Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Temporary FAQ position for linking

Need articals, general tips, ideas.

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

is this taking the place of scratch build?? dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

No Dick, it's an additional thread to gather articles, links and other info for a wider array of topics.

I did this a while back for helping those trying to use TurboCAD. I've brought it up again for the FAQ.

____________________________________
here's a list of helpful hints I did some time ago for another newbie. Much of it will seem like Greek at this point but start with item one and search out what I've tried to say and then do the next point and work your way down. By the time you get to about 5 or 6 you'll be ready to start drawing and then you can add in the rest as they come up. They'll make more sense that way.

And yes I know I said TurboCAD here but the only TC specific issue is the way to get to the snap functions. Just look up what you have and how to get to them and then incorporate snaps into your style.



Once you finish playing start with something simple like a basic wheel. A couple of 180 arcs and straight lines for the front view and a few concentric circles for the side view. Then modify it a few different ways. Copy it and mirror it. Play with it and you'll learn.

_________________________________

OK, time for unca' Bruce's "Baker's Dozen TurboCAD Rulz"....

Item 0 for newbies of course is just playing with the lines, double lines circles and boxes and then learning to EDIT these drawing parts. Play with that for a while and learn where they are then jump right into item 1 below.

[ul]
[*]1- Learn to Snap. Learn what they are, how to invoke them, particularly the shortcuts, and USE them as much as possible. Only very rarely should you start or end an element without using a snap to grid, vertex, middle, center, etc. For TurboCAD this falls under the SEKE (Single Entry Keyboard Equivalent) list. I doubt I draw, move or modify more than 5% of my work without using a snap. This is not only rule #1 but it may be the most important rule as well. A CAD program sinks or swims on the basis of it's snap functions when you know what you are doing. It ensures accuracy and greatly speeds up performing accurate work. CAD programs that make this function hard to access and use should be relegated to life as a coffee table coaster.
[*]2- Never draw the same thing twice. Sounds simple but sometimes you need to think about it. Tools that allow you to fullfill this tip are Mirror, Array copy (linear, radial and matrix) and Copy/Paste. When I work on a wing I'll do all the work on one side and then mirror the whole lot over. If I have to do a change I do it on one side, delete the WHOLE other side and just mirror the whole lot over again. Use the V key to snap to the ends of the center line or the G key to snap to the grid if you had the presence of mind to align your drawing to the grid lines. Only if I do a couple of simple ADDITIONS will I just mirror the additions. The wing ribs are done by drawing in ONE rib and then selecting it and using the Linear Array tool to replicate a whole set at the right spacing. Use the TAB and enter the actual numbers in at the command bar on the bottom of the screen for accuracy.
[*]3- When using the selector arrow you can add or drop objects to the group of selected objects by using the shift key. Pressing SHIFT brings up a little + beside the arrow. Don't pass over the fact that there are two selector types. The normal one and the Node edit one. The node edit one is particularly handy for changing the elements of a curved line but work on all types of elements. Here again you can either drop the node freehand or with a SEKE.
[*]4- Placing elements or groups of elements accuratley can be done by using the snap. But often the reference point is not where you want it. Another SEKE that is useful in this case is the D key. Pressing that while elements are selected lets you move the reference point to anwhere you want. Dropping it using yet another SEKE ensures that you put it where you want it.
[*]5- Use the right mouse button a lot. It brings up the greatest option boxes at the best times. It's position sensitive too. Over the drawing it has one set. If an item is selected it has another set of options. If you right click on a tool button it opens up the Properties for that tool, line type, text formating, etc.
[*]6-Always draw in full size. It's a lot easier and the computer doesn't know or care if you're asking it to make the paper the size of Manhattan. It'll still come out fine on your 8.5x11 at print time if you just set the paper that way and check the "fit to page" box. This will save you a LOT of math and make the drawing correct for later printing at Kinkos or other large plotting services.
[*]7-The hard drive has LOTS of room so don't ever delete anything. Allways keep the old file until you KNOW you won't need it and even then keep it for another month. THe same thing applies for the drawing. If you want to try some aesthetic changes to a model copy the present version and paste a second copy to one side and work with that until you are sure you like the new version better. In this vein I never work with my "final" plan at first. I work with a file where there are often 3 or 5 versions of the design scattered about with wing ribs everywhere. This is my rough file where no face can be too ugly to the point where it deserves deletion. From that rough file the final choices are made and whole wings and fuselages are cut and pasted to a final presentation file. Most of us do our best work on a scratch pad where there are no rules. This rough file IS that pad when you are comfy with your CAD. Models are an art form. It's OK to create mulitple versions of your own Picasso. (What do you MEAN I can't have both wings on the same side of the fuselage... )
[*]8- The Trim tool is used for lines that are interrupted by overlying elements. To make the drawing look good you want to hide the bits underneath. The Trim tool is the one for this. You start by selecting a "cutting edge". You can add additional cutting edges by using the SHIFT key. Then click on the bit that goes past the line or under the double line or between the first and second cutting edge. For example you can SELECT all the ribs (double lines) in a wing panel as cutting edges and then click on the bits between each rib's double line to eliminate the hidden bit.
[*]9- The Split tool is nice for splitting a large or long element into two or more if you need to move a part away. For example you want to "lift" the cockpit canopy off a nice long single curved sailplane fuselage side view. Use the Split tool to cut the curve at the ends of the canopy and then select the canopy part along with any formers or other parts and move it up as desired.
[*]10-The Grid comes in handy for a lot of things and as a quick ruler that is always there. I like to set up the drawing so the grid is on and it shows at the 1/2 inch spacing with a heavier line at the 1 inch lines. I actually bring up the Grid Properties and set it to 1/4 inch and then set the frequency to 2 so that the lines still only show at the 1/2 and 1 inch marks.
[*]11-TurboCAD let's you select line widths. Ignore this for the most part until the final stages of a drawing. Using that function to early actually draws the line thicker on the page and as you zoom in and out the line is thicker or thinner. It also make snapping to the line difficult as it treats it as a filled double line and you'll end up snapping to a corner rather than the center of the line as you intended. To make the lines thicker FOR THE PRINT ONLY go into the Options/Drawing Setup/Display and set the box at the bottom of the page where it says "Device pen width when zero value is used" to a new value. I find I like .010 for most 8.5 by 11 and increase it to .015 for vellum prints where I'll be making blackline prints from them later. Other line widths can be set to thicker by select and command as a final step. But save the last "zero width" drawing for reference because it's cumbersome to re-zero them later I found.
[*]12-After a while you'll get to know how you want your drawing options set. At that point open a new drawing and set everything for one last time. Be sure to get it all. The text size and style, default line width, units of measurement, etc. Then save it in the Templates directory as a TCT template file with your name or Models or something like that so you can find it when starting a new drawing. You can also set up a paper size for little sketches if you wish with a border and nice title box. That's assuming that the stock ones aren't enough for you. There's dozens with the standard version of the software.
[*]13- Line types. Just play with them. For curves my personal preference is for the Spline over the Bezier just because I find it easier to get a smooth form. For times where the curve line vertex MUST land on a specific point then use the Bezier and just learn to get along with the fine tuning (node edit mode). For edge on views of balsa the double line works great and allows for ideal and fast trimming as noted above. A trick to making curved sheeting lines is to form the curve baseline using the Spline or Bezier tool. Then right click the double line selection box to bring up the Properties and click on the Right or Left reference. Select the Mulitpoint Double Line and lay down a close spaced set of vertices using the curved baseline and the Near SEKE to snap the double line down onto the curved line. Yes these ARE all little tangent segments rather than a smooth line but if you keep the segments short where the curve is tight and not too far apart where it isn't then the error is lost in the line width during printing. It's cheating but it works and is fast.
[/ul]

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

why not separate it into 2 spearate forums/methods. some of us are Not computor people and some are not paper,pencil and calculator people. we have the habit of coming close with end product. it sort of frustrates me to read about the computor methods, when I know nothing about computors -- have trouble sending EMail-- others do not know how to draw a straight line with a pencil. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Think of this as a rough draft. At this point I see these two threads as information gather more than any final form. This is a tough FAQ to put together and should probably be split into multiple threads or at least specific topic posts within a single thread with a table of contents at the beginning. But ThunderAI seems to be getting more intrest than I was able to when I tried a while back. So more power to him and you guys.

Dick, here's your chance to fight the dreaded 'puter contingent. If you can offer up any manual methods as articles then I'm sure there's an audience for your ideas.

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

The "Design & Building" page on my site, at http://www.nextcraft.com/rcdesignandbuilding.html has a number of scratch building articles, including several composite-related articles, general "design concept" articles, and a CAD "tutorial" that's as generic ( for different software ) as I could make it. You're welcome to refer to any of them, if you think they would be helpful.





_______________
Edited to correct link to Mike's new website.- bcm

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Geepers, step out of town for a couple of days and you get lost as to where things had been.

One fellow is trying something, then throw in a couple of compatible or contrairy advocates, and I can see how things can get confusing for readers here.

You shore lost me in all of this.


Wm.

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Welcome back. ThunderAI has taken the bull by the horns and is keen to gather lots of good stuff to form up a FAQ for the group. And I, not being one to stand in the way of a man with a mission, applaud his grits... :D

It's long overdue.

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Well everyone will need to help, I'm a man on a mission, but I need helpers... Plus, I need you mods to edit the posts as well to update the information as it comes in!

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Hi folks

I think this a great start. I was wonder if some one could explain how the enter a airfoil to a cad drawing. I am using Autocad so help would be great.


Ron

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

thanks for the basic dozen of TurboCAD tips! i just picked up the cheap ($25) Tcad designer 9.2 at Best Buy last weekend. I found printing out the manual has really helped (As opposed to searching through the included PDF). your tips did help me focus on the "important" features, and techniques.

as for importing airfoils: some airfoil plotting programs (Profili(?) is one I believe) will export to a DXF file so you can import them right into your AutoCAD drawing. I plan on doing that eventually myself, Tcad can import as well.

one thing I would LOVE to be able to do is import a JPG, GIF, BMP etc of an aircraft 3-view as a layer and then "trace" over it to do formers, outlines, etc. It seems like a fast, easy way to start a design......does anyone know if Tcad can do this??? perhaps the "pro" version can, but not the cheap "designer" version I have. Grrrrrrrrrrr! =)

-ron

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

in response to thread, I have tried to put almost 70years of model building to words in a logical way, however from what I have read above, thru is no interest in pencil, ruler, etc anymore. guess us old farts will have to keep doing our old fashion things and forget about helping the newcomers. that is unless a couple of the contributors stand up and help. might be pretty strong-- but thats how I feel. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

dick-
in response to your post, I can understand your "frustration".

the way I look at it is this: computers are just tools. the basic concepts of aerodynamics do not change, it is just another way to put ideas and designs down on paper. the ultimate goal is to produce a plan, and from this plan a model aircraft. i love my notebook for sketching design ideas. pencil and paper cannot be replaced in this regard. but having scaled up a 3-view to a full size plan using pen, paper, protractor, french curves, manually plotting airfoils....and then beginning the same process using a CAD program, the CAD just makes things easier! i can focus my time on design and building, and not on re-drawing lines, or re-sizing something, etc. Why not use the best tool for the job? At least, given my knowledge, the best tool for me. The same way using a Dremel tool to grind or shape is faster than doing it by hand...or using a jigsaw instead of an x-acto....or using a power drill instead of a hand drill...or using a calculator instead of doing calculations by hand...or using a glow-engine instead of rubber power! Computers are just tools. they do a good job if you know how to use them. And with the advent of laser cutting and Kinkos print shops offering plotting and printing, it just makes sense to use the best tools to get that plan printed, and that beautiful aircraft all the way from idea through design to building and to flight.

The difference I think, is that I and others have a lot of general computer experience which has been acquired over years, and with basic concepts of computers and software, and the learning curve is substantially less steep. In the case for you and others who do not have that base knowledge, maybe pencil and paper is the most efficient way to design, given the steeper curve of trying to learn the CAD and computer concepts, which are so intertwined. To each their own, use whatever method works best for you! the goal of making a plan, and a plane, has not changed.

just my 2 cents.

In the same regard your design and conceptual knowlege is likely far greater than us younger, newer, modelers. I hope you do continue to help in that regard! Who cares how the person uses the ideas you present.....as long as they get it down on paper, using a computer and printer, or a pencil and paper, it really doesnt matter! So yes, there are two different "threads" here potentially. general design concepts, and CAD implementation of these concepts. or maybe a third...pencil and paper implementation! how to plot airfoils using a ruler and french curves, how to scale up a 3-view, etc. Lots of people still draw plans on paper, and why not? its easy, simple, cheap, and effective. All ideas are valuable. Just not all are applicable to everyone. =)

sincerely,
-ron

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

OK, now let me just say something about turboCAD once again! =) I had asked about importing a picture file to a drawing. I figured out how to do it!

from the Insert menu, click on Insert, Picture, as Object. Make sure you have converted your 3-view to a bitmap or a .WMF picture file. then select it.

The problem I was getting was a message window popping up saying "This action cannot be completed because the other program is busy.....". Im not sure if this is a TurboCAD issue, or just my computer, but in case anyone else encounters is, just click on the "Switch To..." button and wait. The drawing will eventuall appear, and you can begin tracing your outlines or whatever you want to do.

You can refer to the documentation for using Layers, and set the drawing as one layer, and trace "on" it using another layer. Eventually, you can hide or remove the 3-view, and you will be left with your plan. I am still experimenting with this, but the Layer concept is the same as programs like Photoshop if you have used that.

Incidently, I am using TurboCAD designer 9.2, which I got from Best Buy for $25. it seems like it will be able to do the trick, and gives a lot of bang for the buck.

-ron

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

guess I'm alone in my scratch drawing the plans or copying them. will have to stick with it as the computor is a DAAAAHHH to me- have a he-- of a time sending Emails and have resisted learning the computor, at 80 years young the mind does get confused easy, that why I stick to the pencil and carbon paper. more power to whatever method is used, the name of the hobby is BUILD your models and FLY them. will continue to help-- just ask. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

You are correct DickNadine. The objective is to build and fly. One can get really lost in the process if you want.

Computers.

I've found myself going off on a tangent doing a sub program to take in airfoil data. Three days later I realize I'm behind schedule on my obligation to my customer.

The one thing that has saved my cahoonies is taking typing in high school. Found out that the freshman girls took typing so as a Junior I convinced a couple of buddies to take typing with me! I remember my dad having a fit as he could find no redeeming value in a guy taking typing in the early 60's.

As I've been building (off and on) since the age of eight I have mastered the carbon paper and pin method. Best book is Frank Zaic's book. Shows all the tricks to scaling with a simple ruler and paper. The book was first published in 1944. Now I use the confusser and CAD. Still do a bit of cheating with scanning and scaling into the CAD program.

;)

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

sounds super GOOD. as the old guys used to tell me-"it ain't what you do, its how you it". keep up the good work of Trying, the old fashion ways are still pretty good. finished the covering job on the HOOP PLANE tonite. will put the finish acrylic clear spray paint on to morrow, all thats left to do is hook the controls, mount engine and get courage up to head for the field. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Is that silk or tissue and dope????

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

its good old fashioned Coverite. will add a finish spray coat, keep dust and fuel out. will continue to keep all informed of progress. slowed down a little last nite, tried to brand my stomach last night with the iron, hurts a little this am. lesson learned, don't iron without a shirt on. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Taken from another post around here. Special thanks to user adam_one for finding or drawing up these sketches.

What we have here is a good general proportion sketch for a basic model layout. The two sketches show an upper and side view. My own feelings are that the tail moment spec should be noted as 2 to 3 chord lengths but what is shown there is fine. If you go for the 6 chord wingspan option then I seriously recomend the 3x tail moment. It was also noted in the original thread that these proportions also hold true for a low wing model but that for a trainer or second model the dihedral should be increased to roughly 1.5x that shown. For a more sporty model the dihedral can be minimized but for a true low wing design some dihedral will make it track better, perhaps 2 or 3 degrees. Mid wing designs with true aerobatic aspirations won't need any dihedral at all.

Other comments off the top of my head are that for a symetrical or very low camber airfoil (AKA semi-symetrical) the lower end of the stabilizer size range is fine. For a flat bottomed, and especially a thicker flat bottomed, airfoil the stab should be kept up at the 20% point and combined with the longer 2.4x (or 3x) chord for better longitudinal stability.

Other than these little items the proportions in these two sketches look pretty durn good if you want a basic fly around model or even a trainer. If you start stretching things (like going to a higher aspect ratio then it all falls apart so don't stray too far from what you see here).

Be sure to post up your plans if you try a new design based on these. Cheers....

PS: The original pics and more explanation can be found at adam_one's website at http://sky.prohosting.com/air2/ . Check it out, he's got some great stuff there. Thanks adam_one!

http://www.rcuniverse.com/forum/upfi...4587_29284.gif

http://www.rcuniverse.com/forum/upfi...4598_29284.gif

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

its Yellow Coverite and 1 coat of clear Urathane Varnish. will start final assy tonite. will then find out what step I missed, like tubes for the rudder and elevator servo wires,etc. Nadine is painting the pilot up. it ain't done till its in the air. lets KILL the definition of Scratch forum. its getting pretty IDIOTIC over nothing. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Hi Bmatthews,

Thanks for your appreciation, I agree that the tail moment range may be up to 3x chord length and I've updated the sketch accordingly.
I hope it's useful as a guideline for a basic trainer and all constructive suggestions and comments are welcome.
Cheers,
adam

test only
 

sorry test only

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

finally back with you, the computor blew its top and I have had to resort to my old fashion way of producing plans. its still fun. the only thing I cuss out is the smudge marks from the crummy eraser. have more hand drawn plans than I will ever use, next time it be something different-- there it is - that new antique plane, shown in my new bible, "World Ecyclopedia of Cival Aircraft", by Angelucci. check the book sellers. dick

RE: Scratch Building, Aircraft Design, 3D/CAD FAQ
 

Your link does not seems to work Mike.