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Workbench: Azur's 1/32nd
Polikarpov I-16 Early Type-5

By Aleksandar Šekularac


14 January 2006

Here we go again. New Year arrived, and it is time to clean the table, and start better and bolder things. This year I shall be nicer to my neighbors, won't get speeding tickets, exercise regularly, get rich, stop global warming, discover new galaxy, win Nobel Prize…

Well, at least I cleaned my workbench. How many of you can say this much? Now I can start on that perfect model…

The first one to come under the scalpel in 2006 is Azur's 1/32 I-16. I've made a preview for this kit some time ago.

I've selected a very special subject for this model. It is one late type-5 with white number "11" on its ruder, from 13 OIAE, 61 Aviation Brigade, situated in Finland and immortalized on film in early 1940. This a/c sports very bold personal markings (in spirit of the time) and is featured in "Soviet Air Force Fighters Colours 41-45" book, both in profile and photographs. Additional characteristic that drew me to build this one is that it is on skies. Lack of engine and closed front cowling cooling louvers are the biggest letdowns in Azur's kit. Historically, I-16s had these louvers completely shut only when it was very cold and no Vodka left. Ergo, winter in Finland and I-16 on skies!

Facts that Azur packs parts for I-16 type-10 on one side, and I'm determined to make type-5 on the other, can be brought to balance only by plastic surgery. Starting up easy, all the type-10 corresponding details on the fuselage surface and cowling need to be deleted, namely: gun fairings, gun barrels, oil-cooler inlet, starboard cockpit door (why was it there in the first place?). Snip, slice, sand; just me, my little knife, and some 150 grit sandpaper. I dare somebody to start with 150 grit on a Tamiya kit… While at it, why not sand smooth and thin all the fuselage walls from inside. Someone from Azur confused I-16 with T-34, and modeled heavy armor thickness into these walls. They need to be one forth of what they are in the box. Yes, this means we will delete all the molded on cockpit details by sanding, but this is not a big loss really (read my preview). Actually, I consider it killing two flies in one stroke…

While in cockpit, there's some choppin' to do on the floor element. Both sides, connecting to the lateral walls need to be removed.

Now, with only the narrow bridge under the pilot seat, there are gaping holes on both sides where the fuselage meets the wing. I will have to form curved inner cockpit walls that wrap under the central bridge, like a half-cylindrical tub. To do this I'll need to heat and shape some styrene stock (not fun), or find something of appropriate diameter around the house (fun). My wife usually becomes suspicious when she sees me scouting through our home, so I will have to be stealthy… Eureka! Did you know that those hard plastic toothpaste tubes (you know, the ones where you squeeze the button, and piston pushes the tooth-paste out) are perfectly scaled for 1/32 I-16 cockpit-tub? I wager you didn't! Additional benefit: subtle mint fragrance on your model..

Distinguishing features of type-5 aircraft are the exhaust ports, which were somewhat longer and shaped in a teardrop, in contrast to all later types that received more oval openings. To make this alteration I'll start working with the round needle file, changing to sandpaper when the shape is roughed out. The important point is to work slowly, and frequently check the shape.

Now that we warmed up the seat, how about scratch-building those skies? Yes, I used the "S" verb. You see this type-5 had the old 3-D "aerodynamic" skies, not the later retractable 2-D design (check your references). This later ski design is actually provided in the Special Hobby boxing of the same kit, and as I happen to have these pieces; I planned to use them as the base for my type-5 ski. However, after careful study of the available photographs and some measuring of the parts I concluded that I need some six millimeters more in length of the skies to get to the right proportion with the rest of the aircraft. Oh well, more work for my scalpel…

But this is a story for the next installment. Buy for now.

27 January 2006 - Part II

I was able in the mean time to get hold of some more pictures of the early ski arrangement on I-16 (Thanks Sergey!), as well as a scale drawing. The latter confirmed my suspicion that these 3-D teardrop skies were indeed much longer than the 2-D design included in Special Hobby box. So, the idea of using kit parts was discarded, and I chose to start from scratch instead.

I based my method of building skies on a process known in the industry as "rapid-prototyping". Basically, thin two-dimensional layers are progressively built on top of one another, to achieve a 3-D object. I needed sheet styrene plastic, and quite some amount of plastic welder. In the "machine world" two-dimensional layers are already uniquely shaped (by laser or other means) so that when a 3-D object comes to existence it is perfectly sculpted. Since I'm not a machine, I'll just approximately shape 2-D wafers, and then rely on much sanding afterwards, when everything dries.

Obvious choice for sheet plastic would be ever-popular Evergreen, where available. I however opted for more economical, and "environmental" (for those so inclined) approach by recycling extra plastic from one vacu-form kit I have in my stash. I made a template of the ski, and then traced around it with a marker, wherever I found free space on a vacu-form sheets. Then I grabbed my Dremel, and uttered the words: "I love the smell of melted styrene in the evening". After the cutting was done, I roughly cleaned the parts and stacked them up for gluing. In all, 14 wafers were needed for two ski-bodies.

Gluing of the layers needs to be done thoroughly, with liberal application of plastic welder on both matting surfaces. Whenever joining two layers I would slide them relative to each other while the bond is still wet, until liquid plastic comes out around the edges (like jam out of a sandwich). This insures that full surface contact is established, and minimizes amount of imperfections to be discovered later while sanding the dry part. I worked alternating between two skies, allowing the other one to dry a bit before continuing with another layer.

As I finished with all the layers, and the parts started curing, I noticed that they also appear to warp a bit. I therefore joined them foot-to-foot and clamped them to preserve the flatness of the bottom surfaces as much as possible.

After 48 hours of curing, there was still a smell of glue about the parts, but they were sufficiently dry for rough sanding. I laid down a new sheet of my roughest (100 grit) sandpaper on the table and started working. Idea was to first define all vertical sidewalls, as well as the upper plane of the ski-body. This was a slow process but a very controlled one. Actually, the final shape of the ski was achieved entirely though sanding. No carving was involved.

When I was happy with the outline of the ski in plan view, and the side profile corresponded with smallest imaginable box to accept the ski, I started working on the curved surfaces. This especially required frequent checks to the reference pictures and drawings, but the progress was actually faster than what I feared. By now I was working with 400 grit paper, and finally some steel wool. At the end I corrected minor variations in shape between the skies themselves. Even more important than looking authentic is that they look identical to each other once on a model. I imagine that some modelers would scratch-build only one ski as a master-part, and then cast two copies in resin. Having no experience with casting process, I made two parts, and will use them as-is on my I-16.

At this point I will leave the skies aside for couple of weeks, and busy myself with the rest of the kit. From previous experience I know that long-time curing usually reveals some further faint sink marks along joints, and since this was a very glue-intensive job, I will leave the detailing work for a time when I can be sure that the pieces are completely solid.

27 January 2006 - Part III

Planning is very important for me. I tend to diverge a lot from the assembly list when I work on a kit, and therefore I make a step-by-step mental plan. Only in this way I really know what I am doing, and can hope for good results in the end. Point in case is fuselage and cockpit assembly on this I-16.

Decision was made early on to rebuild the pilot's office. With this in mind, I had to plan on how to produce and then fit all the new details in the fuselage. After some deliberation I've chosen to close the fuselage halves first, and then make use of the large opening at the bottom (where the central wing part comes in place) to work on the cockpit. This may seem as backwards approach, but it actually has many benefits that, I hope, will become obvious as we go along.

Anyway, there's one more thing to do before gluing the fuselage halves together. I want to make a longitudinal shallow step on the inside fuselage wall, in the exact position of one of the wooden stringers (horizontal elements of the fuselage structure). The recess of the step will face downwards. This recess will accept my toothpaste-tube-based bottom cockpit tub, so that when I rebuild the inner structure, the walls will appear seamless, and continuous. Pictures can explain this much better than words actually. I started scribing with the tip of my scalpel blade along the metal template, taped to the inside fuselage wall. After initial rough groove was made, I removed the template and continued shaving, and sanding the plastic to achieve straight and clean step. Needles to say, both sides have to be done symmetrically.

In the kit preview I commented about fit problems in the wing root, and at the bottom, where central wing panel meets rear fuselage. Elegant way of diminishing this problem is to broaden bottom side of the fuselage, by inserting a plastic wedge between two halves. To do this, I will now spare from glue this bottom part of the fuselage, and join only the topsides.

I first laid both fuselage sides on the sheet of sandpaper, sunny side up, and sanded the matting surfaces. I deleted the aligning pins, as these serve only to prevent good alignment of parts. I applied plastic welder in segments: to the vertical fin and the back spine, front top and engine cowling, respectively. Once more, bottom joint was left dry. I allowed 48 hours for bond to cure. Here's how everything looked after some sanding of the front-end seam.

I also wanted to detail trailing edge of the metal engine cowling, where it meets wooden fuselage body. There is a visible clearance between these two parts on the real aircraft, and 1/32 scale is large enough to allow for this detail. I started tracing with my scribing tool at a very shallow angle along the bottom of the circumferential step on the fuselage. One should not attempt to make a deep groove in one go. Multiple passes with the light pressure on the tool produce desired results

You may notice that I drilled two symmetric holes in front of the cockpit orifice. I will produce glazing for these holes next. Providing light to deeply buried instrument panel, these openings were introduced on early I-15 models and glazed over, as they were exposed to the free air-stream when the sliding canopy was in the closed position. I am not completely sure if the glass was present on later "open cockpit" models, or if only two holes remained. Aircraft that I am modeling was retrofitted with the fixed windshield at some point in its life, and the remaining sliding canopy rails are still visible on the photographs, so I decided to reproduce glazing over the lighting holes as well. To do this I've cut two thin discs out of the clear sprue bit, and then further sanded them flat. With the piece of sticky tape, closing the lighting holes from inside of the fuselage, I inserted the two (not so) clear bits in their places and sealed them with super glue. When super glue dries more sanding and polishing can commence, to bring the shine back to those transparencies.

Let us now address the issue of the bottom fuselage seam. As mentioned, central wing part is noticeably wider at the position where it's supposed to join the fuselage. I need ~2mm of extra material to bring the fuselage to the same width. Some stock styrene and plastic welder achieve this easily. Everything is sanded smooth after enough drying time.

15 February 2006 - Part IV

I-16 cockpit is usually described as simple, or spartan, yet there is plenty to busy about to make it look authentic in scale. Next on my list was to scratch-build fuselage structural frames. Looking on the drawings, and available cockpit photos, one can see that there are two of these frames immediately visible through the opening. One frame is behind the pilot's seat, containing the headrest, and the other one just in front of the side door of the cockpit.

The back cockpit wall, as it appears in the kit, would be a good candidate for the rear frame if it weren't for the facts that it's missing the bottom section, under the cockpit floor, and that I also made fuselage wider in the mean time. So, I turned to my vacu-form stash again, for some sheet plastic.

This was a good opportunity to try my profile gauge, a tool I picked up in hardware store last year. Up till now it was collecting dust on the window seal next to my workbench, so I finally decided to use it. This tool was really meant for some more robust work then plastic models (it can scratch the plastic surface), but if one is careful, it will save a lot of guesswork while trying to fit the bulkhead inside the fuselage. I've cut two solid pieces out of the white styrene sheet, one for the back and one for the front frame, and then proceeded with fine-tuning with scalpel and sand paper. This work took some time even with profile gauge, but I hope that the look inside the finished cockpit will be worth the effort.

When the outer edge of the frame conforms to all of the fuselage curves, we can start taking material out from the middle, to make a bulkhead into a frame. Drilling, "dremeliing", cutting, chopping, and sanding all helps, but care needs to be taken, especially as the part becomes weaker, and more material is taken away.

I also built a third "half-frame", one that goes to the very front of the cockpit, at the position of the instrument panel. This one is only a half frame, as its bottom end attaches to the tubular wing spar. To make sure that there's no gap between the frames and fuselage walls, I've applied some putty in this circumferential seam, and after waiting about 10 minutes, removed excess with a Q-tip dipped in a nail-polish remover. In this way one can achieve smooth, clean seam without the need for difficult sanding of the inside corners.

When all three cross-sectional frames are laid out, one can begin laying short strips of plastic horizontally between the frames to represent stringers. Quicker said than done…

Rear tubular wing spar is also partially visible through the cockpit cavity, so I decided to produce it out of cylindrical plastic stock. I first made a support for the spar on the front bottom side of the cockpit floor. Note that I also thinned underneath of the floor piece to improve how it sits on the fuselage frames.

For the spar, I took two longer pieces of plastic rod, and glued them parallel with the strip of plastic between them. Then, I was able to fashion the shorter traversing pieces out of the same plastic stock, by measuring exact lengths between the horizontal rods.

Thin, capillary glue makes getting everything together really easy, as one has to only align the pieces, and touch the joint with the tip of the fine brush loaded with plastic welder. I recommend using this gluing method on everything that applies: from joining fuselage halves, to precise work shown here. It is cleanest, most controlled and elegant way to get the glue where it needs to go.

For the end I test fitted all the cockpit components to see how they go together. I applied my "wet-fit" method, using drops of soapy water to make the parts stick without committing them to glue. Looks good to me…

Bye till the next time!

5 March 2006 - Part V

On close examination of the front end of some wartime I-16 it is evident that the engine cowling is most often well beaten up. There are many dings and ripples, chips and scratches, especially in and around the front outer radius of the cowling. Devil that sits on my shoulder told me I must represent this on my model. I smirked and replied: “but of course.” I additionally wanted to open up ever so slightly the front cooling louvers, in the same manner that Hector Mirasol did on his lovely 1/32 Mosca. This slightly opened position conveys functionality of this mechanism, without reviling absence of the engine behind.

I will not describe method of abuse I did to the engine cowling with my rotary tool, for a simple reason that I cannot recommend it, even if it did produce good results for me. One dances here really close to the edge of destroying the kit parts.

Next came Boris The Bolter, Russian cousin of Rosy The Riveter, to add some surface detail to the metal cowling. Starting with rows of small rivets along the panel lines, and around the exhaust ports, the main tool here is a strip-ruler and my loyal compass needle in a pin-vise.

There are also big round fasteners present on the cowling, requiring special attention in 1/32 scale. Basically, I used the biggest syringe needle I could find. You know, the one you would hate for the doctor to use if you were the patient. I have cut the tip of the needle, and sharpened the edge of the new flat end, so that I can impress it into the plastic and leave a circular mark. This requires stronger pressure, and I also found helpful to rotate the needle inside the initial groove. Next I used a drill bit with smaller radius than the needle, to make a shallow orifice in center of the circle, representing the bolt itself.

I used the same method for the smaller bolts at the circumference of the front cowling, but only with smaller needle this time. There were places where putty interventions were necessary, but overall the cowling parts survived the abuse, and the devil was left without his satisfaction...

New shutters for the front cowling were produced out of stock styrene, using already opened slots as a template. Here’s the look of the whole thing after a layer of primer is applied.

I like to have the propeller rotating, so I built the bearing system, from few cylindrical pieces of styrene stock, and a brass rod inside. There’s also a back-disc that goes behind the propeller and in front of the engine cowling, and this part is not present in the kit. As a side note, this spinner back-disk is the culprit for the “crop circles” molded on the front cowling kit part. These were misrepresented as cowling details from few photos showing I-16 with spinner taken off, and this back disc still present (discovered by Sergey Kosachev).

On to the wing! First and foremost, I thoroughly sanded the inside matting surfaces of the wing elements on a flat sheet of coarse sand paper, bringing down the trailing edge thickness.

Next, I glued the outer sections of the wing and used a small styrene strips as partial wing spars, to increase the stiffness of the outer wing when assembled. I’ve also cut through the thick molding in-between main wheel-wells on the inside of the bottom central wing segment (another tip from Hector). This was done to make the wing central section more flexible, as the initial dry fitting revealed some problems in the upper wing-fuselage joint. In doing this, I managed to bust through one of the wheel-wells, but considering that I will have them covered it is not a big deal.

From the available photos of the aircraft in question it is clear that she is late production type-5, with the reinforced outer wing. This fact will save me from having to delete every second rib on the canvas-covered parts of the wing, but I will still have to produce longer, type-5 ailerons. This will however have to wait until another update...

21 April 2006 - Part VI

Progress on the model slowed down recently. I’m afraid that tempo will stay “adagio” through April, due to my pending travels in next couple of weeks.

I’ve turned my attention to the cockpit again. Some work was already done on the pilot’s seat, but now I decided to completely rebuild the back armor, and keep only the seat tub from the original part. I’ve cut the back-plate piece out of thin brass sheet, and formed it to fit over the back padding. All the seat elements were primed with “Surfacer 1000”, and then painted and weathered appropriately. The seat padding in particular received the “old leather” treatment, as I imagine this material didn’t stay new for very long on an open cockpit aircraft.

Control stick was adorned with new hand-grips made of tightly wound metal wire, some more wire detail going into the main column from the handle piece, and new trigger buttons from plastic and… you guessed it, more wire.

Oxygen and nitro bottles do not exist as kit parts. This is only natural, as they are located on both sides and to the back of the pilot’s seat, just behind that imaginary back cockpit firewall. I’ve produced these according to the available drawings from cylindrical plastic stock, some small diameter pipes, and other bits and bobs from my scale-junkyard. One bottle should be painted white; the other one blue.

Instrument panel does come in the kit, but it wasn’t too my satisfaction, so I made a new one. The kit part was sanded smooth and then the instrument holes were drilled out. I have inserted and glued small cylinder bits from stock styrene through each of these holes, and left them protruding a bit on the front side. Now, I drilled through each cylinder again, only with a slightly smaller drill bit. This left a thin ring around each hole, just as one finds on a real instrument panel. I’ve also left few fine holes for flip-switches, buttons and indicator lights. The backside of the instrument panel was then sanded to reduce thickness. Plastic is, of course, very fragile when thinned to an extreme, so this step was left as the last one before painting.

Work then turned to the computer. I’ve scanned my instrument panel bit, with instrument holes drilled out, and in this way obtained an accurate map for instrument placement. Next I drew instrument faces using Microsoft Paint (everybody who has Windows should have this simple program). Just remember, you can draw much more detail than an average printer can resolve when you reduce the size to scale. Therefore test your printer and increase the thickness of your dials and numbers appropriately. I’ve used a laser printer for this job, as my ink-jet at home didn’t like much these tiny details, and first time I tried it the instruments came out as only black dots with some white smudges on them. But, improvement makes straight roads, as they say…

Printing the instruments on plain paper and then covering them with a single piece of transparent (glossy) sticky-tape, produces a nice “instrument-glass” effect. After painting the plastic panel black, and following dry brushing with light gray, I’ve aligned prepared instrument faces to the backside and sealed everything with a drop of super-glue. Flip–switches were made from thin wire, and indicator lamps from stretched clear sprue, painted with “clear red” and “clear green”. Voila, one 1/32 I-16 instrument panel, “prêt à port-air”.