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  #1  
Old 11-04-19, 01:36
MartinCummins MartinCummins is offline
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Default Tank Design Questions never asked!

Over the years, I have asked the following, and without success! So I've come to the fount of all knowledge, tank wise!
1)- Churchill MkV111-The rear Air Inlet Ducts for the radiators have, just below the top cowls, three horizontally placed blanking plates. These cover three openings, protected by wire mesh. What purpose-even Bovington does not know, and a MkV111 guards their entrance! As there was an overheating problem, perhaps the plates (Three for ease of handling/storage) were removed when deployed in a tropical country? Dust intake would increase though.Another hypothesis was that they could be quickly opened when Elephant Trunk wading ducts were mounted, imposing additional restriction. Sure, normally one would swipe them off with the barrel, but perhaps you wanted to use them again. Unbolting would take time, and they would be unwieldy to stow. Any takers?

2)-All British tanks using a Jack were supplied with a pair of Wood Jacking Blocks. As I have never met a tanker who ever used a jack, and the manuals never discuss the use of the blocks, why two? As the base of the Hydraulic Jack sat half on the track, a packing piece would be needed to fill the space between road and base. Perhaps, you used the second block when on bare ground, as one block would sink into the soil?

3)Many WW2 tanks had sight vanes for use of the commander, in assisting the gunner to locate an object. US tanks did not fit "Donkey Sights", so how did their commander assist the gunner?

4)-Some Cruiser Tanks had minimal silencers-The Cromwell relied on Fishtails inside hull apertures. Was it felt that track noise at speed was louder than the exhaust? The Russian T34 had exhausts into boxes in the hull! Could it be that silencers were just intended to assist the accompanying infantry behind a Churchill in communicating with each other. I understand that open areas for exhaust were potential areas for a Flame thrower attack!

5)-The Churchill and other tanks of that era had round ports cut in the rear of the turret.This was to allow a barrel change, presumably the breach being removed first via a top access and overhead gantry. This system seems to be paired up with an inside mantlet. Was the idea behind this design to allow the enlarged breach to exit rearwards, so a smaller port was needed for the turret front. There was less area of mantlet exposed to shell impact, so less chance of damaged trunnions. An external mantlet might be battered back into contact with the turret, but it probably was more rainproof, before gaiters?


Thanks for assistance,
Martin Cummins
Dunstable,
England.

Last edited by MartinCummins; 31-05-19 at 21:32. Reason: Solved
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  #2  
Old 13-04-19, 19:17
Lauren Child Lauren Child is offline
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Quote:
Originally Posted by MartinCummins View Post
Over the years, I have asked the following, and without success! So I've come to the fount of all knowledge, tank wise!
1)- Churchill MkV111-The rear Air Inlet Ducts for the radiators have, just below the top cowls, three horizontally placed blanking plates. These cover three openings, protected by wire mesh. What purpose-even Bovington does not know, and a MkV111 guards their entrance! As there was an overheating problem, perhaps the plates (Three for ease of handling/storage) were removed when deployed in a tropical country? Dust intake would increase though.Another hypothesis was that they could be quickly opened when Elephant Trunk wading ducts were mounted, imposing additional restriction. Sure, normally one would swipe them off with the barrel, but perhaps you wanted to use them again. Unbolting would take time, and they would be unwieldy to stow. Any takers?

That’s actually an early Churchill I/II. The original air inlets sucked air upwards, with the plates (I assume) being fins or bullet shields. While protected, they also sucked up lots of dust kicked up by the tracks, so the design was reworked with inlets to the top.


Quote:



2)-All British tanks using a Jack were supplied with a pair of Wood Jacking Blocks. As I have never met a tanker who ever used a jack, and the manuals never discuss the use of the blocks, why two? As the base of the Hydraulic Jack sat half on the track, a packing piece would be needed to fill the space between road and base. Perhaps, you used the second block when on bare ground, as one block would sink into the soil?
When I’ve worked in a similar way I used two blocks - one beneath the jack to level the jack out on the track as you describe, and one between the jack and the suspension arm as a cushion.

Quote:


3)Many WW2 tanks had sight vanes for use of the commander, in assisting the gunner to locate an object. US tanks did not fit "Donkey Sights", so how did their commander assist the gunner?
It’s to provide 2 methods of sighting in case the primary is damaged. I’m not up on US tanks but I seem to remember the Sherman sights added a sight within the periscope.

Quote:


4)-Some Cruiser Tanks had minimal silencers-The Cromwell relied on Fishtails inside hull apertures. Was it felt that track noise at speed was louder than the exhaust? The Russian T34 had exhausts into boxes in the hull! Could it be that silencers were just intended to assist the accompanying infantry behind a Churchill in communicating with each other. I understand that open areas for exhaust were potential areas for a Flame thrower attack!
Tanks are pretty noisy anyway, so I can’t imagine it was high on the priority list, plus for most of the war they were trying to eek as much power out if the engines as possible.

It may be more about the engine’s history - the Churchill’s twin six was based on Bedford 6 cylinder automotive engines with some readily available designs, while other engines like Liberty and Meteor were based on aero engines.

Quote:


5)-The Churchill and other tanks of that era had round ports cut in the rear of the turret.This was to allow a barrel change, presumably the breach being removed first via a top access and overhead gantry. This system seems to be paired up with an inside mantlet. Was the idea behind this design to allow the enlarged breach to exit rearwards, so a smaller port was needed for the turret front. There was less area of mantlet exposed to shell impact, so less chance of damaged trunnions. An external mantlet might be battered back into contact with the turret, but it probably was more rainproof, before gaiters?
I’d imagine it was simply a case of turret strength - the smaller the hole in the front, the stronger the turret. Although with hindsight external mantlets provide more protection by deflection, they were still working out how best to armour a tank at the time.

Quote:

No more- finally, I have been trying to contact a member of the Canadian Military Collectors Forum for 3 months, as I have scans of a rare manual which would be of interest to a member. However, after receiving a note saying I would be contacted, nothing, and there is no way that the organisers can be contacted. If any body is a C. M. C. F. member, perhaps they might be able to forward a copy of my problem, so I could be contacted by the organisers? (I have already a posting in the Membership Section,but nothing so far!)

Thanks for assistance,
Martin Cummins
Dunstable,
England.
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  #3  
Old 13-04-19, 19:23
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Richard Farrant Richard Farrant is offline
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It may be more about the engineís history - the Churchillís twin six was based on Bedford 6 cylinder automotive engines with some readily available designs, while other engines like Liberty and Meteor were based on aero engines.


Sorry Lauren, but I have to correct you on the Twin Six being based on Bedford automotive engines, you will not find any side valve engines amongst them. This is a myth that has been around a long time.

regards, Richard
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  #4  
Old 13-04-19, 19:38
Lauren Child Lauren Child is offline
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Thanks Richard,

I may be wrong on 1) as well, as the more I think on it the more Iím thinking of something I read on wading. Iím pretty sure thereís a file in the national archives on Churchill air inlet design/trials, so that may have a definitive answer.
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  #5  
Old 06-05-19, 02:06
MartinCummins MartinCummins is offline
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Thanks, Lauren,
1)-Yes, a cast inlet duct, drawing from near the ground, was originally used-Probably good protection from a flame-thrower. As you say, dust intake was excessive, and a fabricated trunk, with a rain/fragment cowl on top, was introduced. Air restriction was now excessive, and I have seen drawings with fillets mounted in the corners of trunk to improve air flow, plus sealing of junctions for wading, for the next version. However, I have not seen drawings of the (last?)type, havng the three apertures cut below the top entry, on the vertical side. Normally these had three bolted cover plates, concealing wire screens mounted over the openings. If these plates werre removed, air flow would be increased, but dust intake also. Perhaps these openings were to be exposed when it was hot, but with low dust being raised by track. I do not know if it was envisaged for use in a jungle,where these conditions might obtain?

2)-Somebody who used the jack! I had not thought of that use for packing, as the arms had no flat seating. I imagine also the situation might arise where a wheel had been damaged, and the track broken, so you would then need two pieces of packing?

3)-Interesting point. Also perhaps the Commander could scan a larger area, then using his optical sight to home into an area of interest.

4)-If the tank was Hull Down, and needed to idle the engine for turret movement, then a silencer might be an advantage. Small auxillary generators, with low noise, might have come later?

5)-Good point, as there would be less tendency to "trap" a projectile with an external mantlet. However, perhaps it would have to be thicker than an internal mantlet, so as to avoid being deformed into contact with the turret. How this affected the inertia of the gun, when firing on the move, I do not know, and also whether impact on the mantlet would damage the trunnion bearings, locking elevation?
Thanks for the mention of a file at National Archives-any idea of reference?

Richard-Thanks for correcting that point-I live only a mile or so from the Assembly Area of the Churchill & I had just gone along with that supposition!
Finally-another point-German tanks often had hinged (Elbow) aiming telecopes, wheras Britain had simple Telescopes. The German system would protect the gunner if a direct impact on the objective occurred. Also, perhaps not forcing the gunner to hunch if tall, and further enabling the tank to be less exposed in "Hull Down". You had to have an accomplished Optical Industry to produce the Elbow Telescope, though. Comments?

Many thanks to you both,
Martin Cummins.
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  #6  
Old 06-05-19, 02:56
rob love rob love is offline
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Quote:
Originally Posted by MartinCummins View Post
No more- finally, I have been trying to contact a member of the Canadian Military Collectors Forum for 3 months, as I have scans of a rare manual which would be of interest to a member. However, after receiving a note saying I would be contacted, nothing, and there is no way that the organisers can be contacted. If any body is a C. M. C. F. member, perhaps they might be able to forward a copy of my problem, so I could be contacted by the organisers? (I have already a posting in the Membership Section,but nothing so far!)

Thanks for assistance,
Martin Cummins
Dunstable,
England.
I am a member of that forum. PM me with who you are trying to contact and I'll see what I can do.
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  #7  
Old 31-05-19, 23:45
MartinCummins MartinCummins is offline
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Default Rejection by CMCF

Rob Love

Thank you for your helpful offer-However, after three months a message arrived out of the blue, last week, allowing me to enter the hallowed portals! I guess they want to test you to see how keen you might be!

I had almost given up with somebody noticing my 'plaint at MLU, so thank you for being so observant! I have culled all the begging messages that I can on MLU as well.

Best regards,
Martin Cummins.
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