Radio Control: Sport and Aerobatics
LAST MONTH I included drawings and calculations on how to locate the "proper" center-of-gravity of an airplane. The reason I wrote "proper" is because there are various "proper" centers-of-gravity. For example, there are some centers-of-gravity which are so far forward that the airplane will be very stable in pitch. In fact, the airplane can be made so stable that it would be very difficult to maneuver. On the other hand, there are some centers-of-gravity which are so far aft that the airplane would be extremely maneuverable. Depending on what is desired, the range of "proper" centers-of-gravity is very broad. My use of "proper" was intended to yield a safe starting point to test fly the airplane. After the initial flights, the center-of-gravity can be moved forward to achieve more pitch stability or aft to get more maneuverability.
Radio Control: Sport and Aerobatics
RECENTLY, I received a letter from Al Seidowski (Cleveland, OH) who requested that I continue with "the light treatment of aero principles." His name sounded familiar-and then it struck me: Al Seidowski is probably as responsible for the current AMA Pattern classes as anyone. I can remember back in the Sixties when I was a member of the Western Ohio Radio Kontrol Society (WORKS) in Dayton, OH, that Al Seidowski came to a WORKS club meeting to promote a new style of Pattern competition. Prior to that time, the Pattern classes were Classes 1, 2, 3 (Novice and Expert). Class 1 aircraft had rudder and throttle control, Class 2 aircraft had rudder, elevator, and throttle control, while Class 3 airplanes had rudder, elevator, aileron, and throttle control. The airplane you flew determined the class you were in. The people in Classes 1 and 2 had big disadvantages to overcome, but they got very good at using the controls they had to produce some very nice maneuvers.
Radio Control: Sport and Aerobatics
THE LONGER I write this column (13 years and counting), the more I get recurring questions. Outside of the downwind turn, the most common question is probably, "How do I figure out where to place the center-of-gravity on my new plane?" The obvious reason that the question keeps coming in is that new RC fliers enter the hobby all the time, and they've never read the answer in previous columns because they joined since it last appeared. It's time to redo the center-of-gravity calculation discussion. I hope to hit a happy medium between boring you with excessive mathematics and insulting your intelligence. It's difficult to do, because the background of RC column readers is so varied.
Radio Control: Sport and Aerobatics
BOY! Did I get letters in the past month! The subjects varied substantially. Only one subject was repeated: Several letters were received about contest rules. It appears that there is a groundswell of concern on the part of contestants on the subject of competition rules. Many of the letters were about the writer's frustrations with the time it took to change rules. All rules change proposals had to be in by last fall (1988), but it won't be until 1990 that new rules can be put into the rule book. In this era of electronic mail, telefax, computer networking, and all the other communication innovations, we are chugging along with an antiquated system.
Radio Control: Sport and Aerobatics
TWO MONTHS AGO I wrote about locating the proper center-of-gravity on a conventional airplane. Last month I extended it to cover canard airplanes and flying wing airplanes. Then I sat back, thinking that the subject was done for a while. Not so. In addition to requests for more information, the mail bag has been full of lots of good questions. Rather than sending answers to only the questioners, I decided to include one of the better questions and my answer here. Many of the questions related to wings which did not have straight leading and trailing edges. A good example was sent by Bob Hanson (Colorado Springs, CO) who was a former club member and president of my club (Eglin Aero Modellers). Bob is working on a Sport Scale Fairchild A-10 and wanted to know how to apply the equations I'd published earlier. The A-10 wing looks something like Figure 1. You will note that the center section of the wing is rectangular, while the outboard sections are swept and tapered.
