Gents, Not to continue this discussion to the point _everyone_ is sick of it, but I'd like to make a little point about contest rules in general.
In general, good contest rules result in airplanes that people like to fly even when they are not in a contest - that is, sport flying. Innovations that make flying more fun, easier or safer are good. Innovations that let models last longer, be less expensive or take less time to build are also good. An example of the former is composite, full house sailplanes - these were developed in competition but are now common sport models because they are fun and fly so well. An example of the latter is EPP (foamy) models: long lasting, cheap and fast to make! None of these were outlawed because of the clear value of the innovations. Skegs are controversial because they can have both positive and negative implications for sport flying. The thesis of this note is that it is possible with a little rules work to separate the positive from the negative. First, a definition of "skeg". To me, a skeg is a ventral fin located behind the aircraft center of gravity that is designed to support much of the weight of the airplane upon landing. Some skegs do this without digging into the field or otherwise creating high friction while others are designed to dig in and plow the field. The value of the skeg in competition landings is that it results in a nose-down airplane attitude that reduces or reverses the wing lift such that the landing slide is reduced. Secondarily, because the skeg is near the CG it tends to inhibit strong yaw motion on touchdown, preventing flip-overs common in planes with a lot of dihedral. The additional value of a skeg in sport flying is that it protects the bottom of the fuselage, wing, tail, flaps and ailerons. I have used skegs on sport models since 1986 and I value their contribution to my model's longevity and landing consistency much more than the small performance loss. The protection of the airplane is especially important to those of us who fly from dirt and gravel fields. Where skegs become problematic is when they are used as, or with, landing arrestors. I define a landing arrestor as a device intended to dig into the field such that it is not mere friction, but rather a mechanical connection to the field is created. Examples of arrestors include the nose of the airplane in a dork landing, sharks teeth, and forward-swept skegs with a sharp tooth or teeth. Divots, craters (!) and furrows are the products of an arrested landing. The problem with arrested landings is that they are very tough on the airplane. They can damage the fuselage, wing and radio gear, and shake all manner of stuff loose inside the airplane. I hate to make dork landings or abruptly stop my models, even in competition, not to mention sport flying. So, I propose that some contests outlaw arrested landings while permitting skegs. The shape of skegs could be specified to make them ineffective as arrestors. For instance, the leading edge to tip transition of the skeg could be required to have a radius of no less than 1.0 inch (25 mm for the rest of the world) with the bottom of the skeg parallel to the bottom of the fuselage. If the skeg were piano wire it would would be required to follow this leading edge shape. If you are going to make such a rule then all arrestors and dork landings should be outlawed as well. Such rules could lead to short, consistent landings with models that are protected from flipping and lower surface scrapes. My two cents worth. That's all for now. Blaine Beron-Rawdon Envision Design San Pedro, CA http:members.cox.net/evdesign RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
