1/16 scale Po-2, "Night witches" version

[OSTOJA]

Scale 1/16 requires a very detailed granularity. So far, your work is guaranteed. Good luck.

[milenio3]

I chime in with all the others, to say this is going to be an over-the-edge thread and paper airplane.

Carry on!

[Leif Ohlsson]

Thank you, Allen, Glen, Don, Ray, Peter, Chris, Bernoullis, Michael, Pericles, Ostoja, and Gerardo for the warm welcome. It is good to be among friends. I'd like to start with a few notes on one way of going about this business of enlarging already printed models.


Preparing the original model for printing at 1/16 scale

The preparatory work for making a rescaled home-printed original involves several distinct steps:
• Scanning
• Resizing & color adjustment in a graphic programme
• Rearranging parts into new sheets that will fit your printer; also done in your graphic programme
• Printing


Scanning

From previous experience I've learned that I will most certainly want to work with the colors after scanning, adjusting levels, contrast, color hues, etc. In order to get the same result for all sheets, I stick a small pre-printed strip with three shades of grey on all pages:



Above: The strips contain three small fields of 100% black, 50% black (grey), and white. Later, they will be used for getting the same "level" adjustment on all sheets. ("Level", I understand, is the Photoshop term for "degree of lightness".)


Resizing & color adjustment

The second thing you will have to think about is scanning at a convenient dpi number. This time I wanted 300 dpi originals after enlarging. Scaling from the printed 1/33 original to my desired scale 1/16 means enlarging by 206,25%. Therefore I scanned at 619 dpi. Importing into my graphic programme, I just have to adjust the dpi value of the scans to 300 dpi (with the option "do not resample" checked, which I understand as "spread the existing pixels 206,25% thinner, while not changing the actual content"). This will get me my 1/16 new scanned originals at an instant; true "one-click enlarging".

In the graphic programme, the black-grey-white strips were sampled in the "levels" dialogue box to get the same adjustments for all sheets.

The next step is important. I wanted to adjust colors further, and to ensure that I get the same adjustment for all sheets, all color sheet scans were collected into one huge master file, and the B&W sheets into another. In the large color file I changed color tones and levels further to something much lighter than the already adjusted scans. The goal here is to make all details come out as well as possible, and the colors as true to what you believe is correct as possible. The result is closer to the printed originals than the scans, and even somewhat lighter. It's what looks good to me. You've got to trust your own judgement sometimes.


Rearranging parts

The third stage is fun. This is where you create your own new actual print sheets. I print most large parts on what I pride myself about as my own little invention, the "L3" size paper, which is A3 length (420 mm) cut down to Letter width (216 mm). This is the maximum width my ordinary printer will accept (I don't have an A3 printer). This size has long since been entered as an extra option in my printer (a most simple and old Epson D88) dialogue box.

Now parts are cut from the original "parts" layer to a new "sheets" layer so that they will fit into marked L3 paper sizes until all parts have been moved to the "sheets" layer in the same document, and the parts layer is empty (this is an easy way to ensure that you really get all parts into your new sheets, and don't forget some little detail). Here's what the result looks like in a "before & after" comparison:



Above: Parts from each original scanned sheets to the left are copied into proper, separate print sheets to the right. As you can see, the original 4 color pages, once in A4 size, now have multiplied into 12 large "L3" sheets. This is par for the course. One A4 page at 1/33 scale, will usually require 3 large "L3" sheets at 1/16 scale.

You will perhaps also notice that the large wing parts had to be divided into outer and inner sections. This is not a big problem; joining them can be done pretty invisibly, particularly since I made the divide at the point where the ailerons start, so there's already an interruption of sorts.

Note also that I managed to save some space by a more sensible arrangement of the "N"-shaped wing- & center section struts.

The same procedure was applied to the B&W parts. Here, I preferred to make a mixture of large L3 sheets for the larger parts, and ordinary A4 sheets (A3 cut in half) for the smaller ones.


Printing

When you cut the A3 sheets to L3 size, you will get a lot of left-over strips 80 x 420 mm. Cut these in half to 80 x 210 mm. They can be used for printing extra copies of parts you will want to make extra copies of.

Make a template A4 sheet with a guide 80 mm from the top. Paste parts which you will want to have extra copies of here, like wheels, instruments panels, inside of cockpit (to make simulated framework). For some of these, like the framework parts, you may want to print several copies.

No big deal, since the paper you are going to use is scrap anyway. Keep the rest to be able to print parts you mess up later. You save a lot of paper this way.



Above: The new sheets actually printed beautifully - the lightening and color adjustment of the scans proved to be perfect in my own wiew. New, printed sheet in the foreground - corresponding part of the original model in the background, in the middle of the left page.

Leif

[John Bowden]

Flashback---------------- I see............ a Large Scale Russian P-39 Airacobra.......... no wait.

It's just another fantastic build thread by Leif!

Yes, this will be a pleasure and learning experience all in one.

Gather around boys and girls this is something you will regret missing!

Oh and you will need to take notes, not for a test, but to improve your modeling experience.

[OSTOJA]

Leif, for the bending elements is important the direction of the paper fibers. It is better to bend if the fibers are arranged along the bending line.

[bernoullis]

This time I wanted 300 dpi originals after enlarging. Scaling from the printed 1/33 original to my desired scale 1/16 means enlarging by 206,25%. Therefore I scanned at 619 dpi. Importing into my graphic programme, I just have to adjust the dpi value of the scans to 300 dpi ...... This will get me my 1/16 new scanned originals at an instant; true "one-click enlarging".

Well I'll be darned! I would never have thought of doing it that way! That is ace, Leif!

Yes, this will be a pleasure and learning experience all in one.

You are not wrong there, John!

[Leif Ohlsson]

Hello John, nice to see you, too!

Ostoja, thanks for the warning. I think your concern is about the wing parts. We'll have to see.

Bernoullis, I find that particular technique of enlarging very rewarding as well. Learned it on the site from someone else, of course.

Here's the challenge that really enticed me to start this build, and report it:


Redesigning the engine compartment for electric motor & battery

Since I'm building a model of a decent size, I thought it would be nice to have an electric motor and rechargeable battery in it to turn the prop, just for fun, to get the CG more or less right - and for showing off. That meant redesigning the engine compartment - which isn't trivial, since that section of the fuselage is the only one not built up of any framework parts, except for front and back formers.

The replica (paper) engine is glued to the front former, but the section behind that consists of nothing but a skin part, which requires some complex forming when installing. For drawing parts that will fit in this empty, former-less, space, I found no better approach than to enlarge the sideview in the instructions.

To get the exact proper size, I positioned one of the scanned cockpit framework sides parts in the drawing and enlarged the instructions sideview to fit that part perfectly. For the rest I will have to trust that the instructions drawing is reasonably correct. Here's what the engine compartment redesign drawing & the parts derived from it look like:



Above: In the redesigned engine compartment you will note that there now are two sets of framework parts fixing everything: the mount for the electric motor, which also serves as mount for the rechargeable battery, and the bottom mount for on/off switch and recharging receptable.

If anything is wrong in the instructions drawing used, and the covering skin part doesn't fit when the time comes, I will just have to resize the skin part to fit exactly. I know from experience that this is doable (see this fairly interesting attempt to fit a BPM model winter Po-2 skin onto a KK model of the Po-2). At this point, of course, I still hope that the drawing used is accurate, and that the nose skin part actually will fit.

Here's what the new engine compartment framework looks like with motor and battery mounted:



Above: The motor and the the battery comes from an old scrapped electric toothbrush. The top former you see is actually the nose former, as evident from the paint work. The engine replica, not built yet at this stage, will be stuck onto the motor, with the shaft extension sticking throught the front conical end of the engine replica, still to be built.



Above: On the bottom side of the framework the on/off switch is at the front (top in the image) and the recharging receptable (pointed at in the photo) close to the rear former, where there already is a small opening in the original aircraft.

The bottom frame section with the switch and receptable was sanded to the outline of the front former. I'm sure more sanding will be required when the skin is to be fitted eventually.

[MrB17]

This is going to be a good one. I just got same model in mail yesterday. I will certainly be watching this masterpiece come to fruition.

Jeff

[OSTOJA]

Originally Posted by Leif Ohlsson

Ostoja, thanks for the warning. I think your concern is about the wing parts. We'll have to see.

Exactly, wings and empennages and everything that has a small bending radius.

Originally Posted by Leif Ohlsson

Redesigning the engine compartment for electric motor & battery.

Be careful, it will fly.

[GreMir]

Great job building and presenting the process!

Maybe the model will not fly (after all it's going to be huge!), but it will certainly be capable of taxiing on it's own