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Michel_Krauss · Posted: Sun Mar 14, 2010 9:58 pm Post subject: Sherman Firefly

Hi folks

I'm reading an book (yes I'm already old enough to know what that is) called "Sherman at war"

And in the book they dicuss the history of the Sherman and it's variants, including the British 17pdr (Firefly) version

At the end of the Firefly description it tells that there are records showing that the US army had, at 1 point during WW2, about 100 Sherman's armed with British 17pdr available

Also that it is not clear what has happened to these tanks after the war

Does some of you know more about this story?

Michel

the_shadock · Posted: Sun Mar 14, 2010 10:21 pm Post subject: Re: Sherman Firefly

Michel, how old are you?

I've never heard of such a thing called "a book"...

P-O

26 y-o

Michel_Krauss · Posted: Sun Mar 14, 2010 11:33 pm Post subject: Re: Sherman Firefly

35 years and 3 month's young Cool

An book is an bunch of printed e-mails however both sides of the paper is used Laughing

Michel

JeffStringer · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 637

This is the only information I know about them
freespace.virgin.net/s...usnew.html
and it's little.

Doug_Kibbey · Posted: Mon Mar 15, 2010 12:20 am Post subject: Re: Sherman Firefly

I wonder if any of these were among the stock of "Fireflys" acquired by Argentina and upgraded as "repotendiados" or if all of those vehicles came from exclusively European stocks (which had been my understanding)?

binder001 · ***Power User*** Offline Joined: Jan 25, 2006 Posts: 363

These tanks probably went immediately from the depot to surplus. The unit(s) that were undergoing conversion training to the 17-pounder were probably told to immediately turn in their vehicles. The 17 poounder project was stopped just as the ETOUSA was near to having operational Fireflys, but since the gun with its associated parts and ammo were non-standard they were dropped like a hot rock. I imagine that the US Army "Fireflys" were either scrapped or merged into the stocks of tanks that were provided to European armies. The primary features seem to be the US vision cupola for the commander and a variation in the radio box design. There have been questions about any use of HVSS or wet stowage hulls. Otherwise a "US" M4 with 17 pounder would be functionally like the British ones. THe M4A3s would have been unique, but except for a possible one found on a firing range, there haven't been any sightings of an M4A3 "Firefly".

warddw · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 24

Mark Hayward's book on the sherman firefly has some documented US usage in Italy - recommended - a good read exclusively devoted to the firefly...

Michel_Krauss · Posted: Mon Mar 15, 2010 5:24 pm Post subject: Re: Sherman Firefly

Hi folks,

thanks all, for the info

Concerning the dropping of the 17pdr because of being non-standard in the US army... Rolling Eyes

Indeed it woud make more sense developing an complete new 76mm gun with new ammo for the 76mm Sherman Twisted Evil

Instead of using an proven gun design

For what I could find about the history of the Firefly there was another main reason the US army did not want to use the 17pdr gun

Concerning teh book about the Firefly, I have that
It's an the pile of books, still to read

Michel

bsmart · Posted: Mon Mar 15, 2010 6:03 pm Post subject: Re: Sherman Firefly

- Michel_Krauss

Hi folks,

thanks all, for the info

Concerning the dropping of the 17pdr because of being non-standard in the US army...

. . .

For what I could find about the history of the Firefly there was another main reason the US army did not want to use the 17pdr gun

. . .

Michel

Michel - I'm curious, what was the other reason the U.S. did not want to use the 17pdr? Or am I reading something into your comment that isn't there

The reasons I have heard over the years (And I'm not saying which I believe, I'm just listing theone I remember being suggested)

1) Supply constraints - All possible production was being used by the British units. A variation of this is that even if there were enough guns 17pdr ammo was a constant shortage item

2) Command did not see the need for a more powerful gun

3) The very poor performance of 17pdr HE ammo

4) NIH [ Not Invented Here ]

Michel_Krauss · Posted: Mon Mar 15, 2010 9:55 pm Post subject: Re: Sherman Firefly

Bob,

the ones you listed are the ones I know also, only in an different line-up

1) NIH [ Not Invented Here ] (especially true with-in some locations of US army command)

2) Command did not see the need for a more powerful gun
The "more" powerful 76mm was developed for the Sherman, so there was need for an more powerful gun according some one's idea.
Also certain part of command thought there there was no need because there was an special branche in the US army called the tank destroyers.

3) Supply constraints - All possible production was being used by the British units. A variation of this is that even if there were enough guns 17pdr ammo was a constant shortage item

The US industry made ammunition and all kinds of other stuff for the British army
The US air force had the (British) Rolce-Royce Merlin engine made in license to put them in the P-51 Mustang
The navy copied the (British) all steel flight deck on the aircraft carriers to replace the wooden fligth decks
The US army could not copy the 17pdr design........... Confused

4) The very poor performance of 17pdr HE ammo
The 76mm gun was developed to deal with the German Pz 5 and Pz 6 armour
Also the 76mm HE ammo wasn't know in the service for it's good performance either
In the field the 75mm was prefered for HE because of it's better performance

Michel

Joe_D · Posted: Tue Mar 16, 2010 2:24 am Post subject: Re: Sherman Firefly

I think between the tanks not being fielded in time for ETO and the need for commonality after the War these tanks were destined for surplus.

Commonality for the 75mm and 76mm would not be a problem since US wartime production of this ammo would last a long time after hostilities ceased. We have (more like had) an amazing capability to produce large amounts of munitions during the war. Once peacetime kicked in everything ceased and munitions were stockpiled. I was still firing WWII manufactured API and API-T in Iraq for my .50 cal back in 2007. With the 17pdr a new production line would be needed and since the war ended why continue making ammo when you don't really need it. I imagine this would have been a major factor in it's demise

The M26 was coming on line and the Army had pretty much decided the 90mm was the gun of choice for tanks. So much so that when they made the higher velocity 90mm for the M47 they made sure it could still fire the older rounds but tapered the newer rounds near the forcing cone to prevent their accidental use in the older tanks.

Fielding a new gun in peacetime is not that hard, having ample munitions for it is another story. When the M60 came on line there was a serious shortage of 105mm ammo for her. This led to the M48A3 not receiving the 105mm gun. Priority for 105mm was in Europe to counter the T55 and T62's. They figured the 90mm was plenty for other areas, and were proven correct in Vietnam.

bsmart · Posted: Tue Mar 16, 2010 2:51 am Post subject: Re: Sherman Firefly

Michel
I wasn't putting them in any particular order but going with your order

1) There is no way NIH can be discussed or defended it is a 'religious issue'.

2) Tank Destroyers are a doctrine issue separate from the weapon issue itself. It does play into the discussion but I'm going to avoid it just because I don't even want to try to justify the decision based on it. Yes it had an affect. Given the overall offensive role of the U.S. Army in NW Europe it could be considered a flawed doctrine. But if the U.S. had been tasked with a primary defensive role (As the Germans were at the time) it may not have been seen that way. I believe the doctrine that had tank battalions outside the Infantry division structure and only attached them 'as needed' (Which ended up being almost all the time) was at least as much of a doctrinal flaw that can be laid back at the feet of Gen McNair as the TD doctrine can.

3) Yes the U.S,. did supply a lot of ammunition to the British. But except for small arms ammo I believe the great majority was for American spec weapons. The lead time was fairly extensive. The best example of ammo interchangability is the 6pdr/57mm which was used in both armies in large numbers. I believe it took over a year for the 6pdr gun to be put in production in the U.S. as the 57 mm. A lot of that time was spent changing detail drawings to American Standards that could be released to US manufacturers for production use.

The Merlin engine had the same issue in being set up for U.S. production. There were enough differences in the Rolls Royce and Packard engines that Lancaster bombers were given different Mark numbers based on the engines installed and engines from the different manufacturing pools could not be interchanged.

The difference I see with the 17pdr is the time frame that some 17pdr proponents think the adoption could have been made in. Given the time it would have taken to adopt the 17pdr as a standard there were two other solutions coming along. Th e76mm in the short and mid term and the 90mm gun tank in the long term. I think if the effort had been put into rushing an increase in 90mm gun production and adapting the T23 turret to handle it, or pushing the T26 turret forward faster and installing it on the Sherman there would have been no discussion of a 17pdr Sherman for the U.S. Army.

The steel flight deck was adopted for other reasons (Jet exhausts) If you mean the armored flight deck we will have to move that to a different forum. I believe that argument makes the Sherman discussion look simple and straight forward. Rolling Eyes

4) I used to have a comparison of the various HE rounds (It was from a message on the old AFV news) Yes the 75mm was the best the 76mm was less effective and the 17pdr was at least twice that far below the 76mm. Only when the tank gun is stepped up to the 90mm did a tank gun equal or exceed the 75mm
In my amateur opinion I see the difference as being directly related to the muzzle velocity of the gun. As the MV increased it was necessary to increase the thickness of the shell wall to handle the increased stresses. This cuts the size of the HE filler down. Some people will say 'so what the higher MV makes it a better AT round. The problem comes when the uses the tanks were put to is examined. While tanks had to be prepared to fight other tanks they spent most of their time fighting non-tank targets where HE was the preferred round. Even the British didn't use the 17pdr in all tanks in a unit.

I have also heard that there was another problem with the 17pdr in the Sherman. I remember reading that the 17pdr had some elevation restrictions in teh Sherman and could not be fired at 'certain elevations' because the gun could not recoil the full way at those elevations (I seem to remember that it was at elevations where the turret ring interfered with the full recoil)

I was curious if you had some other factors that I hadn't heard of over the years

Michel_Krauss · Posted: Tue Mar 16, 2010 7:24 pm Post subject: Re: Sherman Firefly

Hi Bob,

I thought you had them in an particular order, so.. Mr. Green

1) concerning the NIH I have to agree on that, there are an lot of people who already tried to discuss or defend that

2) I mentioned the TD branch because that was an reason to block an capable AT gun in the Sherman. If they had put the 17pdr or 90mm in an Sherman it would have made the TD branch an sort of ... obsolete

3) Concenring the ammo, if I remember correcty the US also produced bigger ammo then only small arms ammo
For sure the US produced the fuzes used for British artillery shells, according British spec's
They also produced ammo for non-US spec small arms, for an example the US .303 rifle ammo was made for the Bren MG. However because it was not according British spec, the cartridges got bended and they got stuck in the MG. After this the US .303 cartridge was only allowed to be used for the British Lee-Enfield rifles

I only mentioned the Merlin engine and the metal Wink

flight deck to illustrate the fact that they where willing to incorporated already existing better solutions, instead of inventing something new

4) Concerning the performance of the HE rounds. The 76mm was primarily developed for dealing with the armour of the German Pz 5 and Pz 6 tanks. The performance of the HE round was not the main reason to develope an new 76mm gun.
The 76mm was based on an 76mm AA gun with an high MV. They redesigned the cartridge to make it suitable for handling it inside an tank turret, however keeping the same performance as the AA round. After the first protoype's they decided to shorten the barrel, because it was sticking to far out Shocked

However with the shortening of the barrel the AT performance of the gun dropped, because the MV dropped

Concerning the 17pdr breech sticking out to far, that was only true on the first versions. Latter versions had an redesigned shorter breech.
The British had one 17pdr armed Sherman on every four tanks, so they had the HE performance and the AT performance combined

About the MV of an shell to knock-out an enemy tank
There are 2 type's of shell suited to take an tank out;
1) it has an high MV, giving it high impact energy
2) the shell is big enough, no matter what type of shell it is. The Russian 152mm HE shell of the ISU-152 was big enough to take out an German Pz 5 or Pz 6, only because of it's size

Nothing new to ad Wink

Nice such an discussion, should we do more often

Michel

bsmart · Posted: Wed Mar 17, 2010 12:28 pm Post subject: Re: Sherman Firefly

Some interesting side points

Yes we produced fuses to British specs. In fact my mother in law worked in a factory in Elkton MD that produced fuses. They hated it when they did fuses destined for British stocks. They had quotas and when doing British spec fuses it took much longer to produce the same number of fuses.

I don't think it was a case of the TD branch blocking the good gun in the Sherman. I think it was a case of once the TD doctrine was established it was impossible at the highest levels to justify the better gun

Armor Branch Officer - We need a better gun to kill German tanks
Staff Officer - You aren't supposed to be killing tanks, that is the job of TDs
A O - but sometimes we run across German tanks
S O - Then call for TD support
A O - (shaking head) The Germans won't wait for the TDs to show up, They kill our tanks and move on

I just had an interesting thought
Actually deployment of the Firefly was actually just taking the TD doctrine down to the platoon/troop level. If the U.S. had made a tank platoon two M36 TDs and three 75mm Shermans you would have the same thing as the British had without having to add a new weapon to the system.

and yes big shells have a capability all their own. Beldon Cooper mentions using M12 self propelled 155mm guns as AT weapons. In that case you had large caliber and high MV Shocked

And yes I like discussions like this. We used to have them more often , maybe they will come back

Massimo_Foti · Posted: Wed Mar 17, 2010 3:25 pm Post subject: Re: Sherman Firefly

Actually deployment of the Firefly was actually just taking the TD doctrine down to the platoon/troop level. If the U.S. had made a tank platoon two M36 TDs and three 75mm Shermans you would have the same thing as the British had without having to add a new weapon to the system.

In post-war years, once a larger amount of tanks was available, the italian army tried to mix Shermans with 17pdr and 76mm with Shermans with 105mm at the smaller unit level possible. I guess they came to similar conclusions

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