I was always taught that stability in flight depended on several things, some that relate to one another and some that can be considered independently. For instance: a single example of improving aircraft stability that will effect other flight characteristics but can be accomplished singularly is the CG placement relative to the Center of Lift or Center of Pressure. The closer these 2 are the more the plane feels like it is balancing on a fence post. The further they are a part, within reason, the more stable the plane feels and behaves in flight. Close would be like balancing on one foot, vs. spread would be like standing with your feet a full stride a part. I think people are mistaking stability for effectiveness of the surfaces when increasing the arm or distance of a control or stabilizing surface. It sounds like the same thing, but by definition that I was taught, stability has more to do with the plane's response to being upset, where as effectiveness has to do with how good they work. A plane is evaluated for its Static Stability and its Dynamic Stability to determine if it is functioning within its design perimeters, and whether it is safe or not. Static Stability is what the plane does first right after being upset. Dynamic Stability is the plane's response over time. The elevator/rudder is effective due to its arm or distance from a datum point or measuring point decided on before beginning such measurements. This should be the same point used for weight & balance. When this arm or distance is increased, then it is like getting a bigger pry bar, the surface has more leverage over the same plane. If one increases the surface size, it has the same effect but at the penalty of more drag due to a larger area, hence the frame stretch, which is less of a penalty. I believe Troy's larger horizontal stabilizer and reduced elevator was an effort to reduce pitch sensitivity, not increase stability.
I personally, and this is my opinion, find it difficult to attribute an increase in aircraft stability either solely, or due to using the new wing. All the planes mentioned have several changes made to them that would all have a part in increasing a plane's stability. My plane has the RAF48 wings with Dan Diehl skins, and when I am solo full of fuel the plane is very stable if the air is smooth. A 1100 pound plane is going to be "active" in bumpy air no matter what wing it has, or who is flying it. As an example Larry Flesner's plane has shorter wings, which will make his plane behave like a heavier KR due to the fact that there is less wing loaded with the same weight causing his to be more stable. The new wing will effect cruise speeds, stall speeds, takeoff and landing speeds directly. The reduced angle of incidence will make for less drag and higher cruise speeds due to the fuselage being oriented into the relative wind better. If you are about to start your wings and have not bought anything but raw materials, by all means use the new airfoil. But if you have already invested in Diehl skins, or like me already have an existing set of wings, fly them. The wings alone are not going to make that much of a difference compared to attentions to details like CG control, and keeping the plane light etc... From my personal flying, and what I am reading from other pilots with both airfoils, they fly enough alike that you would be hard pressed to tell a difference unless you had 2 planes just alike, weighing the same, flown by the same pilots, with each wing. Too many other variables that have been incorporated to improve their planes to say that the new wing is doing it all. Alot of "The Gang" are still flying the old wing and having a BLAST! Just get her finished. To quote Dan, the time for building is long since over.... Corvair engine on the stand beginning teardown... crain...@cfl.rr.com http://kr-builder.org/Colin/index.html KR2(td) N96TA Sanford, FL Apex Lending, Inc. 407-323-6960 (p) 407-557-3260 (f) crai...@apexlending.com
