In this episode, we’ll teach you about the weakest part of a tank’s design – visibility.
How was this problem solved by the designers of the first vehicles?
Why does a tank need a periscope?
And which was the first model to be equipped with night-vision devices?
The Nuts and Bolts of Tanks: Observation Devices.
Even in the earliest stages of tank-development, designers discovered one of the biggest problems for these vehicles
— limited visibility for the crew.
They tried to solve this visibility problem using different methods and technologies available at that time.
The development of observation devices had two objectives.
First, the designers attempted to widen the field of view and bring it as close to all-around visibility as possible.
Secondly, they wanted to protect the eyes of the lookout from bullets and fragments.
In the British tanks of the Mk.I through Mk.III series,
both the commander and driver used the lookout hatches in the front armor plate, which were covered with armored shields.
Observation slits were cut into the hull sides.
However, battle experience showed that the hatches didn’t provide decent visibility.
On top of that, fragments and lead bullets striking near the slits injured the faces and eyes of the tankers.
When under fire, the crew had to close the armored observation hatches, cutting off their view completely.
Starting with the Mk.IV modification, the vision slits were covered with back-folding steel shields
made with a grid of little holes and the crew received eye-protection goggles and masks.
However, visibility from inside the tank was still unsatisfactory.
In the Mk.V, the cabin was enlarged to improve visibility.
A rectangular hatch with a back-folding door appeared in its roof,
and an additional cabin with lookout hatches was mounted in the rear.
Observation slits were protected with triplex glass units that didn’t break into fragments inside the tank when hit.
The next important step in the development of effective observation devices was made by the French engineers.
In the Renault FT-17, they implemented a mushroom-shaped observation cupola with five observation slits around it.
Although they were not protected with triplex safety glass or armored shields,
the tank commander could view the battlefield without having to rotate the turret.
This was an important new feature that was then used in most tanks.
The French were also the creators of another important innovation.
The heavy 2C breakthrough tank had a commander cupola with a stroboscope.
A fixed slit in the armor was placed in front of the viewer’s eyes,
and a rapidly rotating metal ring with vertical ports was put in front of the slit.
A tanker constantly saw the space in front of the slit, but a bullet or a shell fragment would hit the metal ring,
which had a high rate of rotation, and bounce off it.
Despite the originality of these devices, they were complex, unreliable, and expensive, so they didn’t become widespread.
During the Inter-War Period, anti-tank artillery and large-caliber machine guns became widely used.
They were small and could be easily camouflaged in the field.
If an anti-tank gun was not detected in time, its sudden fire posed a serious threat for a tank.
Also, tanks themselves were effective anti-tank weapons, and tank duels became a common occurrence.
Spotting an enemy tank first gave a considerable advantage.
All this led to greater requirements for observation devices.
It was time for the German designers to have their say.
They completely relieved the Pz.III commanders of their secondary duties.
Observation of the battlefield was a priority task.
For this, a commander had an observation cupola with observation devices around it.
The German Pz.IVE tank held the record for the quantity and quality of observation devices – as many as 14.
However, tank commanders of all countries still had to risk their lives
and look out of the open hatch for more effective battlefield analysis.
Observation devices in the tanks of World War II continued to develop
and allowed observation under both heavy small-arms fire and HE shell bursts.
Observation slits were protected with armored glass.
Both fixed and mobile periscopes were mounted on the turret and hull roof.
Despite these solutions, the visibility from inside the tank was still insufficient
due to the narrow field of view each observation device offered.
At the end of the war, hand-held HEAT grenade launchers became widely used.
Their shells could penetrate any tank armor.
Detecting a soldier armed with a faustpatrone in time was vital for a tank crew.
Those critical moments were why the commanders still had to stick their heads out an open turret hatch for a clear view.
Following the results of World War II, it was mutually decided to give up on observation slits.
They weakened the tank armor to a great extent.
They were completely replaced by periscopic observation devices that allowed viewers to look around
and change the angle of vision by tilting the periscope.
Some models were even equipped with a stabilizer, an electrical remote control,
and had variable image magnification ratios.
The designers also focused on all-weather use of observation devices.
To do so, the optical devices were equipped with car-style wipers, defrosters, a compressed air defogger system,
and a pressurized liquid washer system.
The development of observation devices has moved in the direction of unification, compact versatile modules
protected with an armored case and equipped with a multi-channel electronic means of visibility
—high definition color video cameras and long range infra-red thermal imaging devices.
Additional section:
Observing the situation on the battlefield is a hard task even in fair weather.
But it gets even harder if the battle is fought at night.
In your comments, you asked about night vision devices and their implementation in tanks.
Now it’s time to answer these questions.
Night battles and battles in limited visibility conditions were a big problem for tanks.
The headlights did not shine far and revealed the vehicle’s position.
One of the solutions for this problem was the mounting of infra-red electro-optical night vision devices
with terrain illumination by infra-red searchlight.
Tests of this type were conducted in many countries in the late 1930s to early 1940s.
German designers developed a solution like this for the Pak 36/37 guns, and later for the Pak 40 gun.
At the same time, Soviet engineers tested a similar device in BT-7 tanks.
However, they didn’t have time to finish the projects: World War II broke out.
For the first time in the world, mass-produced night vision devices were mounted on the German Pz.V Panther tanks
in the fall of 1944.
A standard device allowed targets to be spotted at a distance up to 400 meters.
This solution became a success on the battlefield.
In the following years, engineers tried to deal with the visibility problem by mounting a more powerful
infra-red searchlight on armored fighting vehicles.
The resulting vehicle received the name “Eagle Owl” (Uhu) and illuminated targets at a distance of up to 1.5 km.
However, due to further developments in this field, the additional illumination of targets became unnecessary.
In the post-war period, scientists worked on a new solution—a thermal imaging device.
These devices had been actively used by naval forces but were considered to be too bulky for tanks.
As a result, tanks only became widely equipped with them in the 1980s.
The technology race for the greatest visibility has been as intense as any arms race.
If you create a tank that detects targets well in all conditions and directions,
you take a step towards creating a versatile combat vehicle, capable of handling any challenge.