Sorrows your post simply proves you know nothing about the subject of tanks.
First of all co-axial guns are hard mounted in line next to the main gun in the main guns cradle. Thats what co-axial means you moron. They must elevate and traverse with the main gun. The turret traverse speed and main gun elevation and sighting are totaly unsuited to tracking airplanes. These guns are not gimbal mounted and I have no idea where you got that stupid idea from.
Most Soviet tanks DID NOT carry any turret mounted AA machine guns till late in the war. Even then only late production JS2m and ISU series had a single 12.7mm DShK, this was extremly rare and mostly seen in the May 1945 Berlin fighting. T34s never had turret roof AA MGs in WW2. The only other soviet battle tanks that had AA MGs were some early 1941 KV1s and some of the prewar/ early war T28, T35, and T100 large multi turreted heavy tanks. Then that was only a DT 7.62mm MG which is useless against any mid-war plane.
If you dont understand just how slow a tanks turret traverse and elevation are, you have no business posting on this subject. You simply betray your ignorance of the issue.
Sorrows have you ever had a WW2 fighter fly low over your head?
I had a P51D fly 30feet over my head at about 250mph he was gone in a flash. My head rotates much faster than a tank turret and could barely turn around fast enough to see him depart before he was little spec above the ground. A tank turret could not track this speed. Try tracking a plane in the turret of AHs Panzer IV, through the main gunners sight.
So the only MG left in any tank now would be the bow MG, usually operated by a 5th crewman in the front hull. This weapon is usually gimbal mounted.
First of all this weapon was hard mounted in the JS2 so it could only be aimed by the driver steering the tank. There was no elevation for this gun. JS2 hid have a 7.62mm in a ball mount on the turret rear but this weapon only had about 5-10 degrees of elevation as it was used to sweep infantry tank killers off the rear deck. It simply could not elevate enough or sight planes thrugh its little peep hole gun sight.
As for the T34 it had a ball mounted 7.62mm bow MG, with identical elevation and sighting restrictions. Plus it obviously cold not fire backwards.
As to your assertion that several tanks tried to bang away at planes with their main guns thats true, there certainly is nothing to stop them from doing so. But you also add that they had NO sucess which simply proves my point, battle tank turret traverse, sighting and elevation are too slow to track ground attack planes.
As for your assretion that attacking armored colums of battle tanks being suice please read up on the sucess of heavy cannon armed tank busters such as the Stuka, Sturmovik and HS129, I am assuming that you are indeed literate?
To close it up I offer you this quote by famous Panther Ace SS-Oberscarfuhrer Ernst Barkmann of 2nd SS Pwnzer-Division "Das Reich", when asked about aircraft attacks.
BTW Sorrows please remember Panther has one of your murderous 7.62mm AA MGs on the turret.
Heres the Question and Answer by Barkmann.
Q: What defense did you have against air attacks?
A: (Barkmann) NONE, smoke was our only EFFECTIVE defence.
Im may be unduly hard on you sorrows , and I apologize, but you know very little about tanks and I feel I must educate you so you dant make such mistakes again.