Bell P-39Q Airacobra Cobra II racer - Conversion of Arma Hobby 1/72nd injected kit

Photo from the SDASM photostream 

https://www.flickr.com/photos/sdasmarchives/14307273294

(The completed model is here:

https://wingsofintent.blogspot.com/2023/07/bell-p-39-airacobra-cobra-ii-racer-arma.html

I am not interest in military models, but for the sake of fellow modelers that still for some reason do (and the kit is actually intended for them, not for me), the sprues provide three different props (I will have to scrounge my own four-blade one for the racer), two different nose wheels, two exhausts (six and twelve stacks rows) and some boom-boom bonga-bonga parts, plus decals for several subjects. 

Now, to obtain a racer from this kit all military equipment and detail should be of course deleted, the carb air intake after the canopy perhaps extended a smidgen (I have to look at that), and a large fairing volume installed on the belly that may have housed extra radiator equipment. An additional trim tab or small rudder extension was added, no nav lights can be seen and it is most likely that the landing light provided in the kit needs deletion. The Pitot was relocated to the spinner tip. A new four-blade prop will replace the kit's three-blade one. Photos of the racer (there are many on the Net) should give a clue as to what external detail to modify. 

Parts washed and let to dry while we have a look at the wonder-moldings:

The fuselage sides have -most likely for molding reasons- two "crowns" of pips that need removal at the front as per instructions:

To delete the chutes putty is pressed from the inside:

Some parts can be assembled before painting, but some require to be painted in advance to make the modeler's life easier. Radio and gun-sight should be omitted for the racer:

 The kit has a lot of detail molded in the instrument panel/s, but also provides decals for them. Not sure if the modeler is meant to sand off the detail if the decals are used, but I tried them on the parts (as the instructions indicate) as they were, and with some setting solution they surprisingly settled down nicely:

Do not forget the metal balls, in fact glue them as early as you can in order not to miss adding them:

The fuselage is assembled. It has some locating devices that resemble the tabs modelers use in vacuformed models. I didn't use the part that holds the prop assembly, as I will have to replace prop and spinner for the racer one. The aft part joined neatly, but the fore part needed a smidgen of "convincing":

Wing halves fit was great:

Wing to fuselage fit is perfect. On the right is the top part of the nose tip, the gun details are being puttied over:

The tail feathers interlock facilitating alignment, they are really nice, but the rib detail is somewhat simplified being depicted as bars and needs a slight pass with a sanding sponge to tone it down a bit. Remember to add the small tab added to the rudder (not there yet):

My bid for the belly radiator fairing of the racer, using the kit's disposable fuel tank:

The lips are thinned down:

The part is glued to a relatively thick piece of styrene sheet to be able to round those corners:

This is the decal sheet that I intend to use:

As none of my four-blade spare spinners fits the bill, the kit's prop is assembled, for the blades to be later removed. Once the area is smoothed out, new holes for the four blades of a Quickboost set will be drilled:

The cannon holes are plugged with stretched sprue. The wing nav lights have to go:

The Pitot locating hole on the left wing has to be plugged too, and the formation lights underneath the right wing have to be erased as well. 

The new cooler fairing is given a laminar flow separator as per photos. The extra small surface was added to the rudder. The tail unit is being assembled. Beware that the elevator is sided, the clues are extremely minute notches in the outer hinges of both elevator and horizontal tail:

The tail unit is added. I debated a while about the advantages and disadvantages of painting the rudder and elevator black before adding them, which would have implied separating the one-piece elevator into two, but opted for doing that after assembly as I tend to mess things up when I add painted components. It will take some masking and care, no doubt. An extension to the mouth of the carb air intake is already glued. It was carved from leftover sprue:

Now comes the delicate task of working on the seams without messing the surrounding detail, always a challenging stage.

As a curiosity, I found this on the Net, a kit of the same racer by "Classic Plane". Other than this image, not much can be found, so this seems to be very old news. The kit's depiction on the lid is missing the additional cooler fairing under the belly and has the wing registration in an inaccurate position (it started at the wing root and went over the wheel bay doors) which shows poor research. There are other racers by this firm, but again, almost nothing can be found online:

The substitute propeller is assembled as mentioned using the reworked kit's spinner and blades from the aftermarket Quickboost resin set. The extension to the mouth of the carb air intake is already blended-in:

The very tip of the prop is drilled, to be able to pass the Pitot tube that the racer had:

As well as the prop. The idea is that the Pitot will be anchored in the fuselage, the prop may rotate freely around it, and the tip will of course remain stationary as it's solidary with the tube:

The two Cobras:

 Transparencies are on. Academy divided the canopy in two parts, front and back, glued to a central structural arch, plus one door, whilst Arma has a full canopy plus both doors separated:

Masks applied and first primer coat airbrushed:

Both Cobras are painted white as a base for their colors:

 White and then yellow are airbrushed:

Main colors on both Cobra:

The props for both models are ready:

First set of masks off. Now the masking to paint the black control surfaces has to be applied:

A bit of a complicated masking to paint the control surfaces black:

Masks off:

The decals are very good indeed, allowing positioning, not tending to fold easily, and conforming to the details pretty well The carrier virtually vanishes. The nose gear in this kit has a very awkward way to install its parts. The aft leg has to be maneuvered trough the opening twisting and turning until you get it in place, due to the narrow space available. Same for the nose leg. Their actual positions and the way they should lock is clearly described in the instructions, but they are nonetheless very finicky to install. It is done after some fussing without breaking anything. The main legs do not have real inserts (hole and peg, let's say), but a socket that feels a bit wobbly and not sharp. They are, again, installed without trouble after some fussing. Not sure why Arma have chosen this way to secure the landing gear, too uncomfortable for the nose and a bit vague for the main gear. I reiterate that it was done at the end -if with some perspiring- and all looks good:

The Draw Decals instructions state that the rudder trim was extended which is inaccurate, in fact an additional trim of sorts was installed above the existing trim, extending outwards from the rudder training edge, as any photo on the Net will show for both Cobras:

Decaling done. No problems in general, images are sharp, they have excellent adhesion and nearly invisible carrier: A little peeve, though: On both Draw Decals sets the "Cobra" lettering is too big. I had to juggle a bit the nose "comet" rays and the Cobra text to make things fit:

As you can see, the weight Arma provides needs the prop installed to finally balance the model on its nose wheel, which is not practical, as even with the nose installed (and this is actually a heavier nose, with 4 blades and a metal tube extension) the model is a tail sitter at the least provocation. One more gram of weight was all that would have been needed. Modelers building this kit may like to add a smidgen of weight where they can in the nose, to obtain a more decisive nose-down attitude. I added the recommended weight on the Academy Cobra I conversion (7 grams) and it firmly stands as it should, and if tipped back it returns by itself to land on the nose gear.

Both "Cobra" racers completed:

(The completed model is here:

https://wingsofintent.blogspot.com/2023/07/bell-p-39-airacobra-cobra-ii-racer-arma.html