Google+ Panzerserra Bunker- Military Scale Models in 1/35 scale: 2016
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The publication of any images or informations related to nazism, fascism or any other totalitarian regimes must be understood as the reproduction of historical accuracy and not as apology to these regimes, leaders or symbols.


quarta-feira, 21 de dezembro de 2016

A34 cruiser tank Comet - case report

Lads !!!
      As I'm traveling and far, far away from my workbench, I am going to show a work unpublished here, done years ago. Let's meet the A34 Cruiser Tank Comet.

A34 Cruiser tank Comet in rough terrain - 1945.
History:
      The Comet tank, or Tank, Cruiser, Comet I (A34) was a British cruiser tank that first saw use near the end of the World War II . It was designed as an improvement on the earlier Cromwell tank, mounting the new 77mm HV gun (a variation of the famous QF 17 pdr. gun) in a new lower profile and part-cast turret. 
Churchill inspecting a Cromwell tank
    This 77mm gun was effective against late war German tanks, including the Panther and, at most ranges, the Tiger. The tank was widely respected as one of the best British tanks of the war, and continued in service afterwards. Comet, which was a development of the Cromwell, rendered the Challenger obsolete, and led to the development of the A41 Centurion tank. When firing APDS rounds, the 77mm HV was a superior weapon to the 75mm KwK 42 gun of the equivalent Axis tank, the Panther.
A41 Centurion I - early version.
      The Comet saw action in the closing stages of the Second World War, then combat during the Korean War, and remained in British service until 1958. In some cases, Comets sold to other countries continued to operate into the 1980s.

Development:
      Combat experience against the Germans in the Western Desert Campaign demonstrated to the British many shortcomings with their cruiser tanks. Hence a request was made in 1941 for a new heavy cruiser tank that could achieve battle superiority over German models. For reasons of economy and efficiency, it had to use as many components as possible from the current A15 Cruiser tank Mk VI Crusader tank.
Crusader II tank roaring in the Western Desert - 1942. 
      The initial designs for the new Cromwell tank evolved into the A24 Cruiser Tank Mk VII Cavalier tank and the A27L Cruiser tank Mk VII Centaur tank, both powered by the Nuffield Liberty. Design progressed through the Cruiser tank Mk VII (A27M) Cromwell, a third parallel development to the Cavalier and Centaur, sharing many of the same characteristics.
     Under the newer A27M specification, Cromwell integrated a number of new and advanced features. The new Rolls Royce Meteor engine (derivation of famous Rolls Royce Merlin) proved to be very reliable and gave the tank good mobility, but some problems appeared based on the vehicle's shared heritage and significant jump in engine power. See a Meteor engine starting below:

      The tank was prone to throwing its tracks if track tension was not maintained properly or if it turned at too high a speed or too sharply. There were also some problems with suspension breakage, partly due to the Cromwell's high speed. Cromwell ran through a number of design changes as a result.
      The biggest complaint, however, was related to firepower. Cromwell had originally been designed to carry the 57 mm Ordnance QF 6-pounder, also retrofitted to the Crusader tanks. In combat, these were found to be useful against other tanks, but lacking any reasonable high explosive load they were ineffective against anti-tank guns or static emplacements. Prior to the Cromwell entering combat service, the Ordnance QF 75 mm was introduced which equipped the majority of Cromwells, essentially an adapted version of the 6-pounder firing shells from the US 75 mm gun from the Sherman. This offered somewhat lower anti-tank performance than the 6-pounder, but its much larger shell provided a truly effective high explosive load.
Churchill Mk IV with Ordnance QF 75 mm main gun.
      Several attempts had been made to further improve the firepower by fitting a more powerful gun. In parallel with development of the Cromwell and QF 75mm gun, a new Vickers High Velocity 75mm tank gun had been in development. This proved too large for the Cromwell turret ring, and left a shortage in offensive anti-tank capability. A prior requirement for a 17-pounder armed tank led to development of the A30 Cruiser Mk VIII Challenger.
A30 Cruiser tank Challenger
      Based on the Cromwell, the hull had to be lengthened and a much larger turret set on top to allow a second loader for the 17-pounder, a requirement of the older specification believed necessary for the larger 17-pounder ammunition. The very high turret of the Challenger was considered a liability and this led to experiments with the similar A30 Avenger version, a dedicated anti-tank version with an open-top turret.
A30 Avenger SPG.
      Conversion of the Sherman tanks to the Sherman Firefly (a Sherman tank fitted with the 17 pounder gun) was significantly faster than Challenger production however, and driven by operational needs of the Normandy invasion production of Challenger was dropped. Fireflys (and the limited number of Challengers) provided additional firepower to Cromwell and Sherman armed troops. One Firefly would be issued to each troop of Cromwells (giving three Cromwells and one Sherman Firefly).
Sherman Firefly IC Hybrid
      Problems were encountered due to the different maintenance requirements and associated supply complication of two tank models, as well as the performance difference between Cromwell and Sherman and the Sherman's silhouette, even larger than the Challenger. The large size and obvious difference of both Challenger and Firefly made them a priority target for Axis forces.
      Recognising that a common low profile vehicle was required to replace the mixed fleet of Cromwell, Challenger and Firefly tanks, a new specification of tank was created. This removed Challengers need for a second loader and mounted the newer Vickers High Velocity weapon intended for Cromwell.

The Comet tank:
      With the A34 (the General Staff specification), later named Comet, the tank designers opted to correct some of the Cromwell's flaws in armament, track design and suspension while building upon the Cromwell's main strengths, its low height, high speed and mobility. The first prototype featured a suspension without return rollers, much like the Cromwell suspension.
A34 first Prototype: notice the suspension
      This replaced the need for Challenger and Firefly, and acted upon the experiences gained through design and early deployment of Cromwell.
A34 Comet from 11th Armoured Division - Germany, 1945.
      Originally, it had been expected that Cromwell would use a new gun from Vickers: the "High Velocity 75mm". However, as designed, the gun would not fit into the turret size available. Development of the gun continued, and as work commenced on the Comet, the gun design evolved into the 77mm HV. The gun now used the same calibre (76.2 mm) projectile as the 17-pounder, but the cartridge case was from the older QF 3 inch 20 cwt anti-aircraft gun loaded to higher pressures. The resulting round was completely different from 17-pounder ammunition. Overall the round was shorter, more compact and more easily stored and handled within the tank.
The 77mm HV shells being loaded in the Comet
      The 77mm HV gun was effectively a shortened 17-pounder. This made it possible to mount the gun on a smaller turret ring. The gun was still capable against opponents, and firing APDS rounds, it was more accurate and consistent than APDS from the 17pdr and 6pdr, which were inaccurate over 700m and often ricocheted. The Challenger turret had been so large to allow space for two loaders. Several other improvements were made over the Cromwell's original design, and many of its design revisions were incorporated, such as safety hatches for both driver and hull gunner. The hull was now fully welded as standard and armour was increased, ranged from 32 mm to 74 mm on the hull, while the turret was from 57 to 102 mm.
      A new lower-profile welded turret was created using a cast gun mantlet for the 77mm. The turret was electrically traversed (a design feature taken from the Churchill tank), with a generator powered by the main engine rather than the hydraulic system of the Cromwell. Ammunition for the 77mm gun was stored in armoured bins.
Comet tank turret
      Comet's suspension was strengthened, and track return rollers were added. As with later Cromwells, the Comet tank's top speed was limited from the Cromwell's 65 km/h to a slower, but respectable 51 km/h. This change preserved the lifespan of suspension and engine components and reduced track wear.
Comet suspension
      Similar to later Churchills, Comet benefitted from lessons learned in the co-operation of tanks with infantry. It was fitted as standard with two radio sets: a Wireless Set No. 19, for communication with the regiment and the troop, and a No. 38 Wireless for communication with infantry units. Like many British tanks, it also had a telephone handset mounted on the rear so that accompanying infantry could talk to the crew. Comet tanks were built by a number of British firms led by Leyland, including English Electric, John Fowler & Co., and Metro-Cammell.
 A Humber scout car and Comet tank of
11th Armoured Division in a German town, 30 March 1945.
      The mild steel prototype was ready in February 1944 and entered trials. Concerns about the hull gunner and belly armour were put to one side to avoid redesign, but there was still sufficient delay caused by minor modifications and changes. Production models did not commence delivery until September 1944. Comet was intended to be in service by December 1944, but crew training was delayed by the German Ardennes Offensive. By the end of the war, 1,200 had been produced.

Service history:
Second World War:
      The British 11th Armoured Division was the first formation to receive the new tanks, with deliveries commenced in December 1944. It would also be the only division to be completely refitted with Comet by the end of the war. Due to its late arrival in the war in north west Europe, the Comet did see combat but did not participate in big battles.
A Comet tank of 11th Armoured Division in
the Weser bridgehead - Germany - 7 April 1945.
      The Comet was involved in the crossing of the Rhine and the later Berlin Victory Parade in July 1945. The Comet's maximum speed of 51 km/h was greatly exploited on the German Autobahns.
Comet leading Sextons in Berlin Victory Parade
Variants:
Comet had two hull versions:

  • Model A: with exhaust exiting the top rear of the vehicle using a Normandy cowl similar to Cromwell.
  • Model B: a post-war update with twin fishtail exhausts exiting the rear armour.

Other vehicles were based upon the Comet:

  • Comet Crocodile: One surviving photo reveals the existence of the Comet Crocodile. This mounted a flamethrower and pressurized trailer similar to the Churchill Crocodile. Little is known about it.
Comet Crocodile
  • FV4401 Contentious: The Comet was used as the basis for the experimental FV4401 Contentious, a self-propelled air transportable anti-tank gun mounting a 105mm L7 gun in an open mounting on the shortened hull of a Comet, and using the vehicle's hydraulic suspension system to adjust elevation, similar to the method used on the Swedish S-Tank. One or two prototypes were built and tested before the project was cancelled.
FV4401 Contentious showing his hydraulic
suspension system to adjust gun elevation.
Conclusion:
      The Comet was the last of the British cruiser tanks, and also the last British tank designed to take part in WW II. His popularity was not unanimous, and she came under heavy criticism mainly because his detractors believed she perpetuated Cromwell's defects, which in fact occurred in some minor respects. Examples were front plates and a hull machine gun. However, to move them would require an extensive reprogramming of the project and the construction of specific equipment for the factory. This, however, was out of the question in 1943. The disappointment over the lack of effective ventral shielding was not so easy to disprove, since this deficiency had been anticipated before, but it only deserved attention when it was too late. But it can not be denied that Comet could have been with the German Panzers ... and this, without a doubt, was a great progress.

Specs:





A34 Cruiser tank Comet 
TypeCruiser tank
Place of originUnited Kingdom
Service history
In serviceDecember 1944 - 1958 (UK)
Used bysee Operators
WarsSecond World War
Korean War
Production history
Designed1943
ManufacturerLeyland Motors Ltd
ProducedSeptember 1944
Number built1,186
Specifications
Weight33.53 tonnes
Length6.55 m excluding gun
Width3.04 m
Height2.67 m
Crew5 (Commander, gunner, loader/operator, driver, hull gunner)

Armour32–102 mm
Main
armament
77 mm HV
61 rounds
Secondary
armament
2 x 7.92 mm Besa MG
5,175 rounds
EngineRolls-Royce Meteor Mark III V12 petrol
600 hp (447 kW) @ 2550 rpm
Power/weight18 hp (13.3 kw) / tonne
TransmissionMerrit-Brown Z5
SuspensionChristie
Ground clearance0.5 m
Fuel capacity527 liters
Operational
range
250 km
Speed51 km/h

The kit:
      When I build this girl, I used the British cruiser tank A34 Comet Bronco's kit #CB35010, in 1/35 scale. The kit was packaged in a reinforced carton box, with all the trees packed individually in sealed plastic bags and all the components in a larger bag, only in the loss of any parts would occur.
British cruiser tank A34 Comet Bronco's kit #CB35010
      The injection was very good and the dark green plastic was soft. The kit includes a set of resin idler wheels of the same color (WWII version), plus an excellent photo-etched shet with two-piece exhaust valves and other small parts. A metal cannon (but without muzzle brake ...) and a synthetic string to make the steel cable complete the kit.
      The disappointment is due to the absence of the exhaust grille of the engine in metal and the absence of muzzle gun, which forces us to use the two halves of the plastic (???). On my own, I invested in the purchase of a resin set, made by Bronco himself, of the canvas cover of the gun mantlet, since most of the photos of this vehicle show this detail.
Bronco's resin mantlet cover
      The decal sheet was well assorted, with the possibility of building 6 versions of the Comet: 4 being WW II era and 2 postwar:
  • “Ironduke” from 1st RTR, 7th Armoured Division, Germany, April  1945.
  • “Celerity” from 3rd RTR, 29th Armoured Brigade, 11th Armoured Division, Belgian, March 1945.
  • “Cobra” from 3rd RTR, 29th Armoured Brigade, 11th Armoured Division, Germany, March 1945.
  • “Crusader” from 3rd RTR, 29th Armoured Brigade, 11th Armoured Division, Germany, April, 1945.
  • 3rd Royal Tank Regiment, Sek Kong Camp, New Territory, Hong Kong, 1957.
  • Ps252-24 from Finnish Armoured Brigade training unit, 1961-1980.
Decal sheet
      In this version of kit, the tracks were in vinyl, but with internal and external detailing, with good finishing:
Bronco vinyl tracks
      Today, the new Bronco kit comes with injected tracks LBL:
New Comet Bronco kit #CB35010SP
      I started the building following the booklet, by the hull and suspensions. As always, I separated all parts for cleaning and subsequent building.
Hull and suspensions parts
      I glued the suspensions arms to the hull and prepared to glue the side shields of the hull, which hide these arms from the Christie suspensions:
Testing the alignment of the hull, looking for kinks ... Okay, so far ...
      The booklet guides install all wheels now ... The idler wheels are in front (the Comet is rear-wheel drive ...). There are two sets of idler wheels in the kit: a pair of injected wheels, spoked, post-war models and a set of wheels on solid-perforated resin compatible with the versions of WW II. And of course mine will be a WWII model ...
      Building with cyanoacrylate as resin does not bind to the welders (which I usually use ...).
WWII idlers wheels in resin
Idlers wheels in position
The front wheels in position.


Return rollers in dry-run
      Injected handles. I will replace by copper wires
Cutting the injected handles
Metal handles. .. much better
The hull and chassis in dry-run. The girl was growing...
Metal work in rear deck
And talking about metal: Tin welding
(solda means weld in Portuguese)
Exhaust covers glued in position: WWII type
While the exhaust covers dry on site, we'll take care of the turret. Here, a minor surgery is necessary to adapt the powder protector in resin to the turret:
Testing the turret in the hull...OK!!
      After cutting at the junction between the mantlet and the turret. Note that the lower portion of the turret (the floor) has not been cut off:
Original mantlet off. Notice the turret's floor intact...
      Now, a very delicate cirurgy: cut the turret floor, but KEEP the turret's circular lip. A precise horizontal cut made with fine-cut saw:
The part that should be removed in green.
Note that the turret's circular lip remains.
The gun tube is in dry-run...
The turret lip
Ready to glue the mantlet...
Making a marking guide with pencil
(Colar means to glue in Portuguese)
Mantlet glued with superglue in position...
Good!!
Replacing the handle (alça, in Portuguese...) injected by a metal part in scratch...
Cutting the handle...
Putty and scratch...
More handles injected in surgery...
The aerial's base in metal (kit's PE)
...and in position: Notice the handle in metal (red) but
the handles of hatch not yet ready (in green...)
More metal work.The spiraled  wire of the beacon
is an exercise in creativity ...
Adding details...
Making the steel cable with polyester thread
The steel cable made with polyester thread
Details...
Rear details...
Kneaded and battle damages on the rear mudguards
Notice the detail in metal in the towbar...
      Now, the best part: painting and markings!!
Painting the girl!!

      As usual, I like to have a guide for my paintings and markings:

      A serious problem in this old version was the lack of one marking triangle on the original Bronco decals sheet for Celerity. As you can see in the figure below, the decals sheet has only two yellow triangles (item 22 on the sheet).
Decal sheet
      But the original Celerity features three triangular markings: one on each side of the turret and one on the neck of the turret, as is evident in the picture that is part of Bronco Models' instruction booklet. Note, in the photo below, that another tank in front of Celerity also features this marking on the neck of the turret (arrows):
Celerity - actual pic.
 Luckily I had a yellow triangle in my spare decals box, or otherwise I would have to do with paint. Sorry don't have the pic of decal application, but...the final is this: A34 cruiser tank Comet "Celerity" from 11th Armoured Division, 29th Armoured Brigade, 3rd RTR, in duties in Belgium, March- 1945.
A34 cruiser tank Comet "Celerity"
11th Armoured Division, 29th Armoured Brigade, 3rd RTR
Belgium, March- 1945
The figure is from my spare box






A34 cruiser tank Comet "Celerity"
11th Armoured Division, 29th Armoured Brigade, 3rd RTR
Belgium, March- 1945.
Kojak is in vacation!!!
      Thanks for follow, Lads!!
Merry X'mas!!!