Control Line: Aerobatics
On President's Day weekend, the Dallas Model Aircraft Association (DMAA) hosted a Stunt [Precision Aerobatics] Forum and contest. After many years of envying the wonderful forum hosted by the Garden State Circle Burners club, I really looked forward to this inaugural happening. I'd seen several of the Windy Urtnowski tapes on the Garden State Circle Burner forums, enjoyed them, and I recommend them. Chief organizer Tom Niebuhr, with DMAA President Mike Scott, did a superb job of organizing the presentation and keeping the proceedings moving throughout the day. The list of forum topics was varied, ranging from designing a semiscale Stunter, to designing a Stunt paint scheme, to various construction tips and tools. Since I can't recount all of the presentation, I'll pass on some of the tips that I thought were of value.
Control Line Aerobatics
WHEN I STARTED modeling in the late 1940s, we builders didn't think too much about what to paint our airplanes with; it was nitrate-based dope with butyrate dope over it for fuel-proofing. The early brands were Testors, Speed-o-Laq, AeroGloss, and other locally produced or packaged materials. Most brands worked reasonably well as long as you kept the butyrate over the nitrate; they worked well enough so that the process was just "there," working. The advent of many high-performance automotive materials made them the "in" finishes; they were self-leveling, highly fuel-resistant, and beautiful. However, they did not come without potential problems-most were multipart and highly toxic. They required that the user wear protective garments and a special mask with an outside air source.
Control Line: Aerobatics
I haven't written about trimming in a while, so I thought I'd get into a very narrow subject that can seriously affect many other trim adjustments: the vertical center of gravity (CG). When I think CG, I usually focus on the fore-and-aft CG, which does have a big impact on flight characteristics. Having an airplane with the vertical CG not located in line with the leadout exit will prevent you from achieving the usual first step in the trim process; the leveling of the wings. Before I get too far, I'll explain what I'm considering. Your airplane is suspended by the leadouts. If there is a displacement of the vertical CG from the line where the extension of the leadout exit intersects the fuselage, there will be a force created that will pull on the fuselage. That pull will attempt to force the vertical CG into line with the leadouts when the model is flying. The force working on the fuselage naturally affects the wings so that if the displacement is just a little off, the wing cannot be leveled properly.
Control Line: Aerobatics
EACH NATIONALS (Nats) has its own character. The contests have a way of defining themselves by the people who come to compete and be part of history. With the large number of overseas guests in Control Line Precision Aerobatics, this year's Nats had a distinct international flavor. US pilots were challenged at every level of competition. We are one of the few countries that permits competitors from other nations, and this broadens and enriches the week of competition. For the Open and Advanced fliers, the guts of the competition week began with qualifying rounds on Wednesday, July 14. All four of the "L-pad" paved circles are filled with competition. Judges are in teams that see one round of Open and one round of Advanced fliers.
Control Line: Aerobatics
While I was participating in the annual contest lunch at the Memorial Day Houston contest, I was asked to put more in the column for the up-and-coming flier. In the past, I have run the gamut of topics, from flying to building-many subjects prompted by personal "adventures." My orientation has been to share technologies, sometimes in a series of columns, with the thought that readers could use what applied to them. Meanwhile, they were exposed to other information. Reflecting on that discussion in Houston, I've decided to periodically focus columns on the new fliers to help them get off to a good start. Suggestions for topics are welcome, as are pictures. The best place for beginners to start is to read everything available. It sounds elementary, but there has been an explosion of published information during the last 10-15 years.
