Tracing vintage model glider plans - curved elements

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Robert36
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Joined: Wed Feb 21, 2018 8:37 pm

Tracing vintage model glider plans - curved elements

Post by Robert36 » Fri Feb 23, 2018 9:50 am

I'm curious if anyone has any thoughts on how I'm going about the following:

I'm using QCAD Pro to trace vintage model glider plans.

Aside from issues associated with poor scans or drafting errors, it's a fairly simple task. Tracing curved components such as wingtips, rudders, fuselage can be more or less difficult based on how simple the shape and line quality. I've used the following methods:

-Formers are often elliptical, those are easy.

-Use different shaped circles and ellipses, play with size and angle. It could take a couple circles and an ellipse to rough out one tip. The next step I typical use the spline tool set to snap to entity and cherry pick the underlying form.

-create a series of cross hatches the intersecting points describe the curve the connect the dots with spline tool.

Then typically I'll explode the spline, select the new entity and move to the proper layer if it isn't there.

I'd love to find some tricks. This kind of task can flow easily or fight me to no end. I'm not sure my results are as smooth as I'd like them. This is likely a slightly screwball task, reminds me of land surveying...... You try to find a few known landmarks, look for as many known measurements as you can find published, then you can of walk it out, do your circuit and hope you end on the point you started at.

I'd appreciate any tips or critique of my current method.

Thanks,
-Robert

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Clive
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Re: Tracing vintage model glider plans - curved elements

Post by Clive » Fri Feb 23, 2018 1:01 pm

Hello Robert,

For me what I do is set up a new dedicated layer called 'Trace' with a colour of Red and an appropriate line weight, then I use all the drawing tools available to trace over. In particular for curved drafting I use the spline tool with the various snap options and also with a free snap, especially for organic or free flowing curvy type parts.

Hope this helps a little :wink:

Many thanks

Clive
For the best support please state your operating system, QCAD version and add any supporting DXF/DWG files, screenshots etc...

Robert36
Junior Member
Posts: 15
Joined: Wed Feb 21, 2018 8:37 pm

Re: Tracing vintage model glider plans - curved elements

Post by Robert36 » Fri Feb 23, 2018 3:36 pm

Thanks Clive,
Ill give freehand a go. sometimes I have a tough time seeing as if the cursor is obstructing my view. Do you find yourself having to smooth out or refine the outline at all? One thing I haven't done is change the thickness of the line to match, that could make quite a difference I suppose.

Thanks again

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Clive
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Posts: 1327
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Re: Tracing vintage model glider plans - curved elements

Post by Clive » Fri Feb 23, 2018 4:29 pm

Robert,
Changing the line thickness will definitely help, after a while I became quite proficient with tracing to point where I could produce drafting for production output.
For the best support please state your operating system, QCAD version and add any supporting DXF/DWG files, screenshots etc...

Robert36
Junior Member
Posts: 15
Joined: Wed Feb 21, 2018 8:37 pm

Re: Tracing vintage model glider plans - curved elements

Post by Robert36 » Sat Feb 24, 2018 9:27 pm

Clive,

Thank you again. I went back and have been experimenting with using the spline tool freehand. I had tried that early on and simply didn't find it manageable at the time. With a bit a reasonable number of hours and a better understanding of QCAD and the process itself, I was able to get acceptable results.

The plan I'm currently working on is a glider first drawn in '56 but published around 1959. It's Jim Moseley's Walking Shoes. It's a special leasure to work on this because Jim is available and open to questions himself. He used naca 6509 for an airfoil but noted that he worked rather intuitively most often and would make changes relative to what looked right to his eye at the time.

With an imported airfoil as a guide, it is easy to see where he went off on his own and why. working freehand was a good fit here.

Cheers.

-Robert

Robert36
Junior Member
Posts: 15
Joined: Wed Feb 21, 2018 8:37 pm

Re: Tracing vintage model glider plans - curved elements

Post by Robert36 » Sat Feb 24, 2018 10:07 pm

This might be useful for some fellow modeler:

When tracing shaped part free hand, sometimes I get lumps or indentations where the fit point of a spline wasn't perfectly place.

To smooth a lump in a nicely flowing curve, I use the following:

select the curve to show fit points. At the fit point causing the lump a place a horizontal or vertical auxilliary line along the axis I want to drag the fit point. If it was a vertical line, I then place a horizontal line just below the fit point, often appearing to rub against the fit point.

I then grab the offending fit point and place it on the newly created intersection. It sounds fussy but its quite simple

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