What a friend gave me.

Nice Viper repairs. I have one NIB, never had the time to fly it.

For Cox planes, there are several products available that will chemically weld the polystyrene plastic very effectively. They are not glues in the ordinary sense, like Testors, but are actually very thin solvents that wick into the cracks and joints and melt the plastic, thereby fusing it back together. It is a cold weld process.

The most available is a product called Plastex, which comes in a kit with the Acrylic Monomer solvent, plastic dust ( for filling gaps and reinforcing), and a piece of rubberized molding material that can be heated and softened in hot water and then pressed over the part you want to duplicate and make a mold. The kits come with a variety of the plastic powder: clear, white, and dark grey, which has glass and carbon fibers in it to make it more structural.

For clean breaks and cracks, you can simply clean the part and then apply the solvent, allowing it to wick into the break by capillary action. It helps to tape the pieces together so they will not move. It takes several hours for it to set up, overnight for a full cure. If the break need reinforcement, you can saturate a piece of glass cloth or fiber mesh with a mixture of the desired plastic powder and solvent and apply it to the break after abrading the surfaces for better adhesion.

Another product you can buy from a chemical supply is called Methylene Chloride. It is a solvent for polycarbonate plastics (lexan) ABS ( a styrene ) and polystyrene plastic. Again, it is not a glue, it is a solvent that melts and fuses the two broken pieces back together. So, the joint must be clean and fit as closely together as possible with no gaps.

For missing pieces, or filling holes that are stripped, the Plastex powders are used. The rubber material from Plastex is heated in hot water and pressed over and around a good part to make an impression/ mold of it. After it has cooled the mold is removed and filled with the desired plastic powder and solvent to make a soft paste. Solvent is applied to the edges of the original part that has a missing piece, and then the mold placed over the part that has the missing section and allowed to cure for several hours before removing the mold.

I have a PT-19 that split the fuselage on top from the engine mount to about an inch behind the rear cockpit. It also broke the plastic in front of the cylinder. I used the solvent to repair it, and reinforced the underside of the section in front of the cylinder with glass cloth and the grey fiber plastic powder. It has held for years now and had many more crashes and flights.

BTW, Testors plastic cement does contain acrylic monomer and methylene chloride, but in very small percentages and it is also mixed in with a thickening agent to make it easy to apply to surfaces without running. But, it will not penetrate cracks very well, and has limited ability to penetrate and full dissolve the plastic, so it is not as strong structurally.

Hope That Helps, as back in the old days, we could never find any adhesive that would fix a broken Cox plane effectively.

Jay