Introduction and Education
Not much can be said about chapters 1 to 3. Chapter 1 is the introduction and licensing information for the plans. Chapter 2 is a bill of materials, as well as foam layouts. Chapter 3 is the most important with a lot of "how to" information. I keep finding new stuff in this chapter that I seem to miss or forget over time, but Nat reminds you to re-read this chapter over and over again. At some point after I finish I might remember it all, it seems it takes just one complete goof up to plant it solidly in your mind.
One of the first things that you need to do is to build a jig table. This took the better part of a day to do. But I built it according to plans (yes even that is included in the book!). So now I have this huge table laying upside down in my garage. Beverly (now just 5 months pregnant) helps me rotate it onto it's side. This thing is seriously heavy!!! Now how to get it upright??? I could have used three strong friends to do this. But then it comes to me, I lift one end of the table and Beverly pushes a 5 gallon bucket of epoxy under, and I set it on that. Then on the other end we use an old cooler (ice chest). We continue end to end until the thing it about 36" off the ground. Then with one giant push from the side, it rolls onto the floor making a loud bang as the legs hit, it was up!!!
Measuring the Goo
Everyone has a favorite method to measure the sticky goo. If you like to waste time and money, use the Rutan measuring scale shown in Chapter 3. It is sure to fluster even the most even tempered person...But it works! I looked at the sticky stuff dispenser and thought that was too pricey for my budget when I started. So I ran down to Staples and purchase a digital scale for postage. It was close to $40 with tax. Then I cruised on over to my local boating supply store and bought some epoxy pumps for dispensing Epiglass $8.00. Then I hopped over to Lowes and bought two 1 gallon metal containers ($2). The setup is simple, pour a gallon of resin and hardener in each container, place the pumps...and you are ready for action (almost). Because the epoxy mixes by weight, you have to calculate the ratios, I use Aeropoxy (PTMW) the ratios are easily calculated with simple division (if you can't do this, give up now!). I keep a chart (written on my jig table in permanent marker) with all applicable ratios to make from .6 oz to 6 oz. One full stroke of the resin pump delivers about 1 oz, the hardener is delivered at .2 oz per stroke, which is very close to perfect! But ALWAYS WEIGH THE EPOXY!! The biggest problem with this method is that when you work, epoxy is all over your gloves (or hands), so you tend to leave traces on the scale, which build up over time. This isn't a problem with the scale since it has an auto tare feature but the button that turns the scale on stopped working on me (epoxied in the off position). At one point I disassembled the scale and cleaned the button, it worked fine again. Another advantage to using the gallon containers is they are very compact and easily heated. Heating makes the epoxy a little less viscuous and helps makes your layups a little lighter. Most people build tiny insulated boxes with a low wattage light bulb to keep the epoxy at temperature. If I had to do it over, I would probably go ahead and get the sticky stuff dispenser, it is just plain easier to use and fill. But since I am so far into this I will keep doing the same old thing. I also use bathroom disposable cups when making small batches of epoxy, micro, and flox. These are great because they are inexpensive and unwaxed! In general they are single use, so if you need to make two batches of goo, use two cups they are too fragile to stand up to overuse.
Several methods are used to cut foam, depending on the type of foam. The most simple is a utility knife and straight edge. You simply mark the foam where you want to cut and cut it! Marking the foam can be simple too, I use two different pens to mark the foam. The first is a roller ball ink pen (not ball point!), I use it to mark the more dense foams. The second is a sharpie felt tip (used on soft foams like urethane). The marks it leaves are wide so be careful when cutting!! Another method used for airfoils is a hotwire saw. The saw is nothing but a piece of stainless steel wire strung tight and heated by running a small electric current through it. I used a simple setup using two battery chargers, which was not only inexpensive (since I already had one) but effective. The essential key to cutting is not too hot, not too fast, not too slow. It is a lot to control and while I believe that perfect cores can be cut with this method, most will have some flaws. My suggestion is to start with something easy...like winglets. I found that cutting winglet cores was very easy compared to the wings. Another method that I use to cut very dense foam is a scroll saw (I tried a sabre saw, but it was too difficult to control).
Micro..the other white glue
Micro beads are nothing more than very tiny hollow spheres (I think a bead can actually pass under the head of a hard drive!). They are mixed in with the epoxy in varying amounts to create a Non-Structural filler. When mixed as a slurry (my son thinks it is elmers) it is used to coat foam surfaces before glassing to eliminate air bubbles and help adhesion of the glass. Wet and dry micro (more like bread dough) will be used to fill divets and hold larger blocks (like wing pieces) together. It seems that you can never have enough of this stuff on hand...Order it in large quantities! I keep it in inexpensive rubbermaid containers to make sure that it is free from moisture.
Flox? Is that a word?
Flox is epoxy mixed with flocked cotton. It has the consistency of paste, and is used a structural filler. A gallon of flocked cotton seems to make quite a bit of of flox. I only keep one gallon of this stuff around.
Defects, Boo Boos, and Oops
No matter how much care and preperation one takes, no matter how many times you go over your layups there will always be an occasional mess-up. For some of us, there are many more than others, but don't let that get you down! Almost everything can be repaired, patience and time are that are needed to fix what may seem like the biggest blunders. More glass, foam, and micro can fix almost anything! But not always, there may be times when it is better to scap the piece and start over...This happened to me on a winglet!
Nail it together??
It would seem that Nat likes to hold things together with nails, and I have to say it works quite well! But make sure that you have a supply of nails available in different sizes. I most frequently (and like the most) 1 1/2" brads. They leave small holes, and if ever one gets stuck and won't come out, it can be tapped in with a punch and hammer and become a permanent member of the airplane (note: only 2 to date have been entombed!).