Purpose of this blog

Dmitry Yudo aka Overlord, jack of all trades
David Lister aka Listy, Freelancer and Volunteer

Sunday, May 20, 2018

I spy a T-64!

Earlier in the week I took advantage of the fact I was made redundant and went to visit an archive. Whilst there I saw a document that I thought might be of interest. It is a technical assessment of the brand new Soviet tank, the T-64. Here is what the British thought the T-64 performance would be like. This is what the British were able to speculate from the intelligence sources they had, and these intelligence sources are varied and seem to have gone right to the heart of Soviet tank design.
"What's that? No I'm not British. Comradski!"
In September and October 1976 large numbers of a new Soviet tank were seen being issued to Group of Soviet Forces Germany (GSFG). The British had information about the T-72, and its planned introduction, and so thought this new tank was the T-72. This tank obviously sparked the British interest, especially as a large amount of information was being presented. Because of this excess of information, the Military Vehicle Experimental Establishment (MVEE) was tasked with creating a paper in December 1976. This paper involved the work of two British intelligence groups, the Technical Information (Army) and the Joint Air Reconnaissance Intelligence Centre.  MVEE had finished the paper by June, but were soon to be back at work as in November it was announced that the T-72 would take part in the Moscow Parade that year. The pictures immediately caused a concern, as all the agencies expected to see the tank they had identified beforehand, but it wasn't. It looked different. Initially these two tanks were known as the "GSFG T-72" and the "Moscow T-72", but intelligence data quickly identified the "GSFG T-72" as the T-64.
TI(A) and MVEE drew up a fully detailed 1/10 scale plan of the tank based on measurements from photographs. The internals were worked out from a variety of sources including defectors and a photograph of a turret trainer. The latter would have been used in class rooms to help instruct crew. How the British got a hold of this picture is an interesting question, as it seems that at least someone in tank design, or tank training school was spying for the British.
The turret trainer
Equally the British received a pair of recordings of the engine noises of the T-64. They analysed these and found out that most of the noises were in the high frequency range of 4000-80000 Hz. This, it was worked out, corresponded to a gas turbine engine with twenty compressor blades producing 800hp with a shaft rotation speed of between 12000 and 48000rpm. The British speculated that it might be a modified version of a MI-24 Hind engine that had been fitted to a tank. There were other sounds on the tapes that indicated an auxiliary power unit was fitted, which was a 6 cylinder four stroke engine running at 4000rpms producing some 75hp. This it was expected could be used when the tank was snorkelling to propel the tank at 0.5mph to cross the river.
But no T-64 was actually fitted with a gas turbine, so the likely source for these tapes is the Object 219, which was a prototype T-80. This would indicate that someone within the Soviet tank design departments was actually spying for the British, as a secret Object test bed vehicle isn't likely to be driving down the main road regularly enough for a spy to position themselves to make a recording.

This tape and the subsequent analysis did lead to some knock-on effects in the British version of the T-64. Due to a gas turbines high fuel consumption the British loaded the tank down with extra fuel to maintain a 500km radius of operation. This was achieved with some 920L of fuel in external tanks, which the British could see and measure. These due to the way they were linked by exposed fuel lines were considered for movement use, and not for combat use.  A further 360L was stored in the engine compartment, while a final fuel tank was placed on the drivers left hand side holding 1400L.

The drivers position was another oddity. While it was reported as having power steering the position was deemed to be very uncomfortable. This was ascertained by using the position of the episcopes the driver would use to see out of his tank while closed down. This in turn meant that the British knew where the drivers head would have been, and then using the "Soviet 95 percentile" of height (which meant that 95% of Soviet males would be close to this height), worked out how much space would be needed. The Soviet 95% figure was 5ft, 6in. The only place the foot pedals could be placed was on the nose plate, however the leading suspension arm’s torsion bar had to run through that space. This meant the pedals had to be placed higher up the nose plate than would be normal. It meant that the driver had to assume a hunched half crouch while reclining on the seat. It also meant that a set of duplicate pedals had to be installed for when the driver was unbuttoned. As well as the fuel tank the British designers placed some eight spare rounds of ammunition in the drivers compartment.
The loading arms removed for auto-loader maintenance.
The British also knew about the auto-loader mechanism as some photographs showed the loading arms of the auto-loader removed during maintenance. These, along with pictures of the ammunition, allowed the British to manufacture a loading arm to the same design as the Russian one and work out how it fitted into the tank. They estimated the ready ammunition would be between 28-30 rounds. The 125mm smoothbore gun was presumed to assume a loading position automatically after each shot and would have about 450mm of recoil travel. Total vertical movement of the gun was given as -5 to +16 degrees.
The copy of the loading arm the British built. In the left hand one you can see one of the wooden rounds that were also constructed.

The wooden rounds
Although the gun came with a thermal sleeve it was noted to lack a muzzle reference device which would affect the accuracy of the gun. The gunners primary sight was a variant of the TPN-1-21-11 sight with an optical rangefinder across the turret although no sign of a laser range finder was present at the moment it was expected to arrive on later models. The commander had at his disposal a TKN-3 day/night sight, with an assumed ability for hunter-killer automatic laying. All vision devices, including the drivers were deemed to be IR types, which needed active illumination by IR searchlights.

The armour was measured for the turret by taking the space needed for the internal layout and deleting it from the external dimensions. This gave a raw thickness. The report stated that there was no sign of any "Chobham style special armour” and suggested that the use of electroslag remelt was possible. In fact the T-64 had aluminium cores to its armour to save weight, while the T-64A had high hardness steel up until 1976 when corundum-ball inserts were used.

To assist with the hull armour values the report stuck with a Soviet standard of using some 50% of the total tank weight for armour. This figure is a bit of a pain to us in the modern day as we don't know what the total weight the British were using. Combat or loaded weight? But in comparison a Leopard 1 has 39% of its combat weight as armour, but a massive 57% of its empty weight. Equally one source I have has about 25% of the total weight of a Chieftain as armour but fails to mention what state the tank would be in when this was measured. However, it made sense to the British of the time as they knew what they meant. From that they came out with the following armour values for the hull:
Due to the turrets shape it was trickier to map, so MVEE took the simple route and sliced the turret into 100mm sections and plotted those thicknesses.
Cross sections of the turret showing armour thickness.
Because of the small wheels and torsion bar suspension hidden behind the wheels the side hull was seen as vulnerable to chemical anti-tank warheads such as HEAT, for this reason a series of paddles were fitted to the hull. These could be swung out a few degrees cover an arc of about 25 degrees with spaced armour. These were thought to be quite light steel and sprung so that they would be able to swing out of the way of a tree then spring back into position.
"Ulybka dlya britanskogo shpiona tovarishcha."
Other speculated protective features included a potential radiological sensor that would fire small charges upon detecting a nuclear bomb detonation, these charges would automatically close all the grills and louvres on the tank. In addition, an over-pressure NBC system was fitted, however the crew would wear grey NBC suits and individual gas masks.

The T-64 was seen as a step up in Soviet tank design, as well as abandoning their tried and tested technique of re-using the same components over and over again. Despite this it failed to meet the current Western standards. For example, the West were designing Chobham style armour into their tanks, and fitting thermal vision as standard, while the Soviets were still using IR. Equally on items like the NBC system, on British tanks a common air feed was provided to the crew stations meaning the crew could plug into air supplied from the tanks NBC pack, meaning a constant supply of clean cooled air was available to help with crew discomfort. In addition the drivers position was seen as particularly awful.