Rebuilding Your Model By James Goss      I think we will all agree that rebuilding your model is not as fun as the first go around. Each rebuild that you do is always different from the previous in some way or another. I have had crashes that I thought would take weeks to rebuild, but when I got started it was not as bad as it looked and would only take a few days to get it back in shape. Other times a simple mishap in landing that should only take a few hours to repair would end up requiring several days to repair. You never know until you get started and check all the structural damage that is hidden from the eye. I guarantee that you will always find some if you look hard enough.        It's funny how some crashes are all clean breaks and others are splintered into hundred of small mangled pieces of balsa. What causes some to splinter so badly and some not to splinter at all? I think the main deciding factors are how well the plane is glued together and if it has proper bracing in key places. If the gluing is strong enough to not let go, then something is going to break elsewhere during a crash. I have found that an inferior glued model may survive a crash with less damage than one that has good glue joints. Of course we need to keep in mind that the crash may have been caused by the poor glue joints in the first place. As an example I will use the crashed plane that I am now working on. This plane went into the ground at full speed and almost at a ninety-degree angle to the ground.           This kind of crash normally produces the most severe damage that can be imagined. The fuselage only took about two hours to repair and the wing about 30 minutes. I could not believe how everything went back together with ease. The rubber bands really saved the wing, just like a weak glue joint giving under stress. The sides of the fuselage had absolutely no damage at all. The firewall had very little glue on it so it gave away immediately on impact and was pushed to the rear about three inches. This is what really saved everything else. Even the fiber engine mount was still in good shape. The breaking loose of the firewall dissipated all of the crash energy. It took about ten minutes to restore the firewall. I do not know who built the plane, but they used ca glue on the firewall and that should never be done. Always use epoxy, or at least I have always thought that you should. A breakaway firewall may not be a bad idea! Have it strong enough to support the engine and then give if it receives a direct blow. This would act like a big shock absorber. We have breakaway engine mounts to protect the engine so why not have a breakaway firewall.      I had much rather have the firewall move back during a crash and still be in one piece than to have it come apart and take out the fuselage sides as well. Mounting the ¼ inch firewall by using epoxy on all sides to anchor it to the fuselage for a .46 size engine may be more than we need anyway. I am sure someone can design a firewall system that will uncouple itself from the fuselage on impact. If nothing else, use nylon bolts of the proper size to strip away and allow the firewall to travel straight back into the fuselage. It is a lot easier to replace a couple of formers than to rebuild the front end of your airplane. We complain about the ARF's not having good glue joints like our homebuilt planes. Could it be that an ARF will survive a crash better because they don't have superior glue joints, who knows? So the next time you build your favorite plane, be sure to use very little glue and if it crashes you may not be saying YEEEEEOOOOOWWWWW!!!