Whatever you want to say
about the state of British tank design, the Royal Artillery did not muck about. They produced some of the finest field pieces of the war. In terms of anti-tank guns, a year before the 6-pounder had entered production at full rate, they had started working on the successor. By the middle of 1941 they had concluded that a 3-inch round was best, and by May 1942 what was known as the 17-pounder entered production, finally seeing service at the late end of nineteen forty-two. It was only a matter of time before somebody had a thought: “hmm, let's see if we can put this into a tank.” Well, the solution from the Department of Tank Design was the A.30. However, a number of folks looking at this design were not massively enthralled by it and thought, “well, can we do better?” Enter two folks by the names of Brighty and Witheridge, initially working independently but then they ended up working together. Their initial attempts to fit the 17-pounder into the Sherman turret were less than successful in the middle of 1943. Eventually, however, they were ordered to stop by the Department of Tank Design and quit mucking around trying to upgrade the perfectly good gun on the Sherman. Now, David Fletcher intimates that was probably actually just a little bit of protectionism, the DTD were worried about their own A.30 design. Being good officers, however, they did indeed heed the direct order and they stopped working on it. Then they immediately started working on getting the order changed. It happened that Witheridge knew from service in North Africa the new director of Royal Armoured Corps, a chap name of Briggs. He said “Mr Briggs.. or General Briggs, would you mind awfully getting this decision reversed?” Briggs very happily did do so. He went off to the Ministry of Supply, “can you get this order changed?” “Yes we can” said the Ministry, “just for you” and the 17-pounder Sherman became an official program of the British military This however meant that you no longer could have the amateurs trying to do this. Enter now Mr Chertsey of Vickers. Mr Chertsey is now the guy who's really responsible for figuring out how to get a really big gun into a really small turret. Now, what he did exactly we'll get into a little bit later, but the bottom line was it worked. Orders for about 2,100 of these things were placed, and it would enter service with the nomenclature “C” at the end of it. Most of us however will know it as the Firefly probably the most famous of the various Sherman variants. We're still at Arsenalen in Sweden, and we're taking the opportunity to take a quick break from the Swedish tanks to check out the Firefly they have because it’s proven surprisingly difficult to get access to one that we can clamber around inside. Sweden, of course, never did use the Firefly, they simply got a couple for testing purposes and they were nice enough to leave one lying around for us. Now we're probably gonna cut a couple of corners because already done a small hatch Sherman, but this time we've gone through a welded front slope so it’s the constant two inches thick up all the way to the top. You can see the bulges for the driver and bow gunners’ positions. That is necessary basically to leave room for there actually be a hatch for them. In order to reduce the vulnerability of these bulges you would sometimes see welded armor plate in front of them and this tank was originally equipped with it. However it seems that when they were converting it from a trials vehicle back to a museum vehicle, the people doing the conversion thought it was something that the Swedes had added so they chopped it off. The obvious point that you are dealing with a Firefly and not another Sherman, assuming you can’t see the gun, is the blanked off bow gunner’s position. Because the ammunition was so big, in order to carry a reasonable amount of ammunition they had to drop a guy. The seat was removed, he was replaced by a rack of ammo although curiously in this particular tank they took the rack out and put the seat back in again. The mantlet has to be the big type. If you use the earlier m34 mantlet you couldn't fit the 17-pounder into it correctly. There is actually a small slew of requirements that made eligibility for a tank whether or not you could convert it to a 17-pounder or not. The housing is the original three-piece type, Chrysler built their tanks with three-piece housings pretty much all the way through. Not much else to be said, your standard array of headlights. The British always did like the steel-type track. As you come around to the side you can see the two armored panels for the protection of the ammunition and an additional applique armor panel up on the turret, and the reason they did this was because in order to leave room for the traverse mechanism they had to grind out part of the inside of the turret wall. This led to a weak point which they had to fix. The short-term fix was the appliqué armour, the long-term fix was they simply cast thicker turrets with a bulge on the outside. As you move down, you can see another distinguishing feature. There is a large gap between the road wheels with the bogeys. This is done because the A57 multibank engine was so long that they had to elongate the entire hull, and they had to spread out the suspension accordingly. And so we get to Chrysler’s A.57 multi-bank engine. This marvel of mechanical complexity is basically five conventional L-head inline-six engines all mounted around a common shaft. Each engine has its own crankshaft, gears are then used to match up with a single power output shaft. This has the flywheel and the clutch on it. All in all, the 1253 cubic inch engine puts out about 445 horsepower. Now, the catch is that all this together comes in the somewhere North of two-and-a-half tons. By way of comparison, the Ford V8 GAA is about a half a ton and also adds an extra 60 horsepower to the total. Now if you add the extra weight of the engine to the extra weight of the metal that you are using to stretch the tank to fit the engine into in the first place, you start to see a significant reduction in the power-to-weight ratio. Indeed the vehicle becomes so heavy that this is why the heavy-duty VVSS bogey was created to work for the M3A4 medium tank which was the chrysler multi-bank powered version of the m3. The US Army was never a huge fan of the A57 multi-bank, they considered it overly complex and “full of bugs.” They thought that carbs were inaccessible, the clutch was too weak, so on and so forth. Now the British had a slightly different point of view of things, because they were going to be allocated pretty much the full production run of the 4300 or so of the m4A4s that was scheduled to be produced, and they didn't like the idea of having an unreliable tank engine. Similarly Chrysler were not incredibly pleased either: Not only do they consider it their duty to give their fighting men the best possible equipment, but they also saw this reputation as a smirch upon the company name. As a result the British and Chrysler joined forces and set about fixing the problem, and some of the most obvious fixes are easily available: For example the carbs are now quite visible and accessible at the top of the engine bay. By the time they were done the A57 was proving to be the most reliable of the petrol engines. Indeed I ran across a document in the British archives dated late 1943, it was one of the American-based liaison officers notifying home that the m4a4 was about to go out of production and that they were going to lament the loss of their old friend. Because the engine is so big it's taking up room in the engine bay which would otherwise be used by the vertical fuel tanks. On the other hand you have
now extended the length of the hull which means that the sponson tanks can now be bigger, they each holds 80 gallons. Total of a hundred and sixty is only 8 gallons less than a regular M4 anyway, so the difference is pretty negligible. The 30 cylinders sipped
relatively little of the 80-octane fuel and you were expected to go
a good hundred miles on a single tank. Another advantage to having the elongated hull was that your trench crossing ability has now gone up from seven and a half to eight feet. This was not however the fastest of the M4 variants, the maximum sustained speed was only 20 miles an hour, and maximum burst, twenty five. All the Fireflies were converted
from low bustle 75 turrets, but the other visual distinguisher that you're looking at the Firefly if you can’t see anything else is the addition of the radio box on the back side. This was done for two reasons. Firstly it left a bit more room to manipulate the radio without interference from the 17-pounder. The other reason was that it acted as a counter-weight for the rather large heavy gun which has just been added to the front of the vehicle. This brings us to an end of the tour the exterior and part 1. Guess what we're doing in part two? Yes, inside. See you then
