no anti-tank gun in the world could stop it tanks of other nations would be left in the
dust by its staggering mobility and featuring some of the most advanced technology of its day
this is the story of the is-7 and how a tank that succeeded at everything still failed to
enter production throughout history there have been countless tanks all designed to kill but
not all have been a success what happened to the ones that never made it and why did they fail
my name is ConeOfArc join me as we journey through time uncovering failed projects and
forgotten creations in cursed by design huge thanks once again to the coldest water for
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as other upcoming videos and i really like it not only does the insulated exterior keep your
drink cold for over 36 hours but it keeps the cup from sweating all over my desk which helps
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now let's get back to the video the is-7 began its life at the very end of world war ii it began with
three designs drawn up during 1945 known as object 257 258 and 259 each featured a different power
plant but all would mount the 122 millimeter d25 cannon by the end of the war an analysis of the
strengths and weaknesses of these designs saw the creation of object 260. with this the tank that
would receive the designation is-7 was born on september 9 1945 just one week after the end of
world war ii the is-7 was to receive the same pike nose style armor as the is-3 with the thickness
being increased to 150 millimeters in a similar style turret albeit much longer and more heavily
armored at first it was expected that the tank would mount a 122 millimeter gun like the initial
designs but due to that cannon not being ready in time it was decided to use the 130 millimeter
s26 despite the massive armament in a relatively compact space a fire rate of six to eight rounds
per minute was achieved thanks to an assisted loading mechanism which used a pneumatic system to
ram the rounds into the breach after the loaders had placed the charge and projectile into position
the tank also was equipped with a total of five machine guns with one 14.5 millimeter above the
barrel two 7.62 millimeters mounted coaxially and an additional two 7.62 millimeters mounted
on the whole sides to move this 65 ton behemoth it was decided to use twin v16 engines to produce
the power they were looking for but when the idea failed they created a new td30 diesel engine based
off the ach-30 aircraft engine this allowed the tank to achieve an astounding 60 kilometers per
hour top speed to support the weight an advanced suspension system was designed utilizing some
technologies never used on a soviet tank till that point such as tracks with a rubber metal hinge
double acting hydraulic shock absorbers support rollers with internal shock absorption and beam
torsion bars just one day short of a year after the object 260 design was finalized the first
prototype is-7 left the factory to begin testing on september 8 1946 it was shortly followed by a
second on december 25th another two holes and turrets were also produced for firing trials
the first of these prototypes performed well managing to travel 1000 kilometers
during testing without major issues the second however suffered issues after only 45 kilometers
the results of these tests were then used to improve the design these improvements included
widening the hull and lowering the silhouette of the tank by flattening the turret further
this is also when the tank received its curved hull sides these changes increased the weight
of further 3 tons to 68 tons total to offset this weight increase a new engine was installed which
produced 1050 horsepower this thirsty beast was fed by its 1300 liter fuel capacity increased from
800 liters through the use of flexible rubberized fabric fuel tanks these specialized tanks allowed
the fuel to be stored along the curved side as solid metal tanks would be difficult to produce
and expensive while also having the potential to crack from the vehicle's vibrations while moving
however these would be blamed for the loss of one of the tanks when it caught fire and
was unable to be put out despite the fact that the is-7 was equipped with an automatic fire
extinguishing system this new version of the is-7 would also receive a new improved armament
the previous s26 cannon being upgraded to the 130 millimeter s70 along with this the sights
were improved and the pneumatic loading system was replaced with an electric one adding to its
plethora of machine guns another 14.5 was mounted on a tall mount on the turret roof this gun was
capable of being remote controlled allowing it to be operated from within the tank as if this
wasn't already enough two more 7.62s were added to the outside of the turret facing backwards
the tank was to be crewed by a team of five with a driver in the hull and a gunner and commander
in the turret despite the assisted loading system two loaders were also to be placed in the turret
with four of these new improved versions of the is-7 completed in the summer of 1948 more
testing was performed during the factory tests it reportedly excelled still able to attain its
exceptional speed and also performing well cross country after these initial tests were concluded
they were then delivered to the state where the tank greatly impressed those who witnessed it
the chief tester of the ussr ministry of transport engineering E.A Kulchitsky wrote i
was given a great honor i received an offer to be the first to give movements to this wonderful tank
it is difficult to convey in words your feelings above 60 kilometers per hour
this heavy machine easily responds to even the smallest effort on the levers and pedals gears are
shifted by a small lever the machine is absolutely obedient to the driver on a side note he was also
the same test driver who performed the legendary tank jump in a bt-7 a decade earlier this smooth
driving experience the is-7 provided was leagues ahead of soviet tanks of the era with many being
notoriously grueling to drive the protection the armor offered was also outstanding with the tank
being all but invulnerable to test this dogs were placed within the hull before it was shelled not
only by the german 128 which was regarded as the best anti-tank gun in the world at the time but
also its own gun the results were the same with both guns and the dogs suffered no ill effects
obviously there were still issues with the tank and some damage was sustained during these trials
but overall the is-7 proved to be an impressive machine all of this was followed by an order for
50 is-7s which was received by the Kirov plant in 1949 however this would never come to fruition at
the time the initial batch of is-7s was ordered there would have been no tank in the world capable
of matching this incredible machine even the tanks of the early 50s produced in the west such as the
m103 and conqueror would be unable to defeat the immense protection provided by its armor
while also being unable to match its mobility it would take years or even decades for anything from
beyond the iron curtain to be on equal terms with the is-7 yet despite this the tank would
never progress past the initial order with even those initial 50 units being cancelled
but why would they terminate a tank so technologically superior to its opponents
in the end it would largely come down to soviet doctrine and logistics
unlike the germans and their ill-fated late war designs the ussr understood that although the tank
might be powerful even bordering on unstoppable it meant very little if the tank couldn't reach
the battlefield at the time soviet railroads would have been unable to transport the nearly
70 ton beast reaching their limits around 50 to 55 tons even if this could have been
remedied the facts still remain that the is-7 was expensive to produce the cutting-edge technology
and overall size of the tank not only would cost more in resources but also would take more time
as the cold war ramped up and nuclear war seemed more and more probable the idea of having
large numbers of medium tanks was deemed to be the better alternative however as the 50 ton
is-8 or t10m as it was renamed after stalin's death would still enter production and service
it's clear the weight was the primary factor in closing the book on what could have become
the best tank in the world thank you all so much for watching i hope you enjoyed this look
into the history of the is-7 as usual i'll include all the sources i use for this episode below so if
you're interested in learning more i encourage you to check them out if you want to see more videos
like this check out the playlist that will be appearing on your screen any moment now since you
clearly have an interest in soviet war machines i recommend starting with my video on the kv-2
don't forget to leave a like on this video and subscribe for more as well as checking out the
coldest water using that link i mentioned earlier looking forward to seeing you in the next video