tinwakr

Just would like to know how to design a RC airplane, Things like, what airfoil to use, how long of a fuse, wingspan, etc., etc..

Thanks in advance.

Chuck

William Robison

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Tin:

Going to sound like A Snidely (Snively?) Whiplash here, sorry, but if you want to be a successful scratch builder you have two practical routes.

First, you can go to school, and become an aeronautical engineer.

Second, and more practical for most of us, us build MANY kits, or planes from plans. Learn construction and strength considerations, and develop your eye for basic good design.

Then you can whack out a pretty good plane with no plans at all. A true scratch builder.

Actually, there's a third method. Just start building. Sooner or later you will probably have something that flies. Your eye should keep you in range of reasonable proportions, but the structure is more easily learned by kit and plan building.

Bill.

cappio777

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Chuck, nothing is impossible but what William said is very true. I made my very first RC airplane at the age of 12, never built a kit in my life but I been making free flight models from an early age. Needless to say the airplane flew well while I was able to keep it in the air, first time flying RC too, but when it came for landing it hit the deck and broke in multiple pieces. Want to guess why? Well I made the entire airplane out of balsa, no plywood anywhere. So the first impact the firewall broke, the landing gear broke off the fuselage and the wing rubber bands pulled the dowels so hard it crushed the side of the fuselage.
Although the incident was a success for a 12 year old boy doing everything by himself for the first time. I would have wasted less money and time if I would have gotten a kit from the getgo, or at least some plans! Now, if you are familiar with the building procedures for gas powered aircraft then get yourself some plans and start scratch building. Otherwise better get some kit building time under your belt. [sm=biggrin.gif]

Deadeye

You could start with coroplast. It's cheap, easy to use, and builds beautiful aircraft if you take your time with it. Check out my [link=http://www.rcuniverse.com/forum/Cor%2DStar_60_Version_2%250_plans_and_pics/m_1201120/tm.htm]Cor-Star 60[/link]. 30 hours and 30 bucks, and you have an awesome flyer!

BMatthews

This is a common topic around here both from the aerodynamic as well as the structural standpoints. There's no one easy answer. The best thing you can do is read back through past posts in this forum and in the Aerodynamics forum for some background material and links to other sites. Come back with further questions when you have something more specific.

Just asking "how do I design an airplane" is like asking for the equivalent knowledge of a university course in 50 words or less. First do your homework and then come on back.

cappio777

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Thats a cool bird Deadeye!

tinwakr

I really wasn't asking how to design an airplane the question was "Howto design an RC airplane" although one in the same thing.

All I really wanted to know was how you go about choosing an appropriate airfoil, what the wing loading should be for a good flying bird, fuse length etc. For example, I have heard experienced scratch builders talk about one airfoil being much better for a particular plane over another. There must be some sites that have info on this subject.

I have built a few planes from scratch(plans). I have seen hundreds of well designed plans and I think I have the ability to design and build one if I knew the basics of selecting the proper type of components for the airplane.

Deadeye, thanks a bunch for the coroplast tips but I have already done the Coro thing, hehe. I built a DasPlaStick. Not a very good design in my opinion, but it was a ton of fun!

Anyway, thanks very much for the replies.

Chuck

cappio777

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There are an infinte group of parameters. First of, what kind of bird are you thinking about? Trainer, sport, fun-fly/3D, pattern....
Each airplane has a particular flying characteristic therefore a particular structure as well. Let us know of your idea, what you want the airplane to do, and I am sure the guys here will help you tweak the design.

tinwakr

I am thinking about a sport or 3D type of airplane. I will draw a couple of views and post soon.

Thanks,

Chuck

Mike James

Hi Chuck,

I've been assembling answers to the kinds of questions you're asking, on my non-commercial web site, at http://www.nextcraft.com/rcdesignandbuilding.html for a few years now.

There's a general set of guidlines there for most types of aircraft, and links to others who know much more than I do, as well as references to some books that you'll find helpful.

I created this pages specifically to help others, so I hope they do. Have fun!

cappio777

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Mike, thats a great site!, what a great way to help beginners and even experienced builders with all that info. Kudos

Ozelot

A very good starting point is to get a copy of "The Basics of R/C Model Aircraft Design", published by Model Airplane News. It covers basic design without getting lost in theory.

Jens

BMatthews

Ah, now this is a little more specific and can be answered without writing an encylopedia...

The answer is that.... there IS no answer. In general there are any number of airfoils out of the thousands out there that are suitable for any one model design. It's more the FAMILY of shapes that you are interested in. The Epplers with the forward high point versus the NACA's with the conventional shapes.... or the various lower cambered "semi symetrical" class used for sport models.

The only really animated discussions about closely comparable airfoils takes place among the sailplane guys. And even they are quite susceptable to the "flavour of the week" syndrome. There are at least 10 airfoils that are quite capable of winning a world championship at the moment and about 1/2 of them have had their day in the sun.

For your fun fly idea it's a lot simpler but more confusing all at the same time. Simpler because it doesn't really matter since you'll be using questionalble construction methods vis a vis accurate modeling of the airfoil shape anyway. And powering it with a massive amount of thrust so any drag versus lift considerations are pretty much a moot point. Complicated because folks think it actually MATTERS on fun fly models. Basically you can copy one and it'll be good. About the only thing you should perhaps avoid is a shart leading edge line and thickness ratios that are over 20% for the main part (no ailerons considered) of the airfoil.. Basically for a fun fly if it looks comparable to what you see on some other ones it'll probably fly just as good as anything out there.

cappio777

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what he said.........

franc

Numerous articles are available if you go to the following Links page and look under Aircraft Design. A whole lot of other interesting links too by the way!!


http://homepages.ihug.co.nz/~atong/

Francois