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Starting New Project RCM Cessna T-50

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Old 02-23-2017, 07:27 AM
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oldbassard
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Default Starting New Project RCM Cessna T-50

Hey Gang

About ten years ago I ordered the RCM Cessna T-50 plans. Finally I have decided to dust them off and fire up my Cad to draw the parts. About 30 years of drawing structural, mechanical and electrical things for a living Now I am drawing something I want to draw. One thing I don't understand about these plans. in some areas they specify for a part to be made of soft wood and I don't know what wood they are talking about because in other areas they specify balsa.
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Old 02-23-2017, 07:43 AM
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If it looks structural it might mean Basswood!
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Old 02-23-2017, 07:56 AM
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old, how about a little tutorial of how you are proceeding to convert the plans into cad. What cad are you using? How are you scanning the plans into the cad? Dan.
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Old 02-23-2017, 08:23 AM
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AutoCAD will allow you to insert Images and PDFs which you can scale up to the scale of the model you wish to design. Then it is a matter of tracing. The down sides are the most images not sharp enough after scaling up so some times you trace it at a convenient size and then scale it. The other BIG problem is the most of the images and other documents are not 1:1; vertical and horizontal, so you have to rubber sheet it by making a block out of it and the insert it with the vertical and horizontal scaling number you need to make the span and fuselage lenth correct! I use Bob's Documents and the Smithsonian for sources of better documents!
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Old 02-23-2017, 09:21 AM
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Dan, I am not going to scan them in. The problem with the plans is they aren't accurate as far as the shapes and sizes the years of them setting copies of the lines are distorted and warped to a small degree.. . I will redraw the entire short kit. there's enough info on the plans to get it right. I will test fit all parts on CAD before I have them cut. I do plan to "update" this model for flaps and retracts. I have also found several areas that without risking structural integrity I can lighten it up (Old plans).I am using AutoCAD 2014
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Old 02-23-2017, 09:24 AM
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Loud thanks, but I have looked at these plans carefully and they aren't accurate, and I agree with what you had to say.
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Old 02-23-2017, 10:07 AM
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Even the best of the line drawings you can find take days to justify the sections to the plan and profile. The I go to "airliners.net for as many photos that will help me see the true shape. The stuff I got for the Beechcraft 350i King Air I am finishing up had sections that were very round. But found some fore and aft end view that showed the sides bottom and top were not so round the had almost the same radii on the corners front to back!
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Old 02-23-2017, 10:10 AM
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Are you into solid modeling the models? Love to learn how that is done might speed things up and make stations that are more compatible one to the other. Sometimes I do not see the problem till I start making the cut side stringers.
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Old 02-23-2017, 10:53 AM
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Loud you are a big help to me, Thanks. I also have access to Cadworx which will let me actually draw the parts and test fit them. It does make the project a little reliable I guess but I have been doing autocad so long, I don't see any problems. I see what you meant about the drawings not being "true" . I am seeing that on this Cessna vertical stabilizer also and haven.t checked the horizontal or elevator yet..
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Old 02-23-2017, 12:46 PM
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I started drawing with angles , 'T' square and pencils of different hardness! Then a Amiga 200 and a then very good CAD program. Then to AutoCAD in '94'. been in it ever sense! All my designs are done 2D. I have used SolidWorks 2016 3D at work, but on simple shape and nothing like a fuselage or wing. I am hoping to get into AutoCAD 3D, I have ACAD 2014.
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Old 02-23-2017, 03:56 PM
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load, thank you for the information. Which Windows are you using AutoCAD 2014 in? Dan.
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Old 02-23-2017, 05:28 PM
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Add ~ w10 pro [who is load]
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Old 02-23-2017, 07:24 PM
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load is Loud with a typo.
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Old 02-24-2017, 02:40 PM
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Default ME AND MY BIG MOUTH, Cessna T-50

I said I am going to redraw the RCM Cessna T-50 and I am. For the last few days I have been measuring and figuring the model. I wanted to tell you something that is a great help for silhouettes. If you buy a high quality plastic model kit such as Hasagawa, Tamyia and other brands. You can scan a picture of the parts into your CAD and get the correct radiuses and shapes and correct scale. I have been using a micrometer for the last few days checking the Czech plastic Model kit and looking at pictures online to check if it looked correct, it does. The model is 1/48 scale, all I have to do is upscale it to 1/12. The RCM is roughly 1/12 scale with several things that aren't correct. So I am going to fix that. So with my big mouth I have gotten myself into a lot of work LOL.

I also wanted to say thanks to you guys here for your help.


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Old 02-24-2017, 04:49 PM
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What I am using at the time is AC 10 light
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Old 02-24-2017, 08:24 PM
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Don't know that one???
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Old 02-25-2017, 05:16 AM
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. Loud AutoCAD 14 light is the version without the 3d. I really have the most experience with 2D, I can do 3d but am more familiar with 2d, my son is a hot shot with 3D. I can do anything I need with 2d, it just takes a little longer.
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Old 02-25-2017, 05:43 AM
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Default Cessna T-50 Progress

I have spent the last few days studying the original plans from RCMS Cessna T-50. Thanks to Loud design and some of you others here, I decided to pretty much completely redesign this thing. I have been gathering information and also bought a plastic kit that I have been checking with calipers and mics and a scale converter for accuracy so I can take pictures of the vertical stabilizer, rudder and various other parts to import them into my cad for shape.. Someone suggested I scale the model, this is my first foray into drawing a plane. After checking at how exacting these newer plastic model kits are, I thought it a good idea to check one out for accuracy to use for outlines.

I take my hat off to the original drafter who drew this RCM model because the technology from 1964 and today is so different. I know what he did to draw this thing, but so far I have found so much out of scale, I have decided to redesign the model completely. I will still be able to use his plans to assemble and ideas for design. I just hope when I am finished it will fly a little better than a city bus.
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Old 02-25-2017, 07:54 AM
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old, is that the original AutoCAD 14 you are talking about? Dan.
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Old 02-25-2017, 09:03 AM
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One thing I do that you might try, is if you are a Excel user make a spread sheet with sections for the various parts; wings, fuselage[station/formers] and the trail components. take all your measurements and record them, then start drawing!! You can set up the scale formula so that you enter the raw measurement and Excel with fill in the scale-up measurement in the next column!
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Old 02-25-2017, 10:58 AM
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Loud, good idea
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Old 02-25-2017, 05:26 PM
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Dan, Yes. It's called CAD light because it's their mot simple version. You can do about anything with 2D you can do with 3D except make a model, it just takes a little more work and thinking.
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Old 02-25-2017, 07:31 PM
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Oldbassard, since all three threads are about the same project I've merged them into one thread.

It's a better way to do this since it makes it easier to find it later and follow the progress instead of starting a new thread about the same project every other day. So please keep all your T50 project posts to this one thread.

The Bobcat is one of my own favorites too. I'll be watching this with keen interest.

Have you seen the Paul Matt drawings of the T-50? Might those be a better place to start.
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Old 02-26-2017, 10:00 AM
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BM, I understand that, by all means
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Old 02-27-2017, 07:14 PM
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I have been having a better look at the design on this plane, Loud Design was right when he suggested using 3d. But that's about a 60 mile round trip for me to my sons office and I'd be in the way. I will tough it out with 2D and have already started. Later I will post some picts of my methods using 2D if anyone is interested
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