oldbassard

Hey Gang

I have started cad work correcting a hand drawn plan from 1964 sold by RCM. The plans are a Cessna T-50 with a 60 inch wingspan (about 1/12 as close as I can so far gather). I have stepped to far off now to quit. I have already started ordering parts for the plane while redrawing the plans to figure out what changes I need to really update them to todays technology.


The plane is sure enough old school and I want some old school techniques in it, for instance I want to cover it with fabric that has be colored and sealed with dope. The original plan call for no flaps or throttle on the K&B 35 engines. I am going with electric on this puppy. and also put the flaps on it. I will make my own fiberglass parts for it, nacelles and nose cone.

I am not well experienced with fabric or the methods of stenciling or decals. I mean by what methods you get them made or where. I bought these plans a few years ago and have been trying to learn a little more before I jumped off. I wanted to build it as a loner, but I realize I can't do it by myself, I will need the knowledge of some of you guys here.

At the time I am drawing the wing ribs etcetera in 2d to get them laser cut, I will also fit it all up in 3d model before I send the DWG memory stick to a cutter. These plans do have a lot of small problems, after I have finished them, is there somewhere I can send the plans to for future use. I mean someone that might keep or sell them. After I do this, I am not interested in making money off it, I want to do it to show me I can. But I'd like the work not to go to waste.

Although it's early to tell about all the measurements, I can tell some things are drawn out of square and not oval where they should be. I do give consideration and respect to the guys who did draw them at the time. Technology has came so far. What took them hours to draw, not completely right. Technology allows us to do perfectly in minutes.

KW_Counter

Bassard,

Sympathy on your endeavor. I am converting plans for a Bridi Super Kaos 40 to cad for lase cutting purposes.
Learning cad in the process, I have some drafting experience from high school.
I was fortunate in that I had a pdf of the plans before I started.
It took some work but finally got them into QuickCAD at the proper scale.
I'm curious, how did you get the shape of the ribs into cad?

You may want to check out his forum here on RCU:
[h=2]Scratch Building, Aircraft Design, 3D/CAD[/h]
Good Luck,
KW_Counter

Lone Star Charles

Not to hijack, but maybe to help you, KW-Counter. I use AutoCAD for design, but I suspect that the features and processes are similar. First, I create the wing plan form. Second, I layout the rib locations. Third, I dimension the chord length for each rib. Now comes the fun part.

I go to some airfoil data source like http://airfoiltools.com/ and select an airfoil. There are other sites that are just as good, but I find this one fairly easy to get around in. Once you have selected an airfoil, you can download the .dat file for its coordinates. Draw a p-line using these coordinates and then smooth the lines. You will wind up with a rib of your choice with a chord length of one (1). Then all you have to do is to 'insert' the rib into your drawing using the measured chord length as the 'scale' for the 'insert'.

If you like, I'll be glad to make one for you. Just sent me a PM.

oldbassard

KW_Counter&Lonestar, thanks for your replies. I own a cad design business, but it's for pipe design, not RC airplanes so I am in new territory. KW thanks for the link. I will have a look. I completely agree with Lone Star, The wing is the place to start and the link he put up is very helpful. It is a challenge and also fun to attack this project. KW, if you need any help with the program let me know. Maybe I can show you a few things.. I use autocad full version, cadworx and 3d plant. and a few others.

lionstalker

For silk or silkspan or tissue paper you first need to practice on something. Build a false wing or something at least 6" x 12" to practice on. It's all done with bare hands and sharp scissors and a very good brush. Apply clear dope to the wood and let it dry. Spray water on the cut, trimmed fabric to soaking and let excess drip off. lay out fabric over area to be covered very evenly and flat. Apply clear or colored dope to top of fabric where wood to attach to is below (all is stilll wet). Using fingers spread and push fabric on wooden frame until properly fitted. It will stick to wood pretty quickly even when wet. While still wet, paint light coat of dope on entire fabric surface. Allow about an hour to dry and it should shrink tight as it drys. Now apply as many coats of dope as you wish to get effect you want but a light coat at a time and allow it to dry between coats. Most important tool will be your finger for spreading it on the frame.

oldbassard

Lion Thanks for the tips

GREG DOE

Old Bassard, Let me add two more tips. While it's not definate that you will use silk and dope, remember that silk has a "grain". (tissue, and silkspan have a grain too) The grain should run span-wise on a wing. If the covering is applied with the grain chord-wise it will sag between the ribs. Read up on finishing with silk and dope, or seek out the old-timers in your club, and they can show you how to determine the direction of the grain in silk, or paper like tissue. The second tip is that dope will blush, or turn milky in humid conditions. If you have this problem you need to add blush retarder to your dope.Blush retarder is just a slow drying thinner. Good luck, Greg

oldbassard

Greg Thanks. To me it sounds like the dope must have a lacquer type base. I appreciate the tip

zx32tt

My Feedback: (9)

While I admire your efforts for covering the model "old school", I personally would not want go back to that method. If you insist on fabric, you could consider Stitts, or Solartex. Doped silk, nylon, or silkspan will never be as durable as any of the iron on films. I've been modeling for over 50 yrs, before monokote was even available, so I've done it both ways. My $.02.

TomCrump

I was thinking the same thing.

While I am frequently accused of being "Old School" the use of more modern materials can save time, while producing superior results.

I'm a Solartex user, myself. It's easy to apply, paintable, and produces a realistic finish.

Rodney

I'll second the suggestion to use Solartex. However, if you want authenticity, try Ceconite from Spruce Specialties. Use the lightest grade which is almost identical to any of the tex's such as Solartex, Colortex, etc. You will have to use an adhesive (regular dope--not butyrate) and put it on just as you would silk or any other fabric. It will heat shrink just as the tex's do and is a very durable material. You will have to paint it though.

oldbassard

I guess it sounds ridiculous but I was to young in the 50's and early 60's to build these planes. I was either too busy chasing girls, learning youths pleasures of life or out of country in the late 60's and early 70's. I started building in the 80's and quit till 2012. I had an older friend that passed at the age of 94 recently that built and flew balsa planes pretty much since they had been made. I see these building planes as an art, not just a hobby.

I had seen pictures of some of these airplanes from his magazines published in the 60's besides some that he still had, he used aliphatic glue, material or paper and dope for covering. The plans I am working with are from that time period. The builder at that time didn't have even close to what the builder has today and if you have never seen what some of these older guys did, you would not believe how well some of their planes came out. The plans I have are 50 years old, I thought it might be a challenge to build the plane as they did then so I could see for myself what it took.

I guess I see it as a modern sculptor would see ancient artifacts maybe as a modern artist might see Davinci. Now I am also getting the urge to get a shovel and go dig dinosaur bones.

TomCrump

If you want to go the silk and dope route, by all means, do it. There's nothing wrong with those methods.

acdii

SIG Stix-it is good to use for attaching the covering, then it goes on like Monojoke. I used it with store bought cloth, and then used dope to finish it off. I will be doing my SIG Cub in Koverall using this method.

oldbassard

acdi Thanks for the tips on Stix it

oldbassard

Rodney, thanks for your response, I will look at Ceconite

Rodney

One of Ceconites biggest advantages is that you can get it any length you want plus (if I remember correctly) it is about 5 feet wide. A great advantage for those big models. You can cover large areas with no splices.

swify

Sig Koverall is a real durable fabric. I covered a sig 1/6 scale clipped wing cub with it more than 20 ears ago because I wanted to try a fabric and dope finish on an aircraft. The plane looked as good on the day I crashed it last year as it did when I first finished it, no sags in the covering, no discoloration of the dope. For my first effort at a fabric and dope finish I was quite proud of it. Have since done a 4 star 120 with koverall and dope.

Lone Star Charles

Rodney is correct about the width of the and length of other 'aircraft' fabrics. I use polyfiber from http://www.s****.com/ and have the same experience. I seem to waste less by using polyfiber (or ceconite).

Edit: I forgot that the forum will asterisk the letters, even if they are imbedded in a perfectly good word, if those letters can spell one of George Carlin's 'seven words you cannot say on TV'. Guess you will just have to google " Radio Controlled Model Airplane Products by Polyfiber "

acdii

rshsr take the next letter up for the real word. Didn't know we needed ciphers to note web sites. st it s

dadragon

I use stix it and sig coverall on all my open wing and fuses and it shrinks perfect.my first few small planes back in the 60's were all silkspan and dope man am i glad those days are gone.on all the big stuff is fiberglassed or sig.