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 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 1942. Now 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 A30. 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 Withridge. Initially working independently but then they ended up working together. Their initial attempts to fit a 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 this would probably actually just a little bit of protectionism, the DTD worried about their own A30 design. Being good officers however, they did indeed heed the direct order, and they stopped working on it. And then they immediately started working on getting the order changed. It happened at Withridge, new from the Servicin North Africa, the new director of the Royal Arroyd Court. A chap named Briggs, a 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. Churchy of Vickers. Mr. Churchy 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 will get into a little bit later, but the bottom line wags it worked. Orders for about 2100 of these things were placed, and 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 Arsalanan 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 actually surprisingly difficult to get access to one that we can camber around inside. Sweden of course never did use the Firefly. They simply got a couple of foretesting purposes, and they were nice enough to leave one lying around for us. Now we're probably going to cut a couple of corners here because we've already done a small hatch Sherman, but this time we've gone to a welded front slope so it's a constant two inches thick up all the way to the top. You can see the bulges for the driver and bow-gunners position. That is necessary basically to leave room for that to 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 were dealing with a Firefly and not another Sherman, as you can see the gun, is the blanked off bow-gunners position because the ammunition was so big in order to carry a reasonable amount of ammunition you 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 mountlet has to be the big type. If you use the earlier M34 mountlet, you couldn't fit this 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-priced or built-there 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 armor panels for the protection of the ammunition and an additional applique armor panel up in the turret. 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 it had to fix. The short-term fix was the applique armor. The long-term fix was a 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 of the bogus. This was done because the A57 multi-bank 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 A57 multi-bank engine. This marvel of mechanical complexity is basically five conventional L-head inline six engines all mounted around a cron- and cron-crank shaft. Each engine has its own cron-crank shaft. 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 a summer north of two and a half tons. The way of comparison, the Ford V8 GA 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're using to simply stretch the tank to fit the engine into in the first place, you start to see a significant reduction in the powered 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. Now the US Army was never a huge fan of the A57 multi-bank. They considered it overly complex and quote full of bugs. They thought the 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 to full production run of the 4300 or so M4A4s that were 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 did they consider it their duty to give their fighting man the best possible equipment but they also saw this reputation as a smurge upon the company name. As a result the British and Chrysler joined forces instead 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 proven to be the most reliable of the petrol engines. Indeed around across the document in the British archives dated late 1943, it's one of the American based liaison officers notifying that the M4A4 is 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 taken up room in the engine bay which are otherwise used by the vertical fuel tanks. On the other hand you've now extended the length of the hull which means that the sponsor tanks can now be bigger they each hold 80 gallons. Total of 160 is only a 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 with good 100 miles on a single tank. Another advantage to having the elongated hull was that your trench crossing ability has now gone up from 7.5 to 8 feet. This was not however the fastest of the M4 variants the maximum sustained speed was only 20 miles an hour and maximum burst 25. All the fireflies were converted from low bustle 75 turrets but the other visual dising sure that you're looking at the firefly if you can't see anything else is the addition of the radio box on the backside. This is down for two weeks firstly it left a bit more room to manipulate the radio with out interference from the 17 pounder. The other reason was it acted as a counterweight 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 of the exterior and part one. Guess what we're doing in part two. Yes inside. See you then.