georbeckha

My Feedback: (12)

Hello all,

I have decided to take the plunge and Scratch build a plane from Plans.
I have plans for a Brian Taylor 69 inch BF109 that I want to enlarge to accept a Zenoah G38. (Yes, Large to Giant Scale)

My questions are...
Will simply blowing up the plans be ok?
What do I need to look out for if I just blow up the plans 30 - 40% (Making an almost 100 inch wingspan aircraft)
Any advice would be very welcome and appreciated!

Thanks
George

Jim_McIntyre

The bigggest stumbling clock I've encountered is distortion.

Most photocopiers distort the image at the extents (distortion increases as you approach the outer edges).

Also, even the higher end systems do not retain a perfect aspect ratio. One copier service I use have figured this out and apply separate magnifications to the X an Y acis to compensate.

Just to be sure, I mark scale on both axis at both inner and outer locations

An alternative to the local copy centre (If you have the time) is to use a data or overhead projector, tape paper on the wall, project the image onto the paper and trace at the scale you prefer while using marked scales to ensure (and tombstone) aspect is correct.

Best of luck!

the-plumber

In addition to distortion, there is the problem of line size.

As the magnification is increased, the lines on the output paper grow wider, and you face the problem of 'cut to which side of the line ?'.

If your cutting (or sanding) is inconsistent with respect to the increased line widths you'll have ill-fitted parts.

Jim_McIntyre

Good point.

I generally cut to the outside, and sand to fit. When It get's really bad, I trace to the centre of the blurred line with a different colored marker.....

pauliox1

i suppose (correct me if im wrong, which i probably will be haha) if you have good drawing skills and some idea of how to scale things up then you could redraw the parts cut em out stick em on your wood and cut out, or how ever else you cut your bits.

Paul

Chad Veich

My Feedback: (60)

All your wood sizes, ie sheeting, spars, stringers, and whatnot are going to end up at odd sizes. It will be up to you to go back and redraw to fit standard wood sizes and decide if the structure needs to be beefed up or not at the larger scale. (it usually does) A sound knowledge of engineering and materials is definitely recommended. IMHO, a G-38 is marginal for a 100" Me-109 unless you plan to build exceptionally light. Taylor makes good airplanes, if you do get it built I'm sure it will fly well. Best regards, Chad Veich.

BMatthews

A lot of the problems folks are identifying here are valid when the enlargement is 1.5 or more. How much would be be enlarging the 69 inch span? If it's within 25 to 30% then it's not a big deal. The lines will still look fine and hopefully the distortion will me minimal. Some of the wood can remain at the original size and some will need to be thickened up to the next size up from the plans. Depends on the application.

iaclmac

I have been scratch building for close to 25 years. Blowing up a good set of plans is not a big problem. If you have a full service Kinko's close by it is pretty easy. If your orginal plans call for a 69" span and you wish to go to 100" span ... simply divide 100 by 69. That will give you the percentage of enlargement. In your example 100/69 = 1.45 or 145%. Take the plans to Kinko's and tell them to enlarge the original by 145%. Now there is only one catch. Depending on the layout of your orginal plan, it might have to be copied done in 2 passes to capture all the information. In essence you ned up with a sheet with the wing and a sheet for the fuse. It isn't a fate worse than death. Another hint for you ... when I have plans enlarged, I always pay to have a second copy made. This way I can cut up one for building and I still have a presteen one in case I wish to build it again or possibably make modifications

Jim_McIntyre

Another good practice.

The ink from many copiers is heat activated. You transfer the shape to wood simply by ironing the back of the plan with the inked side on the wood.

Jim_McIntyre

Also, many copy shops now offer large format scanning.
This not only allows me to better organise my plans but, I can enlarge to suit by using a data projector to project onto paper at the scale I desire, and simply trace the projected lines.
If you have a cad program handy, it's even easier. Simply load the graphic to a layer and trace to another layer. Toggle the drawing layer visibility to ensure you capture all the lines, now resize at leisure.[8D]

SCALECRAFT

My Feedback: (13)

A few things to also look out for. If you use the Kinkos continuous roll copy machine, it will elongate the finished size. Ribs and bulkheads included. Even at 1 to 1 with no enlargement. May have been the machine at this location, but it happened. Also if you use a Overhead projector, be sure you project on a surface that is at a perfect 90 degree from all angles from the projection and the surface flat as possible. And of course see if it looks right.

Steve

grbaker

My Feedback: (29)

I agree with Chad here. I have seen a TF P-51 (85" wing) fly with a G45 and it was not overpowered. A 100" span warbird would be better with a G62.
If you need to use your G38, I would only go to about 80" span which would be about a 116% enlargement of the original plans.

dicknadine

whichever method you use, will work for the outline and not spacing of the internal parts. the wood sizes will also go up the same perentage. ie. if you triple size the outline the part sizes are also tripled, 1/16 is now 3/16, 1/4 is 3/4, rib spacing was 1" now 3". you have to have prior design and build experience of structure. so remember upscaling is good for OUTLINE only. dick