RE: Raster to Vector question for Autocad users
A single bit TIFF (true black and white) will have clearly delineated lines rather that the JPG's usual gray scale that softens the edges of the lines. I've traced 50 dpi images but prefer at least 200 dpi images. It does not mater what the dpi is when you import into Acad. It would matter should you be taking the whole image and are trying to figure out what size you want to print it out through photoshop or illustrator.
Import the image into Acad to a layer that you make for it such as "Images". Don't bother with scaling either axies. Find a straight line such as the wing spars or even a centerline down the fuse top view and rotate the image to match the x/y of the drawing. This way you can leave the x/y lock on (ortho) and draw the straight lines. Once you have traced most of the image lines ( I use arcs and polylines besides the regular lines -- never splines) You can scale the image and tracings using a known dimension from the original scanned plans. I use other layers for lines; ribs, spars, etc.
I put center lines down the ribs and bulkheads rather than two lines as their material thickness. Scaling may not result in the 1/8" or 1/16" material thickness or you may want to change the material thickness. I also will develope/detail just one side or half and use mirror to create the missing half.
Tracing older plans is a labor of love. It's also a chance to introduce a newer model airfoil and beef up the structure.
Taking the parts out for laser cutting is another thread.