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.”

 

 

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6 Comments

Filed under Airplanes in my novels, Aviation, Uncategorized

6 responses to “Spin Recovery in the P-39

  1. “If the procedure is not followed closely, the airplane may not recover.” Ouch! The scariest part is that this would have had to be discovered by a test pilot… Do you know if these characteristics have anything to do with the P-39 being mid-engined? I know very little about the type other than the fact that it was mid-engined with a ‘car door’!

    • Matthew, one of the things that emerges from anecdotal accounts is that even firing off a few rounds of 37mm ammunition in the cannon could have interesting effects on the airplane’s handling. The P-39 was very sensitive to elevator forces — you needed a very little deflection on the elevators for a lot of change in pitch. It was an airplane that rewarded a pilot with good hands, sensitive hands, but anyone else, well…

      One thing to remember is that a lot of the pilots early in the Pacific War were thrown into the cockpit of the P-39 with as little as 200 hours total time, about as much as today, here in the States, as a civilian commercial-instrument pilot has. (Probably a contemporary pilot would be better on instruments!) You’ve done a lot of research on the RNZAF (read your book, you know!) and you probably ran across accounts of how the pilots behaved when they went from biplanes to the P-40 … and the accident rate that resulted.

      Most of that was how extremely fast aviation was changing in those days.

      There’s a great book (other than mine, of course!) by a guy who was there, Edwards Park, titled Nanette: Her Pilot’s Love Story, that’s well worth a read. Park flew P-39s with the 5th AF in New Guinea, and has a lot of insights about flying the airplane in combat.

      The real experts on the P-39 in combat might be the Soviets. Most of Bell’s production run of P-39s and its successor, the P-63 Kingcobra, went to the Soviets, who were evidently major fans of the P-39. The Soviets fought mostly at low to medium altitudes where the P-39’s performed the best.

      Hope this isn’t too much information!

      • Thanks for the info – not too much information at all! I find all this stuff fascinating. My frustration is that I have only limited time to explore it! The rate of change in aviation technology during the period was simply stunning. One thing that became clear to me when researching ‘Kiwi Air Power’ – and again just last year when I interviewed a Brit aviation writer about his researches on the Fleet Air Arm for an article that was spiked by the commissioning magazine – was the ‘hoon’ factor. A lot of the pilots were barely out of their teens, and they’d just been given one of the most powerful pieces of aerial hardware around. The temptation to hot-dog the things was one to which many seemed to succumb. And of course they really didn’t have the piloting experience if they got into trouble.

      • “Hoon” factor? That’s a new one on me! What would you think of the proposition that aviation, as a technology, was “waiting” for several other fields of engineering to “catch up” — materials engineering, for example, as particularly related to the metallurgy required to cast blades for high-speed turbines. First needed for piston-engine superchargers, but then for compressor section blades in turbo-jets? Which technology, after all, Frank Whittle patented in what, 1928?

  2. I’m not sure whether I coined that phrase or not. We use ‘hoon’ in NZ as a term to describe young male drivers who carelessly hurtle their over-powered and under-handling cars around suburban streets. I think you’re right on the catch-up idea for tech. I suspect the First World War laid the grounding for quite a bit jump – but it took a while to then develop the technology to make that possible. There seems to have been quite a coalescence of revolutionary concepts and methods by the mid-late 1930s – stressed-skin duraluminum construction, a swathe of applications for thermionic valve electronics (including the polyphonic synthesiser, video phone and TV) – all of which was only possible on the back of a lot of other work in prior decades. But many of them didn’t get anywhere just then (especially the synthesiser), the TV lacked infrastructure and so on. Physical manufacturing also lagged – jet engines were definitely ahead of their time in the sense of the concept pre-dating the ability to actually build it, and even after they were available it took a while to make them reliable. What fascinates me about this – jets as a specific example, but the technology in general – is that it created a discontinuity – a ‘jump’ (as in aircraft speeds and performance) but it wasn’t an unlimited rising curve; it stepped up to a new plateau, beyond which more was possible, but expensive or difficult (I’m thinking Concorde vs the usual jet airliner speed that, if anything, has slipped a bit since the 1950s).

  3. Stuff like this always reminds me of James Burke and his great show Connections.

    I get the plateau thing. We can build jet fighters that can go Mach 3+, but their engines gulp so much fuel (that pesky action-reaction thing) that the faster they go the less endurance they have. Gets to the point of being self-defeating. It’s the same concept as the armor-armament-engine triad in dreadnaught design. Interesting common principles here. Like, maybe, a fighter can’t be too big because of the aerodynamic drag penalty. But it has to be big enough to carry a useful fuel load. Then there’s a tradeoff between “defensive” weapons (ECM and other electronics) and “offensive” weapons (missiles and guns.) The engines can be made more efficient, but if so, it only ameliorates the problem — and if efficiency generates greater thrust, using it also increases fuel consumption.

    “Hoon” — I’ll have to remember that one!

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