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Inside the Chieftain's Hatch AC 1 Sentinel


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The_Chieftain #1 Posted 28 March 2016 - 10:13 AM

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MaximumSomething #2 Posted 28 March 2016 - 03:11 PM

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Interesting to see. I wish your art guys would stop mirroring images of the Sentinel, it is not symmetrical and makes my brain itch.

 

I hope you won't mind, a few points:

The first prototype, the E1, was finished about 3-4 weeks after the Pearl Harbour attacks, it was handed over 10/1/1942. First production tank was as you say August '42.

 

The 18A turret, I'm not entirely sure but the Army only ever formally accepted the first 25 tanks before ceasing acceptance until, as they put it, the DAFVP stopped producing defective tanks. The first 12 of those 25, the token plates cast at the time showed signs of temper brittleness so they could not be sure the armour was up to specification. These 12 were supposed to be reserved for training only. If you were to look at the hull of 8006, the tank WG donated to the AAAM, it is stamped "NOT ARMOURED". It is armour steel, it just the heat treatment is uncertain. For 8049 the "A" in 18A is "armoured" perhaps? you'd really need to take the turret toolbin off to be sure, but I don't think they'd let you.

 

There's something like a dozen different track types for the ACs. Mk1 and 2 are probably something like the Crusader but that is partly a guess on my part but the description doesn’t make sense any other way. Mk3 is an Australian copy of the T41 imported from the US. Mk4 is a steel shoed version 6 inch pitch end connector type track with the guide horns moved to the ends of the track block, it's interchangeable with the usual US types. Mk5-11 are all 4 inch pitch single pin designs, they look pretty much like CDP tracks, the Mk5 is the most common in photos, there is a photo of the Mk8 fitted to tank 8002, the Melbourne Tank Museum had a short run to some Mk10. The manual also show the Sentinel fitted with WE210 Double I track.

 

Bogies are held on by 7 (seven) bolts. Three up behind the return roller, two just above the volute spring, two at the bottom of the hull. The trailing return roller type is earlier not later, you only see them on the three experimental vehicles (E1, E2, and E3). There are two bogie Mks, the on the Mk1 the return roller is raised by means of a small mounting block, on the Mk2 the casting has been modified to remove the need for that.

 

The DAFVP did get 200, I think, P&W engines, then decided the Cadillacs were more suitable. Lend Lease in the US were not happy with this and wanted them back. But then again Lend Lease were never happy.

 

The external tank is connected to the main fuel tanks by some sort of siphon. I think you can actually see the remains of the connector in the video. It's the green thing just to the right of the centre line of the engine deck. What appears to be the siphon hose is also visible in the Rats of Tobruk film as the "German" tanks have dropped their fuel tanks.

 

Transfer box is located right under the turret ring, as in dead centre. It has to be the slip ring sit on top of it. It is not mounted on the engine sub frame, it's bolted direct to the hull from memory, and if it was on the sub frame you'd need to put the turret off first to remove the engines.

 

I don't know why the escape door would have been welded in place. Might have been done before it left Australia, you wouldn't want to open it if you didn't have to as I can't imagine putting it back in the hole would be any fun.

 

Bloopers are good. I don't know of any welded bogie systems, but you knew this was going to happen anyway, well not this exactly, but you knew some smart arse was going to chime in so I don't feel too bad, it is 7, not 4. (Photo taken with the permission of the RAAC Tank Museum)

 

Looking on with interest for part 2. :popcorn:



The_Chieftain #3 Posted 29 March 2016 - 04:16 AM

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Chap over on the NA forum is telling me that the "A" in the turret number indicates a turret designed to mount either the 2pr or the 6pr.

MaximumSomething #4 Posted 29 March 2016 - 07:54 AM

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I had a quick read over what he's written, it's largely correct. The Sentinel turret was designed for the 2 OR 6 pdr from the start, the 6 pdr was not available as the order placed for 6pdr tank guns had not been acted on. I think he might be a little mixed up on the designations. Following British practice a change in armament is denoted by a suffix, so Bovington has an AC1, had it been rearmed with a 6pdr it would be an AC1A, 25pdr -> AC1B, but that would apply to the whole vehicle not just the turret. The ammunition stowage for example would have to be changed. Puckapunyal's is just BK T 35. There is just something different about that turret that needed to be noted by an "A".

 

2. You are right and he is wrong, the axle housing is removable for access/major servicing. I admit there is a documented procedure to remove/install the gearbox and differential without unbolting the axle housing. It involves removing one 3rd of the floor and digging a pit under tank. It is noted as bad engineering practice.

 

4. Yeah, still 7 bolts per bogie not 4. Photographic evidence says the E3 still had the trailing return rollers. The E1 hull was drilled at some point to receive M3 type bogies, the hole pattern is visible from the inside of the hull, I don't know how you would want to count that, 23 perhaps?

 

6. I wouldn't rely on that numbering pattern. Engine numbering appears arbitrary within the document concerned to me. The drawings of changes to the cooling system to resolve the unequal flow of coolant that lead to engines overheating/cracking/seizing has them numbered front left 2, front right 1, rear 3, which is 1 3 2 in his scheme, no common points at all. There aren't separate radiators for each engine, it's a combined cooling setup. DAFVP had a pretty good idea what the problem was and how to fix it (mostly).



Inglorious_Aussie_Tanker #5 Posted 31 March 2016 - 10:26 AM

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Good stuff looking forward to Part 2

Vote NOW, to Wall up the Lakeville Valley Pass.

So Many Idiots.

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The_Chieftain #6 Posted 13 April 2016 - 02:24 AM

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Part 2 added

Jarms #7 Posted 13 April 2016 - 09:42 PM

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The only things I can find regarding the vent/chute are:

 

"The vent itself like all vents on the Australian Cruisers were protected by heavy wire mesh grills."

"On the left of the photo is the hole for the loaders periscope and in front of it a smaller air vent with a recess for the wire mesh grill."

http://www.mheaust.c.../sentinelab.htm

 

I was always of the belief that they were either air vents, or a primitive form of ventilator. The Sentinel was designed with the 6-Pdr in mind and many other 6-Pdr armed vehicles had ventilators for the gun fumes. The other idea that comes to mind is some kind of overflow for the water cooled vickers, otherwise the turret might be filled with steam, or maybe even excess water.

 

Out of curiosity, were you able to get a good look into the vent/chute? Was there no entrance to the crew compartment at all?


Edited by Jarms, 13 April 2016 - 09:51 PM.


The_Chieftain #8 Posted 14 April 2016 - 03:08 AM

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Direct center. There is a theory that this 'chute' is not welded directly to the wall, and thus allows ventilation. I don't recall this, but I'll bear it in mind to look more closely next time I find a Sentinel.

karl0ssus1 #9 Posted 15 April 2016 - 04:40 PM

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Hrm, the more I look at it, the less sense it makes. The upper part could make sense as a vent, but the lower part is bizarre. Seems a somewhat poor position for shell casing ejection (because Id imagine empties rolling around near the turret ring is a bad bad idea), and if its for ventilation why was it not simply blanked off when they decided that it was superfluous?

 

Unless.

...

Perhaps its part of some attempt at using a radiator to cool the Vickers water jacket? Convection or forced induction through a flue containing a radiator, later deemed either unworkable, unnecessary or unreliable? The placement seems right, and presumably the thing was stuck in that particular location for a reason (although judging from the turret ergonomics, maybe not...).


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MaximumSomething #10 Posted 15 April 2016 - 06:44 PM

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View Postkarl0ssus1, on 15 April 2016 - 04:40 PM, said:

Hrm, the more I look at it, the less sense it makes. The upper part could make sense as a vent, but the lower part is bizarre. Seems a somewhat poor position for shell casing ejection (because Id imagine empties rolling around near the turret ring is a bad bad idea), and if its for ventilation why was it not simply blanked off when they decided that it was superfluous?

 

It's just a vent, no great mystery. It's not blanked off it is supposed to look like that. The first prototype had larger air vents under the overhang of both sides just like the hull, those got moved to the rear corners of the turret, that one stayed more or less where it was and got blended into the overall shape of the turret for the production vehicles.



karl0ssus1 #11 Posted 27 April 2016 - 06:07 PM

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View PostMaximumSomething, on 15 April 2016 - 10:44 PM, said:

 

It's just a vent, no great mystery. It's not blanked off it is supposed to look like that. The first prototype had larger air vents under the overhang of both sides just like the hull, those got moved to the rear corners of the turret, that one stayed more or less where it was and got blended into the overall shape of the turret for the production vehicles.

 

Then how is it ventilating? Most of the confusion is coming from the whole setup not appearing to actually allow any airflow to the turret interior. If it was decided it was superfluous but they didnt want to reshape the turret, youd assume it would be blanked off, not turned into what is apparently a chute running through the side of the turret.

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MaximumSomething #12 Posted 28 April 2016 - 11:27 AM

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View Postkarl0ssus1, on 27 April 2016 - 06:07 PM, said:

 

Then how is it ventilating? Most of the confusion is coming from the whole setup not appearing to actually allow any airflow to the turret interior. If it was decided it was superfluous but they didnt want to reshape the turret, youd assume it would be blanked off, not turned into what is apparently a chute running through the side of the turret.

 

Around the edges where there is no metal of course. Were those welded in plates not present it would be likely to be possible to climb up on to the tank a shoot directly into the crewed areas.

karl0ssus1 #13 Posted 28 April 2016 - 08:29 PM

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Interesting. Kinda strange solution to the problem.

 

FYI, probably best to lead with the picture next time, especially given

View PostThe_Chieftain, on 14 April 2016 - 07:08 AM, said:

Direct center. There is a theory that this 'chute' is not welded directly to the wall, and thus allows ventilation. I don't recall this, but I'll bear it in mind to look more closely next time I find a Sentinel.

 


RIP DM, 2012~2014 


MaximumSomething #14 Posted 29 April 2016 - 03:22 PM

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View Postkarl0ssus1, on 28 April 2016 - 08:29 PM, said:

FYI, probably best to lead with the picture next time, especially given

 

 

Well live and learn. :unsure:

 

Look at it from my point of view: I have seen it, it looks unusual but after a couple of seconds it became apparent it is just a vent. Now because an internet personality doesn't know what it is and says so in a video there are dozens of comments and posts here and elsewhere about what the Illuminati intended to use it for. It's a vent. That it required photographic proof, I didn't know it advance. I wasn't even sure I had a picture of it from the right angle. It is very strange to me that of all the things that the Chieftain has misunderstood or gotten wrong in the video, usually to the detriment of the Sentinel, that vent is what people have fixated upon.:confused:



MaximumSomething #15 Posted 07 May 2016 - 04:16 AM

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View PostThe_Chieftain, on 28 March 2016 - 10:13 AM, said:

 

 

I almost wasn't going to bother but I can't sleep so, "Things Which Are Missed Or Wrong in Part 2":

 

The swivelling commander's seat: There is a remark something along the lines that the commander's seat height adjustment range be increased by turning additional groves in the support, it is possible that the swivel is a by product of the height adjustment, or that it is not locked or tightened down properly. It is possble the gunner has some height adjustment also, it might be in the field trials report but I don't have a copy of that.

 

Commander's position: The curved box to the rear (The Chief's right elbow) is for Bren magazines. A Bren came standard with the tank for protection from aircraft. The two mounting points for it are on the Commander's cupola, you can see where the plugs are retained by short chains at the start of the video.

 

Gunner's position: The manual is not unclear about disconnecting the manual traverse handle. The manual doesn't mention it because disconnecting it is not possible. It is not possible because it is not required and the handle is not going to "come 'round and take your leg off". Working backwards the turret ring has teeth cut in it in the form of a large ring gear. A pinion from the turret drive gearbox (behind Nick's left shoulder) engages this ring. In the gearbox is a differential, arranged in the opposite manner to a car axle but a differential nonetheless. One of the inputs to the differential is a worm wheel driven by a worm powered by the turret traverse motor (bottom left of the screen). The second is a worm wheel driven by a worm turned by the manual traverse handle. It should be clear at this point that the worms function as one-way drives and it is therefore unnecessary to disconnect the manual traverse.

 

40 volt Generator: Yes there is a gain of truth in what Nick says, but the overall impression conveyed is wrong. The voltage does vary, at 1200, 1300, 1600, 2000, 2400, 2500 rpm (2800 and 3000 could not be obtained due to a faulty engine) volts were 46, 49, 42, 38, 40 and 40 respectively. This variation is unimportant as there is a voltage regulator and the output from that is 40, 40, 40, 38, 38, and 38 respectively, so within 5% and later adjusted on the tank under test to give 41 volts under load. So as far as the turret traverse system is concerned there is effectively no variation in voltage as a result of changes in engine rpm.

 

There is only one shunt motor (sort of visible behind the periscope). All the shunt motor does is switch the traverse motor on and off very quickly, the duration of the "on" time being determined by the position of the gunner's controls. It is essentially a pulse width modulation system. There is no reversing motor, there is a set of switches in the traverse controller that do that.

 

Power traverse: What Nick points to as he says power traverse is a secondary control method that seems to have been intended to be used to smoothly track moving targets. The primary control method is back down on the manual traverse crank. Just visible is some of the shots is a line of three gears between the handle and the central axis of the crank, this connects to a second shaft running up through the bevel gears to a sprocket and chain under the cover running over to the shunt motor assembly. By pulling on a trigger/lever on the handle (missing on that tank by the looks of it) a clutch engages and by twisting the handle this motion is transferred by the gears to the sprocket and chain to the traverse controller, which begins sending pulses to the traverse motor which moves the turret under electrical power in a continuous range from 0 to around 20 degrees a second left or right depending on which way the handle was twisted.

 

The guns: The gun mounting is pretty much a standard British 2 pounder tank gun mounting, shoulder controlled elevation and everything. I believe the drawing for it may have been obtained from Canada. Yes there are two handles, same as you'd find on any British tank so armed, Crusaders, Valentines, etc. See for example the Chieftain's Hatch, Matilda part III at about 9 minutes, it has two handles. So right hand on the weapon to be used for the selected target, left hand on the crank moving to the hand wheel if the target is moving such that it needs to be tracked and you can't manage the fine control required through the hand crank.

 

The gunner's periscope or lack thereof: The periscope Nick mentioned is on the Thunderbolt, not the Sentinel. So it is late production ... kind of. The loader has one too on the Mark 3.

 

The Vickers: I do not know what Nick means by "big" and  "huge", a quick look at the numbers suggests it is about the same length and weight as say a Besa, the Vickers has more volume around the barrel but it's water cooled so you'd have to expect that.

 

The ammunition stowage: The hull ammo racks are bolted to the hull side but they sit above the battery boxes. At a guess, in a museum vehicle you'd probably want to at least disconnect the batteries if not remove them altogether to eliminate the possibility of acid leaks or short circuits from old wiring. To do either of those the hull stowage bins need to be moved out of the way.

 

The steering system: The 58 feet quoted is the circle drawn on the ground by the outside track, as the sprocket and tensioning idler sit off the ground so the actual cleared area required to turn is larger at about 63 feet. There is no particular reason why the Sentinel should turn any tighter than the M3 or M4 as the controlled differential gearing is unlikely to have been altered. The Sentinel does have compressed air powered brakes/power assisted brakes but that won't help it turn any tighter. It is likely just different characteristics being measured vs the M4.

 

Top speed: The Sentinel hit a maximum speed of 40mph in tests with a sustained average of 39mph, so the gauge is more realistic than you might think. The 24mph is the maximum training speed, the maximum permissible is 29.5mph.

 

The further developments and the rest: There were something like a half a dozen or more different guns produced in Australia during the war including the likes of the 6 pounder, and 3 and 3.7inch anti aircraft guns, and the 17 pounder. The 6pdr tank gun order was placed but not acted on, by the time this had been realised it would have taken the same time to make 6 pounder tank guns as 25 pounder tank guns so the 6pdr was skipped. The 25 pounder tank gun was first tested in June 1942, which is a couple of months prior to the first production tank leaving the production line and the twin 25 and 17 pounder in November 1942 or 4 months after the first production tank. To fit the 25pdr and its ammo, and the 17pdr for that matter, they had to get rid of one of the machine guns (singular) specifically the hull gun. The coax remained, it is in photographs, the specification, even the stowage lists item (9) Vickers MkXXI (coax) 1 in turret and item (15) Ammunition .303 (10 boxes) 2500 4 boxes in turret - 6 in hull. So while a tank without a machine gun may be bad, all the Australian cruisers have at least one machine gun. Just as a side note the AC3 gunner's seat is described as comfortable. The AC4 is not an AC3 turret with a 17 pounder, it was going to be a new hull with a larger turret and turret ring, and then an even more extensively redesigned turret with a sort of mechanical magazine in the turret bustle none of which was completed when the project was shut down. With regard to production, only one of the 6(?) state railway companies was working on tanks, probably a greater disruption to their regular business were things like the local pattern carrier work and making parts and ammunition for 25 pounders. Australia did cancel projects that were deemed no longer necessary of its own volition, like the 3" mortar carriers and the Heavy Armoured Car, however the cruiser tanks were killed off primarily due to American insistence, absent that Australia would have continued making tanks through 1943 at least. The parts commonality sounds good in theory but in practice the Australian forces needed their own supply chain anyway as the most used Australian tank in the Pacific ended up being the Matilda and not the M4, by comparison the Sentinel does have some parts interchangeable with the M3 and M4.

 

None of the ex-Melbourne Tank museum tanks nor the Puckapunyal tank have the escape doors welded shut, that might have been done to the Bovington tank to prepare it for shipment to the UK.



Inglorious_Aussie_Tanker #16 Posted 09 May 2016 - 06:27 AM

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Great work there.  Very informative.  :honoring:

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The_Chieftain #17 Posted 11 May 2016 - 11:52 PM

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View PostMaximumSomething, on 06 May 2016 - 08:16 PM, said:

 

I almost wasn't going to bother but I can't sleep so, "Things Which Are Missed Or Wrong in Part 2":

 

The swivelling commander's seat: There is a remark something along the lines that the commander's seat height adjustment range be increased by turning additional groves in the support, it is possible that the swivel is a by product of the height adjustment, or that it is not locked or tightened down properly. It is possble the gunner has some height adjustment also, it might be in the field trials report but I don't have a copy of that.

 

Commander's position: The curved box to the rear (The Chief's right elbow) is for Bren magazines. A Bren came standard with the tank for protection from aircraft. The two mounting points for it are on the Commander's cupola, you can see where the plugs are retained by short chains at the start of the video.

 

Gunner's position: The manual is not unclear about disconnecting the manual traverse handle. The manual doesn't mention it because disconnecting it is not possible. It is not possible because it is not required and the handle is not going to "come 'round and take your leg off". Working backwards the turret ring has teeth cut in it in the form of a large ring gear. A pinion from the turret drive gearbox (behind Nick's left shoulder) engages this ring. In the gearbox is a differential, arranged in the opposite manner to a car axle but a differential nonetheless. One of the inputs to the differential is a worm wheel driven by a worm powered by the turret traverse motor (bottom left of the screen). The second is a worm wheel driven by a worm turned by the manual traverse handle. It should be clear at this point that the worms function as one-way drives and it is therefore unnecessary to disconnect the manual traverse.

 

40 volt Generator: Yes there is a gain of truth in what Nick says, but the overall impression conveyed is wrong. The voltage does vary, at 1200, 1300, 1600, 2000, 2400, 2500 rpm (2800 and 3000 could not be obtained due to a faulty engine) volts were 46, 49, 42, 38, 40 and 40 respectively. This variation is unimportant as there is a voltage regulator and the output from that is 40, 40, 40, 38, 38, and 38 respectively, so within 5% and later adjusted on the tank under test to give 41 volts under load. So as far as the turret traverse system is concerned there is effectively no variation in voltage as a result of changes in engine rpm.

 

There is only one shunt motor (sort of visible behind the periscope). All the shunt motor does is switch the traverse motor on and off very quickly, the duration of the "on" time being determined by the position of the gunner's controls. It is essentially a pulse width modulation system. There is no reversing motor, there is a set of switches in the traverse controller that do that.

 

Power traverse: What Nick points to as he says power traverse is a secondary control method that seems to have been intended to be used to smoothly track moving targets. The primary control method is back down on the manual traverse crank. Just visible is some of the shots is a line of three gears between the handle and the central axis of the crank, this connects to a second shaft running up through the bevel gears to a sprocket and chain under the cover running over to the shunt motor assembly. By pulling on a trigger/lever on the handle (missing on that tank by the looks of it) a clutch engages and by twisting the handle this motion is transferred by the gears to the sprocket and chain to the traverse controller, which begins sending pulses to the traverse motor which moves the turret under electrical power in a continuous range from 0 to around 20 degrees a second left or right depending on which way the handle was twisted.

 

The guns: The gun mounting is pretty much a standard British 2 pounder tank gun mounting, shoulder controlled elevation and everything. I believe the drawing for it may have been obtained from Canada. Yes there are two handles, same as you'd find on any British tank so armed, Crusaders, Valentines, etc. See for example the Chieftain's Hatch, Matilda part III at about 9 minutes, it has two handles. So right hand on the weapon to be used for the selected target, left hand on the crank moving to the hand wheel if the target is moving such that it needs to be tracked and you can't manage the fine control required through the hand crank.

 

The gunner's periscope or lack thereof: The periscope Nick mentioned is on the Thunderbolt, not the Sentinel. So it is late production ... kind of. The loader has one too on the Mark 3.

 

The Vickers: I do not know what Nick means by "big" and  "huge", a quick look at the numbers suggests it is about the same length and weight as say a Besa, the Vickers has more volume around the barrel but it's water cooled so you'd have to expect that.

 

The ammunition stowage: The hull ammo racks are bolted to the hull side but they sit above the battery boxes. At a guess, in a museum vehicle you'd probably want to at least disconnect the batteries if not remove them altogether to eliminate the possibility of acid leaks or short circuits from old wiring. To do either of those the hull stowage bins need to be moved out of the way.

 

The steering system: The 58 feet quoted is the circle drawn on the ground by the outside track, as the sprocket and tensioning idler sit off the ground so the actual cleared area required to turn is larger at about 63 feet. There is no particular reason why the Sentinel should turn any tighter than the M3 or M4 as the controlled differential gearing is unlikely to have been altered. The Sentinel does have compressed air powered brakes/power assisted brakes but that won't help it turn any tighter. It is likely just different characteristics being measured vs the M4.

 

Top speed: The Sentinel hit a maximum speed of 40mph in tests with a sustained average of 39mph, so the gauge is more realistic than you might think. The 24mph is the maximum training speed, the maximum permissible is 29.5mph.

 

The further developments and the rest: There were something like a half a dozen or more different guns produced in Australia during the war including the likes of the 6 pounder, and 3 and 3.7inch anti aircraft guns, and the 17 pounder. The 6pdr tank gun order was placed but not acted on, by the time this had been realised it would have taken the same time to make 6 pounder tank guns as 25 pounder tank guns so the 6pdr was skipped. The 25 pounder tank gun was first tested in June 1942, which is a couple of months prior to the first production tank leaving the production line and the twin 25 and 17 pounder in November 1942 or 4 months after the first production tank. To fit the 25pdr and its ammo, and the 17pdr for that matter, they had to get rid of one of the machine guns (singular) specifically the hull gun. The coax remained, it is in photographs, the specification, even the stowage lists item (9) Vickers MkXXI (coax) 1 in turret and item (15) Ammunition .303 (10 boxes) 2500 4 boxes in turret - 6 in hull. So while a tank without a machine gun may be bad, all the Australian cruisers have at least one machine gun. Just as a side note the AC3 gunner's seat is described as comfortable. The AC4 is not an AC3 turret with a 17 pounder, it was going to be a new hull with a larger turret and turret ring, and then an even more extensively redesigned turret with a sort of mechanical magazine in the turret bustle none of which was completed when the project was shut down. With regard to production, only one of the 6(?) state railway companies was working on tanks, probably a greater disruption to their regular business were things like the local pattern carrier work and making parts and ammunition for 25 pounders. Australia did cancel projects that were deemed no longer necessary of its own volition, like the 3" mortar carriers and the Heavy Armoured Car, however the cruiser tanks were killed off primarily due to American insistence, absent that Australia would have continued making tanks through 1943 at least. The parts commonality sounds good in theory but in practice the Australian forces needed their own supply chain anyway as the most used Australian tank in the Pacific ended up being the Matilda and not the M4, by comparison the Sentinel does have some parts interchangeable with the M3 and M4.

 

None of the ex-Melbourne Tank museum tanks nor the Puckapunyal tank have the escape doors welded shut, that might have been done to the Bovington tank to prepare it for shipment to the UK.

 

Pretty thorough post.

 

 

Fair point on the commander's seat, it is certainly possible that there is a lock which was 'unlocked.' Mechanics aside, the location of the manual traverse handle is unsatisfactory for use. OK, it's not going to take your leg off, but when you do decide you want to crank it, it's really poorly located. I believe I did explain that the purpose of the system was to provide a steady turn regardless of the power input to the motor, but I do plead guilty to misreading shunt fields in the manual as shunt motors.

 

 

The periscope I mention as missing is shown in the diagram for the instruction book for the 2pr tank (Fig 12). I can't explain the presence or lack thereof. With regards to top speed, in trials vehicles frequently exceed service speed. For example, the early Abrams clocked in once at about 100mph (And pretty much wrecked the running gear doing it). However, you have me on training vs permissable speed, I just screwed up reading the manual. Not sure where I got the idea of AC3 not having a coax either, so yeah, not my best effort on this one. I'm putting a couple of annotations up on the video to correct.

 

 

 



MaximumSomething #18 Posted 12 May 2016 - 12:58 PM

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View PostThe_Chieftain, on 11 May 2016 - 11:52 PM, said:

 

Pretty thorough post.

 

 

Fair point on the commander's seat, it is certainly possible that there is a lock which was 'unlocked.' Mechanics aside, the location of the manual traverse handle is unsatisfactory for use. OK, it's not going to take your leg off, but when you do decide you want to crank it, it's really poorly located. I believe I did explain that the purpose of the system was to provide a steady turn regardless of the power input to the motor, but I do plead guilty to misreading shunt fields in the manual as shunt motors.

 

OK. Rightly or wrongly on my part the impression I was left with on watching the video was that turret speed was coupled to a degree to engine RPM.

 

View PostThe_Chieftain, on 11 May 2016 - 11:52 PM, said:

 

The periscope I mention as missing is shown in the diagram for the instruction book for the 2pr tank (Fig 12). I can't explain the presence or lack thereof.

 

 

That illustration would seem to be based on a photo taken through the commanders cupola. It's one of the commander's periscopes. It would have to have been taken right about where your cameraman was while you were in the gunner's position,  and actually your video has the periscope in view for the same reason. My mistake I thought you were referring to the gunner's periscope on the Mark 3.

 

View PostThe_Chieftain, on 11 May 2016 - 11:52 PM, said:

 

Not sure where I got the idea of AC3 not having a coax either, so yeah, not my best effort on this one. I'm putting a couple of annotations up on the video to correct.

 

 

Peter Beale's book "Fallen Sentinel"? I'm pretty sure that one makes the odd claim of no coax. A.T. Ross's "Armed and Ready" might as well but I'm not sure about that one, it's been years since I read it.

 

 

The ergonomics and so on, if you say you don't fit or you can't work the controls, then you don't fit and can't work the controls. That's fine, no argument from me. I find it surprising that no one at the time found it quite so unworkable as you did, not even the British and Americans who either worked on it, or inspected it.

 

Regardless, it was very nice to get a glimpse inside the Bovington exhibit. It isn't likely I'll get a chance to go to the other side of the planet and if I did I doubt they'd let me poke around inside that tank. So thank you for ... enduring? it. :great:

 

Perhaps for future videos you could maybe get a few short clips of the crew positions and internal bits without that Irish giant in the way, just a couple of seconds to pan across the engine or armament or the controls or whatever he is describing. It is instructive to see him in position, but some times I can't what I want to see because he is in the way.  :hiding:



The_Chieftain #19 Posted 13 May 2016 - 02:30 AM

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Quote

That illustration would seem to be based on a photo taken through the commanders cupola. It's one of the commander's periscopes.

 

Son of a... Yep.. you're right. Shows you how cramped I found the turret that I thought a commander's periscope in that position would be suitable for a gunner.

 

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Peter Beale's book "Fallen Sentinel"? I'm pretty sure that one makes the odd claim of no coax.

 

Entirely possible. It's one of the books I used during scriptwriting.

 

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I find it surprising that no one at the time found it quite so unworkable as you did, not even the British and Americans who either worked on it, or inspected it.

 

Perhaps they had no particular knowledge of 'what right looks like'? The Americans I can understand, as they didn't have any three-man turrets, really, anyway. The British less so, unless they similarly were dispatched over to Australia before getting a chance to look inside Matilda or some such. Or maybe they just were more willing to accept issues than I am.

 

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Perhaps for future videos you could maybe get a few short clips of the crew positions and internal bits without that Irish giant in the way,

 

No argument. It's actually one of the less-well filmed tanks I've done in a very long time, but it was unfortunately the best I could do given the time and filming assets available to me.

 






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