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Old Mar 07, 2013, 03:33 PM
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It's hard to answer your questions without more information about what you want to do. If you were interested in a rubber powered pistachio model, then 8 inches would be the only possible answer. If you're interested in large rc scale, it's another story. But these would not be beginner's models in any size. We also need to know where you can fly, how much room you have, etc. Plus if you can get a good instructor or not.

Are you specifically looking for something that looks "vintage"? You could check out Ben Buckle, Balsa USA and SIg, where you'll find some trainers that look old.

It's probably not a good idea to do a scale model for your first effort, especially not one with a fat round fuselage and a low wing!

I recommend something light and slow, moderately large (say, 4 to 6 feet depending on weight), with a high wing. It should be simple, because most likely you will crash it and need to repair it. The easier it is to build, the lower your emotional investment will be and, most likely, the less nervous you will be when learning to fly.

This thread is for vintage models and I think you'd do better to ask this question in the fuel plane talk or the electric plane talk forums. Let me know if you do, as I have lots more to say on this topic if you're interested. I've instructed a dozen or two people over the years, so I've developed some informed opinions.

BTW, unless you already know glo engines and like them, I suggest you go with electric, as they are easier to keep running, and you've got more places to fly them since the noise is so much less.

Once you know what you're doing, designing a conventional RC plane is no big deal, but don't try it just yet as you probably don't know what's important and what's not. Studying plans for planes that you know are good ones is pretty educational, though.
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Originally Posted by gatosgr View Post
I don't have an engine yet, what size engine should I get and for what plane?

I might build the weddel-williams even if I don't fly it , I have the materials..and I really like this plane.. what wing span is optimal ?
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Old Mar 07, 2013, 10:21 PM
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O_P: You probably learned a lot doing all those calculations, but it's not necessary to do all of them to get a decent flying glider.

I'm not laughing my head off. That would only happen if I had lost the bolts.

I may have forgotten more about aircraft design than you'll ever know if you count the 2nd, 3rd, and 4th time I forgot each bit of information. Otherwise, I doubt it.

If you want to design something that's as good as, say, a Drela design, then you probably DO have to get into great detail. I'm pretty sure he runs designs through this piece of software with a really nasty user interface that calculates all sorts of extra things. Calculations for turning and for straight flight, using different airfoils in different parts of the wing, etc. I don't have that kind of patience. But I'm sure if I design something similar I will be shamelessly lifting things off his stuff.
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Difficult.......well, that depends on how deep you want to get into the aeronautical calc's. I just finished a scratch build that was very loosely based on a previous design, and by the time I finished with the lift coefficients, mean aerodynamic center, size and location of the vertical and horizontal stabilizers, and about twenty other things, the only thing my plane had in common with the original was the kind of paper the plans were printed on.

Having said that, I had lots and lots of help, courtesy of most of guys on this thread, and especially from Lincoln. He's probably forgotten more about aircraft design than I'll ever know. More than once, he kept me from making some bone head mistake...he's probably laughing his head off right now!

Here's a link to a Trainer Design site that offers both a common sense and technical approach to building an R/C aircraft. I found it helpful.

http://adamone.rchomepage.com/design.htm

There are a number of good design sites, and a wealth of help to be found here. Most of these guys have been building and flying most of their lives, and they are both patient and generous with their time and help....and the neatest thing I've found is that the answer to a question can come from anywhere in the world.

Like I said before, it all depends on how deep you want to get into the math.....On the other hand, lots of successful models have been built and flown without benefit of airfoil analysis at low Reynold's numbers.......Lincoln is laughing again.

My suggestion is to build a kit first.......something that will be forgiving....and go from there.

Good luck

O_P
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Old Mar 08, 2013, 09:40 AM
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I've just finished calculating dimensions for a 2.5 kg trainer with 1,80 m wing span , it took me 4 hours to do it by hand.. trying to remember elementary school geometry .. I also calculated characteristics for the weddel racer because I like it's shape , just for educational purposes some characteristics for the wedell racer :
max fuselage width beneath wings is 21.4% , compared to 8% for a trainer , max width is 24% , compared to 10% , wingspan to chord ratio is 3.8% compared to 6% , wing angle is 5.8 degrees and max wing width to wingspan ratio is 3.5% , compared to 15% for slow flyers.. a plane like wedell racer well is strictly for high speed ... not very fun plane for a beginner since you need binoculars to see where it's going.. I though about using the fuselage shape and relocating wings, changing dimensions but it won't work as I hoped it would.
Thanks for your help.
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Old Mar 08, 2013, 04:23 PM
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I just restored a plan from the free flight forum and I thought I would post it here to try to keep all of the old plans in one place. Its the Douglas O-38 army biplane from 1931 as a rubber model at 40" wingspan. Has a long nose, good for balance.

Planeman
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Old Mar 08, 2013, 10:27 PM
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I don't really recognize all of your numbers. At least, not by those names.

If you're really stuck on the old time racer theme, some of them had high wings. You might be able to make a decent trainer that looked like the Mr. Mulligan, one of the other Howard DGA high wihg planes, or the Cessna CR-3. Other high wing candidates might be the Dayton Wright racer, Lockheed Vega, or some version of the Monocoupe. (There were several, some look slicker than others.)
Don't be afraid to make the tail surfaces a bit oversized. Here's some info on that:
http://www.eaa62.org/technotes/tail.htm
Maybe there's something in the scratch built foamy section.

Of course, there are at least two drawbacks to the fancy approach:
1. You'll need a test pilot unless you find an existing design that's easy to fly.
2. You'll hurt much more when you crash and need to repair it.

If you're really stuck on designing your own, you might try reading Martin SImons' "Model Aircraft Aerodynamics".

Again, this really should go to a new thread in one of the other forums.
Quote:
Originally Posted by gatosgr View Post
I've just finished calculating dimensions for a 2.5 kg trainer with 1,80 m wing span , it took me 4 hours to do it by hand.. trying to remember elementary school geometry .. I also calculated characteristics for the weddel racer because I like it's shape , just for educational purposes some characteristics for the wedell racer :
max fuselage width beneath wings is 21.4% , compared to 8% for a trainer , max width is 24% , compared to 10% , wingspan to chord ratio is 3.8% compared to 6% , wing angle is 5.8 degrees and max wing width to wingspan ratio is 3.5% , compared to 15% for slow flyers.. a plane like wedell racer well is strictly for high speed ... not very fun plane for a beginner since you need binoculars to see where it's going.. I though about using the fuselage shape and relocating wings, changing dimensions but it won't work as I hoped it would.
Thanks for your help.
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Old Mar 08, 2013, 10:45 PM
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scanning Airflow stuff again

Here's some more plans I just scanned from Airflow. I think John Whittles was the editor for all of these issues.

from September/October 2001:
-Challenger, a 15 inch stick model by Peerless. If I'm not mistaken, it was the one design high time model for the Glastonbury Aeromodellers for the 2001/2002 indoor season. Gerry Donahue supplied the plan to the editor.

from January February 2001:
-Vega 12 1/2 inches, by Megow. Dime scale job. Relatively thin airfoil compared to many models of the Vega. The fuselage looks a bit anorexic too.

from July August 2000:
-Piper Cub by H.K. Weiss. About 14 inches. Sheet fuselage and tail. I seem to recall we had these as the one design model for the Stealth Squadron not too long ago. Lots of people had trouble making them fly well, not sure why.

From October 1999:
-Pesco Special by Paul Plecan from the "1944 Model Plane Manual". Something like 18 1/2 inches. Supplied to the newsletter by Jack Rice.
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Old Mar 08, 2013, 11:49 PM
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Quote:
Originally Posted by gatosgr View Post
I've just finished calculating dimensions for a 2.5 kg trainer with 1,80 m wing span , it took me 4 hours to do it by hand.. trying to remember elementary school geometry .. I also calculated characteristics for the weddel racer because I like it's shape , just for educational purposes some characteristics for the wedell racer :
max fuselage width beneath wings is 21.4% , compared to 8% for a trainer , max width is 24% , compared to 10% , wingspan to chord ratio is 3.8% compared to 6% , wing angle is 5.8 degrees and max wing width to wingspan ratio is 3.5% , compared to 15% for slow flyers.. a plane like wedell racer well is strictly for high speed ... not very fun plane for a beginner since you need binoculars to see where it's going.. I though about using the fuselage shape and relocating wings, changing dimensions but it won't work as I hoped it would.
Thanks for your help.
Those parameter don't look familiar to me either! I would follow the suggested reading if I were you. And look at lots of plans and do lots of reading etc.
My suggestion is to buy a well proven cheap foam trainer from HobbyKing to learn to fly with. There are good stable aircraft for well under $100 - or even $50!. It will stand a bit of abuse and won't break your heart if and when you crash it.
Meanwhile, build something of your choice, preferably a simple design.

For what it's worth.......

Jim.
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Old Mar 09, 2013, 06:54 AM
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thank you for your suggestions
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Old Mar 09, 2013, 10:19 AM
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Duet
by Ted Strader
46" Wing Span Biplane
.15 IC FF
Flying Models - May 1958
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Old Mar 09, 2013, 11:44 AM
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Originally Posted by rchopper56 View Post
Duet
by Ted Strader
46" Wing Span Biplane
.15 IC FF
Flying Models - May 1958
Wow, that's nice. Ted Strader sure did have good eye for design.
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Old Mar 09, 2013, 03:43 PM
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Napa, CA
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Just wanted to say THANKS to Rufus & Gene for the two nice plans they just posted. You two gentlemen always do such nice work restoring these beautiful plans. Once again, thanks for the nice work!
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Old Mar 09, 2013, 07:54 PM
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I venture to guess that we were all newbies at one time. Part of being a newbie is not knowing what you don't know. And then, for anyone to sustain an interest in this hobby, they have to be a bit of a non conformist, and ignore at least some of the messages they get. Otherwise, they'd just be watching the ball game on TV all the time, drinking beer, and wondering why it doesn't seem to attract beautiful women (or men, as the case may be) the way it does on TV. So let's be nice.
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Doncha just luv it, not only do newbies want to learn to fly with a Spitfire, they also want to redesign Mitchels marvel.

Regards Ian
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Old Mar 09, 2013, 09:12 PM
UMs & parkflyers... for now.
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Kind works for me, too.
I like the Duet. So many pretty plans. So little storage space.
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Old Mar 09, 2013, 11:09 PM
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Australia, NSW, Lane Cove West
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The Peregrine from the 1954 May edition of Aeromodeller
I posted this on the FF pages a while back. Here's a plan that I've cleaned up and kept all the original plan outlines but retyped all the text and got rid of the messy cross hatched background.

The other plan is for the Frog Vixen that I've cleaned up a bit.
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Old Mar 10, 2013, 03:07 AM
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Mr Raglafart. Two very fine plans. Many thanks.
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