US Army Fireflies - corrections to v.15

[Charles M]

I am pleased to see that you decided to use some of the information and comments that I supplied in respect of:

US Sherman Fireflies
AEC armoured cars
The Cromwell and Centaur tanks
among others

Concerning the US Firefly, Unit No. 186, Icon No. 140 you are, alas, in error or perhaps you are stretching hypothetical instances a wee bit too far.

The photo accompanying this unit is of an M4A4E8 with T23 turret and 76mm gun, uparmoured using plates taken from scrapped German or US tanks. Nice try, but no cigar!

The T-23 turret as used for the American 76mm armed Shermans was NOT suitable for Firefly conversions, the main reasons being:

1. The 76mm turret front armour was thinner than that on the 75mm armed Sherman turret (64mm compared to 76mm), see Bird & Livingstone, p. 76 among others. Fletcher, Sherman Firefly, p. 44 merely states that “...the T23 turret was inadequate in terms of armour”, whereas an American document gives additional reasons

2. “The conversion cannot be readily adapted to the 76mm gun turret because it would require a complete redesign of the 17 pdr. cradle and recoil mechanism assembly. The M3A1 gun mount has the trunnions and trunnion bearing mounted in the inner mantlet, and the present 17 pdr. conversion gun mount is designed accordingly The 76mm gun turret has the trunnion bearings mounted in the front sides of the turret proper”. Zaloga, p. 38, quotes a British report explaining why M4A1 Shermans with the T23 turret and 76mm gun could not be converted into Fireflies. Apart from the unsuitable trunnion positions the telescope and elevating gear would also have needed relocating.

As an aside, this document also explains why the M4A2 Sherman was not used for Firefly conversions. Fletcher's book states that the reason for the M4A2 not being used is unknown. The assumption has always been that because it was a minority type in British service, it was deemed less desirable from the point of view of spare parts, whereas the US document states “Medium Tank, M4A2, is not practical for the conversion because of the large dual clutches take up an excessive amount of room in the fighting campartment”.

Consequently only gasoline-engined Shermans with the M3A1 gun mount and Oilgear traverse system were ever converted into Fireflies. Because of this internal space problem, only the more compact but otherwise interchangeable Oilgear traverse system was used in Fireflies, the extra bonus being that this system gave far more control under power for fine gun-laying, which neither the Westinghouse electric or Loganport hydraulic systems could manage.

I would recomment that the blank Unit Nos. 039, 175 or 177 be used to produce US Firefly counters based on the M4, late M4 with cast hull front (British Sherman Hybrid), and M4A3 versions all based on the 75mm turret with M3A1 gun mount. The exact number of M4A3 conversions is not known, but we know that at least two were converted. Although the UK offered to convert M4A4's for US troops, this type was not used by the American army and no Fireflies of this type appear to have been sent from the UK to the ETO for American use. The twelve Fireflies issued to the 755th Tank Battalion in Italy were Sherman Hybrids (late M4's).

The only photo of a US Firefly to my knowledge appears in Zaloga, p. 34. This is an M4. An M4A3 mock-up, with a Firefly turret dropped onto an M4A3 hull, was photographed at Fort Knox in 1944 but unfortunately it is a three-quarter rear view shot, see Hayward, p. 145. A colour drawing, front three-quarter view, can be found in Fletcher's book p. 31.

Happy to assist further but as I rarely use the website please sent me a private message.

Sources

Memo to General Eyster, 9 August 1944, 'Armored Fighting Vehicles & Weapons' APO 887: 'Availability of Medium Tanks, M4 series (75mm gun) for Conversion to British 17 Pdr. Gun' by Captain IRL D. Brent, II, Cavalry

Lorrin Rexford Bird and Robert D. Livingston, World War II Ballistics: Armor and Gunnery, Overmatch Press, New York and Woodbridge Connecticut, second edition, 2001

David Fletcher, Sherman Firefly, New Vanguard # 141, Osprey Publishing, Botley, 2008

Mark Hayward, Sherman Firefly, Barbarossa Books, Tiptree, 2001

Steven J Zaloga, M4 (76mm) Sherman Medium Tank 1943-65, New Vanguard # 73, Osprey Publishing, Botley, 2003

[DRG]

That's a lot of information about a vehicle that never saw combat and is at best a trivial curiosity.

I am SO SORRY the photo I used and modified to approximate a M4A3 with HVSS hull and 17 pounder did not meet with your critical approval. I could have just tossed in the existing British Icon but I thought I would make the US one stand out and I used that hull mated to a regular 17 pounder turret as info I found suggested some were used experimentally (Zaloga).


NOTE that the Icon DOES NOT use the T23 turret and that the photo used if you look REALLY CAREFULLY will see it's a 17 pounder muzzle brake not the one on the 76mm gun. I did not see the need to photoshop the entire turret .....alas, silly me



The entire program was an experiment and as such the unit has been moved to the Prototype formation where I should have put it in the first place.

But thanks for reminding me that pleasing everyone is impossible. AND why this is all REALLY getting old and why there will not be any other versions added as the one we have was a waste of time and even if I did as no photos exist any photo I did use would be "wrong"

[mkr8683]

"Nice try but no cigar" on so extremely esoteric a subject is the most hilarious criticism I've ever seen of Don and Andy's work over the past decades.