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

[Soarntz]

Only 2 weeks till it's going to be ready?

[JimD]

I am still confident, but I hear the tick tock for sure.

[Pgoldsmith]

I’m planning on having mine there...

[gunny11]

That's great! You and Erich need to get pictures of the two Schweizers together... 1-26 and 2-33

[JimD]

Could be two 1-26's and two 2-33's...just say'n

[Sinkhappens86]

Are you not bringing your 2-33 Gunny?

[gunny11]

No, it's just that I'm not bringing me.

[JimD]

We waited until everything else was finished on the fuselage before adding the nose blocks, mainly because of the added weight. The blocks were previously glued to the center spines and rough cut to shape. Then the lead weight was added.

This assembly was glued to the F1 former with slow set epoxy mixed with West Systems 404 filler. Make sure of the alignment before walking away! Vertical is on the centerline and the horizontal is at the bottom edge of the plywood side where it meets F1.







Once the epoxy cured, we carved away as much material as possible with a long knife.

[JimD]

Next, we used 80 grit sandpaper on a sanding block and sanded a flat on each of the four sides, sanding until the charred edge of the plywood spines started to go pale.









Then we added tape to protect the planking as we used the sanding block to bring the nose blocks down to the profile of the fuselage.







Then the tape was removed and sanding to profile was refined.

[kjkavaney]

just an awesome thread....this will help me so much next winter when I build mine...thanks.
kevin

[JimD]

Included semi-scale tailwheel mount pieces.



These mount by straddling the 3/8" spruce stringer that runs down the bottom of the fuselage and touching up against the forward side of the last fuselage former. These are designed to work with the DuBro 1" tail wheel #DUB100TW. In order to set spacing for this wheel, use some of the scrap 1/32" plywood in the kit to make two thicknesses attached as shown.



The hole in the DuBro tail wheel will need to be drilled out with a 7/64" drill bit to accommodate a 4-40 axle bolt. We used a 1-1/2" bolt with a smooth shaft for the axle. This bolt was cut to 7/8" length. Plate washers were used for spacers.





This arrangement will perfectly straddle the 3/8" bottom stringer. Using 3/8" stick for demonstration here.

[Soarntz]

This is very thorough build thread Jim, if one were to print it might take a forest... Hmm, a use for some of those annoying trees out front of Highpoint... They can go to the papermill!

[JimD]

We actually thought of that and had a tree guy come and look at them. Unfortunately, they were too short and bushy. Said by the time all of the branches that are too small in diameter to use are cut away, there is not enough good wood to be worth while.

[Sled-Works 1]

Great build Jim. Thanks.

[JimD]

Time to join the fin and fuselage. First, we slid the wing joiner rod thru the fuselage and attached the horizontal stabilizer. Then the fin was inserted and we checked to see if the stab and wing rod were in line and if the fin looked perpendicular to the stab. Looked fine, so measured just to be sure and it was fine.





We made a "stirrup" out of scrap 1/8" x 1/8" balsa on the F21 fuselage fin base platform to keep the fin in alignment at the base.



The fin wanted to tilt to the left on our initial trial fit, so we added a small piece of 1/32" ply on the left side of the F1 fin base rib at the spar joint.



It still wanted to wobble a bit, so we added another small piece of 1/32" plywood scrap on the right side of the fin post bottom.



Now, between the "stirrup" and the two shims, the fin sits perfectly...time to mix the epoxy! Even though the hole in the top fuselage sheeting had to be cut big enough for the F1 fin base rib to drop sown through, the sheeting was still fairly snug (especially from the spar line back) around the fin. Small strips of scrap balsa wood was inserted to fill the gaps.



Then we finished off with some balsa color filler.

[JimD]

Glue is set and filler is dry, so after a little sanding things look great!

[BryanB]

Is each side of the saddle sufficient for the horizontal stab?

[JimD]

Each side is plywood and the stab center section of the stab is sheeted with plywood, so when screwed together the mount is very sturdy.

[JimD]

We built the left wing first and learned a few things that we used when we built the right wing. For example, the servo bay parts. On the left wing, we laminated these together and then glued them into the space between the ribs. Problem was how to cut out the opening in the wing skin without damaging the inner plywood part.

This time, we glued the first part into the wing...then cut out the skin and sanded the edges smooth...then glued in the second part of the servo tray mount holder. We also discovered that it is much easier to cut the 1/32" plywood skin with a construction grade utility knife than an X-acto knife.

[JimD]

Another issue was gluing the 1/32" plywood sheeting to the 3/8" square balsa leading edge. The way the 3/8" square fits into the ribs, the top sheeting will follow the curve of the rib right down over the 3/8" square no problem...but the bottom is a different story. There is a sharp bend at the front edge of the rib and kinking the 1/32" sheeting onto the 3/8" square leading edge was not easy and posed another challenge when sanding out the leading edge shape.

Our solution was to add a strip of 1/8" x 3/8" balsa to the front lower edge of the 3/8" square balsa leading edge and then, using a razor plane and sanding block, taper it in cross section to follow the curve of the lower rib. Perter has since added this suggestion to the plans and included the 1/8" x 3/8" balsa sticks.

Here you can see the problem and the solution.

[JimD]

Not a problem, sanding the plywood is interesting because as you sand out a taper the glue between the layers appears as stripes. Kind of a handy visual reference.

[JimD]

The first 20 kits were already finished when we came up with this idea, so just adding to the extra stick was the fix. Luckily the plans were not printed yet so the update was added.

Gong forward, Peter is experimenting with rotating the 3/8" square stick so that it aligns with the curve of the bottom of the rib. Then the top of the stick could be shaped as needed. Would be easier to manage sanding and shaping on the top side.

[ARUP]

FWIW- my method is to put a false LE 'normal' to the ~chord (against 'flat nosed' ribs). The 'D' tube sheeting attaches to the ribs and false LE. Then add true LE to be sanded fair to the sheeting.

[JimD]

The wing is easy to build with the lower spar and ribs being glued right onto the lower wing skin. On the first wing, we debated what to do about cutting off the excess wing skin sheeting. After experimenting with the first wing, we concluded that it is much easier if you glue on all the ribs (applying glue to the rib behind the spar but only a short bit in front of the spar. This allows the wing sheeting to remain flat on the workbench surface while all of the ribs get attached.

Next step is to add the top spar. A little hint here...test fit the top spar before gluing. If the spar does not fit down into all of the rib notches so as to be flush with the top of each rib, sand as necessary to make this happen. You will be very glad you took the time to do this now!

Glue in the top spar and add weights on top to keep the wing true while the glue sets.

Make an ink mark on the wing sheeting about 1/8" behind each rib. Use a straight edge to connect these marks into a good straight line for the trailing edge. Use the construction grade utility knife to cut the sheeting along this ink line and remove the excess and cut out the aileron bay.



Moving to the leading edge (and this is before the leading edge 3/8" square balsa is added. Pull the sheeting up to each rib and mark where the front bottom edge contacts the sheeting. Now measure 3/8" out from each of these marks and use a straight edge to draw a straight line. Again, use the utility knife to cut on this line and remove the excess sheeting.







With weights on top of the wing, we pulled the sheeting up to touch the bottom of the ribs and held it there by inserting a 1/4" thick stick underneath and an aluminum L. Each rib is glued and held in place until the glue sets. The 3/8" square balsa leading edge has NOT yet been installed.

Once the ribs are all securely glue to the sheeting, the 3/8" square leading edge is modified as stated above and glued in place. You will need to sand a bit to customize this fit so that the 3/8" square fits neatly into each rib notch. Again, taking the time to do this will make things go much easier later when you sand out the leading edge shape.

[JimD]

A key part of a radio controlled model is the radio. We selected the new Spektrum Power Safe 12-channel Telemetry Receiver and Spektrum HV servos throughout. Now the question is how and where to mount everything. This is what we decided:






And then we added a seat.



And cut the canopy to fit the frame.



...and we did a little painting!