Jump to content

Inside The Chieftain's Hatch - Ac I Sentinel


Nikolas93TS
 Share

Recommended Posts

I agree - good stuff.

 

This tank is the best reason I ever found (well, Valiant also...) for the need of Ergonomics. Thought that chute could be a kind of cooling duct for the MG water, but the reservoir is located too much to the back of the turret for it to work. Perhaps the place of that reservoir was temporary and the hypothetical production vehicles could have put it more to the front. God knows.

Link to comment
Share on other sites

  • Replies 77
  • Created
  • Last Reply

Top Posters In This Topic

I agree - good stuff.

 

This tank is the best reason I ever found (well, Valiant also...) for the need of Ergonomics. Thought that chute could be a kind of cooling duct for the MG water, but the reservoir is located too much to the back of the turret for it to work. Perhaps the place of that reservoir was temporary and the hypothetical production vehicles could have put it more to the front. God knows.

 

The "chute" thingy is just an air vent, the peculiarities of it's design possibly result from the need to clear fumes from near the MG and around the loader, possibly also due to the requirement that the tank be resistant to I think it was thermite and Molotov cocktails, so no air vents in the top surfaces like the engine deck. It is odd though.

 

Just how small was the turret diameter of the AC1?

 

Usual British, 1370mm//54".

 

 

 

Turret traverse isn't that hard to understand. 40V generator is powered off the transfer case, 40V goes to 40V regulator, then current limiting relay I think, to the rotary junction box, to the turret traverse control motor where the magic happens. This motor spins at 650 rpm and at the end of the shaft is an eccentric brush, so this draws out a circle. Under this is a disk with contacts on it also placed eccentrically so the circle drawn by the brush goes from near the centre to the edge. At rest the brush passes over none of the contacts as the disk is rotated left or right the brush begins to pass over and make contact with the conductive regions, after about a half turn a separate bypass contact closes and sends continuous current, the output of of all of this goes to the turret traverse motor and turns the turret anywhere from not at all to about 20 degrees per second left and right. So it is a sort of reversible, 650 Hertz mechanically-switched, pulse width modulation electrical control system. Crank for manual, there should have been a kind of trigger lever on the handle, pull that and then twist left/right for power.

 

What is fitted to that tank looks different to what is in the manual and photos, and given the low turret number might be non standard/non production equipment. Some of the problems encountered in testing was traced in part back to just that.

 

Manual traverse is permanently engaged, it doesn’t need to be disconnected as the manual and power traverse are combined through a differential, manual through a worm drive so that's going to have naturally high resistance to being driven backwards by the motor, and the turret traverse motor has a solenoid brake on it to prevent it being turned backwards by the manual control.

 

Link to comment
Share on other sites

 

 

 

The "chute" thingy is just an air vent, the peculiarities of it's design possibly result from the need to clear fumes from near the MG and around the loader, possibly also due to the requirement that the tank be resistant to I think it was thermite and Molotov cocktails, so no air vents in the top surfaces like the engine deck. It is odd though.

 

 

The problem with that theory is that the chute is sealed from the roof to the hull side. No way for any ventilation to happen.

 

You can see it here.

 

http://i.imgur.com/4H9le1v.jpg

Link to comment
Share on other sites

 

 

 

 

The "chute" thingy is just an air vent, the peculiarities of it's design possibly result from the need to clear fumes from near the MG and around the loader, possibly also due to the requirement that the tank be resistant to I think it was thermite and Molotov cocktails, so no air vents in the top surfaces like the engine deck. It is odd though.

 

 

The problem with that theory is that the chute is sealed from the roof to the hull side. No way for any ventilation to happen.

 

You can see it here.

 

http://i.imgur.com/4H9le1v.jpg

 

 

Yes there is, the plates welded in do not extend to the turret wall along their edegs. With the engines pulling air in from the fighting compartment air entering from the outside flows down\up behind the fabricated channel and front-left/rear-right along the turret wall. The same thing happens in the back corners of the turret, the air vent is part of the casting and additional plates are welded in, I imagine the intent is for them to act as baffles as keep out bullet splash and fragments.

 

Also it might be a tiny little optimistic but with reason, the Sentinel is capable of 40mph. Probably not recommended though.

Link to comment
Share on other sites

(...)

 

Yes there is, the plates welded in do not extend to the turret wall along their edegs. With the engines pulling air in from the fighting compartment air entering from the outside flows down\up behind the fabricated channel and front-left/rear-right along the turret wall. The same thing happens in the back corners of the turret, the air vent is part of the casting and additional plates are welded in, I imagine the intent is for them to act as baffles as keep out bullet splash and fragments.

 

(...)

That seems to make sense.

Link to comment
Share on other sites

 

 

 

 

The "chute" thingy is just an air vent, the peculiarities of it's design possibly result from the need to clear fumes from near the MG and around the loader, possibly also due to the requirement that the tank be resistant to I think it was thermite and Molotov cocktails, so no air vents in the top surfaces like the engine deck. It is odd though.

 

 

The problem with that theory is that the chute is sealed from the roof to the hull side. No way for any ventilation to happen.

 

You can see it here.

 

http://i.imgur.com/4H9le1v.jpg

 

For what it's worth, I'm pretty sure that bracket bolted to the vent baffle is a mounting plate for the Loader's WS19 control/selector Box.

Link to comment
Share on other sites

With the gunner's seat arrangements, Manic, did the seat have a height adjustment or position swing that was perhaps not functional? Given the free elevation arrangements, if the seat swung/folded away then the gunner would crouch on the floor and operated the gun.

Link to comment
Share on other sites

 

Just how small was the turret diameter of the AC1?

 

Usual British, 1370mm//54".

 

The same as for the turret of the M3 Medium, which also had a three man crew. So it is strange that a turret ring of the same diameter resulted in such a cramped condition. Below is a picture of the M3 37MM turret. As you can see there are three seats, Loader, Gunner, Tank Commander and I don't recall anybody saying the turret of the M3 was unworkable.

 

Link to comment
Share on other sites

 

 

 

 

 

The "chute" thingy is just an air vent, the peculiarities of it's design possibly result from the need to clear fumes from near the MG and around the loader, possibly also due to the requirement that the tank be resistant to I think it was thermite and Molotov cocktails, so no air vents in the top surfaces like the engine deck. It is odd though.

 

 

The problem with that theory is that the chute is sealed from the roof to the hull side. No way for any ventilation to happen.

 

You can see it here.

 

http://i.imgur.com/4H9le1v.jpg

 

For what it's worth, I'm pretty sure that bracket bolted to the vent baffle is a mounting plate for the Loader's WS19 control/selector Box.

 

I wonder if the Vent might have been used at first and then found to be redundant and sealed up?

Link to comment
Share on other sites

Manic, there's a 7th Sentinel tank in Austin Texas. I've been there and I saw it myself in the winter of 2014/2015 when I went back to the US on vacation.

 

http://kingshobbyshop.com/ac1_sentinel

 

Well, there was... I put it there. That tank is now in Cairns. http://www.sunshinecoastdaily.com.au/news/resurrected-australian-sentinel-tank-hits-world-st/2977134/

 

Great video, 27 minutes went by fast :)

With the gunner's seat arrangements, Manic, did the seat have a height adjustment or position swing that was perhaps not functional? Given the free elevation arrangements, if the seat swung/folded away then the gunner would crouch on the floor and operated the gun.

 

Possible, and I didn't check, but I would argue still hardly ideal.

Link to comment
Share on other sites

 

 

Just how small was the turret diameter of the AC1?

 

Usual British, 1370mm//54".

 

The same as for the turret of the M3 Medium, which also had a three man crew. So it is strange that a turret ring of the same diameter resulted in such a cramped condition. Below is a picture of the M3 37MM turret. As you can see there are three seats, Loader, Gunner, Tank Commander and I don't recall anybody saying the turret of the M3 was unworkable.

 

 

 

It is a bit of a puzzle isn't it. Apparently Col. Watson amended the specification to include a low silhouette, dunno if it was him or not but it seems reasonable he was the expert. As Nick says at the start of the video it is a small tank, two and a half metres tall about the same height as the listed heights of the Matilda, Cromwell and T-34, the difference being that being based on the M3 the Sentinel has a whole load of drive shafts below the turret basket. Oddly there is no mention of Nick's problems at the time, either it was regarded as normal or perhaps a reasonable trade off. An alternative view might be that the space appears and feels more crowded than it actually is due to the internal stowage of, well, junk, things that could just as well be stowed outside like crew rations, the water tank and so on. One of the things not mentioned in the video is the Bren AAMG. The Bren fits in the cupola but it is stored in the turret basket and you can see the rack to store the magazines next to the radio mount, that's something that is rarely going to be worthwhile but takes up internal space.

 

I had a little look through what I've got on them and I did actually find one drawing that has the hand wheel that Nick says in the video is the power traverse. The drawing shows it located below not above the chain and chain cover that links the hand controller to the traverse controller, so it is one way to run the power traverse, I think the Bovington one might have been disassembled/reassembled in the wrong order. It doesn’t really matter, you never need to take your left hand off the manual crank to use either.

Link to comment
Share on other sites

If stowage bins were demounted and remounted incorrectly that could be a problem for gauging the space within.

 

I think Manic would have trouble wih the commanders space on Vandal too.

Link to comment
Share on other sites

From peering inside of it, it actually seems fairly workable. Had it been in Europe 1940, it would have been a world class tank and quite dangerous to everything. It's really amazing how a year or two makes all the difference in how a tank was received and it performed.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share


×
×
  • Create New...