The Friday Flyby - The P-39 Airacobra

P-39 Кобрушка (Little Cobra)
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So, an aircraft built around a cannon, we're talking the A-10 Thunderbolt II¹, yes?

Nope, we're talking about the "lowly" Bell P-39 Airacobra.

So if you'll remember, about ten days ago I did a post on the "Best" Fighter of WWII. So I figured at some point I'd do a post on the "Worst" Fighter of WWII.

This isn't it.

Two aircraft, much maligned by historians, got a mention in that post, not as the best but as possible candidates for the "worst" fighter of WWII, the Brewster F2A Buffalo and the Bell P-39 Airacobra. When I started doing the research for the "Worst" fighter (false started twice BTW), I saw the Buffalo on almost every list, the Airacobra was on a couple of lists. But a couple of guys who actually flew the bird (one you probably know) had this to say about the P-39

“It was a great airplane, and its presence in New Guinea deterred the Japanese from landing in Australia, I can guarantee that,” asserts Colonel Charles Falletta, who totaled 16 aerial victories during the war, including six while flying P-39s over New Guinea. Most of the “rumors about the P-39 were from pilots who never flew the airplane,” contends Brig. Gen. Chuck Yeager. “It’s hearsay,” he concludes.

Yeager put in some 500 hours in the P-39 and once had to bail out over Casper, Wyoming, when a flight test of a new stainless steel prop went bad. The well-respected Yeager, who later became the first man to break the sound barrier, notes that “most pilots learn when they pin on their wings and go out and get in a fighter, especially, that one of the things you don’t do, you don’t believe anything anybody tells you about an airplane.” (Source)

As I've mentioned before, the Russians loved their "Little Cobra"², a number of Soviet aces ran up some big scores against their German opponents flying the P-39 -

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As you can see, all save one of those pilots were in "Guards" units. Guards troops were considered to be elite and they actually won that accolade in battle. This honorific was introduced in September of 1941, both to boost Soviet morale and to honor those units who had distinguished themselves in hard fighting.

Soviet P-39 in Guards livery, note the emblem on the pilot's door.
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Soviet Guards Badge

An aside on that "tank busting" note on the picture. From what I've read, that's really a myth. The Russians used the aircraft for a number of things, ground attack was not one of them, though I'm sure from time to time a Soviet pilot probably strafed a ground target or two. In actuality that big cannon (which I'll get to in a moment) wasn't actually supplied with armor piercing ammunition.

Now there are a couple of cool things about the P-39 that I have always thought were cool. One was that cannon firing through the propeller hub, that monster has a bore of 37 mm. As you might recall, the A-10 cannon is "only" 30 mm. The other thing I liked about the P-39 were the doors, one on each side, kind of like a car!

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Now both of those things which I found "cool" presented some problems for the pilot. First of all, the cannon only had thirty rounds, had a slow rate of fire, and tended to jam. Not really great attributes for an aircraft cannon, and those doors, notice which way they open.

Yup, into the slipstream. Try opening one of those at speed. So how do you bail out?

In the Pilot's Manual for the P-39Q-1, on page 17, it tells you how to "emergency exit" (Yes, that's what the manual calls it) from the aircraft -

Reminds me of Major Moran, "Oh my God, the tank is on fire!" (By the way, you can get your own copy of the P-39 Pilot's Manual here. It's only 33 pages long.)

Yup, just slide off the wing, that works for me. (When going up in the SNJ-6 a while back for aerobatics, the crew chief instructed me, sitting in the front seat, that if we had to "emergency exit" the aircraft to "Slide the canopy back, hit the quick release there, then dive over the trailing edge of the right wing." My pilot added, "If I say jump, don't ask questions, you'll be talking to yourself." Right...)

Now how did this wee bird wind up with that big cannon anyway?

In February 1937, Lieutenant Benjamin S. Kelsey, Project Officer for Fighters at the United States Army Air Corps (USAAC), and Captain Gordon P. Saville, fighter tactics instructor at the Air Corps Tactical School, issued a specification for a new fighter via Circular Proposal X-609. It was a request for a single-engine high-altitude "interceptor" having "the tactical mission of interception and attack of hostile aircraft at high altitude". Despite being called an interceptor, the proposed aircraft's role was simply an extension of the traditional pursuit (fighter) role, using a heavier and more powerful aircraft at higher altitude. Specifications called for at least 1,000 lb of heavy armament including a cannon, a liquid-cooled Allison engine with a General Electric turbo-supercharger, tricycle landing gear, a level airspeed of at least 360 mph at altitude, and a climb to 20,000 feet within 6 minutes. This was the most demanding set of fighter specifications USAAC had presented to that date. Although Bell's limited fighter design work had previously resulted in the unusual Bell YFM-1 Airacuda, the Model 12 proposal adopted an equally original configuration with an Allison V-12 engine mounted in the middle of the fuselage, just behind the cockpit, and a propeller driven by a shaft passing beneath the pilot's feet under the cockpit floor.

The main purpose of this configuration was to free up space for the heavy main armament, a 37 mm Oldsmobile T9 cannon firing through the center of the propeller hub for optimum accuracy and stability. This happened because H.M. Poyer, designer for project leader Robert Woods, was impressed by the power of this weapon and pressed for its incorporation. This was unusual, because fighter design had previously been driven by the intended engine, not the weapon system. Although devastating when it worked, the T9 had very limited ammunition, a low rate of fire, and was prone to jamming. (Source)

Here's what the cannon looks like without the airframe around it -

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You might also notice that the engine for this bird is rather a long way from the propeller. Note that the drive shaft for the propeller runs under the cannon and, as a matter of fact, is behind the pilot. That drive shaft runs under the pilot (between his feet actually) and is actually offset down from the propeller center line. The design uses an offset reduction gearbox to drive the prop, which you can see the back of here -

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By the way, that horse collar looking thing is the magazine for the cannon. We'll see that in this video -

Here's the cockpit with the seat removed and the shroud removed from around the stick -

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Now that cannon wasn't the only bit of weaponry on the P-39, it also mounted two .50 caliber machine guns on top of the engine, and two more in the wings (one per side). She packed quite a punch!

I think another reason why I like this aircraft is that my brother and I built a kit of it way back in 1965!

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I always thought that the canopy provided better visibility than a lot of early WWII designs and that tricycle landing gear was pretty modern as well.

A pretty cool video of the P-39 from my favorite flight sim, Il-2 Sturmovik -

The flyby by the C-47 in the beginning is pretty cool, the engines sounded "just right."

Here are two cutaway diagrams of the P-39D, one is the "stock" US model with the 37 mm cannon and the other is the Soviet model with a 20 mm cannon. (You'll need to click to embiggen, I didn't want to lose any detail by shrinking the drawings to fit.)

US Version
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Soviet Version
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Oh, one more thing about that cannon, as you fired off the cannon ammunition, the center of gravity of the aircraft tended to shift aft as the nose got lighter. The P-39 had a distressing habit of going into a flat spin if you yanked and banked over-enthusiastically when that happened!

The Pilot's Manual has two sections (page 19), first is Maneuvers Prohibited -

The following acrobatics are prohibited:

• Outside loops and spins
• Never try any acrobatics with a tail-heavy aircraft

Then there's second, ever popular, Maneuvers Not Recommended -

The following acrobatics are prohibited:

• Snap rolls
• Spinning

So yes, don't spin the bloody thing, ever! I call those two sections "don't ever do this" and "really, you really shouldn't do this either." Good to know.

The instrument panel was rather straightforward (I've seen some a lot more complicated) -

Key to the figure below

P-39 Airacobra Instrument Panel

I don't really know why, but I really like the P-39, it has a certain je ne sais quoi. Perhaps "coolness" is how I'd put it. Besides, the Juvat's flew these back in the day!

USAAF P-400 of 80th Fighter Squadron "Headhunters," 8th Fighter Group

The P-400 is a modified version of the P-39:

In September 1940, Britain ordered 386 P-39Ds (Model 14), with a 20 mm Hispano-Suiza HS.404 and six .303 in, instead of a 37 mm  cannon and six 0.30 in guns. The RAF eventually ordered a total of 675 P-39s. However, after the first Airacobras arrived at 601 Squadron RAF in September 1941, they were promptly recognized as having an inadequate rate of climb and performance at altitude for Western European conditions. Only 80 were adopted, all of them with 601 Squadron. Britain transferred about 200 P-39s to the Soviet Union.

Another 200 examples intended for the RAF were taken up by the USAAF after the attack on Pearl Harbor as the P-400, and were sent to the Fifth Air Force in Australia, for service in the South West Pacific Theater. (Source)

The Headhunters of the 80th? These guys -

Known as the "Juvats" due to the squadron motto -

Audentes Fortuna Juvat - Fortune Favors the Brave

And yes, "our" juvat flew with those guys. No, no, not in World War II, he's nowhere near Old NFO's age, he flew with them in Korea, in the 80s. Yes, the 1980s. When I was there.

Anyhoo. Cool aircraft, I likes it. Yes Precious, I do.

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Someday I'll do that "Worst" fighter of WWII post, today is not that day.

From the Pilot's Manual

From the Pilot's Manual

Don't underestimate an aircraft until you've flown it! (You've been warned.)


Suggested Reading and Sources:

• America's Worst WWII Fighter Link
• Yanks Air Museum P-39 Link
• This Day in Aviation, 01 Sep 1946 Link
• National Museum of the Air Force, P-39 Link
• National Museum of the Air Force, Allison V-1710-85 Drive Train Link
• Warfare History Network, the P-39 Link
• Wikipedia, Bell P-39 Airacobra Link
• Wikipedia, Bell P-63 Kingcobra Link
• Skytamer Images, P-39N Link
• Avgeekery, The Fighter US Pilots Disdained Link
• Lt Ivan Baranovsky's P-39 Link
• Russian P-39 Freed from Frozen Grave Link
• P-39 Airacobra Discovered in Russian Lake Link

Those last three are all different takes on the same story, a Soviet WWII-era P-39 recovered from a Russian lake. With the pilot still inside, God rest his soul.


¹ AKA Warthog, or just Hog.
² Actually the Russian word "Кобрушка" (Kobrushka) is the diminutive term for the Russian word "Кобра" (Kobra). Just as Billy is the diminutive term for William. More of an affectionate term than anything else...