Erprobungsträger mit 3-achs Stabilisiertem Turm

Jason Dykstra (Wyvern)

Jason Dykstra (Wyvern)

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This vehicle probably has the longest name for a tank I have ever seen, but there is something more special about than just the name. It had a 3-axis stabilisation system. Many World War 2 era American tanks, mainly on the Sherman, only had a stabilisation system in the vertical plane only. Postwar tanks such as the Centurion Mk.3 all the way to today's MBTs such as Leopard 2s and M1 Abrams have two plane of stabilisation; vertical and horizontal. This tank however, was to have three; horizontal, vertical and roll on the axis of the main gun. The tank was based off of a heavily modified Leopard 1 chassis and was mainly built for experimental purposes, however, if it was meant to go into production, it was too expensive and wouldn't be viable. The roll on the axis of the gun was dealt with by having the barrel roll on its axis from side to side. It was also armed with a 20mm autocannon mounted next to the gun.

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Not much. It would counteract the roll of the tank from side to side, so the gun could remain stable when aiming and loading. As I mentioned previously, the barrel would roll from side to side to side to keep it steady. The benefits were that if it was on rough terrain, which would roll the tank from left to right or vice versa, the gun would be on a bearing and would roll, thereby cancelling out that movement. One of the reasons why it was discontinued was, besides its cost, the side to side roll on a tank wasn't much of an issue. I remember reading that the Centauro dealt with this problem by having a sight which would roll rather than stay in a fixed position, similarly to the gun on the Erprobungsträger mit 3-achs Stabilisiertem Turm, however, the Centauro's system would be more cost effective and simpler.
 
some info about this vehicle
 

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Hi,

Wyvern said:
This tank however, was to have three; horizontal, vertical and roll on the axis of the main gun.
Click to expand...

From the German title, I'd say it was probably a bit more complicated than that. The full name of the tank translates to "test platform for a three-axis stabilized turret", and as confirmed by the German article monochromelody posted, it was in fact the entire turret that was three-axis stabilized. The turret rotated not only in yaw, but also in pitch and in roll, by virtue of having a spherical base. (As that required a lot of power, a 74 kW auxiliary power unit was installed in the chassis to drive the stabilization.)

So the system didn't actually induce new hazards for the loader, as the gun moved with the turret, and the ride probably was smoother than in a conventional tank. I suppose the main purpose really was to eliminate aiming errors, but I wouldn't rule out increased crew efficiency as a secondary objective.

I believe I read about Flak guns on German battleships in WW2 using similar stabilized mounts, but I know even less about battleships than I know about tanks, so please don't take my word for it :)

Regards,

Henning (HoHun)
 
Thank you for this information that I have missed! Indeed, from what I had read, I got the impression that only the gun would move, so I must have misunderstood what I was reading. I do apologise for the mistake, and I cannot thank you enough for the clarification.
 
monochromelody said:
some info about this vehicle
Click to expand...
Thanks for posting those great drawings!
Holy "do it the hard way"!
Rolling, pitching and yawing the entire turret!
Of course they needed an auxiliary generator to move the biggest part of the armament!

It would have been simpler to just roll the gun in the mantlet, but - as Foo fighter pointed out - that would have risked injuring the loader.
OTOH merely tilting the sight on the Centauro tilted only the lightest component of the main armament.

Nowadays, modern engineers would only tilt a few electrons to adjust the aiming point in yaw and pitch to compensate for roll.
 
Hi,

riggerrob said:
Of course they needed an auxiliary generator to move the biggest part of the armament!
Click to expand...

Well, technically they didn't have to supply the force to move the armament as inertia would cause the turret to stay in the desired position. They only had to compensate for the friction in the turret mounting, which would have imparted a bit of rotation to the turret whenever the chassis rotated about its axes.

riggerrob said:
It would have been simpler to just roll the gun in the mantlet, but - as Foo fighter pointed out - that would have risked injuring the loader.
OTOH merely tilting the sight on the Centauro tilted only the lightest component of the main armament.
Click to expand...

Only adjusting the sights to show the new impact point, either mechanically or electronically, would not have given the tank the capability to hit while moving, as that would only have demonstrated to the gun aimer that the impact point changed continuously while the tank moved over rough terrain. To actually hit the target reliably, the gun would have to be laid in a way to actually hit the (stabilized) aim point.

The problem of the tank rolling around its longitudinal axis on the move can be described as follows: If the gun is aiming at a target somewhere at the front right quadrant for example (12 to 3 o'clock, in the horizontal plane), rolling to the right will cause the impact point to shift right and down. To get the impact point back on target, the gun needs to be re-laid by yawing the turret left and increasing elevation. That does actually require rotation of the biggest part of the armament, and I'd suspect that it would be very difficult to do that quickly enough to allow reliable hits with the tank moving over heavy terrain.

So in a way, the German test platform actually chose the simplest way of accomplishing the goal, which must have been the capability to fire very accurately at longer ranges while on the move. As this solution obviously was quite complicated while also introducing a lot of design restrictions to the tank which detracted from its combat value in other ways, I'd suspect that the desired capability was found not to be worth it. But as pointed out before, I don't know much about tanks!

Regards,

Henning (HoHun)
 
I hate to think of what the cannon's recoil will do to the delicate stabilisation mechanism.
Even before terrain rocks and dust/mud/water/whatnot move in...

To my jaded mind, this looks like the elucubration of a bunch of engineers who have no clue about operational conditions...
 
dan_inbox said:
I hate to think of what the cannon's recoil will do to the delicate stabilisation mechanism.
Even before terrain rocks and dust/mud/water/whatnot move in...

To my jaded mind, this looks like the elucubration of a bunch of engineers who have no clue about operational conditions...
Click to expand...
Agree, this is limitless money. A short discussion about the idea, would decide it wasnt worth it, before you built it!
 
Hi Dan,

dan_inbox said:
I hate to think of what the cannon's recoil will do to the delicate stabilisation mechanism.
Click to expand...

With 100 kW required to, basically, overcome internal friction in the gears, I'm confident the stabilisation system was pretty substantial :) According to the article quoted above, the problem was more the bulk and inaccessbility of the three-axis drive system that was a problem.

dan_inbox said:
To my jaded mind, this looks like the elucubration of a bunch of engineers who have no clue about operational conditions...
Click to expand...

It's my impression that in the 1960s, a lot of experimental projects were given to the industry without regard to the operational usability of the end product, just so that they could build up technical knowledge (especially with regard to electronic control systems) and keep their highly qualified people employed. So you're most likely right that operational conditions weren't really considered!

Regards,

Henning (HoHun)
 
What a fascinating design. The three axis stabilization concept is certainly a interesting one and how they achieved it in this design is pretty unique.

I do wonder though if the concept was inspired partially by French oscillating turret designs, or experiences with the German Kugleblitz SPAAG which also featured a oscillating turret.
 
Tony Williams said:
Reminds me of the USN's quad-1.1 inch AA mountings of the late 1930s. That had three axes of movement, the extra one slewing the guns sideways to make it easier to keep them pointing at vertical dive bombers.
Click to expand...
There's been quite a few naval AA mountings that had triaxial stabilization. The 10.5cm SK C/33 on Kriegsmarine cruisers and battleships for example.
 
So far i know this was part of MBT70 program
And prototype was build to test (various ?) 3-axis stabilisation system.
It was prone to system failure and needed extended repairs
as MBT70 was terminated do high cost and too complex, the Prototyp ended up in Museum.

How far this 3-axis stabilisation system influence MBT80 or the Leopard 2 design is unknown to me.
 
Michel Van said:
So far i know this was part of MBT70 program
And prototype was build to test (various ?) 3-axis stabilisation system.
It was prone to system failure and needed extended repairs
as MBT70 was terminated do high cost and too complex, the Prototyp ended up in Museum.

How far this 3-axis stabilisation system influence MBT80 or the Leopard 2 design is unknown to me.
Click to expand...
To my knowledge, they completely ignored it and went to a simple turret, adjusting the turret angle and gun elevation separately for cant.
 
Scott Kenny said:
To my knowledge, they completely ignored it and went to a simple turret, adjusting the turret angle and gun elevation separately for cant.
Click to expand...

They never publish the results of the test shooting of that system.
And those worked on project say that system constantly broke down and needed repairs.

with other word it dosen't work.
but it was perfect match for MBT70 and its overcomplicated systems, that had similar issues...
 
Michel Van said:
They never publish the results of the test shooting of that system.
And those worked on project say that system constantly broke down and needed repairs.

with other word it dosen't work.
but it was perfect match for MBT70 and its overcomplicated systems, that had similar issues...
Click to expand...
I mean, the fact that you need to cut a spherical bearing race some 2m in diameter is bad enough. Then it's open and getting dust and muck thrown into it all the time. It imposes serious dimensional and shape limits on the turret, you can't really have any part of the turret overhang the turret ring or it will limit the range of motion.

It ends up being the perfect answer to why we don't bother with a 3-axis stabilized gun system on tanks.
 
Having seen a few demonstrations of how good the stabilization is on the latest Abrams and Leopard variants even without that roll axis I don't think it's really needed at all. Though I'd imagine this particular vehicle gave some useful data in general.
 
Marder I with 3-axis stabilized turret, heard it was a predecessor of the TURMS III turret, sort of like a proof of concept
 

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The three axis system could be stabilized by a gyro instead of using active stabilizers, which would simpliefy the system. Of course, the amor protection would be more effort and the height and weight of the tank would be increased, which is a significant disadvantage.
 
Actually "Erprobungsträger mit 3-achs Stabilisiertem Turm" is a describtion/Title and not a name. In German names are usually a single word.
 
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Hi.

Does anyone here know where this tank is located in germany? I saw some quite newish photos of it, so it's not been scrapped.

I hoped to find it at the "Wehrtechnische Sammlung der Bundeswehr" (the german armies collection of prototypes/test vehicles as well as other nations vehicles) in the city of Koblenz but it was not there, at least not on display.

I would be really thankful if someone has more info on that because I can't find anything on the internet, neither in english or german. I would love to see this tank irl.
 

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