Mark Scrivener's Build Log

THIS IS MARK SCRIVENER'S BUILD LOG FOR A 1-23 1:4 SCALE

Getting Started

Hello Everyone and welcome to my build log. Even though I only picked up my kit two days ago, my build started over a week back - with the construction of a new workbench. The laws of workshops state:

1. You can never have too much workbench space
2. Any newly created bench space will be immediately occupied by a new project.

And so it has been in my shop. Despite having ample bench space, it was all occupied. So I built a new bench - and now it is occupied with my 1-23 build! Since others might be in a similar predicament regarding bench space, I thought I'd start with how I built my bench. Now there are only 3 rules concerning workbenches. A workbench can never be 1) too big, 2) too sturdy, or 3) too inexpensive. With that in mind, I took a trip to the lumber yard and picked up some kiln dried 2x4's and some 4x4. Don't get the supper cheap 2x4's from your home improvement store as they are typically wet and will warp. Go to a good lumber yard, pay for the dried stuff, and pick through the pile to find straight boards. Here is my framework after building and painting:

The paint is just leftover house paint and helps keep moisture out (to prevent warping). The board leaning in front of the bench is a hollow core door - 80"x36"x13/8" - which cost all of $23 from the local home improvement store and will function as the bench top. The door is very flat (check with a large straight edge before purchasing) and just big enough for this project. As you can see, this bench also serves as a garage for my son's soapbox derby car! Here is the bench with the top in place:

The next task is to top the bench with a surface that will accept pins. Cork is the traditional choice, but the only cork I could find was extremely thin and would have cost $50 to cover the entire surface. Acoustic ceiling tiles are cheap and hold pins well. The pin holes don't "heal" like cork does, but at only a few dollars to cover the bench, who cares! I use the back side as my work surface. The tiles come in 2'x2' and 2'x4'. A utility knife and a straight edge work fine for cutting to size. I probably could have used one more tile for the corner, but since nothing was going to be built in this corner I decided to leave it...

And here is the wing plan on the bench. As you can see, 80" is just enough to build a wing. The portion overhanging is not part of the build layout.

 

Bench done. Now to build a sailplane!

Building the rudder

I decided to start with the rudder since it is a relatively simple piece and it is nice to get a sense of accomplishment early in the project. The rudder consists of a leading edge spar (R1), trailing edge (R2), ribs (R3-R10), and a user supplied balsa block for the top. In reviewing the plans I discovered 2 minor errors that Tom is correcting for future kits.

1. R2 bisects rib R10. I solved this by removing the middle section of R10. The photo below should make this clear.
2. Ribs R3-R7 are not as wide as spar R1. My plan is to make small filler pieces so the sheeting material will contact the ribs.

Again, Tom has already corrected both these issues - so future builders need not worry.

Here is the "new" R10 rib ready to glue into position:

And here is the rudder pinned up and glued. Note the "bottom" half of R10 is lying on the plans, it will be glued later. Also note the vertical fin is already underway...

Note on the vertical that V14 (the ply sheet at the bottom of the fin) protrudes slightly below the bottom rib and beyond the rear spar. I  think Tom originally intended the rib above V14 to be slotted, hence the slightly over sized part. This will be easily corrected on the belt sander.

And here are the vertical fin and rudder with the balsa top blocks attached. The blue tape on the rudder is holding the other half of R10 in place while the glue dries.

Note V14 has now been sanded smooth. I also sanded R2 (the trailing edge ply piece on the rudder) level with the top rib. This gave me a flat surface to mount the top balsa block.

Once this is all dry, I'll sand the top blocks to shape and widen the ribs as noted above. The only thing left at that point will be installing the hinges before sheeting. The spars are drilled for pin hinges, but I haven't decided what I'll use. I have been considering using flat/slot hinges (like in the photo above) and adding small balsa blocks to provide a mounting structure. The nice thing about these hinges is you can easily remove them by pulling a pin. However, Tom pointed out Robart (maker of the pin hinges) has "pin hinge pockets" that allow removal of the control surface. I plan to order some of these and see what I like best.

So after sanding the top to shape, I'll place the vertical aside until the hinge parts arrive and work on the horizontal.

-Mark

Hinges and Sheets

The time had come to make a decision on hinges. Since the hinge pockets required to make the hinge pins removable had still not arrived, and since I had a nice bag of Dubro nylon hinges "suitable for 1/4 scale" (printed on the bag), I decided the Dubro hinges were in. Obviously this would require slotting the parts to accept the hinges, and building some type of reinforcement to insure the hinges had a secure mounting. The first problem was easily solved by using a motorized hinge slot cutting machine - aka the "Slot Machine" by Great Planes. If you don't have one of these, get one. It could be the best $20 tool purchase you will make. BTW - if you go this route, you will also need the optional thicker cutting blades for nylon hinges (another $3.50).

I added small pieces of balsa behind S1 and E1, essentially making them "thicker" to accept the hinges. The same concept was applied to the vertical tail. Here is the horizontal tail after hinging:

Plenty of elevator travel!

With both tail surfaces hinged, the only task that remained was sheeting. First step was to make sure all trailing edges were sanded to a fine edge (includes rudder), leading edges were rounded, and there were no bumps, dips, or irregularities with the ribs. I wanted to make sure the sheeting material was going to make solid contact with the structure at all points. So.....out came the sanding block again, along with a straight edge, and all surfaces were closely inspected. Once complete, it was time to sheet!

There are numerous ways to apply sheeting - but here is one of my favorites. After cutting the sheeting material to size, apply wood glue to both surfaces with a brush and allow to partially dry. Typically 30 min works well, but actual time may vary due to temperature and humidity. You simply want the glue to be reasonably dry to the touch. If there are still a few wet areas, that is OK. Now lay the sheeting in place and use your covering iron (set at about 125 deg C) to press the sheeting down on the structure. The heat will activate the glue and bond the sheeting in place. You may have to hold the sheeting down for a min while the glue cools before it holds, but usually the bond is near instant. This saves the trouble of trying to insure the sheeting is in firm contact with all the structure while the glue is drying.

Here is the stabilizer with the first piece of sheeting ready to go:

And here is the current state of affairs. Notice the blue tape on the tips of the horizontal stab. Initially there wasn't enough glue to close the sheeting at the tips, so I added more glue and taped the sheets together until dry. The elevator is done, as is the rudder. Still need to sand the horizontal, and need some more ply for the vertical. But at last - this "tail" is nearly complete. Only a fuse and two wings to go!

-Mark

Building a Scale Tow Release

Every Schweizer sailplane I’ve seen has a distinctive tow release under the nose. The latch is unique in that it will automatically release should the sailplane pass the tow plane. Looking at these photos (both 1-23’s) it should be fairly obvious how the release works:

 

 

 

 Tom’s plans show the common commercial release available to modelers installed in the nose. This is a good functional release, inexpensive and easy to install – and since Schweizer’s have a hole in the nose for the pitot static, it doesn’t detract from the scale appearance. But this just didn’t seem right to me, so I decided to build a scale release…

 

The first task was to scale the photo above for use as a 1:4 scale template. I knew the overall length of the “hook” was about 4” – so I scaled the photo to yield a 1” long hook when printed on plain paper. I then physically cut the hook out of the printed image and laid it on a piece of 1/8” Al as a template. A bench vice, hacksaw and a file were then used to cut the hook. A Dremel with a drum sander bit was used for final clean up.

 

The full scale hook mates with a square hole in the catch piece. Since milling a tiny square hole would be a chore, I decided to machine a round pin on the end of my hook and drill a matching hole in the catch piece. Now there are 3 ways you can do this:

 

1. Drill a hole in the hook and insert/epoxy a short piece of wire as the pin.
2. File the end round to make the pin
3. Place the piece in a 4-jaw chuck on a lathe and machine the end round.

 

I chouse option #3, but any of the above would do fine. The catch piece was made from 1/8” Al.

 

To hold these items in place I needed side plates that would make a sandwich with the center keel (F18). In retrospect I should have made these from brass (1/16” or possibly thinner). Brass would have provided a better bearing surface – Aluminum to Aluminum surfaces can gall and bind if not properly designed. That said, I made side plates out of 1/8” Al and was careful to round edges and provide clearance to avoid galling and binding issues. A portion of these plates must protrude through the nose tripplers – so I milled that portion down to 1/16” and milled a similar clearance in the tripplers. Using thinner material would have made this portion easier or even unnecessary. The following photos should make everything clear:

 

Basic release mechanism assembled and laid over plans. All hardware is 2-56.

Cutting the center keel for clearance.

Sandwich:

Release in assembled fuse. Side frames were epoxied and bolted. Locktite used on all pivot nuts.

 

The next task was to add a servo to activate the release. After much deliberation, I decided to mount the servo behind the instrument panel and use a cable, run through a loop on F1 to pull the release lever open. A spring from an old transmitter provides return force to close the latch. And here it is:

 

For those wishing to duplicate a catch like this on their build I have good news and great news. The good news is it isn’t that hard and can be done with simple tools. The great news is Tom is looking into having these releases produced to offer with all of his SGS kits.

 

 

 

 

Building the Fuse and installing the Radio gear

With the tow release designed, the next step was to plan out the radio gear placement BEFORE gluing up the fuse. I dry assembled the fuse using clamps, rubber bands and tape to hold things together so I could visualize the gear placement. I used the F5 bulkhead for mounting much of the gear. The ability to remove F5 and cut/drill mounting points proved very handy.

I assembled the fuse over the plans using a long piece of ply as a center line for holding the formers in place. Go slow and use a T-square, straight edge, and any other alignment tools you have on hand to insure the fuse is assembled straight and true. Once you have made any modifications for radio gear/etc and are ready to glue, use a slow drying glue and make sure you have plenty of clamps, rubber bands, and blue tape on hand for holding parts in position.

Pay particular attention to the tail section to insure it is straight, and F25 (the mounting point for the horizontal) is true and square with the fuse. It is also a good idea to place the wing rod in position and insure the wing rod is square with the sides of the fuse. Any potential problems are much easier to correct before the glue dries than after.

I decided to reinforce the area behind the F17 side formers with carbon mat. This should add strength to the wing rod and insure stress from this area is carried through to the bulkheads F5 and F6.

Next I installed the radio gear while I had easy access before adding the 1/8"x3/8" stringers.

Next time we will sheet the fuse.

Sheeting the Fuse

Forming 1/8" balsa to the tight curves of a 1-23 fuse can be challenging. There are basically 2 approaches:

1. Bend the sheets by wetting, applying heat, or both, and working S-L-O-W-L-Y.
2. Cut the sheets into small planks. This reduces the bending but greatly increases the sanding and fitting.

I basically used both techniques - planking the nose section but bending the largest sheets I could get to work everywhere else.

I started with the tail and added small blocks of balsa under F25 to give the sheet something to attach to in this area.

I then started fitting sheets working from the tail forward. I used sheets of typing paper to make templates for cutting the panels. Try to cut the pieces oversize and then sand to fit.

To hold the large sheets in place I used blue tape, rubber bands, velcro straps and anything I could find. Unfortunately as you close the fuse up, traditional clamps become less useful and you have to get creative. The going can get slow here, but just try to do a little every day and it will be completed before you know it.

Here you can see the wiring under the cockpit floor and small blocks that were added so screws, not glue would hold the cockpit floor down (this allows for removal of the floor later on). Glue has been applied and the area is ready to be sheeted:

I decided to leave one section of the lower left nose area open for now so I would have better access for adding ballast and achieving a crude balance once all the wood work was finished. For the same reason I built ply formers for the nose but did not fill in with balsa yet.

And here she is...ready for sanding and filling (minus a small opening for balancing)...If you are sharp there are several other changes you might notice in this photo...but we will cover those next time.

Making Paul Bickle's 1-23E model

Most people associate the 1-23 with Steve McQueen's H model in the movie "The Thomas Crown Affair". However, there is another very important 1-23 you should know - Paul BIckle's "E" model which set 2 world attitude records (max altitude and altitude gained). Only 2 sailplanes have ever gone higher, and neither even came close to Bickle's attitude gained record. I discovered Paul's E model while exploring sailplanes at the Hollister airport in search of a paint scheme for my model. You can read about Paul's flight and see a picture of his plane here.

Once I saw Paul's plane and learned it's history I knew this was the 1-23 model I had to build. Paul's E model was/is a one off - it is even labeled "Experimental", and has some distinct features not seen on the other 1-23 models. They are:

1. Long wings like used on the later "H" models, but the small tail of the early models

2. A fairing that partially encloses the wheel. This plane originally only had a skid with no wheel, so the skid was expanded to become a fairing when the wheel was added.

3. Symmetric dive brakes that cantilever away from the wing surface (the H brakes are smaller under the wing and larger above the wing. Models before the E only had a brake on top of the wing).

4. Wing skids with square wing tips

I decided to include all these features in my build. Since I had already built a H style rudder, I called Mike and he graciously agreed to send me parts for a new rudder. Using the drawings on Tom's plans I cut a early style trailing edge from ply and modified the ribs to produce an early style rudder. This is a very easy mod for anyone wanting to build an A-E variant of the 1-23.

Here is the new trailing edge:

And the new rudder being laid out:

To make the skid/fairing I simply stacked pieces of ply to widen the existing skid slightly, and then added balsa to bring it out to the desired width. I then sanded and used filler to obtain the final shape. To avoid sanding the fuse skin I placed tape on the fuse during sanding. Here you can see the fairing taking shape. Notice the initial stair step as the fairing gets wider to the rear. This will be smoothed out by sanding and filler.

And here it is almost done:

The dive brakes and wing skids will be covered in a future post when we discuss building the wings.

-Mark