F/FSport H
by david mitchell You can reach David Mitchellat 230 Walnut St. NW, Washington, District of Columbia 20012, or via e-mail at
davedge@me.com
i folks! That sound you hear is thunderous applause for Larry Kruse, who is stepping down after three decades as the FM F/F Sport columnist. In his place, you
get...me. It’s an apples-to-oranges trade—the depth and breadth of F/F savvy that Larry brought to the magazine through the years will be impossible for me to equal. So, I’m not going to try! We’re starting from scratch. In addition to showing off your interesting projects and occasionally reporting from my insider’s perch on the Flying Aces Club Coun- cil, I intend for this column to be something of a builder’s “how-to”. We’ll start out exploring the ins and outs of different approaches to the myriad small engineering challenges that a stick and tissue model presents, and let the column grow organically from there. My primary interest is in rubber powered F/F with an emphasis on scale, though I have been known to dive into a sport job and/or an electric from time to time. Given that my flying skills are at best erratic, I’m not going to start dispensing trimming ad- vice any time soon. So that leaves design and construction!
You might well ask, “How much can there be left to discuss in a branch of the hobby that has been basically repeating itself for the past 80 years?” Ha! I counter that you might as well ask what is there left to dis- cuss in philosophy, or music, or art? Bear in mind that most of us have forgotten more than we ever knew, or something like that. And that those who forget the past are doomed to repeat it.
Right, you’re missing Larry already, aren’t you? Never fear, you’ll get used to me. We’re going to get straight into it without further adieu, though I warn you I’m in no hurry, and some topics may stretch on for several columns.
PHOTO: RONNY GOSSELIN Mark Fineman with his Bestetti-Nardi BN-1. Twin fuselages mean twice the fun in building!
So nice you build it twice My friend, Wally Farrell, has decided to build another twin rubber job. Not just any twin, but Mark Fineman’s original twin- fuselage Bestetti-Nardi BN-1 (recently fea- tured in the July 2012 issue of Model Avia- tion). This is a lovely design of an uncommon airplane, and a fine flyer to boot. As a con- struction project it presents a variety of challenges, neatly blending traditional building methods with some more advanced techniques.
The first of these challenges is obvious: you have to build four identical fuselage sides. Gah! As if two weren’t bad enough! When I think identical, I aim for just that.
Heaven knows I have seen plenty of models with wavy fuselages and warped wings fly amazingly well, but nevertheless the objec- tive is four identical sides, to be framed up into two identical fuselages. Whew. Thinking about this gives me pause, and brings to mind Mitchell’s Maxim #1: Sim- plicity is an illusion. Behind every apparent- ly simple achievement there is a reservoir of highly developed, but more or less uncon- sciously applied skills. If you don’t believe me, just try teaching a kid new to modeling to build a “simple” box-and-former fuselage, or even a Guillows half-shell design; you’ll be backpedalling to a Delta Dart faster than you can say Frank Ehling. Me? I’m new to being a columnist, so I think I’ll start with the assumption that revisiting ideas can never hurt. A simple technique to you is someone else’s revelation.
So, about those fuselage sides. Look at the BN-1 plan, and you’ll see that the line of the upper longeron is straight from nose to tail—never mind the break for the wing sad- dle. We can use that as the main reference for beginning our layout. Take a strip of scrap 1⁄16 × 3⁄4-inch balsa with a straight edge, the length of the fuselage, and pin it down securely so that it lines up to the top of the fuselage side on the plan. You can then register the top longeron of your fuselage against this strip for each of the sides to be built.
PHOTO: COURTESY MODEL AVIATION
Small view of the Bestetti-Nardi’s plan. Notice that the top fuselage longeron runs straight from nose to tail, despite the break for the wing saddle.
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How do you know that top line is straight? Well, you could eyeball it. That used to work for me, until I realized that my glasses intro- duced enough optical distortion that I could- n’t trust them anymore. What you need is a reference straightedge. A cheap flat metal ruler will do, as long as it is true: test by drawing a pencil line along one edge, then flipping the ruler on its back and checking the same edge against the line you just
APRIL 2013
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