The P-39 an all-metal, low-wing, single-engine fighter was one of the main fighter aircraft in service and available at the beginning of American involvement in World War II. It's mid-engine design left the nose of the ship open to range of armament second only to the P-38 Lightning in it's firepower with it's 20 or 37mm cannon and twin 50 caliber guns. Early models had four wing mounted .30 caliber machine guns which on later models were removed or replaced with underwing pods containing a single .50 cal machine gun each.
The P-39 saw significant action in the erly days of the War in the the New Guinea area, as part of the Cactus Airforce and in the Aluetian Islands, attacking Japanese forces occupying Attu and Kiska Islands
It also saw action in the Mediterranian and North African theatres and many an American Ace got their first kills in the P-39

Plagued by high altitude performance issues, the P-39 performed poorly above 15,000 feet and found itself outclassed as an interceptor and the type was often used at lower altitudes for such missions as ground strafing.

More than 9,500 Airacobras were built during it's production run with more than half going to the Soviet Union as part of Lend Lease.

This unique aircraft has always been one of my favorites. From the first time I built it back in the 60's to today's offerings. It's now available in a range of sizes from 1/144 through 1/32 scale and I've gone out and bought three of the 1/48th kits vailable from three different manufacturers.
I've also included it's sibling, the P63 King Cobra

Below is my two cents worth on these kits

Monogram 1/48th

Might be my all time favorite kit. When available, this kit is still the most complete offering on the market. Although the molds are old this kit still gives you the best bang for your buck. Of the kits I've built, this one is the only kit in 1/48th or 1/72nd scale that includes the weapons bay and the engine. The parts are pretty free of flash and there's no issues with fit. Unlike the other two kits, the Cockpit door windows are separate parts.
Downside... Raised instead of engraved panels lines, and no after market accessories specific to this kit.
you need to be creative in your use and placement of weight to keep all three wheels on the ground or use the clear post provided in the kit. craft shops now sell a tungsten weights and putty that weigh more than lead or

This kit comes with markings for the 67th Fighter Squadron, Cactus Air Force, Guadalcanal, the 51st Fighter Group, North Africa, and the 49th Fighter Squadron, Canton Island

Eduard 1/48

Eduard offers the Airacobra in three different versions. All three versions offer the same basic kit and usually multiple variations. The current "weekend edition" offers the "N" or "K" Variant
Each kit has parts enough for all versions of the P-39/P-400. You'll find three different exhausts, three different nose sections and both 3 and 4 bladed propellers depending on which kit Eduard is presenting to you.
They all come with a full color instruction booklet and an extensive set of stencils on their decal sheet

The parts are clean and clear of any flash or mold marks and go together well. The engraved panel line are crisp and well defined. I did have an issue with the fit of the clear parts, the canopy was a little too narrow and the doors didn't sit very well in the closed position.
The upside of these kits is the potential..The level of detail in the cockpit will depend upon which kit you decide on, and the engine compartment and weapons bay are there just waiting to be utilized with aftermarket parts.
Verlinden made a very nice set if you can find one at a reasonable price on online bidding hostage sites

Eduard and several other companies make a resin engine compartment, flaps, wheel wells etc. but other than the verlinden set, there's nothing i've found available to detail the weapons bay

The "Weekend Edition"
This is their basic bare bones kit. What you see in the photo's above are what's in the box. The basic bag with three trees of parts molded in grey and a clear tree with canopy along with instructions and markings for two aircraft.

The "Profi-pack"
This kit contains a small sheet of photo etch for the cockpit, Masks for the canopy windows and markings for five aircraft. The instrument panels are two part pre-printed with gauges and are overlaid with a second pre-painted panel.
This kit runs about the same price as the Hasegawa kit

The "Dual Combo"
This set is a limited edition Eduard offers from time to time. It contains 2 complete kits with markings for 9 aircraft and multiple variants. It contains multiple sheets of photo etch with different control panel variations as well as interior detailing.
Since the P-39 had Tricycle landing gear, eduard includes cast resin "weighted wheels" to help keep the aircraft on all three wheels (wheels that are flattened in one area to depict weight and keep the kit from rocking backwards)

   

Hasegawa 1/48

Six flash free sprues molded in gray, plus one in clear with the canopy, windows and navigation light lenses.
Of these three kits, this one has the most cockpit detail straight out of the box, the individual gauge details on instrument panel are well detailed with needles and and level gradients around the edges.
Again, no engine or weapons bay details and it's not as upgrade ready as the eduard kit but there are plenty of upgrades available
Like the basic Eduard kit, this goes together quickly with 2 versions in three different configurations and markings for three aircraft.
The decals are a little on the thick side on this kit, they didn't settle into all the little nooks and crannies as the other two kits did and required several applications of solvaset

Still Under Construction

Kitty Hawk, 1/32

Of the offerings available in 1/32 scale, I chose this kit because it has interior details lacking in the Revell and Special Hobby kits, from the gear box in the nose to the radio equiment in the tail and everything in between. Full cockpit, engine and weapons bay.
The wings include the landing flap interior detail as well as open compartments for the 30 caliber machine guns. The underside of the wing has the ejector holes for the .30 caliber shell casings which will need to be filled if you chose the -Q model.

I was disappointed that the instrument panel gauges lacked detail, with only a decal. I plan to cut out the individual dials from the sheet rather than use the entire decal or invest in the eduard cockpit detail set. Another minor detail I noticed was the bullet proof glass behind the pilot was left out of the kit.

P-63 King Cobra
Dora wings, 1/48 scale

I included this kit due to it's family relationship to the Airacobra
It's available in several variations and three sizes. Like the Eduard kit, it comes one size fits all with parts for multple versions of the aircraft inside the box.