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Old Dec 23, 2010, 09:36 AM
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Originally Posted by Dickeroo View Post
..."The KFm's did really well. Examine the CL (coefficient of lift) and the Zero Lift angles. Very good. You'd have thought we knew what we were doing!"

My late father-in-law was a big fan of old timers, and we shared a common love of well drawn model airplane plans. (I'd wallpaper with Frank Ziac if I could afford it) He and I spend many a pleasant hour going over them, and talking about their qualities.

One of the things I've noticed from this is how model airplane design has evolved with the hobby. For instance early free-flight designs started with parasol wings, airfoils on the horizontal stabilizers, and very short coupling on the nose. These were planes designed for heavy engines without much power, and were intended to self-stabilize to maximize flight time. They are large, heavy (for balsa, mind you) and draggy. They also are beautiful in the air, but that may be just my personal opinion.

Now contrast that kind of design with a flat plate foamy made for 3D flying. Every single aspect about the plane has changed, from wing location, to proportion of wing area to stabilizer area, to power source. All these changes came about because the knowledge of model airplane designers increased, along with the abilities of the pilots to control them.

The one thing that hasn't evolved much is airfoil design. I guess on average airfoils have gotten slightly thiner, but by and large they still mimic 1930s airfoils designed for airplanes with Re numbers in the millions. There are good reasons for this, mostly because it wasn't cost effective for a governments to research airfoils below a certain Re number, until recently that is. And yes, a lot of amazing work has come from private sources over the last 20 years of so. This is especially true of glider airfoils, coupled with the technology to glass bag wings.

But in all of model airplane airfoil history, I can think of only two major evolutionary steps, steps that radically affect how modelers build and fly their planes. The first I already mentioned above; that is the flat-plate airfoil, which technically is a very thin, fully-symmetrical airfoil. The other is of course the KFm series of airfoils.

Mind you, I may be all wet on this, as my knowledge of airfoils and model airplane design is admittedly limited. But that being said, I thing the FKm airfoils represent the largest evolutionary step from the past. A step that I think will eventually revolutionize the hobby just as much as cheap brushless motors (more accurately, cheap brushless motor controllers) cell-phone (li-poly) batteries, and cheap, easily available sheet foam, have done for the hobby.

After such a long winded ramble, here's my point. It is easy to assume that what we did in the past was the right thing to do because reasonable men, some even really smart, all agreed on a particular design. The problem with this logic is the assumption that those smart reasonable men of the past knew what we know today. They didn't. They built very good planes based upon their knowledge, and limitations to the hobby at that time. Today's model airplane designer has so much more knowledge, so many more materials to chose from, way more methods of controlling the plane, and a plethora of power sources to move them along. And best of all, so many more airfoils to choose from.

As the song says, "the future's so bright, I gotta wear shades." Thanks Dick for helping us move along, and think new things.
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