From: Toronto and Lima
Removing the wing guns left 1 cannon (37mm or 20mm) + 2 50cal machine guns, and this is a lot of firepower from a Soviet point of view; no Soviet fighter, with the exception of the old I-16 had anything better; Soviet designs prioritized performance (rolling, maneuver) over firepower, if they needed a lot firepower they simple use numerical superiority
I haven't read about swaping the 37mm; the early versions were former RAF, and therefore they got Hispanos, but I haven't read anywhere they were fond of Hispano 20mms.
Check this interview, if they disliked the 37mms they could had swapped for their own ShVAKs, and they didn't
A. S. Describe the machine guns, cannon, and sights.
N. G. The first Cobras that we received from Moscow had a 20mm Hispano-Suiza cannon and two heavy Browning machine guns, synchronized and mounted in the nose.
Later the Cobras arrived with the M-6 [should be M-4 – ed.] 37mm cannon and with four machine guns, two synchronized and two wing-mounted. We quickly removed the wing-mounted machine guns, leaving one cannon and two machine guns.
The Cobras had interesting charging and trigger mechanisms for the cannon—hydraulic. At first, in the English variant of the Cobra, we had a lot of trouble with them. The hydraulics froze up. It seems that the Cobras had been intended for North Africa, because the hydraulic fluid was thick and clogged up the passages in the hydraulic cylinders. Our technicians replaced the hydraulic fluid with Soviet fluid and enlarged the diameter of the passages. The charging mechanism began to work normally. By the way, on these Cobras all the hydraulics froze, not just the charging mechanism.
The machine guns were charged mechanically, by hand, with a special handle. The receiver portion of the machine guns extended back into the cockpit. The triggers for the machine guns were electric. The sight was American. A very simple sight—a reflector and crosshairs.
A. S. Nikolay Gerasimovich, if you compare the Hispano-Suiza 20mm cannon and the ShVAK, which was better in your opinion?
N. G. Ours, without a doubt. The ShVAK was twice as reliable. The Hispano simply required an unbelievable amount of maintenance. The smallest exposure to dust, congealed lubricant, or any other kind of little thing, and the gun would not fire. Very unreliable.
The ballistics of our cannon were better. Our cannon had a flatter trajectory, which is significant for applying lead. When you talk about the Yaks, then one didn’t even need a sight. The tracers were almost straight, take aim and fire, and where the nose is pointing is where the rounds struck.
Our ShVAK had a higher rate of fire. Regarding the target effect, these two cannons were about equal. In either case, there was no difference that I could see with the human eye.
A. S. Was a 37mm cannon necessary? Wasn’t this too large a caliber for a fighter? You had so few rounds of ammunition. And wasn’t its rate of fire slow?
N. G. One cannot say that the 37mm cannon was a disadvantage or an advantage. Look at it from this perspective. The M-6 cannon had its strong and weak points. One had to take advantage of the strong points and compensate, as much as possible, for its weaknesses.
These were the weaknesses: 1. Low rate of fire. 8 rounds/second [this is incorrect—the correct rate is slightly over 2 rounds/second (130 rounds/minute) – J.G.] This is indeed a low rate of fire.
2. The ballistics of the projectile were abysmal. The flight trajectory of the projectile was arching, which required large lead angles. But again this was at long ranges, especially when firing at ground targets. When firing at ground targets we had to apply two rings of the sight for lead.
3. Minimal ammunition supply. Thirty rounds.
All these deficiencies could be compensated for by proper selection of firing range. If one fired from 70—50 meters, there was sufficient rate of fire, the ballistics at this range were acceptable, and the lead required was minimal. Thus, all the weaknesses of the 37mm cannon listed above revealed themselves only at long ranges.
Now regarding the strengths: 1. The projectile was very powerful. Normally, one strike on an enemy fighter and he was finished! In addition, we fired this cannon at other types of targets. Bombers, vessels at sea. The 37mm cannon was very effective against these targets.
2. The M-6 cannon was very reliable. If it was properly maintained it worked very reliably. We could charge the cannon only one time from the cockpit, but this one re-charging was completely sufficient. If this cannon malfunctioned, it was due entirely to unqualified maintenance.
< Message edited by Jorge_Stanbury -- 7/12/2020 3:08:03 PM >