Yes and no...mostly the parts do not have what I would call charred edges. Peter sets his laser to just have enough power to cut through the parts. This produces more of a toasted or brownish edge.

The parts have little tags on them that hold them in the sheet from which they are cut. I always lightly sand the edges of the parts to remove these tags and in the process I remove some of the toasted edge. What I am doing is more to true up the parts rather than to sand down to a bare wood surface.

This build has used almost no CA adhesive. The Deluxe Materials Speed Bond and Aliphatic Wood Glue both seem to penetrate the edges of the wood in spite of the toasted edges.

If a part has really burned black carbon edges, I will clean that off with more aggressive sanding.

[ARUP]

Very nice work, Jim! Only thing... where are the shop inspectors?

[JimD]

Those guys were on winter break!

[Tango Juliet]

Where's the "Love" button?

[gunny11]

Wow, fantastic build! You really are into this build. Nice that Peter engraved you beta build kit with your name.
Sweet!

i guess the cat inspectors got tired of you fast pace. Lol

[ErichS]

How many days before Spring Cumberland?? Go Jim Go

[JimD]

Okay Erich, here is what you have been waiting for!

This 1-26 build is the #2 kit after Peter's #1 prototype kit and it is the first to have the Scale Tow Release mechanism installed.

The exact way this will work is not totally known, so we are basically making this up as we go!

Peter modified formers F1 and F2 by adding notches for parts F24 and F25 to fit into, and fabricated the plywood mounts F24 and F25. These mounts are three pieces laminated together to get the correct thickness



The release is attached between F1 and F2.



Then this assembly is installed as a unit into the airframe. We noted that F2 positions 1/8" behind the scribe lines for its placement on the fuselage sides.



Rubber bands were very helpful in holding the fuselage sides together. Next, the bottom fuselage spines that hold the wheel were added, but had to be modified to fit around the tow release.





Axle doubler added.

[JimD]

We boxed in the tow release mechanism



With all of the stringers in place and the F17 spines, the bottom plywood wheel well planking was added.



We discovered that the mechanism is not in the perfect position, so we used a milling file to improve upon things.





Yes, we have no bananas!!!

[Swiss1]

Jim, I was about to say that maybe your side former's of the tow hook assembly should be curved to follow the keel! Just thought I would share the assembly I made for the Musger, from drawings that Tom Pack provided. I no longer have the pictures after the fire at the shop, but see page 36 here.

http://www.rcsoaringdigest.com/pdfs/RCSD-2013/RCSD-2013-08.pdf

Jeremy

SCCAAA TT TN

[JimD]

Jeremy, I had these keel pieces from the non-scale release parts and decided it was easy to use them. After filing the sharp edges off of the release mechanism, I plan to add a strip to the keel parts and sand it to follow the contour of the release more closely. Stay tuned!