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foeth

M33/M45 Maxson mount

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Posted (edited)

By accident I've stumbled on the M33 Maxson mount in British service, the twin 0.50" precursor of the quad 0.50"M45 Maxson mount. The M33 was placed on the M13 and M14 half tracks (the latter intended for British service) and the M45 was used on the M16 half tracks. The differences between the M33 and M45 appear to be superficial but I cannot find too much information on the M33 so it's difficult to tell.

 

  • Are the Maxson M33 and M45 more or less identical, except for two additional hard points? (edited in manual: differences are superficial)
  • Are there any good drawings (i.e., ISO views and to scale) of either mount? Any references that may contain these drawings (Hunnicutt?)?

 

Editing in useful (?) resources

Technical Manual

Edited by foeth

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Posted (edited)

Dragon-6421-1-35-US-Quad-Gun-Trailer-M55

 

So, something derivative but I guess close enough: from Dragon's (6421) 1/35 US Quad Gun Trailer M55. Only make it a factor of 10 smaller and done...

 

Also, within 30 minutes driving: https://westland.nl/product/quadmount

Edited by foeth

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There is a video clip of the M33 mount emplaced on a British coastal defence position which appears every now and again on history programmes.  Presumably dismounted from half-tracks as we didn't have much liking of or use for the AA variants we received.

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Posted (edited)

The M33 I found is indeed for coastal defense (Maunsell army fort). I thought of buying the Dragon kit for measurements but it appears to be sold out. I also found a few specimens in local museums, so it should be fairly easy to visit and bring a tape measure... 🤔

 

This pic shows them clearly (took me forever to find out what they were in the first place but this mystery is now solved)

 

world-war-ii-4th-october-1944-outposts-o

 

Edited by foeth

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I've never seen - or perhaps noticed - them on a Maunsell Fort before.  The one I saw was on a concrete emplacement.  But a CIWS on the Maunsells makes some sense as the 3.7s and Bofors had limited engagement capability against close-in fast-flying aircraft and none against close surface targets.  Things that might actually target the forts themselves.  Several twin 50's can spoil a pilot's or an E-boat's day.  I wonder if they were modified for extra depression, and were there 2 more on the other side?  I believe that end tower mounted a radar.  The twin Bofors tower is behind, 2nd from left was the command tower with a searchlight and the other 4 mounted 3.7s.

 

None of the drawings I've seen nor any of the descriptions mention the M33 mounts and Mr Google showed me only 1 more image where they can be seen, a more distant view of your photo.  Do you know which of the forts this is? Their layout was identical.  Did they all have the M33s?  It is often forgotten that 3 more Maunsells were built in the Mersey Estuary too, but I can't see any of those needing CIWS.

 

As for the M33, the most obvious difference with the M45 is of course the guns being mounted centrally on the trunnions.  I'm sure there might have been other detail differences: I believe the sights changed and that Dragon may have depicted a post-war type.  The power unit on the M45 might have been upgraded for the extra weight.  I can't see it being adapted to take electrical power from the fort by slip-ring, although that might have been more useful and reliable than pull-starting the on-board generator every time there was a Stand To.  Relatively few M33s were made as many M13 and M14 were completed as M16 and M17 with the M45 mount.  Having said this, about 1,600 M14 came to the UK and all were converted to other roles: lots of spare M33s

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Posted (edited)

The layout of the forts was in fact not identical. The layout of the Mersey forts was in-line: from the central control tower the four gun towers were placed ahead in an arc, with the Bofors and searchlight tower behind it. The Thames fort had the aft searchlight tower connected to the left gun tower, not the Bofors tower. The main reason for doing so appears to be the ability to engage surface targets. Initially there was some discussion if the layout of the Thames forts would be detrimental to their AA ability and the additional required manpower. The other differences appear to be minor: there is a difference in draft with the Thames forts support legs being a about quarter shorter than the Mersey fort legs (and presumably a different Oxford frame), plus, there are minor differences in construction and plating. The radar fit appears to be more or less equal (difficult to say with sensoring), except searchlight radar on the Mersey forts.

 

The fort in the pictures above is Shivering Sands (Turner's books; some have it as Nore but that's internet 🤔) . The railing outline is built to accommodate the M33s and this is not present on the other side of the same tower; the same outline is (still) present on Red Sands fort. One image of Nore shows two 'blobs' at the M33's position. So a careful conclusion would be that a) they were only placed on one side and b) they were present on all Thames forts. I cannot observe them on what few photographs I have of the Mersey forts (and the emplacements are not on the constructional drawings either). Very strange, but I always seem to have insufficient research material.

 

About the M33's; using the units own power would be very easy to install so there is no need to modify them to use the forts power? A simple bolt-on solution. And indeed, the guns are more central on the M33 compared to the M45.

 

Research ongoing (errors to be corrected later 😖).

Edited by foeth

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I meant the Thames forts being identical to each other, not identical with the Mersey configuration. IIRC the longer view of that photo was captioned as Red Sands, apparently incorrectly.

 

Yes, self-powered is an easy installation but the power units were not marinised and I wondered about reliability. I guess OK with adequate maintenance and running-up. All the weapons would have needed much cleaning and oiling in that salt-laden environment anyway.

 

I also wondered if the M33s might have been added later, but couldn't find any event that might have caused it - other than the sensible need for a CIWS.  The M14s (and a very few M13s) arrived before the forts were built so they could have been installed during build. Being only on 1 side and with limited arcs I presume they faced seaward? Using sponsons at a lower level, somewhat like the German Flak towers, M33s could have been fitted to all the 'outer' towers without impeding the main armament field of fire.

 

Thinking of surface action, wasn't one of the forts credited with a U-Boat 'kill'?

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Posted (edited)

This is all most interesting. 

 

Common sense would suggest that if the Maxson turrets were used at all on land, they were mostly used on the south and east coasts of England against low-level raiders 1943 on, and (from June 1944) in the coastal gun belt of the anti-V1 deployment known as Operation Diver. Their placement on the Thames forts makes excellent sense. 

 

Unfortunately there does not seem to be any mention of Maxson turrets in the index of Colin Dobinson's book AA Command (but he does refer to a plan to emplace 0.5" Brownings on unspecified mounting types in London in 1945). He does say that they tried out quite a variety of light AA weapons in the coastal belt of Diver beside the 3.7 inch and 40mm Bofors. But doesn't list them. His books on Britain's defence emphasise documentary and surviving archaeological evidence and don't go into the details of the weapons (understandably, as they are published by English Heritage aka Historic England). I don't suppose a Maxson turret would leave much if any archaeological evidence - it might not even be bolted into the concrete if they made some removable underframe for it. 

 

Dobinson has more recently published a book on Diver, which might be worth checking, though I do not have a copy:  

 

https://www.amazon.co.uk/Operation-Diver-Landscapes-Defence-Monuments/dp/1848024754/ref=sr_1_1?qid=1563872681&refinements=p_27%3AColin+Dobinson&s=books&sr=1-1&text=Colin+Dobinson
 

 

 

Edited by Lothian man

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Agree this is an interesting subject.  Clearly they were used, even if only in limited numbers, yet records and books etc seem silent on the subject.

 

If we had 1,500-1,600 twin 50 turrets available from converted M14s it would seem logical that they were put to use.  As noted, they were self-contained being self-powered and required minimal installation - and were effective.  Four guns were just more effective.  We had access to the ammunition: not sure the UK manufactured 0.50 BMG during WW2 but it certainly came over from the US.  We were deploying single, twin and quad Lewis guns, twin Brens and twin 303 Brownings plus single 20mm Hispano for local defence of airfields, gun batteries and searchlight positions.  The Navy were even breaking out Hotchkiss Mk1s from store.  In N Africa, Australian AA regiments and some RAN ships were equipped with captured Breda 20mm.  So the availability of so many twin 50s would seem like manna from heaven.

 

The film clip I recall has no positional reference. It's coastal and on a concrete base, IIRC with a sentry stood At Ease next to it.  Taken from behind the mount looking seaward.  Local defence of coastal gun batteries, which sprouted up all round the coast, would be logical.

 

I'm not sure that the 50 Browning had the effective or accurate ceiling to deal with V1s, but the proverbial curtain of lead has an appeal. 

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Posted (edited)

The M33s indeed face seaward. I cannot see any remnants of the Maxson turrets but I also do not have many pictures that show the roof on the searchlight tower clearly.

 

One E-boat was claimed by Tongue Sands (Navy style), but according to Turner two E-boats collided in response to the fire with one damaged and scuttled.

I’ve analyses the drawings of the M45 on an M20 mount by both Dragon (1:35) and Armory Models Group (1:72); both instructions show several views. The Dragon kit is long sold out by now, but when relying what pictures I could find in the manual the Armory model is more consistent with the measurements in the official documentation. A nice starting link was this one:

 

https://edoc.pub/weapon-mounts-for-secondary-armament-3-pdf-free.html

 

From there on I found  few other manuals. The measurements I found are:

TM9-223 (TM9-1223)

M45 81.5" wide

M45 55.0"  High

TM9-2010

M45 55.0" wide

M55 82 3/8 wide

Trailer height + wheels 83.25"

Trailer height - wheels 56.25

Trailer length 113.75"

 

So the width on the mount is apparent different on a trailer, even though I do not quite understand how that is the case.

 

OTS_Maxson_01.jpg

 

In the front view, both the width (TM9-223) and Trailer height without wheels match well, as well has the length of the Browning 0.5”. The trailing length looks ok but this scan is a bit warped. This is where Dragon really does not match the given lengths (assumed the pic a few posts above is a good scan).  The height plus wheels is a bit off here (edit: just noticed; very accurate without the tires). The blue lines are a 48” distance for the base ring, but I have no idea of that is correct (it simply matches). I ordered one kit on Ebay (only a few pounds).

 

@ Lothian man: The books certainly sounds interesting and I ordered a copy. I already spend quite some time look at material on typical 3.7" batteries trying to find out a typical layout and finding out the equipment one can expect on the Maunsell forts.

Edited by foeth

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There were 2 trailers for the M45 mount. The 2-wheeled type shown here, which could not be towed far or fast or cross-country and was usually carried portee in a truck bed. Then there was the larger Ben Hur trailer with 4 truck wheels which could be towed at convoy speed and off-road. That might explain the dimensional difference.

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