AMX-30: A Second Look

[Collimatrix]

Since the AMX-30 is about to be added to World of Tanks, I thought now would be a good time to take a look at the design.

 

 

 

Conventional wisdom would have that the AMX-30 is a sort of retarded little brother to the leo 1.  The designs did originally stem from a joint Franco/German tank project, which, like most multinational programs, fell apart when the partners involved realized they couldn't both be in the driver's seat.  

 

Actually, the AMX-30 and Leo 1 differ significantly in design priorities.  The first surprise from a more careful look at the AMX-30 is that the armor is actually pretty good for the period:

 

 

(And before Olifant and Xlucine freak about the inefficiency of hull sponsons, here is a picture of a bare hull, which shows that the sponsons are only used to support the turret ring and do not extend the entire length of the hull) 

 

Compared to T-54/55:

 

 

100 mm @ 60 degrees is 200mm LOS, while 80mm at 68 degrees is 213mm LOS.  Over most of the front of the glacis, the AMX-30 actually has slightly better protection than the T-55!  The ratio of trigonometric to effective thickness against APDS/AP type threats is about 2 for both of these inclinations:

 

 

So, for sub 40 tonne vehicles, both the AMX-30 and T-55 had respectable protection on the hull.  Indeed, the weak points of both vehicles would be the turret, which had similar LOS thickness, but at less slope and therefore less effective protection against AP/APDS.  The extreme slope angle of the hull would also stand a good chance of deflecting period HEAT ammunition, which often did not fuse properly against highly sloped plates.

 

Compared to the Leo 1:

 

 

We see that, frontally at least, the French tank is much better protected (they're both paper-thin on the sides).  Add to this the fact that the AMX-30 had a healthy -8 degrees of gun depression, and it starts to look like a pretty competent design.

 

One of the tricks the AMX-30's designers used to keep the tank efficient and compact was an unusual layout of the torsion bars:

 

(Thanks to Walter_Sobchack for the image)

 

In a typical tank with torsion bar suspension, the turret basket sits on top of the torsion bars and the torsion bar bushings.  This creates a dead space underneath the turret basket.  The height from floor of the turret to the ceiling must be tall enough for the loader to perform their job (ideally standing, but in some cases crouched), so the height lost to the torsion bars must be made up above the turret ring.  This forces the roof of the turret higher, and so increases the total armored volume of the tank, which increases weight.

 

In the AMX-30 the third road wheel swing arm is reversed into a leading, rather than trailing configuration.  This leaves a nice big gap where the turret basket can live, which eliminates the wasted space.  AMX-30 is, so far as I know, unique among production tanks in using this suspension design.  There was at least one Soviet prototype, the Object 277, that used a similar arrangement.

 

While the AMX-30's suspension was unusually compact for a torsion bar type suspension, it was utterly unremarkable in performance.  With 278mm of combined bound and rebound, it was essentially comparable to the M60A1 with 292mm.  While this was quite a bit better than the British centurion and chieftain, which had utterly primitive suspension that lacked even independently sprung road wheels, it was a far cry from the Leopard 1, which boasted 407mm of independent road wheel travel.  

 

Armament and fire control in the AMX-30 was quite modern; even progressive.  Unlike the T-55 and hilariously awful and primitive British designs, the AMX-30 had an optical rangefinder.  Because the rangefinder had a wide 2 meter base, and because the commander sat behind the gunner, the rangefinder was operated by the commander as a concession to maintaining an efficient ballistic shape for the turret.  The commander's station featured a cupola with 10 direct-vision periscopes (or "windows" as they are sometimes called), a ten power binocular telescope, and a counter-rotating override feature.  The gunner was given two observation periscopes in addition to the gunsight, and the loader had a generous three periscopes.  The vision from the turret of the AMX-30 was, by tank standards, excellent.

 

Primary armament was the OCC 105 F1.  This gun was quite comparable to the Royal Ordnance L7 seen in most other Western tanks of the period, except that it had a slightly longer barrel, a compressed air bore evacuation system, and a slower rifling twist rate.  The French are unique in their rejection of passive bore evacuators, preferring the older style of compressed-air based system.  The German big cats also featured a compressed air bore evacuator, so there is the tantalizing possibility that the French systems are based on that.  If this is true, it would be a germ of truth in the myth that the 75mm gun on the AMX-13 is based on the panther's armament.  I have not seen conclusive evidence one way or another.

 

The reduced rifling twist rate of the OCC 105 F1 was to facilitate the famously weird Gessner "Obus G" projectile.

 

 

Obus G, as I am sure everyone reading this already knows, was a shaped charge warhead where the shaped charge rode inside an outer shell separated by a layer of ball bearings.  This allowed the outer portion of the projectile to spin while the shaped charge would not spin, as spin degrades the effectiveness of shaped charges.  This design combined the accuracy of a spin-stabilized projectile with the HEAT performance of a fin-stabilized projectile.  Actually, Obus G was slightly more effective than the M456 HEAT round of the L7.  The slow rifling twist of the OCC F1 precluded the use of APDS projectiles.  Any APDS projectile long enough to be effective would have too great an aspect ratio to be stabilized by the loose twist of the cannon.  However, in the long run this was an advantage, as the slow twist rate proved well-suited to APFSDS type rounds when these were introduced in the 1980s.

 

In another unusual move, the secondary armament of the AMX-30 was a 12.7mm weapon rather than the usual 7.62mm.  This, if the user so desired, could be increased to a 20mm autocannon.  Not exactly "coaxial," the secondary armament could be elevated to 40 degrees (vs. 20 degrees for the main armament), to be used against helicopters and low-flying aircraft.

 

Prior to upgrades late in its service life, the AMX-30 was let down by that most syndrome of armored fighting vehicles; a dodgy powertrain.  Prior to the 1979 upgrade, the AMX-30 had a rather fragile transmission that required a skilled driver in order for the tank to remain mobile.  Apart from this regrettable downside of not working, the AMX-30's powerpack was admirably compact and helped keep the overall size and weight of the tank low.

 

Had it not been let down by an unreliable powertrain, the AMX-30 could have been a big success on the export market.  More other Western tank designs of the period, the AMX-30 showed excellent design discipline in keeping the tank small and light.  Despite the characterization of the armor protection as useful only against small-caliber threats, the AMX-30 boasted frontal protection that was better than the Leopard 1 and comparable to the T-55.  Alas, for the majority of its career, the AMX-30 was yet another reminder that in the absence of a robust powertrain no amount of clever design features will redeem a tank.

 

 

 

 

(Would be much obliged if someone would repost this to HAV after re-uploading whichever pictures need re-uploaded to imgur.  I am too tired now and CBA)

[LoooSeR]

I am interested in size comparison of this vehicle with T-55 and T-62 (which are roughly equivalent of the AMX-30).

 

Something like this:

 

Do we have detailed size of the AMX-30 hull/turret/overall?

[Priory_of_Sion]

Is there any other instances of AMX-30s in combat besides the successful battle between Qatari AMX-30s and Iraqi T-55s in Khafji?

[Zinegata]

So can the Internet finally stop pretending that the Centurion was much better than the British keep pretending it is?

[Sturgeon]

Hey colli, I am pretty sure the armor diagram you've got there isn't for an AMX-30. Compare it against an actual one, and I think you'll see what I'm talking about.

[Walter_Sobchak]

I did a post on some old articles about the AMX-30.  Technically, these articles are still under copyright, but I doubt anyone much cares considering that they are 40 years old.  

 

http://tankandafvnews.com/2015/04/06/amx-30-articles/

[Collimatrix]

The plot thickens; some AMX-30 prototypes had a pointed mantlet, consistent with the diagram above, but the rear portion of the turret is the wrong shape.  Also, the cupola is on the left side.  Almost no Western tanks have the commander on the left side of the turret.

 

What is that thing?

[Collimatrix]

So can the Internet finally stop pretending that the Centurion was much better than the British keep pretending it is?

 

Centurion is a competent design when you consider that it's the same vintage of the M26.  Chieftain is a rather poor showing.

[Zinegata]

Centurion is a competent design when you consider that it's the same vintage of the M26.  Chieftain is a rather poor showing.

 

It's competent certainly but people keep forgetting it's a 50 ton design as opposed to the 35-tonish AMX-30 and T-55. That's about as big a weight difference as the difference between the Sherman and a Panther and it's not as though the Centurion has massively better capability.

[Collimatrix]

It's not fair to compare British and Soviet tanks designs.  The Soviets are good at tank design, and the British are bad at it.

[Walter_Sobchak]

Enemy gunners, aim for the left side of the hull.  

 

[LoooSeR]

It's not fair to compare British and Soviet tanks designs.  The Soviets are good at tank design, and the British are bad at it.

According to Czechs, this is not true. 

[Zinegata]

It's not fair to compare British and Soviet tanks designs.  The Soviets are good at tank design, and the British are bad at it.

 

Lol, but when the French can make a 35 ton design that's roughly equivalent to the T-55...

[LoooSeR]

Lol, but when the French can make a 35 ton design that's roughly equivalent to the T-55...

French designers are more into tanks than British. Leclerc is actually closer to Soviet tanks than to Chally 2. If Leclerc did not had hull ammorack, it would have been ideal tank in eyes of Russian, that have all we like and don't have everything we dislike 

[Xlucine]

The plot thickens; some AMX-30 prototypes had a pointed mantlet, consistent with the diagram above, but the rear portion of the turret is the wrong shape.  Also, the cupola is on the left side.  Almost no Western tanks have the commander on the left side of the turret.

 

What is that thing?

 

Not an AMX-30

http://www.tank-net.com/forums/index.php?showtopic=37653&p=1029976

[Collimatrix]

So, 50mm glacis everywhere?

 

That's 133mm LOS; about the same as the Leo 1.