Official Firefly Testing.

[Manic Moran]

I'm going to give myself a bit of homework when I have time later, but last time I tried doing a direct weight comparison of the guns, I was foiled by the fact that I could not find an "as installed" weight form17pr in Sherman or M10. If I recall correctly, the 90mm as per M26 was only 300lbs heavier than the 3" in M10, taken from the TMs.

 

A toed comparison didn't work either, because weights for the towed 90mm tend to be given for the large pedestal mount, not the split-trail mount which was developed. I think US just lost interest in towed AT guns, the towed 76mm didn't enter service either, after all, despite weighing much less than the 3".

 

I'll see what I can dig up on the towed 90mm, but in weight, I think the towed 105mm might be more comparable to 32lbr.

 

I also set at 17lbr and 90mm breeches with a tape measure last month, I'll dig that up too.

[DougRichards]

I have the total weight of gun and breech mechanism for the 17pdr as 1,822lbs and for the 90mm 2,290lbs, both in towed form. So in many ways you are right about vehicle mounted guns, whilst the 90mm is heavier than the 17pdr, it isn't dramatically so,. The US 105mm is noted as 6,500lb with a weight in action of approx 16,000lb.

 

Working out the weight of the gun and breech for the 32pdr is obviously more difficult, but still a ball park figure may be derived thus, I would suggest.

 

The US 90mm AT gun (all figures will refer to breech and gun not mounting): 2,290lb The 90mm AA gun was 2,445lb

105mm AT 6,500lb 105mm AA 6,575lb

 

British 17pdr 1,822lb, British 3in 2cwt AA 2,250lb.

 

So in general terms the weight two devices of the same calibre intended to throw a projectile of approximately the same weight should not vary too much from each other. The 32pdr, being 94mm (or 3.7in) should not be far away from the weight of the 3.7in AA gun, that is 6,552lb, which places the 32pdr in terms of weight in the same class as the 105mm.

 

The 76mm AT gun is noted as being 1,212lb for gun and breech, in towed form, so yes, light in comparison with the 3in AT gun, at 1990lb.

Edited March 11, 2016 by DougRichards

[whelm]

105mm T5E1

Estimated tube weight: 5100 lbs

Estimated total weight of gun: 6320 lbs

105mm T8

Estimated tube weight: 5300 lbs

Estimated total weight of gun: 6450 - 6700 lbs

Estimated total weight gun and carriage: 16,000 lbs

 

I actually have a number of hand drawn sketches from the archives of the weight make up for most of the T8's gun.

 

 

http://imgur.com/a/ySCgc

Edited March 11, 2016 by whelm

[Colin]

I have the total weight of gun and breech mechanism for the 17pdr as 1,822lbs and for the 90mm 2,290lbs, both in towed form. So in many ways you are right about vehicle mounted guns, whilst the 90mm is heavier than the 17pdr, it isn't dramatically so,. The US 105mm is noted as 6,500lb with a weight in action of approx 16,000lb.

 

Working out the weight of the gun and breech for the 32pdr is obviously more difficult, but still a ball park figure may be derived thus, I would suggest.

 

The US 90mm AT gun (all figures will refer to breech and gun not mounting): 2,290lb The 90mm AA gun was 2,445lb

105mm AT 6,500lb 105mm AA 6,575lb

 

British 17pdr 1,822lb, British 3in 2cwt AA 2,250lb.

 

So in general terms the weight two devices of the same calibre intended to throw a projectile of approximately the same weight should not vary too much from each other. The 32pdr, being 94mm (or 3.7in) should not be far away from the weight of the 3.7in AA gun, that is 6,552lb, which places the 32pdr in terms of weight in the same class as the 105mm.

 

The 76mm AT gun is noted as being 1,212lb for gun and breech, in towed form, so yes, light in comparison with the 3in AT gun, at 1990lb.

As i recall the 3.7" was heavy for it's calibre, mostly due to the mount, wiki says 20,541 pounds (9,317 kg)

[DougRichards]

 

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As i recall the 3.7" was heavy for it's calibre, mostly due to the mount, wiki says 20,541 pounds (9,317 kg)

 

That is a little deceptive as there were two 3.7in AA guns. The 3.7in Gun Mks 1-3 had a barrel and breech weighing 3,931lb but mountings were 20,541lb for the mobile mount and 23,100 static.

 

The 3.7in Gun Mk6 had a barrel and breech weighing in at 6,552lb (heavier than the 4.5in AA gun), but that 3.7 was actually a 65calibre 3.7in liner in a 4.5in Mark 2 gun barrel. Static only, so in action weighed in at 38,360lb.

 

Mind you, the Mk6 did expel a 28ld shell at 3,425ft/sec, and had a max horizontal range of 25,600 yards, in comparison with the 20,000 yards of the US 105mm AA gun. The 3.7 Mk6 only ever used, during wartime, a timed HE shell.

Edited March 12, 2016 by DougRichards

[Rich]

Ok Gentlemen. Rich and DT Tanker, you have 24 hours to clean up your posts and act, or your existence at Tanknet will be put before staff for remedial action. Tick Tock.....

 

Done, happily, if a bit late; I'm traveling and had limited connectivity the last few days.

[Rich]

 

 

 

 

 

 

Results of that study were "It is recommended that the design features, hardness pattern and the composition of the German armor piercing projectiles be studied for the purpose of improving American armor piercing ammunition."

 

 

Interesting. I know of the studies because of the results, but have never seen them. Do you have references and dates? I would love to dig them out at the Archives when I get a chance to get back to the East Coast. Meanwhile, Kitsap or bust.

[Rich]

 

 

But the revisionist intraweb experts know better than those who were actually there running the war. Like 'There were hardly any Panthers there so a bigger gun was not needed'.

 

 

You still haven't twigged to the fact that YOU are the one who is the "revisionist intraweb" dweeb? They are those who make up nonsense inserted between scare quotes, which are based solely upon their imagination rather than on any actual facts.

[Rich]

 

 

They did have a M4 with an M26 turret for testing.

 

They also wanted to or did? (one source says they did) put a M26 turret on the M6 heavy.

 

Yes, they did have an "M4 with an M26 turret", but it wasn't for "testing" it was for demonstration purposes only...and it was a T26 Pilot turret, not an M26 one. This was a one off and existed for all of about 24 hours in July of 1944. It was apparently done to demonstrate the practicality of doing so to BG Holly, Chief of the ETOUSA AFV&W Section, who was visiting DTA to see the T26 pilots and the M4A3E2 as he pursued his mission to get more tanks and more tank firepower to the ETO. The hull BTW is that of an M4 (105mm), which was pulled from the production line for the demonstration. No changes were made to hull stowage, it was never runn off the arsenal floor, and after the demonstration the two halves went off on their merry respective ways.

 

 

Interesting report from the Canadian archives.

 

 

"As a result of the successful employment of the M4A2E2 assault tank, It is understood that there is now a definite U.S. requirement for an assault tank. At the moment it appears doubtful whether this will take the form of additional M4A3E2s, the T26E5, or of a heavied-up turret and mount on a M4A3 hull with E8 horizontal volute suspension.

 

In order to gain information as to the performance of the E8 suspension, a 2,000 mile test has been satisfactorily run on an M4A3 hull with E8 suspension, carrying a T26 type turret mounting the 90mm gun.

The all-in weight of this trail vehicle was 102,000 lbs."

 

 

Very interesting.So after the one-day experiment for Holly they actually put one together for tests? First I heard of it. Any dates or other references?

[Rich]

I think the 3" AA AP round was actually taken to the AA gun from the AT, not the other way around. The M62 was APCBC round, later than the plain AP and both with different weight than the naval AP Mk.29.

 

Yep. The 3" AA and 3" Tank gun genealogy is:

 

3-inch Coastal Gun M1902M1

3-inch Coastal Gun M1903

3-inch AA Gun M1917 based on the M1903

3-inch AA Gun M1918 based on the M1902M1

3-inch Tank Gun M7 based on the M1918

[whelm]

https://research.archives.gov/id/2133367

 

Aberdeen Proving Ground-Ordnance Program 5886 - 24th Report

5886 seems to be tests of enemy munitions, examples

 

 

 

As for the M4 + T26 turret.

 

January 1945 they first mention it. in British AFV situation report # 30.

 

E8 suspension -- Test for us on assault tank.

"It is now regarded as likely that there will be further production of assualt tanks, similar to the M4A3E2 vehicle. In consequence tests are being conducted at utica proving ground of an E8 type suspension loaded to a gross weight of 92,000 lbs.

 

 

March 1945 was the date of the British Situation report # 32 that contained the blurb on the M4A3E8 carrying the T26 turret, it refers back to the #30 point.

 

 

Col. Robert J. Icks for example says they actually tested the M6 with a T26E3 turret and 90mm as well. When you look at the History of the M6 heavy tank from the archives you would be under the impression it was never built.

 

 

 

They tried other neat turret conversions as well, no idea if this one was ever finished.

 

Edited March 12, 2016 by whelm

[Rich]

https://research.archives.gov/id/2133367

 

Aberdeen Proving Ground-Ordnance Program 5886 - 24th Report

5886 seems to be tests of enemy munitions, examples

 

 

 

As for the M4 + T26 turret.

 

January 1945 they first mention it. in British AFV situation report # 30.

 

E8 suspension -- Test for us on assault tank.

 

"It is now regarded as likely that there will be further production of assualt tanks, similar to the M4A3E2 vehicle. In consequence tests are being conducted at utica proving ground of an E8 type suspension loaded to a gross weight of 92,000 lbs.

 

 

March 1945 was the date of the British Situation report # 32 that contained the blurb on the M4A3E8 carrying the T26 turret, it refers back to the #30 point.

 

 

Col. Robert J. Icks for example says they actually tested the M6 with a T26E3 turret and 90mm as well. When you look at the History of the M6 heavy tank from the archives you would be under the impression it was never built.

 

 

 

They tried other neat turret conversions as well, no idea if this one was ever finished.

 

 

Thanks! Fascinating and very helpful, if confusing. Only in the US Army can the 24th report of a project predate the 15th report. I was also unaware that T33 began testing in 1943; I always thought it was 1944? Anyway, wonderful areas of research to pursue. I need materiel especially to fill out developments in projectiles and then the experimentation in 1945 other than the T26+ tank pilots.

[whelm]

I am not sure what is up with that date on the summary, the actual report states it was between 27th Dec 1944 to 7th Feb 1945.

 

They tested the 90mm T15E1 gun mounted on a T25E1-6 medium tank

a German 88mm Pak 43/41 and a German 75mm Kwk-42 mounted on a panther.

 

Ammo tested for the 90mm was APC M82, AP M77, AP T33.

 

For the 88mm they tested APCBC small cavity rounds

 

The 75mm the standard APCBC small cavity rounds

 

And for the US 75mm they used the M61.

[Rich]

I am not sure what is up with that date on the summary, the actual report states it was between 27th Dec 1944 to 7th Feb 1945.

 

They tested the 90mm T15E1 gun mounted on a T25E1-6 medium tank

a German 88mm Pak 43/41 and a German 75mm Kwk-42 mounted on a panther.

 

Ammo tested for the 90mm was APC M82, AP M77, AP T33.

 

For the 88mm they tested APCBC small cavity rounds

 

The 75mm the standard APCBC small cavity rounds

 

And for the US 75mm they used the M61.

 

Okay. That makes more sense now.

[Manic Moran]

Same report number? It wouldn't surprise me to find tha they did a similar test later in the war.

[whelm]

 

https://research.archives.gov/id/2133367

 

 

Thanks! Fascinating and very helpful, if confusing. Only in the US Army can the 24th report of a project predate the 15th report. I was also unaware that T33 began testing in 1943; I always thought it was 1944? Anyway, wonderful areas of research to pursue. I need materiel especially to fill out developments in projectiles and then the experimentation in 1945 other than the T26+ tank pilots.

 

 

British AFV situation reports have quite a bit (light on details most of the time) on ammo development during the war and shortly after.

 

examples

 

http://imgur.com/a/gha3F

 

Edited March 13, 2016 by whelm

[Rich]

 

 

https://research.archives.gov/id/2133367

 

 

Thanks! Fascinating and very helpful, if confusing. Only in the US Army can the 24th report of a project predate the 15th report. I was also unaware that T33 began testing in 1943; I always thought it was 1944? Anyway, wonderful areas of research to pursue. I need materiel especially to fill out developments in projectiles and then the experimentation in 1945 other than the T26+ tank pilots.

 

 

British AFV situation reports have quite a bit (light on details most of the time) on ammo development during the war and shortly after.

 

examples

 

http://imgur.com/a/gha3F

 

 

 

 

Thanks again! Good stuff.

[cbo]

I didn't say it was. I said, for whatever reason, whatever the excuse, there was no serious consideration given to fielding an M4 with a gun comparable to that of the KwK 40/L43 for the US Army until the summer of 1944. That in my mind would include both the 3" and the 76mm.

 

Why should the US Army push for the 76mm/3" in 1942-43? They had the gun but was not satisfied with the turret so they started the proces of making a new turret to fit the gun, the product rolling off the production line early in 1944 (IIRC). Real urgency about the project did not emerge until some time during 1944 IIRC.

 

The Germans were tinkering with longer 75mm guns for the Panzer IV in 1940-41, IIRC an L/34 and L/40. The idea of modifying the barrel of the L/46 anti-tank gun for tank use as the L/43 was a direct consequence of the German tanks looking silly in the Soviet Union in 1941, causing panic and distress to their gun and tank development. They were thus highly motivated to botch something together in a hurry and live with whatever inconviniences the product had. One of which were the inability of the Panzer IV turret to carry more than 50mm of frontal armour, another the gun recoiling to only a short distance from the tank commanders private parts.

 

Still, the Germans standing on the Russian steppe, bare-assed with the pants around their ankles and a big dunce hat on gets them all the praise for timely gun and tank development. Must be somehting about those cool uniforms and Panzerlieds.......

[Panzermann]

 

Still, the Germans standing on the Russian steppe, bare-assed with the pants around their ankles and a big dunce hat on gets them all the praise for timely gun and tank development. Must be somehting about those cool uniforms and Panzerlieds.......

grass is always greener on the other side.

 

The Panzer III and IV were okay for 1930ies tanks, but already left behind when T-34 and M4 came along. The Panzers only kept on being used, because that is what the germans had available.

[JasonJ]

 

Still, the Germans standing on the Russian steppe, bare-assed with the pants around their ankles and a big dunce hat on gets them all the praise for timely gun and tank development. Must be somehting about those cool uniforms and Panzerlieds.......

grass is always greener on the other side.

The Panzer III and IV were okay for 1930ies tanks, but already left behind when T-34 and M4 came along. The Panzers only kept on being used, because that is what the germans had available.

Panzer III and Panzer IV remind me of the Chi-Ha in that both were 1930s tanks that became main production. M4 and T-34 were both main production tanks starting at a later time. Like you said, the timing of introduction as main stay tanks of the Panzer III/IV and Chi-Ha were at a disadvantage compared to the introduction timing of the M4 and T-34 since these two as later designs could upgrade to something stronger than Panzer III/IV and Chi-Ha lines could.

 

While the Panzer IV series eventually upgraded to the PanzerIVH, the Chi-Ha only went up to the Shinhoto (new turret with 47mm) although later tanks such as the Chi-He and Chi-Nu still had very similar features, layout, same suspension. It is not so difficult to see the Chi-Nu as the final end tank of a series of Chi-Ha based AFVs. Chi-To would be the separate design strong tank like Panther.

[Delwin]

Quick question on the 17-pdr vs. 76 mm issue: how serious was this shatter issue for 76mm? I read some theory but how about the practise? Was it an issue limited (as some internat sources claim) limited just to single (Chevrolet?) ammo producer or to all production?

 

Having in mind that all theory suggest T/D ratios 1.05-1.25 as most "risky" for shatter gap. Since number of "standard" German tanks/SPG has the armour (some parts at least) around 80mm (Pz IV, StuG) it strongly suggests also risks for typical combat experience (where "standard" 75 mm was less risky due to lower velocity). On the other hand though I can hardly recall comments that "standard" German armour was outside of the capabilities of US tanks/TDs. I understand that 90 mm gun get new ammo (T33) to deal with the problem - was anything done with M61 for 76 mm?

 

I happen to concur that overall Sherman (76) was overall better tank than its "Fireflied" older brother assuming however that 17-pdr had just small advantage in shooting the front mantle of the Panther (HVAP not included since being so scarce) - but only assuming that 76 mm was actually just marginally less effective.