Bell P-39 Airacobra

in 1:33 scale
from Paper Models International

by William H. Geoghegan

Model photographs by the author



P39a1
P39b1-1 P39c1-1
Model: Bell P-39 Airacobra
Kit: PMI 109 (Paper Models International)
Scale: 1/32
Price: US$ 6.95 plus S&H from PMI
Difficulty: Medium (3 out of 5)
Number of parts: About 85
Instructions: Good
Diagrams: Good (wire templates and a photo of the finished model are needed)
Fit: Very good
Coloring: Very good
Resources: Some good photos can be found at The "Russian Air Force Museum" site at: http://hep2.physics.arizona.edu/~savin/ram/p-39aira.html. It has a number of links to other sites with good photos. There is also some photographic and background information at the US Air Force Museum site at http://www.wpafb.af.mil/museum/air_power/ap1.htm

This was my first try at a "large" plane since returning to card modeling after about 15 years. I'd tried a couple of the smaller planes from Fiddler's Green and Fabrizio Prudenziati's site, as well as the V108 from Digital Navy. I thought it was time to try a commercially produced model in a larger scale, and chose the P-39 - which has always been one of my favorites because of its sleek lines and unusual design. The Airacobra's performance was compromised by some very ill-advised, cost-driven engineering decisions, and it gained a poor reputation as a fighter among U.S. pilots (who nicknamed it the "Iron Dog"). One of those engineering decisions was to eliminate the supercharger included in the original design, which ruined the P-39's performance above 17,000 feet. On the Eastern Front, however, its heavy armor and large cannon served the Soviet forces very well in a ground attack role. And I still think it was one of the most beautiful planes produced during the war.

Since this was my first go at a commercial hardcopy kit, where I didn't have the luxury of limitless replacements for my mistakes, this review is going to be as much an account of my own "learning experience" as it will a review of the kit itself. Perhaps this will help other beginners. There's a tremendous number of P-39 related resources on the Web, and I did use many photos pulled form the Internet for help with details of parts shaping and placement, antenna rigging, and other minutiae that were not clear from the kit drawings and instructions (see "Resources," above, for some starting points).

The kit itself is simple but well done, with about 80-90 parts overall (depending upon how you count things like exhaust louvers), all printed on a semi-gloss paper that is very easy to work with. The design and markings appear to be accurate. One minor complaint might be that the panel markings are fairly pronounced for a model of this size and scale. With few exceptions, fit was very good, with only minor rework necessary. Instructions and diagrams were easy to follow. Full-size templates for wire parts would have been helpful, however, as would photos of the finished model.

The fuselage uses bulkhead and strip construction. The connecting strips are colored, which helps to minimize the impact of slight alignment problems. The instructions caution you about making sure that the fuselage skin, bulkhead formers and strips are correctly sized before gluing. The importance of this warning became immediately apparent with the first few fuselage sections, one or two of which began taking on an "hourglass" shape. Time to remember some high school math. An error in the diameter of the bulkhead former of a third of a millimeter (little more than the width of the lines used to draw them) will result in almost a one millimeter gap (or overlap) where the edges of the skin butt together. (The circumference of a circle, even one that's slightly ovoid, is approximately 3 times the diameter.) And that third of a millimeter is just about the difference between cutting on the inside or outside of the line used to draw the part! The lesson is to cut the bulkhead a little on the large side (on the outside of the line), and then sand it down until everything fits. I've found that 3M removable tape (which uses Post-It adhesive) works extremely well for holding the skin together while adjusting the bulkhead former and test-fitting the part. Single-sided and double-sided removable "Scotch" tape are now a permanent part of my toolkit.

Don't forget to put the nose weight in section #5 before you glue the sections together. I forgot, and ended up having to feed little pieces of solder through the machine gun mounting holes in order to get the nose to stay down.

Empennage assembly was straightforward, though minor adjustments of outline were needed to match the opposing surfaces of rudder and stabilizer.

Wing construction uses a spar with two ribs, one near the root and one near the tip, and a long gluing tab at the trailing edge. This produces a cleaner trailing edge, but requires that the wing be kept perfectly flat during construction and drying. Be careful to insure that the outline of the spar does not cause a bulge in the upper or lower wing skin - which is especially likely near the wingtip. This is also a good time to do some advance preparation for the landing gear installation. A small piece of Styrofoam glued where the landing gear strut (wire or toothpick) will be mounted would help; or you could glue a piece of thick card to the top of the wing where the strut will contact it. Either method will help avoid the strut raising a bump on the top of the wing when installed.

Fitting the wing root to the fuselage was a bit of a problem, though I think that may have been due more to inexperience than anything else (and failure to do a good job of dryfitting before final wing assembly). Some judicious "restyling" of the trailing edge of the wing root where it joins the fuselage, and careful application of the wing fillet helped to disguise the problem.

Landing gear assembly was not difficult. I used piano wire (.032" or .8 mm) rather than toothpicks for the struts, and followed the diagrams in the instructions for shaping. Full size templates would have helped, however. Wheels were built up with extra layers of card stock, sanded to shape, and colored with a dark gray marking pen. There is a potential problem, however, with the wire for the main gear struts producing a bump on the upper surface of the wings. This could be avoided by following one of the suggestions mentioned above. I didn't do this, and have to be very careful about putting any weight on the plane.

I like the way the propellers are done. The shaft end is completely rounded, with an airfoil formed into the blade. A back is glued onto each blade, and the assembly is then glued to the prop shaft (a toothpick), which also serves as the nose cannon. A little sanding and coloring of the glued edges is required, but the result is very realistic. Wing guns were easily rolled from the paper provided. Nose wheel doors were correctly drawn, but the scribing on the fuselage was incorrect; the small chamfer on the trailing edge of the doors belongs where they join together (as the doors are drawn), not where they are hinged to the fuselage (as the outline of the wheel well is drawn). This is a problem only for those who pick up the model to inspect the underside in detail.

There were no problems with the cockpit canopy, using the thin acetate material supplied with the kit. I used cyanoacrylate glue to tack it in place on the canopy frame. I did have a problem with the air scoop just aft of the canopy. On the real P-39 it hugged the fuselage closely, but on the model it sits up too high, and a rounder shape than it should. This could have been fixed by dryfitting and adjusting before gluing - which I failed to do.

Figuring out how to string the antenna wire turned out to be a challenge. Nothing in the kit, and none of the photos I could find, were clear on how the antenna wire was to be run on this version of the P-39. I finally found one picture that suggested that the wire should be run from the tail to the antenna mast, and from there to the main brace on the cockpit. This is how I wired it, though I'm still not convinced that it's correct.  I used .005" (.013 mm) gray transparent nylon thread, painted gunmetal black. With the paint covering, the antenna is approximately to scale for a 1:32 model.

I used watercolors to tint all exposed edges. I actually used watercolor pencils, but with a fine sable brush to pick up and apply the paint.

A couple of other observations:

  1. It would have been good to build in more cockpit detail, especially given the large transparent canopy. The radio stack behind the pilot's seat would be easy to scratchbuild, for example, and more control panel and flight control detail could be added.
  2. I used cyanoacrylate (CYA) glue to tack several external parts into place, and found that it really discolors the printed surface of the model if it's not applied with the utmost care. The very thick, slow-drying CYA glue is probably okay, but the thin, instant cure glue will create problems. (Notice the nose gear door in the photos.) I had a similar problem with a dark gray artist's marker. The ink bled through the paper and discolored the painted surface.
  3. I found a great burnishing tool in an art supply store, and it helped in rounding and smoothing the edges between fuselage sections, the trailing edges of the wing, and rounded edges in general. I'm not sure what the tool is for in real life, but it has a large curved polished metal surface, and I found it in an art supply store near the block print section.
  4. Color all unprinted surfaces that will be visible when the model is complete, including those that are inside the aircraft. I did a pretty good job on the outside, but failed to color the inside of the cockpit framing, for example. After you glue the canopy in place it's too late.

All in all, it was not a difficult model to make, a good starting point for an "experienced beginner" - someone that's learned the basics of score, fold, cut and paste. I was really worried about what the finished model was going to look like as I piled one small mistake (read "lesson learned") on top of another. But the end result is actually very satisfying. The overall impression outweighs the accumulated mistakes by far.