Building a 1/16 scale P39N Airacobra

Discussion in 'Aircraft & Aviation' started by Leif Oh, Sep 21, 2004.

  1. Leif Oh

    Leif Oh Member

    As many of you know, I usually scale to 1/25 the few models I actually manage to get built. At least that's been the case until now. Almost a year ago I started to build the Halinski model P39N Airacobra in that scale. Although not a completely false start, I somehow felt dissatisfied with my efforts, compared to the potential obviously there, in the design as such.
  2. Leif Oh

    Leif Oh Member

    It was not until this summer, however, that the pieces clicked together in my mind, when writing a review of the kit. In that review I found myself remarking a lot on the amount of detail and the absolute perfect fit of the model, saying that it's almost too perfect (meaning that every fault in the build mercilessly will fall back on the builder), and that it is as close to museum scale as you are likely to get in card modeling.

    Then it struck me - why not at least try to realize the full potential of the kit, and compensate for my clumsy fingers by scaling it even more! A scale of 1/16 seemed suitable. There are a lot of museum models built to that scale, I've gathered from a number of coffee-table books. Perhaps I could do something that would at least qualify as "museum scale" according to my own more modest norms...

    So I started, and now I've passed enough initial hurdles to dare show the progress so far. There's a long way to go yet, and many more problems anticipated (such as dividing the wing parts into printable A4- or letter-width sheets, and then joining them again invisibly), but at least I now think there's a good chance of actually completing this project.

    So here goes, my friends, yet another tall building tale!

  3. Leif Oh

    Leif Oh Member

    1. The basic framework

    The first problem to be solved was materials for those formers and part usually backed up on 1 mm card. 1/16 is roughly double the original 1/33 scale, and the artists' shop luckily carried 2 mm card in sheets big enough to accomodate even the large wingspar anticipated in this scale.

    I decided to print the patterns on 0.25 mm (225 g/sqm) paper (the kind I am using for covering and general parts), and back up the cardstock with the same kind of paper on the opposite side to avoid too much twisting and bending.

    This, as it turns out, was a little bit of a mistake, since the result turned out to be slightly too thick. The fitting as such (tabs in slots, etc.) is no big problem, but I didn't calculate with the slight vertical dislocation of other parts. Even if it's only adds up to less than half a mm, it will make covering parts not quite sufficiently big to cover the area they are supposed to. More of this later.

    So be warned; if you wish to attempt something like this, keep the proportions of the design, and print patterns to be backed up by 2 mm on common copy paper (backing up both sides will be fine, I think, but I'll try that later in the process, for other parts than the fuselage, and get back with a confirmation - or not - on that point).

    As you will see from the following pictures, I couldn't, of course, resist the challenge posed by one of you guys to electrify the whole thing...
  4. Gil

    Gil Active Member


    You have finally moved into the correct scale for "articulate" modeling. 1:16 scale allows for applying an incredible amount of detail and is so chosen by museums for that fact. I'll be following your thread closely.

    Much good luck, Gil

    P.S. Have you given thought about lighting the model?
  5. Leif Oh

    Leif Oh Member

    Thanks for the encouragement, Gil - very heartening!

    Have thought a bit about lighting. But not this time out. Too many new things for one go. I'll save it for something down the line (with a proper passenger cabin, plus pilots instrument lighting).

    Also, I have to get the hang of lighting diodes (is that the term?); how to hook them up; if there are very small ones; what colour best to use for interior lighting, for navigational lights, for pilot's spotlight on the instrument board, etc. And how do you create a proper spotlight, as used in aircrafts from the 30's, etc., etc.

    Questions abound, and I'll be sure to get back about most of them, when the time comes.

  6. Jim Nunn

    Jim Nunn Member

    Nice Project

    LED’s are easy to work with they are just a diode and all you need to do is limit the current to the LED with a resistor. The size of the resistor is dependent on the voltage being applied and the current rating of the LED. That said head over to Radio Shack they used to have a booklet on using LED’s. The title was something like “Engineers Handbook on LED’sâ€. As for colors LED’s are available in Red, Green, Orange, Blue and White.

    A great source for LEDS is All Electronics

    Also consider using fiber optics for the insturmrnts. You can get fiber optic kits at most hobby shops that cater to the model railroad types.

    Jim Nunn
  7. Gil

    Gil Active Member

    Leif, Jim,

    That's my thinking exactly. In Europe Siemens now Osram sell a line of LEDs (Light Emitting Diodes) with varying gradation of colors. The white LEDs are now being used in solid state flashlights. Red and Green LEDs for running lights and white with a flasher unit for strobes..., egads it's easy to get carried away.

    Now an MP3 player for sound effects...,

    Just kidding, Gil
  8. Leif Oh

    Leif Oh Member

    2. An electrifying project

    Just to finish off for now the electrifying business:

    With a model this size, there is no problem getting a cheap electric motor in, and even a rechargeable NiMH 1.3 V battery. So it was off to the electronics shop (decades since I was down that road), to buy recharging socket & plug, a switch, plus even a cheap volt meter (wouldn't want to hook up and solder everything with wrong polarities, and then burying it under card before discovering that little mistake).

    Great fun so far, and actually no big problems. The only thing was that the front former is not part of the designed fixed structure. It is designed to go in with the foremost section of covering structure.

    This of course had to be rectified - but no data for where the former should be located, vertically, and longitudinally. I tried to make some primitive triangulations by measuring the width of the front part and projecting it on the drawing board and finally ended up with some sort of a position for the front former.

    This, as it turned out later was not a good way to go (more later). A better way, I now think, would have been to build a dummy front section, and mark the position of the front former from that. Or at least check with a scale drawing first (stupid me, I even had one!). I'll be sure to do both, the next time a model calls for this kind of modification.

    Otherwise this part went rather smoothly (thanks, Rob, for the soldering instructions!), and blissfully ignorant of troubles to come I was mightily proud of myself at this stage. Compare for the electric installation below - it worked from the very start!
  9. jrts

    jrts Active Member

    Hi leif

    For the light Diodes try your local train hobby shop as they do them small enough to be used in signal lights and even train head light in all colours.
    My lad has them on his 00 scale train set. I have tried to take a photo of it but with my camera it does not show the effect at all. If I took one off he would never talk to again its his pride and joy :lol:

    Glad the soldering bit helped


  10. Leif Oh

    Leif Oh Member

    3a. Building the detailed cockpit

    The interior of the cockpit was what intrigued me most the first time I attempted it in 1/25. Now I would have a chance to do it real justice in style, at a size and scale that let all the details really shine (and enable me to handle them properly too!).
  11. Gil

    Gil Active Member


    Beautiful work....,

  12. Leif Oh

    Leif Oh Member

    3b. Building the detailed cockpit (cont'd.)

    It was a very satisfying time, and I applied a lot of the building tips acquired during this summer from the work of Swinger and others on their very advanced builds in 1/33.

    Using quick-drying white glue, mixed with water colours, were great fun. I could make handles on doors, knobs on levers, flesh out gun handles, and many other great little details.
  13. Huey

    Huey Member

    This is just great work! All those details on the cockpit and with a motor rechargeable battery too. Keep those updates coming :D . Hope to see you do the FLY C-47 next :D (two engines with motor, that would be cool to see :D )
  14. Leif Oh

    Leif Oh Member

    Thanks Huey! Please remember that I am not adding a single detail that isn't already there in the fabulous Halinski kit - just building it at a scale I can handle, and trying to show that the modern generation of card models easily can stand a doubling in scale - with a potential for the more gifted to add correspondingly more details, of course.

    As for a twin-engine, I have one in mind, but alas, not the C-47 as yet. But please, let's not even think of a "next project" for a while, there's ample work here to keep me occupied for the duration... L.
  15. Leif Oh

    Leif Oh Member

    4a. Crunch time I - the doors

    Last time out (when building this model in 1/25), I stumbled on the complicated doors. Couldn't make heads or tails of them. So this time I decided to really take my time and get it right.

    Still, I just couldn't get the hang of what was intended, and it took several failed attempts (including one where the sides of the cockpit were already glued in and then ripped of again, glue already dried overnight - luckily no irreparable harm done!).

    My only advice is, do not glue the sides of the cockpit, and the doors, in until you are very, very sure that you've got it right. Dryfit, dryfit, and dryfit again. Take your time and think ahead. How will the other parts, interacting with the doors, fit in with how they look and fit at present?

    This part is really crucial, since it determines the rest of the model, both backwards, forwards, and upwards (canopy).

    The design calls for a multitude of doubling up patterns printed on ordinary copy paper, doubling with bristolboard (no thickness indicated), and generally doubling up elements ad nauseam.

    I ended up substituting a single layer of my standard thickness 0.25 for double layers of copy paper (should be reasonably right at twice the scale), and substituting this also for bristol board (should be reasonably right, as well). And I also made some slight redesigning, printing patterns for recessed parts directly on panels originally blank white, instead of adding them as separate parts (in order to make the recess deeper). In the end, I think it worked rather well.

  16. Leif Oh

    Leif Oh Member

    4b. Crunch time I - the doors (cont'd.)

    The instructions calls for building the doors separately. This is both good and bad advice. Good, since it is really necessary to be able, at a later stage, to mount certain details with the doors out (mainly the canopy; can't see how that could be done otherwise, but then I haven't got that far yet). Bad, since you can't build the doors separately and achieve a good fit.

    Besides, the doors really have to be in, and glued, when you mount the sides of the cockpit, otherwise you'll never get it right - there is too much flexibility with the doors out, and the side pieces will unavoidably distort and destroy the fit of the doors and everything else later on.

    Solution arrived at: Build the sides of the cockpit with the doors in, not cut out. This calls for some initial computer work, since the doors are actually printed as separate parts. I made new parts, where the doors were integrated with the cockpit sides, both internally and externally.

    Build the sides, with all their layers, and form them to their proper rounded shape, including the integrated doors. Dryfit onto the framework until satisfied. Varnish with matt acrylic. Then - and only then - CUT THE DOORS OUT, edgecolour and apply extra varnish on cut edges of booth the frames and doors, then SPOT GLUE THE DOORS BACK IN!

    This way you'll retain the proper shape and rigidity of the cockpit sides while inserting them, and still be able to detach them at a later stage.

    This took many false attempts and a lot of time to arrive at!

  17. Texman

    Texman Guest


    Thats all I can say
  18. Jim Krauzlis

    Jim Krauzlis Active Member

    Leif, this is truly outstanding work!! :D

    Excellent thread with loads of great tips and techniques!

    I am thoroughly enjoying this build and looking forward to more. :D

  19. Gil

    Gil Active Member


    Nice! In fact so nice it's now slick!

    Can't wait for the next issue...,

    Till then, Gil
  20. Leif Oh

    Leif Oh Member

    Crunch time II - first attempt at glazing

    Thanks guys, even for the dubious "slick", Gil - I do admit to a certain smugness at this point. That, however, soon evaporated during what lies ahead right now...

    With the sides of the cockpit finally in, the dreaded moment had come when I simply had to get down to the canopy. I've always had a secret fear, as well as fascination, for canopies. How could I possibly expect to be able to achieve a good fit between inner and outer layers, glue the transparent sheet in properly between them, get the curvature right, and not smear everything up in the process?

    First time out, making a closed canopy in card models - there was nothing doing but to get down to it. My great respect for this area of modeling made me extra careful.

    Some basic premises were: Use ordinary office overhead transparent film (seems to be tough enough, since it's able to go through printers and copiers under a lot of heat; also I'll always be able to get more of the same kind).

    Use nothing but ordinary white glue, and let's hope that's sticky enough. I simply did not dare any exotic glues, risking never to get smudges off. (Already made some pretty disastrous attempts in previous modeling, with cyanoacrylate and transparencies. They did not stay transparent for many seconds after applying the cyano...)

    First basic strategy: Glue everything together preformed, somehow in a fixed and correct position and curvature. No way to get outer, middle, and inner layers to fit otherwise.

    Second basic strategy: Start from inside and go outwards, never mind the instructions saying go the opposite way. I simply couldn't figure out how to get the transparies into a concave surface without smudging it up completely. Much better to carefully apply it on to a convex surface, one portion at a time. (I'd be most interested to hear of others' experience in this area.)

    So I cut out the inner back cockpit glazing cover oversize at the bottom, and taped it together in the rough shape required with some ordinary masking tape (great stuff; the card modeler's equivalent of silver duct tape). Lo and behold! - the transparency went on very nicely, and seemed to stick well enough. And when the masking tape was released, the canopy stayed in its preformed shape.

    The best part of it was that any glue oozing out from the joints easily could be removed with a tooth-pick without scratching the transparency. And there was no particular need to be in a hurry. That part of the work can very well be done in a semi-dry, or even dry, condition (although it gets a little bit tougher to do it when the glue is completely and overnight dry - though not impossible even then; white glue is great).


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