When Chuck Cunningham wrote his monthly column fo RCM Magazine-every so often he would print a chart giving rule of thumb parameters for aircraft design. Horizontal/Vertical stab size versus wing size, length of fuse, etc. Does anyone have a copy of this chart they could share, or does anyone have their own list. This could be helpful for those of us, like myself, just starting to design/re-design our own aircraft. Thanks in advance for any and all assistance in this matter.

I don't have the charts and information you asked for but I can give a substitute.

In dozens of photos you can see top views and side views of airplanes that are flying in the kind of flight that you are interested in. Scan those in to a computer and make your own versions of the rules. Actually if you look at an airplane you can guess pretty well if it is going to fly right or not. Use those same eye gauging skills when you design your own. The only guess work might be the CG location but there has been some discussion on that subject here before. It can be located with small foam models fairly easily and accurately.

If I wanted to design an aerobatic airplane I would copy something Chip Heyde is flying, scale airplanes - just copy the areas and lengths. Free flight - look at all the models that have been featured through the years in the modelling press. and so on.

The old saying, if it looks right it will fly right is very close to being good. When you step off the beaten track is when things get interesting and Chuck's rules might not work there either. However when things that are flying are analyzed they usually fit into a "rule of thumb" bracked without too much squeezing.

Thanks Ben. This fits into that, "Damn! Why didn't I think of that"?!! category. If anyone does have Chucks chart, I would still like to have it. Its a good "rule of thumb" reference that would be nice hanging up in the shop. But your idea will definitly work. Any Bozo could work it out with a picture, divider, and a ruler. Damn! why didn't I think of that!

I have all of his articles and also a drawing from Ken Willard's column that gives all the percentages. I would e-mail, but they are scanned and each is 1.2-1.6 MB. I'll send the drawing.


Can't do it-you have your e-mail hidden.

Crashburn - are you trying to be sarcastic?? stop that!!

All kidding aside I have had many meetings around a designers drawing board during which very respected members of McDonnell Douglas's aero dept. changed a design by the exact methods I just mentioned. Later the dimensions may be refined but surprisingly not that often. Usually the changes are to optimize performance, rarely due to stability or maneuverability. I was always in awe back in those days in watching an experience mind at work. 30 years later it isn't quite so mysterious as it used to be, but it did bring home that listening to and learning from more experienced aero engineers is always a good idea. You never can tell when you might learn something.

Your advice is sound. We should never stop listening to those around us. Even the less experienced will come up with a valuable idea every once in a while. I hope you do not think I was trying to be sarcastic, and I dont think you did. Sometime we get caught up in things and are unable, or unwilling to reason it out. One thing in my defense, when you spend a couple weeks and more than $200.00 putting a wing together, you really kind of want it to work. Thanks Buddy,

Ron

Hello, I had to get in on this one. I understand what Crashnburn is going thru. I have scratched em for years but just now decided to scale up a few and having a heck of a time making a decision on the rib thicknes. The one that I'm scaleling up is by chance a Cunningham bird.

It's a normal 60 in. wing and I'm taking it to 100 or 120 in. That would make the rib or wing thinckness over 4". I just don't think this would be good. It would be quite draggy. Does anyone have a rule of thumb for this one? Thanks Hooker53

Work out what the original thickness of the wing is in percent of the wing chord. If the thickness is between 12 and 15 percent of the chord you are OK. More is not necessary, just draggy.

Hey thanks loads Ben. The 12 to 15 percent was what I was looking for. For your interest. If you remember Chucks Hooker (1977) than you will know what I'm scaleing up. The 60 in. ver is a dream. It will do axle rolls in a straight line all day with just Ail input. I would love to see what one of these do with a 100/120 in. wing. I also plane to rework how the wings go on. If you have seen how Hanger 9 has the wings on the 1/3 scale sukhoi with the graphite tubes then I think I want to try that. All I have to do is find someone that has thoses two telescoping tube sizes. I will get out the Calculator and give it a look see. Thanks Again. Hooker53

These parameters can be found in Andy Lennon's book "BASICS OF R/C MODEL AIRCRAFT DESIGN".

Chapter 25 covers basic proportions for R/C aircraft design.

Cajun[8D]

Got all the data I needed. Thanks guys, I really appreciate all the help.