The National Air Races went on hiatus during the WWII years as aviation turned its attention to more pressing matters. They resumed back in Cleveland following the war in 1946. When WW II ended large numbers of warplanes were declared surplus and could be bought cheap. Ex-military pilots and mechanics formed race teams and modified the war birds for speed by stripping them down, streamlining, and souping the engines. These were generally wildcat operations operated on shoestring budgets. Three Bell Aircraft test pilots, Tex Johnston, Jack Woolams, and Slick Goodlin went in together to form Skylanes Unlimited race team. Bell sold them two new P-39Qs for $1 each. Being Bell employees they also had use of Bell technical support and hanger space, a distinct advantage. The two Airacobras were stripped of all non-essential equipment. The Allison V-1710-85s were replaced with 2,000 hp V-1710-135s that powered the larger P-63 Kingcobra. This transformed the little light weight P-39s, named Cobra I and Cobra II, into real hot rods. During testing Cobra I crashed killing Woolams. Tex Johnston flying Cobra II won the 1946 Thompson Trophy with an average speed of 373.9 mph. He never trailed.

The Monogram P-39 has been around since the late 60s and continued in production by Revell. It has been superseded by better detailed, more modern kits such as those by Hasegawa and Eduard. Hasegawa and Accurate Miniatures have both kitted their P-39s as the Cobra racers. In them you get the belly radiator, decals, and 4-blade props (the props are wrong in both), but you still cannot build an accurate racer from these kits without modifications. So in light of that I decided to just use a Monogram kit for the basis of this project because….it’s cheap. Despite the raised panel lines and clunky landing gear the old Monogram kit still builds well. They can be had for a song nowadays which offsets the purchase of the aftermarket items listed above. The kit includes a 12 stack exhaust but the pipes are round and kind of twinned and just don’t look the part so I opted to replace them with the CMK set. Monogram Kit instructions are excellent.

 The cockpit is built on a chassis along with the armament bay and also serves as the roof of the nose gear well. Obviously no guns needed so I glued a fishing weight to the chassis so the plane will stand on its legs. Interior was painted an on-hand dark green to represent Bell green. The .50 cal receiver detail and sight bracket were removed from the instrument panel which was painted black. Instruments were picked out by dry brushing with white then a drop of super glue on each dial for the glass. The seat was painted aluminum and the molded on seat belts in white. I didn’t do a lot of detailing because I planned to have the doors shut on this one. Normal assembly sequence has you attach the exhausts from the inside but I didn’t want to have to mask these for painting so decided to glue them on later from the outside. The resin replacements are for the Hasegawa kit so they don’t fit anyway. To facilitate this I glued a piece of scrap over the mounting points inside the left fuselage half to back stop the hole. The engine block back stops the right fuselage half.

I cut the nose gear strut at the oleo and CA’d them back together with 1/16 (1.57mm) aluminum tube cut ¼” long. I drilled a small hole with a pin vise in the cut ends of the strut and glued a small piece of plastic rod into the hollow of the tubing. These fit into the drilled holes to assist in alignment and add overall strength. The scissor link was pieced to fit. Cobra II had the nose gear oleo pumped up to the max for more ground clearance for a larger prop. Photos show the scissor link opened out wide as it will go and the aircraft has a distinct tail down crouch. The nose gear well and strut is painted Bell dark green. Going with the instructions the nose strut and gear doors are attached and the interior chassis glued to the right fuselage half. There are positive locating pins to position everything. The fuselage halves were glued together and the fit was excellent. Given a choice opt for an older Monogram made kit if you can find one, fit is better than the newer offerings. The fuselage glue seam needed very little filler. The gun bay cover, cockpit door, and engine covers were glued in place and again fit is good. The door windows were cemented and masked. The wing guns and pitot were glued in place to help seal the holes and the wing halves glued together. Then the gun barrels were cut off flush and filler applied to seal the gun ports. The wing was attached and again excellent fit with no gaps except that pesky trailing edge to belly seam that needed filling.

With the basic airframe complete it is now time to begin converting it to a racer. There is an auxiliary radiator under the belly. Two bomb halves from the big box of stuff were cut, ground to shape, fitted together, and gaps puttied up. The carburetor air inlet scoop was extended over the rear of the canopy (you can see from the picture that sometimes the old big box of junk just comes through for ya). In light of the Cobra I crash four 3” X 6 foot stiffeners were attached to the rear fuselage. I fabricated these from card stock attached with CA. The nose gun troughs were filled and sanded smooth. All fabric covered control surface detail has to be sanded off as these were skinned with aluminum. Then the tail planes were attached. All running light detail was sanded off. Card stock was cut to make the extended ground adjustable trim tabs for rudder and elevator. The racers had the flaps sealed which is another plus for using the Monogram kit. It has no recessed flap hinge line to eliminate (see, sometimes raised panel lines are good). Cobra II had a cable running across the inside of the windshield to reinforce it. I used a nylon broom straw for this. The canopy was masked with Tamiya tape and the framing cut out with a surgical blade. It was then glued in place.

When satisfied all the seams and gaps had been dealt with I sprayed all the control surfaces flat black because it’s easier to use than gloss. Red Pegasus decals include a black anti-glare panel so I didn’t have to deal with masking that. After curing I masked the black control surfaces and plugged the nose gear well. The airframe and landing gear doors were given a base coat of Testor’s flat white enamel. After letting that cure a couple days I sprayed three coats of Testor’s Blue Angels Yellow acrylic. Personally I think this color looks more like chrome yellow than their chrome yellow does. Takes a lot of yellow to get a good finish so I let it cure for three days. The main gear wells and struts were brush painted my close enough equivalent Bell interior green.

Red Pegasus Decals include a good instruction sheet with 3-view drawings for decal placement. They also list all of the modifications made to the P-39 that transform it into the Cobra racer. The decals are Alps printed so they are not independent of the carrier film. This requires close trimming of each marking. They are thin and conform to panel lines very well. They are a bit fragile, keep them wet while working them and get them in place quickly. I found that chasing small wrinkles did more harm than good. They react very well to decal solvents and minor wrinkles just melted away. They look great and are the closest to painted-on markings I have used. A coat of Testor’s Gloss lacquer sealed everything and gives a high gloss finish. Black pastel was smeared on for exhaust stains and a thinned black acrylic wash was applied to panel lines for accent. Then a final clear coat of AV Satin Varnish to give it a more realistic semi-gloss look. When dry the canopy masking was removed. Had a problem here, my windshield reinforcing cable had come loose during handling. Oh well, sure as heck not going to rip the canopy back off at this stage.

The CMK resin exhausts were trimmed to fit, painted, and glued in place. Some fiddling required due to the non-standard parts but it was worth it. The main gear struts and kit wheels were assembled. A plastic rod pitot probe was glued to the SBS spinner in place of the cannon. Cobra II’s spinner is pointed. To accomplish this I dripped some CA down the pitot shaft to seal the cannon hole. This seemed to work OK so I repeated the process of dribbling CA to build up a point. This was repeated innumerable times, a little bit at a time. Gravity was my friend here as it built itself up in the correct shape requiring only a slight bit of finger shaping (my finger tips are still sealed, hope no one needs a print). Some final sanding and the spinner painted black. I used the SBS prop blades but they are not correct. The Cobra racers used experimental Aeroproducts props being evaluated by Bell and there are just no aftermarket replicas I am aware of. I did square the tips up some to better look the part.

I have always thought the Cobra II was one of, if not THE, coolest looking airplane ever. I enjoyed the project. The modifications were challenging but nothing anyone with moderate modeling skills and adequate tools could not handle. The Hasegawa Cobra kit may offer some advantages, I don’t know, but I really like the way mine turned out.

Red Pegasus Decals instruction sheet,

 www.airrace.com,

www.youtube.com,

www.wikipedia.com.

21 November 2016

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