Spin Recovery in the P-39

The first time I was in a spin it was in a sailplane with very docile handling characteristics, the Schweizer 2-33. Spin recovery is a necessary skill to master in a sailplane, since you spend a lot of time turning inside a thermal a few miles an hour above stall speed. Misjudge that, let your speed drop, tighten the turn a little bit too much, and you depart controlled flight.

But not to worry, not in the 2-33. Center the controls to break the rotation, stick a little forward to pick up airspeed, and the sailplane is flying again.

That’s two pretty simple, even instinctive moves. You can do it in a second or less.

The pilot’s manual for the P-39 Airacobra sets out a recovery technique that’s a little more complicated. There are two phases, pre-recovery and recovery. In the pre-recovery phase, the pilot has to close the throttle, set the propeller control to the low RPM position, and pull the control stick into your lap. Get it? The throttle is at your left hand, the propeller control is just behind the throttle, so that’s a one-two movement as you pull the stick back into your lap.

Now remember the airplane is not in a controlled maneuver. The manual describes the spin as being oscillatory in rate. Sometimes it spins fast, sometimes it spins slow. You don’t have any control over the rate. You have to decide when the airplane is slowing down or speeding up. You have to know that because, to effect recovery, you have to apply full opposite rudder when spin is at its slowest. All this time your surroundings — clouds, ground, horizon — are spinning around you. Imagine standing on one of those old playground merry-go-rounds, right in the center, as your friends push on it to make it go faster. That’s a start on what it would be like, except this spin happens in three dimensions, not two. So you wait for the rudder to take effect and push the stick full forward while applying ailerons against the spin. The actual language used in the manual is interesting: “The spin is usually oscillatory in rate, and it is mandatory that the opposite rudder be applied when the spin is at its slowest.” I particularly like that word “mandatory.” It’s the sort of emphasis you don’t often find in a pilot’s manual.

If you follow the procedure above, “…the airplane will recover in one-half turn. If the procedure is not followed closely, the airplane may not recover.” I think the implications of that last sentence deserve examination. You must follow the procedure closely, i.e., you do exactly what the manual says, or you’re going in.

No wonder the manual begins the section on spins with the statement “Deliberate spinning is not recommended.”

Just for a little context, follow the link below, which takes you to a War Department film on spin and tumble tests in the P-39. Bell Aircraft test pilots did these tests because pilots flying the P-39 insisted that the airplane would, in the right circumstances, literally tumble end over end.  You’ll probably also see why the manual included words like “mandatory” and “closely.”

 

 

Airplanes in My Novels: the Much-Maligned Bell P-39

Bell P-39 night-firing. Note engine exhausts and air scoop behind the cockpit. Wing guns are .30-cal., the two guns firing through the propeller are .50-cal., and the 37-mm cannon is firing through the prop spinner.

Before I started writing Boxcar Red Leader, I knew there was an airplane called the P-39, that it was built by Bell Aircraft, and was fairly unique among fighter designs of the era in having tricycle landing gear and the engine mounted in the fuselage behind the pilot, to leave room in the nose of the airplane for a 37-mm cannon. The propeller driveshaft passed from the engine behind the cockpit, under the pilot’s seat, and connected to a gearbox that drove the propeller. The P-39 was a contemporary of the far-better-known Curtiss P-40. I also knew the airplane was called the “Iron Dog” and there seemed to be a sizable contingent of former P-39 pilots who actively disliked the airplane. There’s even a verse about it, in the old Air Corps folk song “Give Me Operations:”

Oh, don’t give me a P-39
The engine is mounted behind
She’ll stall and she’ll spin
And she’ll auger you in
Don’t give me a P-39!

Evidently the center of gravity and the center of lift in the P-39 were in a very sensitive relationship, far more so than in other, more conventional airplanes. This resulted in an airplane very sensitive to pitch inputs, such that only very small increments of elevator control were needed to effect pitch change. This goes directly to the “she’ll stall and she’ll spin” verse above. When pulling gee in a tight turn one pulls back on the stick; if not done with skill, the turn will tighten to the point where the g-load exceeds the lift generated by the wings, causing what is known as an “accelerated stall.” Entering a stall from a turn will lead to a spin, and evidently the P-39 had interesting spin characteristics, to the point where many pilots were convinced the airplane would actually tumble end over end.

On the other hand, there were pilots who absolutely loved the Airacobra. Chuck Yeager flew the airplane in training, loved it, and relates in his autobiography a conversation he once had with a Russian pilot who flew the P-39 – successfully! – against the Luftwaffe. Edwards Park flew the P-39 in New Guinea, and his account of that time is written in his book, Nanette: Her Pilot’s Love Story, a narrative I recommend as one of the best books about flying I’ve ever read.

My perception is that much of the dislike directed at the P-39 resulted from the pilots who were thrown into the airplane straight out of flight school and then expected to fly the P-39 against the experienced Zero pilots of the Imperial Japanese Navy in the skies over New Guinea. Most of these pilots had never flown an airplane more powerful or faster than an AT-6 trainer. Later in the war pilots like this would be sent to an OTU, or Operational Training Unit, to encounter the P-39 or P-40 under the relatively benign conditions of a stateside training base. In the Pacific, in 1942, kids fresh out of flying school were put in P-39s and P-40s and sent out against the Japanese. The loss rate, from accidents and combat, was horrendous.

The P-39, like the P-40, was equipped with the Allison V-1710 engine. The V-1710 was a fairly good engine, but in the P-39 and the P-40 it had only a single-stage supercharger, and, as a result, the performance of both airplanes fell off sharply above 17,000 feet. If what you have to defend Port Moresby and Seven-Mile Drome from Jap bombers flying at 23,000 feet is a P-39, you face a difficult tactical problem, one not helped by the fact that the defenders of Seven-Mile rarely had enough warning to climb high enough to intercept Japanese bombers with any hope of success.

Between the high loss rate and the poor performance, compared to the A6M2 Zero fighter the P-39 found itself matched against, it’s no wonder the pilots disliked the airplane.

Still, I kind of like the P-39. I’ll never have a chance to fly one, to see for myself just how sensitive and well-balanced those controls are, or if she really will tumble, but there’s something about the way the airplane looks.

Over and above any of that, the P-39 was one of the two pursuit airplanes the Army Air Forces had at the beginning of World War Two available in significant numbers. It didn’t matter, from that perspective, how the pilots felt about the airplanes. It was what they had.