|Apr 19, 2007, 08:04 AM|
Designing a Miles M14 Magister in CorelDraw.
Ok, for those that are interested, off we go.
The first stage was to identify a type. I wanted a sort of speed 480/200W sort of lightweight aerobatic plane with a bit of character.
I didn't want flaps and complicated canopies and retracts.
And I wanted a 3-view.
This one fitted the bill. The drawings are on the Russian Airwars site.
I pulled them down, and disaster struck. Could NOT read the tiffs..in Corel Photopaint.
Fortunately my beloved (today at least anyway ) wife has a MAC with Adobe Photoshop so a quick bit of interchange on the Linux server we both use, got them to her, and she managed to read them and turn them into GIFS. I pulled them back into Photopaint, and turned them from gray scale to sort of blueprint style, because its easier to trace over a faint color than hard black and white.
I then imported hem into Corel Draw.
It turned out that a scale of 1:8 gave me a wingspan of about 50" - perfect.
I used the Corel 'scale and mirror' command to scale the bitmaps up by 150%, and that seemed to get me spot on to a 1:8 scale.
I drew some blocks over the bitmaps the same length as the wingspan, and drew a circle to match the prop diameter.
I have several custom sizes of paper set up in Corel to suit my printer.
As you can see this one is called (for historic reasons) a 1200mm long Peter Rake special ..
One of the most useful things in Corel Draw is that an object that is selected (clicked on with the arrow tool) displays its dimensions in the little boxes in the top left corner of the screen. In the picture second shown you can see that the prop disc circle is selected and shows 260mm..as near as spot on for a 10" prop, which again is perfect since I hoped to use something like a 10x7 prop on this model.
Finally I rearranged the bitmaps not to overlap, and right clicked on each one to select 'lock object' - this is a useful feature that stops you accidentally selecting and dragging the bitmap about..however if you do inadvertently grab and muck up something, CTRL-Z gets you back to where you were, in Corel.
Next step is to trace the outlines and get down to some structural design.
|Apr 19, 2007, 08:38 AM|
I forgot to mention some other things that you need to get set up in Corel
First of all the paper size should suit your printer. In my case 24" wide maximum.
secondly the scales on the rulers should be set up..you can do this in various ways but right clicking on the rulers and editing the dialogue boxes gets you there. I work in mm mostly, as I find it harder to remember that e.g 1/16" balsa is 0.0625" than 1.6mm..
Now, on to tracing. Never ever use the built in trace function. You end up with a mess.
The best way is to build up from basic shapes using the Corel Trim, Intersect and Weld commands and then tweak to shape.
When doing e.g. wings, only do one half, then flip it with the mirror command to get the other wing.
Here I have drawn a box, and pulled a guideline out to mark the model centre line. These just appear naturally when you click in a ruler and drag away. Guidelines are incredibly useful things. However I won't go further into them yet.
Now I right click on the drawn box and select 'convert to curves' - this means the box is no longer a box, but just a selection of (cloed) straight lines, and by using the node tool (double click on the object brings that up) I can set the 4 corners to what I want.
Then I zoom in on the detail and double clicking with the node tool adds a couple of nodes at the wingtip.
All the line segments must be 'curves'
All the nodes must be 'smooth' - that means they do not represent 'sharp' points.
All this is done by right clicking the segments or lines with the node tool selected, and selecting the appropriate option from the drop down list. I cant screen capture this bit though as the ALT-PrtScr cancels the drop down box..
Next the tip shape has to be adjusted. First off move all the recalcitrant nodes onto the tip outline. Then click on segments of line and push them into shape. Finally take the handles on the ends of the Bezier tools to get as near a perfect match as you can be bothered with. If necessary add more (smooth) nodes.
Fortunately the Miles designers had no better than French curves, and Beziers work very well
|Apr 19, 2007, 09:11 AM|
Now to mark the aileron position. I will create a separate outline inside the wing main area for this. You will see why later. Suffice to say its a good idea that every major component has an outline all round it.
This gets a bit 'interesting' so follow carefully.
The first stage is to define a box that sort of matches the aileron.
Then by double clicking on it with the pointer tool, bring up the skew and rotation marks, and skew the outline to match the hinge line..
Select the 'intersect' tool and with the new box selected, make sure the 'leave target object' and 'leave other object' boxes are both checked, and intersect the box with the wing outline.
This creates an aileron shape inside the wing outline. But the box and the wing outline remain unchanged as well. I have colored the aileron up by filling it with color to show this. Use of the intersect, trim and weld tools are vital to make for fast shaping in Corel.
Now we don't want any binding ailerons thank you, so I have used the 'position tool' to create two duplicates of the original box, one 1mm to the right, and the other 1mm to the left. These all have to be welded together.
The resultant box is then used to trim an oversized piece out of the wing outline. we now have two pieces - one is the aileron and the other the main wing.
This is the most basic way to form interlocking but separate objects.
You need it time and time again to turn outlines into parts..With Corel, you just keep adding in the detail as you go. Until you end up with cuttable bits of wood.
|Apr 19, 2007, 09:25 AM|
This is nice. I've already learned a trick or two. Thanks.
I do use Corel's internal trace function for a lot of my work (cutting from print plans). It is as accurate as the hand drawn plans, and, for my use, is fast. Only need a little cleanup every now and then. I would not recommend it for design work though as there are a lot of nodes added and lines that look straight really aren't.
|Apr 19, 2007, 09:36 AM|
Joined Feb 2005
|Apr 19, 2007, 10:15 AM|
no idea what it is..that's what the Airwars site calls it..twin tandem open cockpits..
You tell me. It's just something I grabbed...
Actually I would say it IS that plane but with open cockpits..and with the post cockpit fairing removed as well.
I suspect it was a military trainer adaptation of the thing you posted.
Hmm. On balance it looks more like the Miles M14 Magister doesn't it?
Oh well. The purpose is to get a plane designed, I'll let you decide what it actually IS
|Apr 19, 2007, 10:55 AM|
Joined Nov 2003
following with interest Vintage...corel draw is on the way..will be trying this stuff out as soon as it arrives.
cool thread man.
charlie helped me find the right drawing program..this looks like fun.
|Apr 19, 2007, 11:32 AM|
This is very good, even though I like Autocad much more than Coreldraw. Probably because I don't have much experience with Coreldraw..
I checked the Russian site and downloaded two M14 files; I guess your screen shots also show it is an M14 - if Russians did not make a mistake in identification
One of the Magisters had a Turkish built variant with enclosed cockpit (called Ugur) - I guess this may be the plane. I might convert the plan to that..
|Apr 19, 2007, 11:45 AM|
Autcoad vs corel. Depends on what you want and what you're used to. Corel does some things better than CAD, other ways CAD is faster. Best bet is to choose one and stick with it.
This is a good tutorial on how to use Corel for technical drawing.
|Apr 19, 2007, 11:55 AM|
Yes, don't read me wrong, I am willing to learn Coreldraw. I know a number of modellers are turning out wonderful scale models using Coreldraw, so it must be quite capable..
I could convert those 3-views directly to GIF's using Irfanview (free).. File size decreases around 8 times in GIF format.
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