lets compare the US 90 mm to the 17 pounder

http://web.archive.org/web/200104200951 ... guns5.html

http://web.archive.org/web/200107102304 ... guns7.html

are these figures comparable?

90 mm

1. 90–mm Tank Gun M3. Source: Hunnicutt, R. P.: Pershing: A History of the Medium Tank T20 Series. There were only limited quantities of APBC and APCR projectiles available for Pershings in Europe. The APC M82 (late) APCBC projectile had an increased muzzle velocity due to a greater propellant charge but few rounds reached the troops in time for use in World War II. Note that although the penetration of the APBC and APCBC projectiles is similar, the APBC could penetrate the Panther glacis (80mm at 55°) at up to 1,006m range, whereas the APCBC projectile could only do so at up to 411m range, due to the different effects of slope on the two types of projectile. The 90–mm Tank Gun M3 was highly accurate; after some practice on the firing range consistent hits could be achieved at a range of 572m using German helmets as targets. The APBC projectile was a solid shot round with no explosive filler. [up]

2. 90–mm Tank Gun T15E2. Source: Hunnicutt, R. P.: Pershing: A History of the Medium Tank T20 Series. Ammunition was separate loading so the rate of fire was lower. The APBC projectile was a solid shot round with no explosive filler. [up]


17 pounder


2. Ordnance, QF, 17–pounder Mk.I to Mk.VII. Source: Gudgin, Peter: Armoured Firepower; Hogg, Ian V.: British and American Artillery of World War Two and Hunnicutt, R. P.: Sherman: A History of the American Medium Tank. There are no ballistic differences between the various marks. The first guns were delivered in August 1942, and first saw action in Tunisia in January 1943. Originally provided with an AP projectile, very shortly afterwards with an APC and later an APCBC projectile. I get the impression from Hogg that “very shortly afterwards” means by the end of 1942 for both types of capped projectiles, but this is unclear. Certainly the AP and APC projectiles hardly receive a mention anywhere else, implying that the main ammunition in use during service was the APCBC projectile. From August 1944 APDS projectiles were supplied to the troops. There is considerable variation in the specified weight of the APDS projectile so I have given a range of the values quoted in the references. None of the 17–pounder armour piercing projectiles had any explosive filler. [up]





what about the story that the early apds were flawed because of the sheath of the sabot not discarding correctly causing problems with accuracy

 

20+ views, no comments..

are the penetration tables in the link correct?

 

Yes, it's probably right. I've heard before the the 90mm was close to the performance of the 17 pounder.

 

? I read those table as meaning the 17 pounder was almost as good as the 90 mm

pretty much accross the board..

 

Basically they were comparable with comparable ammo, i.e. HVAP for the 90mm compares to APDS for the 17dpr, ABCBC compares to the ABCBC. The APT33 round was specifically made to tackle highly sloped targets like the Panther Glacis plate, and could penetrate it out to about 1100 yards (Check Hunnicutt. edit to add Stonewall allready has this info in his post) The HVAP round combined the excellent penetration of the 17pdr APDS with exceptional accuracy.

However, there were only a handful of APT33 and HVAP rounds available in the last few months of the war. 99% of 90mm AT work was with APCBC.

In practical terms though, they were still comparable. With the ammo readily available, both the 17pdr and the 90mm could penetrate the turret/mantlet of the Panther at normal battle ranges, both had difficulty penetrating the glacis (Although incidentaly, every single picture of a penetration of a panther glacis I've seen appears to be a 90mm hit, not sure that means much though.). The availability of APDS gave the 17pdr a edge as a AT gun, but at the longer ranges its poor accuracy made that advantage less then it seems. Against that the 90mm always had a excellent HE round, giving it the edge as a all around gun.

 

Just comparing kinetic energy gives the edge to the 90mm, although I have always been under the impression it was a (just barely) less capable AT gun than the 17pdr.
90mm:
Shell wt = 10.94 kg, mv = 808 m/s; KE = 3.57 mega-joules (.77 kg TNT)

17pdr (76.2mm):
Shell wt = 7.71 kg, mv = 884 m/s; KE = 3.01 mega-joules (.65 kg TNT)

The slightly larger diameter of the 90mm also give an advantage in the nebulous T/D (armor thickness divided by projectile diameter) ratio, the nebulous "overmatching" phenomenon. The better HE round also has to be considered an advantage for the 90mm.

All in all, pretty much equal guns.

 

The normal abcbc round had a small explosive "D" filler, which increased damage with penetration, but could also prematurely detonate and cause failure against armor it should have penetrated fairly easily.

 

Thanks that was some of the beef that I was looking for..


I gather the American apcr ammo was almost never available for the 90 mm

 

It was issued in very limited quantities to the M26's that saw service at the end of the war. I'm not sure if any got to the M36 tank destroyers. But in any case I don't think it saw service before febuary of 1945.

 

Finally found what I was looking for. Here are comparative tests of the 90mm against actual Panther tanks.

http://www.wargaming.info/armour06.htm#2

In this test, using normal ammo, the 90mm penetrated the Panther Glacis to 600 yards, and the mantlet at 1000 yards and the turret at 1500 yards. I would assume this Panther glacis is not of the highest quality. (This is with M79 ammo.) The 3in AP used on the M10 tank destroyer (And which should have identical performance to the 76mm on late shermans and hellcats) could penetrate the gun mantlet at 200 yards with the M62 shell. It could not penetrate the Glacis at any range. The 57mm sabot failed against both the glacis and mantlet at 200 yards, its noted how difficult it was to obtain hits on the Panther with the sabot ammo.


Here however, the 90mm does very poorly, the BDF (base detonating fuze) of the M82 shell prevents it from matching the 17pdr and in fact it doesn't do much better then the 76mm.

http://www.wargaming.info/armour05.htm

So with a poor lot of sensitive fuzes could change a lot.

Here is the 17pdr, 76mm at isgny

http://www.wargaming.info/armour07.htm

Note the high quality panther actually withstood a 17pdr SABOT hit at 200 yards! (Although on other penetrated.) Again, the poor accuracy of SABOT ammunition is noted. Also note the claim this lot of 17pdr ammo is substandard, however I think a better explanation is the wide variety of glacis plates on Panther tanks.

 

most informative


8) 90mm Gun, M1A1, AA
AP M77 will penetrate front glacis slope plate up to 600 yards, the gun mantlet up to 1,000 yards and the turret up to 1,500 yards.

9) 105mm Howitzer, M4, mounted on Medium Tank, M4
HEAT M67 will penetrate front glacis slope plate and gun mantlet at 500 yards (see assumption made in paragraph 1c).


(1) At 600 yards, 17pdr APCBC penetrated the lower nose of tank No.1 (average plate), while 76mm HVAP failed to penetrate.


d. The 17pdr APCBC is more effective against the front of a Panther tank than is the 76mm HVAP, T4. Its margin of superiority is not great. Neither one can be depended upon to penetrate the glacis plate in one fair hit on average quality plate.




and the 17pndr Sabot was considered too inaccurate

a. That the 17pdr SABOT of the lot tested is considered an unsatisfactory ammunition because of its inaccuracy.

elsewhere
2) On this basis all twenty-two (22) rounds of 76mm HVAP, T4, and all twenty-three (23) rounds of 17pdr APCBC hit the target. Only one (1) of eight (8) rounds of 76mm APC, M62, which fell short attempting to hit the nose, failed to hit the target. Forty-two (42) rounds of 17pdr SABOT were fired and only 57% [24 rounds] were hits





>Here however, the 90mm does very poorly, the BDF (base detonating fuze) of the M82 shell prevents it from matching the 17pdr and in fact it doesn't do much better then the 76mm.




I entirely missed the part about the 90 mm M82 fuse/?

I found this/?

That upon availability of 90mm APC M82 ammunition in this theater, tests be conducted to determine the effectiveness of this ammunition against the 'Panther' Tank.

But I did see the part about the 90 mm M 77 AP cosistently pentrating the Panther at 600 yards..


400 yards

Two rounds out of two hits of 76mm HVAP w/17pdr SABOT propellant also penetrated.




I am lookingfor more info on the M82 early and late fuse

 

http://www.wargaming.info/armour05.htm

I found your M82 refererence..

b. Phase II - The instantaneous detonation of the relatively large base charge of the 90mm, Shell, APC M82 adversely effects the armor penetration characteristics of this ammunition against heavy armor plate at 30º obliquity. As a result, under certain combinations of range and armor thickness, it can be out-performed by inert loaded 76mm APC M62.

still learning

 

Couple of caveats.

The 90mm was able to penetrate the Glacis of that particular panther at 600 yards, a better quality plate would do better. In addition, the target was dead on, ie facing the attack, any offset would reduce penetration.

In other words, aim for the turret.

 

Panther turret

Talking of aiming for the turret, it has always impressed me just how quickly the Germans responded to the need to eradicate problems in their AFV's, a good example being the shot trap caused by the rounded bottom edge of the mantlet as fitted to earlier Panthers. This curved casting caused shells to ricochet off it and pass downwards through the roof of the vehicle into the drivers compartment. So, what did they do, they redesigned the bottom edge to incorporate a flat section instead of a curved one !
BG

 

Re: Panther turret

I wouldn't exactly call it fast, 2 years from the first model, 18 months from first production, 15 months from first combat use, to come up with a fairly trivial modification to the design and even then it wasn't universally fitted.