Hi Mike: First, I would like to welcome you into the un-ending world of designing model airplanes. A word of caution, however, it is an addiction, be it a skillfull crafted Pet Rock, or a Kluged together world-beater, you will, from now on, be unsatisfied with each and every design. You may come close to what you want for a specific purpose, but after you have flown the model for a while you will strive to achieve something else. With that said, I now feel I should dive in headfirst into the banter on designing. So here goes. I have to agree with alot of what has been stated, and I have to take exception to alot of it also. Much of it is simply opinion. Let's define a few terms: Modified airfoil# means that I really did not like the characteristics of the airfoil and could not find another airfoil which is what I think I need, so I took out the pencil, computer, or whatever, and came up with a new airfoil which has really nothing to do with the original airfoil. Proprietary Airfoil: Means I modified an airfoil, ran it through some evaluation scheme, whether it be computer or a building series, and it works for me, and I do not want to let the coordinates out. Computer Aided Design (or sometimes mistaken for CAD) means that I took a computer and drew the plans using a drawing program. Having said that there are a few designers that actually tried to use some sort of modelling in order to improve a design. Garbage in Garbage out: means that while I think I put real world stuff into the computer, I guessed, and what I got out was just as bad. NIH: Not invented here, meaning if they did not come up with it , it is obviously frivolus or has not real world meaning. (often all too true in this world). Now that I have ruffled a few feathers, I want to say that the protectionist stance of some designers is quite valid for what they are doing, and you do not need to worry about that. (BTW they will never ignore a good idea or approach that you have). A new person interested in designing is at an extreme disadvantage if they want to design a new plane. AND so were all these designers and manufacturers are some time in their careers. So yes, look around and buy a plane to learn to fly, to learn what style of flying you like, learn how big a plane you want, and decide what kind a pilot you are. Then when a plane breaks or crashes, you can replace a stab, or increase the aileron size, or do something to the design that makes it do what YOU want the plane to do. The plane was designed for their concerns, not what you might think. Now to ruffle a few feather some more, you do not have to have a computer to design a plane. Some of the best computational power is contained within your our head. When a designer, who likes to use a computer, tries to design a plane, they put in choices for variables into the program that they have determined by observation. And now to really frost a few wings, there are no computer model sailplane programs which incorporate measured, and that is measured, flight performance data from real world tests. You do not see any real sink rates measured, no LD trials, for performance. You may be starting to see speed guns on launches, and, with respect to John Roe, altitiude measurments, but input of data of this sort has not been done. We may have made fairly close approximations, but there is no real data on an entire airplane, although it was proposed to NASA in the early 70's. We have some partial information for airfoils from well known professors, who we all must thank, but that information is limited. Much of the airfoil data is for 10 " chords, so I really wonder about the 7" to 4" (or less) chords. A number of months ago I spent alot of time looking at the opinions of many of those on the exchange, (Don I had alot composed), but I did not feel it would advance anything. So Mike, try some things, modify some things, design a few Pet Rocks, and have fun trying things out as you learn. There are many on the exchange who you can bounce ideas off of, and many who love to share the information. For me, I put some things on my web site. These things are not mine necessarily, but they are things I use, or find helpful, which have been shared by others on the exchange, at contests, etc. LIkewise, it is not uncommon for a highly competitive pilot to pick up your plane and look it over, if it presents new approaches to current trends. While your design might not be optimal, it may be exactly what your skills can take advantage of, and what you enjoy. Don't assume one plane is necessarily better or worse than any other plane. It comes down more to pilot skill and practice. Only a few contests actually test the flight performance of a plane. I do not consider landings a flight performance feature. At first glance in the soaring community, in my opinion there are 2 contests which test performance (if piloting skills are the same) and that is the International HLG Festival and Slope racing. (there may be others, but they are not TD contests) Neither of these require you to land on a spot, and both require the plane to utilize the design aerodynamics. Other readers/posters on the exchange may disagree as this is my opinion. The closest contest following these 2 is F3B. Yes I agree with Don and Martin that the plane is treated as a whole. Airfoils are only one factor. Too bad that has been the only thing measured. I will surely get a response that each wing and airfoil combination may or may not work, but with simple observations you can get something that works well enough to enjoy and experiment with. Some may get too wrapped up with computation, and sometimes a simple choice of the variables input can place a computation into a false minimum, or maximium, which unless a significant deviation is made in the program's parameters, will always lead you to the same result. Now please don't think that I am knocking computer programs, just step back, understand what is being done, then say to yourself is that a real world result? Wow, I have opened a big can of worms with this post. I wish you luck in your adventures. There are so many great people on the exchange that you will find many approaches for your efforts. After all, that is what designing is all about. See you at the Field, Chris Adams http://www.scrollsander.com RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
