Crea sito
 
I-16 Type 12

Updated on 7 December 2020

back to Sovietwarplanes Pages Index
back to I-16 index
back to I-16 types index

 

In May 1936, the Soviet government decided that it was time to develop fighters armed with rapid fire guns. The governative resolution of 3 May 1936 gave a very close deadline, 25 May, to start the tests.

At that time, the bureau of Nikolay Polikarpov had just drawn the project to install two 20mm ShVAK guns on the wings of a TsKB-12 M-25. The armament installation had to be fully reprojected. The new ShKAS guns had to be located in the position previously occupied by two ShKAS, firing just outside of the propeller's disk. , The plane was projected with a strong air-to-ground armament including eight Der-32 locks for bomblets, two Der-31 locks for medium bombs.

 

TsKB-12P

 

The plane that was converted was a TsKB-12 M-25, substantially a pre-production Type 5 built in Factory 39 engined with an imported Wright Cyclone F-3.

The prototype started the gun firing tests on the ground on 5 May, but it wasn't ready to fly for the deadline of 25 May. Photos seem to show that the main leg of the landing gear was slightly longer than usual, or at least that the stroke of the shock adsorber was reduced and it was less compressed. To save time and start the tests quickly, the landing gear was made fixed; the wheel bays were closed with screwed plugs, and the splined shock adsorber was protected by a dark flexible cover. .

Inflight tests started only on June 14, 1936; up to 16 June, the plane was flown 8 times by the famous test pilot Valeriy Chkalov, that fired with the guns and, to a much lesser extent, with the machine guns.The tests showed that the installation of guns and the guns themselves had a lot to be perfectioned before becoming reliable, but the plane didn't suffer of an excessive loss of performances, vibrations, ruptures or other heavy problems, so the final result was considered encouraging.

The defects of the guns and feeding system were fixed, and the plane fired in flawless way at the tests of 19 June 1936. The following day it was presented to the state tests.

The first stage of state tests ended on July 22, and the plane returned to the factory for some modifications to the gun feeding manifolds; the number of rounds had to be reduced from 120 to 85 for the left gun and to 95 for the right one.

The modified plane returned to the NII VVS on August 31, but the tests revealed new defects on the ShKAS and their feeding, and the plane returned to Khimiki, where the Polikarpov bureau had moved, for corrections that were quickly made, and the TsKB-12P completed the tests at NII VVS on 1 October. The feeding of the guns wasn't still fully reliable and there were problems with freezing oil at -35°C, but the flight performances weren't too affected by the installation of the guns.

It was decided that all the drawings of the gun-armed plane had to be sent, after corrections, to factory n.21 for the pre-series production of 10 planes.

 

Images from Polikarpov's I-16 fighter of Gordon and Dexter

 

Right: a detail of the ShVAK gun and of the ShKAS machine gun protruding from the right wing of the TsKB-12P.

The tube for the expulsion of waste shells protruded from the leading edge just below-on the right of each barrel of the ShVAK.

The ShKAS machine guns were moved from their previous position on the centerplane into the outer wing consoles to make room for the gun as close as possible to the plane centerline, just outside the propeller disk.

Some details of the DER-32 attach points for bombs are recognizable under the wing leading edge.

Image from M-Hobby n.3/2020, article of Andrey Averin

 

The ShVAK guns were inserted or removed passing through an hatch between the 3rd and 4th ribs of the centerplane. Before removing them, the feeding sleeves had to be removed.

The hatch was shorter than the one mounted on successive gun-armed Type 17, 27 and 28, so the weapon had to be moved forward and inclined of 26° to be extracted backwards.

The reloading of the guns was pneumatically actioned; as an alternative, there was a mechanic reloading actioned by levers and cables, but it could function only if the pneumatic reloading system was deactivated on the ground.

Just outside, on the wing console, we see the semi-closed hatch of a ShKAS.

 

Image from Polikarpov's I-16 fighter of Gordon and Dexter

 

 

The ammo of the ShVAK guns were loaded into a small rectangular hatch on the top of the nose; the ammo belts were loaded into ducts passing inside the wings along the front spars and arriving to the guns, where the ammo belts were pulled by the feeding mechanism. This method was preserved on pre-production Type 12, and on later gun-armed Type 17, 27, 28.

The ingress of the ammo belt was made easier by a cable that was pulled by the man acting on the gun hatch, as visible on the photo.

The waste shells were expelled by tubes coming out from the wing leading edges, just on the right of the barrels; the waste links were expelled from slots on the lower surface of the wings centerplane.

Image from Istrebitel I-16 of Maslov

 

 

The ShKAS machine guns were installed at the base of the outer wing console.

It was impossible to preserve the original position of the ShKAS ammo boxes in the fuselage, so they had to be loaded by ducts passing through the whole consoles width, starting with small hatches close to the wingtips.

To load easily the ammo belts into those hatches, long guide rails were utilized.

The duct inside the wing could store 300 rounds.

The waste shells were expelled by tubes coming out under the wings consoles; the waste links were expelled from slots under the wing consoles.

Image from Istrebitel I-16 of Maslov

 

 

On December 19, the guns were replaced with new ones and the plane started another stage of trials. These tests lasted up to February 8, 1937. The installation worked well, but at the time the ShKAS were still too 'green' and had still problems reducing their reliability and durability.

The guns were removed, and the plane started tests with the remaining armament, that was the ShKAS and the underwing loads.

The plane could carry a chemical armament consisting in two VAP-6 gas dispensers, whose supports had been modified to fit the DER-32 racks of the TsKB-12.

The weight of each VAP-6, filled with 36 liters of liquid, was 58 kg

12 dispersion test flight at low altitude, with different speeds, were made with satisfactory results. No real poisonous liquids were used in the tests.

The VAP-6 dispensers could also be used for incendiary liquids, with the addition of an ignition device, appearing as a thinner fuse mounted under the VAP-6. Each device, loaded with 3.5 liters of liquid, weighted 8.5 kg.

10 test flights were made with the incendiary device; in the last one, a real incendiary fluid was used.

There was a problem with the strength of the frontal DER-32 that was overloaded when the ignition device was installed. All the proposed modifications were unsatisfactory.

 

Images from M-Hobby n.3/2020, article of Andrey Averin

 

The final tests stage at the NII VVS was made to check the functioning of the electric devices for the release of the bombs. The plane had:

  • 8 DER-32 racks for 8 AO-8 or AO-10 bomblets, or for 4 AO-20 or AO-25
  • 2 DER-31 racks for 2 FAB-50 or FAB-100 bombs, or for 2 RRAB-4 cassettes.

It was also possible to bring 2 FAB-50 on DER-31 and two smaller bombs on DER-32.

All the releases were controlled by an ESBR-3 electric command located on the left side of the cockpit; in case of emergency, loads could be released all together with the ASBR-1 electric device located on the floor, on the right of the pilot.

Tests were made on the possibility of releasing singularly one of two FAB-100 bombs against different targets; in the tests, the plane flew without problems with one bomb still loaded under one wing, both in horizontal and in dive.

While testing, the plane was equipped with non-retractable ski gear.

Left: details of the DER-32 with 8 AO-10 bomblets, and of DER-31 with FAB-100 bombs.

 

Images from M-Hobby n.3/2020, article of Andrey Averin

 

Right: two details of the DER-31 bomb suspension point: the first image is of the right wing from inside, the second one of the left wing from outside. One can also see the waste link outlets of the ShVAK and, on the first image, of the ShKAS. The smaller thing on the rear is the rear attach point for the gas/incendiary dispenser.

Images from M-Hobby n.3/2020, article of Andrey Averin

 

I-163

 

 

In the meantime, at the beginning of 1937, the Polikarpov bureau was involved into a more radical update of the I-16. One of these prototypes was the I-163, that was thought as the production standard for 1937.

This plane had:

  • the same armament of two ShVAK and two ShKAS in identical installations developed on the TsKB-12P and the same external load racks; only visible difference, the guns protruded through bulbous fairings on the leading edges;
  • performed a more powerful M-25E engine based on the Wright Cyclone M-54 with a stronger supercharger;
  • used an Hamilton-Standard propeller with longer spinner;
  • had a reprojected landing gear, pneumatically actioned by the same cylinders that controlled the opening and closing of the flaps, and had new legs with the wheels sustained by forks instead of cantilever trunnions;
  • pneumatically actioned landing flaps with two positions (closed or fully opened at 53°);
  • shorter ailerons (still slightly larger than those introduced with the successive Type 10);
  • new horizontal tail surfaces similar to those of the successive I-180;
  • an additional door on the right side of the cockpit;
  • a radio equipment with a huge mast and wiring from it to the tips of the wings, of the stabilizer and to the back.

 

The I-163 was more advanced than the TsKB-12P and the pre-series Type 12 already on building, but it had a big defect: it was too heavy, more than what the additional equipment would have justified.

On the plus side, the flaps were highly effective to reduce the takeoff and landing speed.

The problem that stopped definitively the I-163 development was the extreme unreliability of the supercharger of the new engine M-25E; its impeller turned at 22000 rpm, and Soviet-built bearings were unable to sustain this.

The plane was spoiled of its armament, repainted and renamed I163-1, and it went to the NII VVS for tests relative to the flaps that ended on early June 1937. The tests confirmed the effectiveness of the ailerons to reduce the takeoff and landing speeds, even if it was complained that they were not positionable at intermediate angles.

It was decided to implement the ailerons on the production I-16 Type 5 starting with October 1937, but it's not clear if this was really done before the beginning of 1938, because photos of Type 5 with flaps and short ailerons are lacking.

Images from M-Hobby n.4/2020, article of Andrey Averin

 

I-16 Type 12

Because of the problems of the I-163, the more conservative gun-armed Type 12 was still in consideration. In April, 10 pre-production Type 12 were completed in Factory n.21. On mid June 1937, a batch of 8 arrived to the VVS airport of Lipets near Serpukhov. An intensive test session started on 23 June: the planes made many flights with an intensive use of their weaponry. After some days, the weakness of their structure, particularly of the wing consoles, emerged with deformations and cracks; one of the planes had a rupture of a wing console and of part of the landing gear. The test session was stopped on 26 July 1937 and the planes were transported to the Factory n. 21 to be repaired, strengthened and repainted; the wing consoles and the structure sustaining the landing gear were completely replaced with stronger ones.

On August 13 the tests were restarted up to September 11, with better results.

 

The I-16 No. 12215 was transferred to TSAGI to perform research to determine the impact of the rigidity of the wing structure on the accuracy of firing.

Left: Here we see the plane with what seems a gun camera installed under the left wingtip and another one on the back of the fuselage behind the headrest. The comparison of the shots taken while firing gave indications on the loss of accuracy due to the wing deformation.

The plane was spoiled of the landing gear doors and of the spinner, but it still had the suspension points for bombs and other devices.

The photo shows the lack of the ShKAS in the wing consoles; their openings on the leading edge were closed by sealing tape or something similar.

Image from M-Hobby n.4/2020, article of Andrey Averin.

 

Another image of 12215. The thing under the wing was probably an aerodynamic fairing for the gun camera seen on the previous photo.

The livery is very characteristic, comprising three lines (blue-red-blue?) on the fuselage, black-contoured red stars in six positions plus small red starlets on the rudder.

The overall color was probably light grey, with a dark cowling, perhaps red or blue (the comparison to the wheel disks suggests that it wasn't black).

The front of the prop blades was aluminum, while the back had the outer 2/3 painted black, but the black paint had almost disappeared due to the wearing.

Image from M-Hobby n.4/2020, article of Andrey Averin.

 

 

 

In the fall of 1937, it was finally possible to make state tests of the flight characteristics of the Type 12.

Plane 12219 was allocated to the NII VVS (The Scientific Institute of the Air Force); it had the reinforced wings and landing gear.

This plane was fully equipped with ShKAS and ShVAK, but the DER-31 and 32 suspension points were removed to improve the aerodynamics.

Interestingly, the plane had insulators for a wire aerial on the fin and back, so it was predisposed to have a radio receiver, probably not installed during the tests.

The livery seems to have had a glossy grey base, with black cowling and spinner, redstars with black outline in 6 positions and an apparently black 7 on the rudder.

Image from M-Hobby n.4/2020, article of Andrey Averin.

 

Rear view of plane 12219. One can clearly see the wing consoles.

Images from M-Hobby n.4/2020, article of Andrey Averin

 

An enlarged detail of the wing console of 12219 show the differences compared to those of the Type 5 and of the prototype TsKB-12:

  • the metal skinning behind the ShKAS hatch area was common to TsKB-12P, but not to Type 5;
  • Type 12's console had 22 ribs (two of them under the metallic skinning behind the ShKAS bay) as on late Type 5, built after the spring 1937, while the TsKB-12P had 11 ribs as Type 5 of 1936;
  • Type 12's metal skinning on the leading part of the wing uppersurface was nearly absent, probably removed to save weight (the photos show the ribs arriving nearly to the leading edge), while TsKB-12 and Type 5 had the front part of the wing uppersurface reinforced with metal skinning under the outer fabric skinning; probably this modification was the cause of the structural weakness of the consoles of Type 12;
  • the length of the hatches on the wings of both TsKB-12P and Type 12, both of the ShKAS and of the ShVAK, was shorter than those of all other types;
  • a smaller hatch was posed behind the main one of the ShVAK, close to the aileron;
  • there was a small hatch near to the wingtip for the ShKAS ammo as on TsKB-12P, but it isn't clearly visible on this photo.

The white thing on the wing isn't part of the plane, but a thermometer required to report the temperature of some tests.

Images from M-Hobby n.4/2020, article of Andrey Averin

 

An enlarged image of the front/bottom of the wings of Type 12 allows for further considerations:

  • the wing undersurface had 11 ribs, as all other versions of I-16;
  • the metal skinning under the leading edge is less extended backwards than on other versions, but it's visible anyway;
  • the ShKAS of the TsKB-12 and Type 12 protruded from above the leading edge of the console, but it hadn't the aerodynamic fairing used on all the other types: the end of the gas recovery tube over the barrel was protruding;
  • the ShVAK installation resembled that of the Type 17/27/28, but it lacked a lip that covered the upper part of the opening on the wing;
  • on this plane, the DER-31 and 32 suspension points for external loads were removed to improve aerodynamics during the state tests.

Images from M-Hobby n.4/2020, article of Andrey Averin

 

 

 

On the base of the photos, we can trace these drawings of 'typical' pre-production Type 12s; they were characterized by:

  • two ShKAS 20 mm guns on the wings centerplane (as later types 17, 27 and 28) in symmetric position;
  • rectangular loading hatch for the guns over the nose, visible through a cut on the rear of the upper panel of the cowling (as later types 27 and 28);
  • two ShKAS at the base of the outer wing consoles, in asymmetric positions;
  • long ailerons as on Type 5, without flaps nor trim tabs;
  • M-25 or 25A engine (as on Type 5);
  • VFSh propeller, with pointed spinner (as on Type 5 and 10);
  • cowling with 8 pointed vents for a total of 9 exhaust pipes (two pipes came out from the upper left one) as on Type 5;
  • sliding canopy as on Type 4 and 5, with pilot's door on the left side only.
  • OP-1 telescopic gunsight;
  • no armoured backrest;
  • main landing gear with splined shock adsorber and tail skid as all types before 24;
  • 750x150 mm main wheels as introduced in 1937; the TsKB-12P prototype had the 750x100 mm main wheels as used in 1934-36.

Above: top view of the Type 12.

  • The versions armed with ShVAK guns on the wings had big protruding barrels and a short tube for waste shells protruding from the leading edge on the right side of each barrel.
  • The hatches for the guns were shorter than on the following guns-armed Type 17, 27, 28; behind them, close to the ailerons, there were smaller hatches related to the guns;
  • The ShKAS machine guns were installed on the outer consoles, in a slightly asymmetrical position; they protruded without any fairing covering the gas recovery tube over the barrel;
  • the area behind the guns had a metallic skinning with an hatch, shorter than those of other ShKAS-armed types;
  • the loading hatch for the ShVAK guns was the rectangular one accessible through a cut on the rear of the top panel of the cowling;
  • Type 12's console had 22 ribs (two of them under the metallic skinning behind the ShKAS bay) as on late Type 5, built after the spring 1937, while the TsKB-12P had 11 ribs as Type 5 of 1936;
  • Type 12's metal skinning on the leading part of the wing uppersurface was nearly absent, while TsKB-12 and Type 5 had the front part of the wing uppersurface reinforced with metal skinning under the outer fabric skinning;
  • the ailerons were of the long type as on Type 5.

Below: bottom view of the Type 12.

 

  • the wing undersurface had 11 ribs, as all other versions of I-16;
  • the metal skinning under the leading edge is less extended backwards than on other versions;
  • the ShVAK installation had waste links expulsion slots as on the Type 17/27/28, different from those of ShKAS;
  • the ShKAS waste link slot and waste shells tube opened under the wing consoles; they were not specular;
  • there were 8 DER-32 and 2 DER-31 suspension points for external loads; DER-31 were behind the frontal inner DER-32.
  • long ailerons without flaps or trim tabs, as on Type 5;
  • the lower part of the cowling was as Type 5, with 4 individual vents for 4 exhaust pipes;
  • there were not visible intakes or outlets for the oil cooler;
  • the hatches for the wing ShKAS ammo under the fuselage were preserved for uniformity with Type 5, but didn't contain ammo cases.

 

There were not big problems to start the serial production of the Type 12 at the end of 1937.

On that time, anyway, an urgent order of 25 December 1937 commanded the installation of two additional synchronized ShKAS on the nose of I-16s, quickly leading to the production of the Type 10 in early 1938. Besides Type 10 was equipped with pneumatic flaps and short ailerons as the abandoned I-163; clearly it was a good base to develop a gun-armed version more advanced than the Type 12, so the production of this was stopped.

The first prototype of Type 17 was still coded s/n 122133, being obtained by converting a Type 12; the second one was 122134. This suggests that Factory 21 built 34 Type 12, to add to the prototype TsKB-12P built by Factory 39. Of those planes, at least 11 were sent to operative units.

Image on the left:

The prototype of Type 17, s/n 122133. It had synchronized ShKAS aside the wing-mounted ShVAK. It was still equipped with M-25A engine without visible intake of the oil cooler, and the ShKAS still hadn't the protruding blast tubes typical of production Type 17. Some parts from the early production Type 10 M-25A were utilized for the conversion; some of them appear still unpainted. It's not clear if it was provided with flaps as the series Type 17s.

Image from Polikarpov's I-16 fighter, of Gordon and Dexter

 

It's possible that some Type 12, already in service or lying in factory with defective wings, were converted to a Type 17 standard.

This plane, for example, seems to have long ailerons and no flaps, it could have been obtained by modifying a Type 12 with the outer wing panels of a Type 5 and the engine, cowling and synchronized ShKAS from a Type 10.

Image from Istrebitel I-16 of Maslov

 

Credits:

This work is widely based on the articles of Andrey Averin on M-Hobby 3 and 4 of 2020, the best published one on this subject. It was made with the important help of Bernard Le Guenno (BLG) and Daniele Righi (Righidan).

 

Disclaimer

This work collects photos from many sources. This was made for research purposes, not intended to obtain an economical gain from them nor to offend the rights of anyone.

If someone has rights on the images reproduced here, please don't feel hurted, email to me and I shall provide to remove or to credit them.