Perhaps no other VVS aircraft has been the subject over the years of so much speculation, misidentification, and sheer interest than Polikarpov's I-16. I certainly count myself amongst those so befuddled, and for many years the exact identification of the various I-16 variants has been virtually impossible to undertake with any accuracy. It is now clear that I have--along with virtually everyone else--largely gotten all of my I-16 identifications wrong all along.
    However, with the publication of Mikhail Maslov's searchingly brilliant study of the I-16 in the Armada publication on this aircraft the foundation was laid at last for a proper identification of the various I-16 variants and types. Now, perhaps, it is time for us all to step back, discard the old ideas, and for once approach the task of sorting out the I-16 types afresh. Maslov has gone very far indeed toward this goal, explaining the development of the TsKB-12 with a clarity and accuracy heretofore unknown. It is to Maslov's credit that this article, quite in fact, can even be attempted.
 

Part I: What version is it?

    After much thought, and with the new information in hand, it occurred to me that all I-16s are characterized by four major components: Fuselage, Engine, Wing, and Spinner. Thus, one can actually identify any I-16 by comparing the combination of these components to the aircraft in question. This is true largely because the I-16 was very much a developmental programme, and the successive types tended to be derived directly from the preceding model(s), at least in many respects.
    With this concept in mind, I have drawn up a series of tables describing the different permutations of these four components over the developmental life of the I-16 fighter. Each thumbnail links to a larger line drawing of the part in question, and these are color coded for easy identification on the matrix below. The idea here literally is to think of an "I-16 Type 10" as in fact an 'I-16 with this type of wing, those types of engine and spinner, and that type of fuselage'. I believe that this makes a great deal of sense once the idea clicks home, but some readers have preferred to read the I-16 Development section first.

Spinner
 
 

1	Early cone shaped spinner used with the original two-pitch propeller (usually M-25 radial).
2	Larger rounded spinner used with the constant-speed propeller (usually M-62 radial).
3	Rounded spinner with a flared base used with the AV-1 propeller (usually M-63 radial).

Wing
 

1	Original I-16 wing with full-length ailerons and ShKAS guns.
2	Improved wings with full-length ailerons and ShKAS guns.
3	Improved wings with shortened ailerons and ShKAS guns.
4	Improved wings with shortened ailerons and ShVAK cannon.
5	Improved wings with shortened ailerons and no guns.

Fuselage
 

1	Original I-16 fuselage with sliding canopy, telescopic sight, and tail skid.
2	Original I-16 fuselage with fixed windscreen, reflector sight, and tail skid.
3	Original I-16 fuselage with fixed windscreen, reflector sight, tail skid, and cowl gun fairings.
4	Improved I-16 fuselage with fixed windscreen, reflector sight, tail wheel, cowl gun fairings, radio access hatch, and starboard crew door.
5	Improved I-16 fuselage with fixed windscreen, reflector sight, tail wheel, cowl gun fairings, radio access hatch, starboard crew door, and radio mast.

Cowling
 

1	Original NACA cowling with fixed inlet grilles.
2	Improved aerodynamic cowling with shutter type cooling grilles, eight exhaust blisters, and tear-drop shaped outlets.
3	Improved aerodynamic cowling with shutter type cooling grilles, eight exhaust blisters, lower 'T' shaped intake, and upper ShKAS guns and fairings.
4	Improved aerodynamic cowling with shutter type cooling grilles, six exhaust blisters with ski troughs, lower rectangular shaped intake, and upper ShKAS guns and fairings.
5	Improved aerodynamic cowling with shutter type cooling grilles, six exhaust blisters with ski troughs, lower 'T' shaped intake, upper ShKAS guns and fairings, and upper triangular intake.
6	Improved aerodynamic cowling with shutter type cooling grilles, six exhaust blisters with ski troughs, lower inverted 'T' shaped intake, upper ShKAS guns and fairings, and upper triangular intake.
7	Improved aerodynamic cowling with shutter type cooling grilles, six exhaust blisters, lower intake shifted to starboard, upper ShKAS guns and fairings, upper triangular intake, radio mast, and lower center-line UBS gun.

    Those, then, are the various components. The aircraft types resulting from them are as follows:

I-16 Variant matrix, by Component
 

Aircraft	Spinner	Wing	Fuselage	Cowling
Type 4	--	1	1	1
Type 5	1	1	1	2
Type 5, 1938 production	1	2	2	2
Type 6	1	1	1	2*
Type 10	1	3	3	3
Type 12	1	1*	1	2
Type 17	1	4	3	4
Type 18	2	3	3	5
Type 24	3	3	4	6
Type 27	2	4	3	4
Type 28	3	4	4	6
Type 29	3	5	5	7

The I-16 Development Page describes each Type's evolution in the programme.

The Family Tree displays the same information in visual format.

Part II: The Kits

Part III: Aftermarket