Building the Powerhouse - Society of Antique Modelers

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centered when we add left thrust. Before gluing the firewall in place, it is always a good idea to chase the threads with a 4 x 40 tap to make sure no glue got into the threads. Sal Taibi used to make the tank mounts like the one shown in figure 27, but no longer does. The current SAM rules allow for 15cc of fuel, but the rule cycle is due to be voted on again, and there is a movement to go to 8cc (the size of a stock Cox Texaco tank). It is beneficial to run a tank-mount as shown. It spaces the engine out to the proper location (without it, a spacer will have to be made to get the engine where it needs to be). Getting the engine in the proper location will really help with balancing your model as they almost always come out tail heavy. Cox engines have an o-ring in them that is in the middle of the tank. When the tank is full, the o-ring is submerged in fuel. When it gets down to a half tank, it starts to be surrounded by air. Many times, this will leak and cause your engine to lean and only run ½ the tank and the engine will stop. I bend the landing gear and glue it up between balsa sheet wood. When completed, the sandwiched gear should line up with the fuselage uprights, where it can be secured well (see figure 28). The hood (part that fits behind the engine is formed by wetting a piece of 1/16” balsa and taping it around a cylinder. I used a can of spray paint to wrap mine around, and secured it using masking tape until dry (see figure 29). By Figure 29 the formed hood for the Powerhouse performing this part, it will take the bind out of it for fitting and is much less likely to crack later. I soak the wood in water, but some prefer to add a little ammonia to the water thinking it helps with the bending process. I have had good luck with just using water, and don’t have to smell the ammonia. Either will work. When it is dry, I fit it and glue it to the fuselage. The nose block under the engine can be fit and glued on now using medium balsa. Make sure you can reach all the screws that hold the tank to the firewall. About the last thing to add is the sun visor. After shaping and sanding the nose cowl blow out the dust and fuel proof the inside area. I use slow drying epoxy thinned a little with lacquer thinner. A little thinner goes a long way. I mix and brush it on with an acid brush, being careful not to get any in the blind nuts. It may take a few days to dry. A warm climate or room helps. I then sand this area the best I can and brush on another coat. This makes a shiny and smooth fuel-proof engine area. COVERING WITH POLY SPAN I cover all my gas models with Polyspan as it is light and provides a strong, long-lasting finish. I also like how stable it is. Since it is a polyester base material, it is not affected by moisture like many of the other coverings, like silk, or tissue. Polyspan is excellent and helps you have that consistent model you are looking for, with no surprise warps Figure 28 shows landing gear in place Figure 30 brushing on sanding sealer
showing up. Polyspan has a smooth side and a rougher side, where the fibers stick up. It is very hard to see the difference, but the smooth side is a little shinier, and with careful inspection, you can see the fibers on the rough side. The smooth, shiny side goes out and is the finish side. As of now, the only color that Polyspan comes in is white (natural). To prepare the surfaces to be covered, I make sure all are sanded smooth and are blown clean. I brush on a coat of lacquer sanding sealer (see figure 30) everywhere the covering will contact the structure. That means the top and bottom of ribs, all the perimeters, etc. I finish exclusively with nitrate dope, and have found the lacquer sanding sealer to be compatible. If you plan to use an alternative finish, make sure everything is compatible by making a test panel. After my sanding sealer is dry, I sand all the surfaces with 220-320 grit paper and again blow the surface clean with compressed air. I then add a second coat of sanding sealer and sand it with 320 paper. You will notice the second coat will sand much easier and you will have a very smooth surface. Blow the dust off the structure. There are a few products that can be used to attach the covering to the surface, but I have been using Fab Tac also available from Aircraft Spruce (contact information noted previously in this article). The Super Seam used to glue in the blind nuts works great too. I have found the Fab Tac works just as well as the Super Seam, and is about half the price. Both products need to be thinned a lot using Nitrate thinner to get to brushing consistency. I brush on two coats of thinned Fab Tac over all the areas I used the lacquer sanding sealer on (where the covering will contact the framework). It dries fast, so you will have to work fast. Make sure to let it dry fully between coats. When both coats are dried, I make sure there are no defects in it like a run. If I find a defect, I lightly sand that area, and clean with compressed air. Now, I am ready to cover. I usually start with the bottom of the stab. It is always correct to cover from the bottom to the top on all parts. The flat surfaces are very easy to do. Do not forget the fuzzy side goes towards the frame work, and the smooth side out. Cut your Polyspan larger than the area to be covered. You want extra material to hold onto around the perimeter if heating is necessary to get it smooth. Figure 31 covering on wing tip, note wrinkles Figure 32 covering attached to spar with Acetone Figure 33 covering attached between wrinkles from extra covering
Page 1 and 2: How to Build and Fly the ½ A TEXAC
Page 3 and 4: One of the best things to come alon
Page 5 and 6: Figure 17 trailing edge is notched
Page 7: The front of the cabin, where there
Page 11 and 12: Also, make sure it is attached to t
Page 13 and 14: 233+ to be the best masking tape av
Page 15 and 16: on the Powerhouse is about 3 degree
Page 17: ½ A Texaco Specifications Sheet Cl

Building the Powerhouse - Society of Antique Modelers

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