Quite a few prospective builders have emailed me, asking for a list of materials needed to finish a short kit, or asking how to estimate the materials needed, or asking how to figure out where to start. The short answer is that you need to look at the plan, look at the parts included in the short kit, take note of what is not included in the kit, and figure out the total length of the sheets and sticks needed to make these parts.
Well, that sounds like a pretty short answer, so let’s make it more interesting. We need an example to illustrate the point, so let’s use the Sporty Forty biplane, just because a guy bought one and sent me a photo of the parts all laid out.
Now we need to inspect the plan carefully. A good plan will show all parts to be made by the builder, with each part labeled to indicate the thickness of wood needed. This is why I advise less experienced builders to use a good plan from one of the magazine archives. Back in the good old days the publishers always made sure that their plans were of high quality. Sure, there were plenty of drafting errors, but if you buy a plan from the archive of a reputable magazine you will almost always get all the information you need to place a balsa order. Here’s the Sporty Forty plan.
Sorry if this giant image won’t display properly on your smart phone, but I wanted to make sure you could see the details on the plan. You probably want to sit down at a desk and look at a real computer screen to get the info from your plan when you’re making your bill of materials. Also, try to use software that will allow you to edit the PDF, so you can highlight or mark out everything listed on the plan after it has been counted. Or you can do it the old fashioned way, print your plan and mark it with a yellow highlighter.
The first thing to do is to mark all of the notes on the plan that refer to the pieces that are supplied in the kit. Then move on to everything else.
Start with something simple. This plan shows several sticks to be used in edges and corners. Let’s start with the 1/8 x 1/4 balsa found in the peak of the top fuselage deck in the front and rear sections. About 13 inches for the front and 10 inches for the back will do the trick. Now scan the rest of the plan to find any other instance of that same part being used. OK, now that my eyes are strained I can say with a fair bit of confidence that this is the only instance of 1/8 x 1/4. Write it down on your list, and mark that note on the plan with your yellow highlighter so you won’t count it again later. Now move on to the next size. Let’s say 1/4 x 1/4 balsa. It’s in the lower corners of the aft fuselage, and all along the upper edge of the fuselage side. The lower sticks are about 15.5 inches on each side, and the uppers are 36 inches on each side. So three 36 inch sticks will suffice. Write that on the list and mark the note with your highlighter. Whoa, hold your horses! The plan also shows 1/4 x 1/4 upright sticks in the aft fuselage, totaling about another 15 inches. So mark out the note on the plan, and put another hatch mark next to your 1/4 x 1/4 entry. You’re using hatch marks instead of writing digits, right? That’s the best way to do it. Add a mark when you count another item, and when you finish, just count the hatch marks.
Let’s get into something a bit more esoteric. What about that funny sheeting on the bottom of the fuselage? It appears to not be labeled. But if you print the plan and measure the thickness of the wood, it seems to be 1/8″. Looks like you can get that out of a 4 x 16 inch sheet if you run the grain lengthwise as shown on the plan. If you go crosswise, which makes the structure a little bit stronger, you can get it out of a foot or so. Also, go back to item #1, the 1/8 x 1/4 stick. You can easily strip this stick off of your 1/8 inch sheet that you bought for the top deck and bottom fuselage sheeting. Each side of the front top deck is about 2.5 inches wide, if you measure around the curve. So maybe you want to get 3 inch sheet to save some money, Cut a strip off the edge for the sticks, cut pieces for the front and rear deck, and splice the remainder together for the fuselage bottom. You have to count up all the lengths and widths, and estimate how much area it takes to cover everything, and put it on your list.
The plan shows blocks for the wing tips and the top of the cowl. It shows 1/16 inch sheet for the wing sheeting and cap strips. You’ll need ailerons, which you can make by laminating pieces of trailing edge stock to the correct thickness, or by carving a thick plank, or by building according to the plan with sticks and sheets. This is your project, so you can build it however you want. Decide what you want to do, and add the correct materials to your list.
Keep counting until every note on the plan is marked with the highlighter. At the end, every note on the plan should be marked.
When you get everything listed, compile the list into another list of the sizes that you want to purchase. The plan says 4 inch sheeting for the leading edge of the wings, 2 inches for the trailing edge. So if you buy 4 x 36 inch sheet, you’ll need three pieces for each wing, making a total of six. Throw in an extra piece for the cap strips. You can get the cap strips from a 2 inch wide sheet if you want to save some money. Write this new list on a new piece of paper (or on your computer, or in a new area of your Burger King napkin, or whatever). Now you have a new list that shows full size pieces stocked by your favorite retailer, and you can add up your order. Add one or two extra pieces of each item just in case they send you something that resembles ironwood or marshmallows. They try to stock good quality wood, but nowadays it’s harder to get the best stuff, so sometimes we might be a little bit disappointed if we don’t order a few extras.
That’s pretty much all there is to it. I always say that when you order a short kit, you should think of yourself as a scratch builder who has a friend cutting out all of the annoying little bits that take too long to cut out with a knife. But you’re still the big-brain guy who has to study the plan and figure out what to order. There are two main reasons why I don’t provide you with a list. Number one is that my count will probably be off because most people who build airplanes are going to deviate in some way from the plan. This is a good thing. It’s your project, so build it the way you want it. Reason number two is that because it’s your project my heart isn’t in it, so I’m more likely to zip through the process and make a mistake that will screw you up. My poor little brain is already tired anyway from making all of the parts fit together for the kit. You don’t want to rely on me. If you do it you’ll get better at it every time, and you don’t have to worry about me costing you extra shipping charges by forgetting the ailerons.
If you are ordering a short kit such as the Ultra Sport 60 or the Hot Kanary, which do not include the fin or stabilizer, you’ll have to order sheet wood for these parts. This can be an uncertain proposition, because sometimes you get wood that’s too soft to take the forces you’re going to put on the stabilizer, or way too hard and heavy. Ordering extra pieces is a good strategy, but maybe you don’t have the extra cash. If you don’t order extra, and you get unsuitable wood, you’re in trouble. Here’s a solution to the dilemma. Just go ahead and order the wood. If they send medium grade balsa, use it for the tail as shown on the plan. If they send really hard stuff, cut it into sticks and build your stabilizer with sticks. A little bit of browsing on outerzone will turn up an appropriately sized plane with a stick-built tail for you to use as a reference. Well, you’re still in trouble if they send light fluff, but that’s a lot less likely than getting wood that’s just right or rock hard.
Just about everything you build can be approached this way. You can build a cowl from blocks, planks, sticks and sheet, a bottle heated and pulled over a mold, paper and glue, glass and resin, aluminum sheet, card stock coated with epoxy, or probably a few other ways I haven’t thought of. Ditto for wheel pants. You can build control surfaces from thick sheet, or a thin center sheet with ribs on both sides, or from sticks, or even from thinner sticks with thin sheeting covering both sides. Studying lots of different plans and observing the various construction techniques can be very enlightening. Look at a bunch of plans, and then when you choose one plane to build, try to think of two or three different ways to build each part, and keep your options open. If you approach your building project this way, then when you get your balsa order in the mail you won’t be disappointed no matter what they send you.