Building a Sig Kadet Senior
A beginner's first model airplane
The specs are as follows:
Recommended Engines:
.29-.40 cu. in. 2-Stroke
.35-.45 cu. in. 4-Stroke
Wingspan: 78 in.
Wing Area: 1150 sq. in.
Weight: 6 lbs.
Wing Loading: 12 oz./sq. ft.
Length: 62 in.
Radio Required: 3-Channel (elev,rud,thro)
This is my Sig Kadet Senior that I built as my first plane. The following will show step by step photos of the construction of this model with some of my personal tips that you may find useful.
Shown above is the construction of the right wing. I found a ceiling tile to work well as a good flat building surface. The surface is sturdy enough for the construction, but is porous enough for T-pins to stick easily into it as well. It should be mentioned that it is important for the tile to be placed on a flat surface or you may end up with warped wing.
If you didn't notice, I already discovered wax paper much more cooperative to work with than plastic wrap. The pliers were used to pull stuborn T-pins out. All of the ribs, spars, and web spars were glued using a good thin CA. The spar doublers were glued using 6 minute epoxy.
Here the wing half has been completed and the T-pins have all been pulled. The wing half was loosened from the wax paper which by the way, protects the plans from glue sticking to them. All the T-pins were able to be reused by pulling them straight out firmly with the pliers.
Shown here is the left wing half after it has been constructed. The wing halves are now ready to be glued together with epoxy.
Gluing the wing halves together as I soon came to realize, was one of the most critical steps in completing the wing. Shown here are the wing halves placed together with the right one propped up so that the root ribs and spars were flush with one another. This was done to make sure the dihedral would be correct when I was ready to glue the two halves together. I had to work fast because I decided to use 15 min. epoxy. After gluing the wing halves together, the plywood doublers or "dihedral braces" were glued in place. I might add the reason I used 15 minute epoxy was simple, I didn't want to stand holding two wing halves together for 30 minutes while the glue set up. I did use clothes pins to help hold the root ribs together, but I still firmly pressed the halves together till the glue was set enough to hold on its own. This being my first plane, I decided to play it safe! WOW, what a relief that was when it finally was done. One thing for sure about epoxy...it's final!!
The next step was gluing the center balsa sheeting in place to the bottom as well as the top as seen in the next photo.
The basic wing has been completed and is ready to be sanded smooth.
The biggest trick to a stick type fuselage, is to get the two fuse halves identical. The best way to do this is by building the second one right on top of the first with wax paper separating the two. This makes for a fuselage that is straight and symmetrical when you bridge the two fuse halves.
Make sure the two fuse halves are perfectly perpendicular before you start gluing in the crosspieces.
After the crosspieces have been glued in place, balsa sheeting is then glued to the bottom of the cabin area for stability and also will be the bottom of the compartment for the receiver, battery and servo tray.
It was at this juncture that I made another decision to alter the firewall by cutting 1/4 in. off the top edge so the engine muffler would clear the cheeks of the plane. It was purely a cosmetic decision on my part. It should be noted that the plans make no suggestions on building a hatch to gain access to the fuel tank. I built a slide out removeable gate directly behind the tank.
Here the photo shows that the firewall, formers and stringers have been glued in place enclosing the 12 oz fuel tank.
Balsa sheeting is now glued over the stringers as well as the sides. The cheeks have also been glued on and sanded into shape.
The plane comes with a plastic windshield and side windows, but I made the decision to use light balsa sheeting in it's place. Shown here is the windshield being implimented. The trick here was to soak the balsa sheeting with a wet sponge and rubber band it around a 2 liter bottle until dry. This helped tremendously when gluing it into place. I used "micro fill" to fill the cracks around the windshield at the front edge so I could blend it into the fuse surface. There was a lot of fine sanding done so that when the monocoat was applied, there would be no seams showing through.
Here is a photo of the horizontal stabilizer and elevator being built. Pretty straight forward construction with the use of thin CA. As you can see, I did build the elevator while the horizontal stab was still pinned in place. This was done to make sure the edges all lined up perfectly.
The same was also done here with the vertical stabalizer. The rudder was built while the vertical stab was pinned down.
In this photo I decided it was time to check to see how this thing was looking. The engine cleared the cheeks and the landing gear went into place fine. The reason the wing was placed on was to see how the windshield fillet or "cap" as I call it, lined up with the windshield. A lot of fine sanding was done here so the contour would be smooth and even. Be sure to do a good fine sanding of the entire plane and use a tack cloth to remove all the sawdust before you cover the model.
WOW!, Its starting to look like a airplane....
Since this was my first covering job, I don't have much to offer as far as sound advice. I would however say that covering the vertical and horizontal stabalizer BEFORE gluing them to the fuselage, is much easier than covering them after they have been glued in place.
Well here is the plane after the covering had been completed and all the hardware connected. Now it is ready to fuel up and fly! As it turned out, The plane flew great. There are a couple things I might add. This plane is tail heavy, so you will most likely have to add some weight to the nose. Also the Kadet Senior as well as the Seniorita need a little down elevator trimmed into them.
My Kadet Senior has had fourty some flights now and I find that it is still a great plane to fly even after you have learned the basics.
Good luck building your first plane. I hope this page helped give you some insight from a beginner, to a beginner.
Chas Noble
You can e-mail your questions, comments or best joke you have heard to: chasnoble@ncn.net
