PAK 40 over engineered?

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stg 44
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PAK 40 over engineered?

#1

Post by stg 44 » 06 Aug 2016, 02:23

I was watching a clip from 'Forgotten Weapons' on Youtube about the 75mm PAK 40 and the narrator talked about the weapon being over engineered, but didn't really clarify in what way. Could any experts here describe how the weapon could have been simplified in construction?

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Re: PAK 40 over engineered?

#2

Post by Paul Lakowski » 06 Aug 2016, 07:22

compare the amount of reasoures that went into 88 & pak 40. The cost is minor as is the labor, but the amount of resources is critical, especially nickel & chrome. The 88 uses 50% more nickel than the Pak 40 but uses 2/3 as much chrome and nearly the same amount of steel, especially compare resources to product mass [4:1 for Pak 40 & 2:1 for the 88].


http://www.panzerworld.com/7-5-cm-pak-40
Production Costs 7,5 cm Pak 40 Price 12 000 Reichmark Man-hours 2200 Production time Six months

Iron 6100 kg
Chromium 68 kg
Tin 0.5 kg
Copper 28.8 kg
Aluminum 131.2 kg
Lead 0.03 kg
Zinc 18.9 kg
Nickel 15.8 kg
Rubber 67.7 kg


http://www.panzerworld.com/5-cm-pak-38
Production Costs 5 cm Pak 38 Price 10 600 Reichmark Man-hours 1800 Production time 6 months

Iron 2677 kg
Chromium 3.8 kg
Tin 0.3 kg
Copper 3.35 kg
Aluminum 80.8 kg
Zinc 0.47 kg
Nickel 5 kg
Rubber 35.107 kg

http://www.panzerworld.com/8-8-cm-pak-43-l-71

Production costs of the 8,8 cm Pak 43, 8,8 cm Pak 43/2, and 8,8 cm Pak 43/3. Price- 20 000 Reichmark 21 000 Reichmark
Man-hours - 2200 2800 Production time - 8 months 6 months
Iron 7765 kg -
Molybdenum 48 kg -
Chromium 46.8 kg -
Silicon 17.1 kg -
Copper 3 kg -
Zinc 2.4 kg -
Nickel 24.8 kg -
Silver 1.6 g -


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Re: PAK 40 over engineered?

#3

Post by peeved » 06 Aug 2016, 09:18

Based on "Datenblätter für Heeres-Waffen, -Fahrzeuge und -Gerät" (Reprint) at least some of the 8,8 cm Pak figures relate just to the gun without carriage; 20 000 RM price, 2200 man hours and 8 month production time are listed under "8,8 cm Pak 43/2 (L/71) Waffe and 21 000 RM, 2800 hours and 6 months under "8,8 cm Pak 43/3 (L/71) (Waffe)".

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stg 44
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Re: PAK 40 over engineered?

#4

Post by stg 44 » 06 Aug 2016, 18:58

I appreciate the responses, but that isn't what I was getting at. We also don't know what those metals were used for without knowing more about the design and why it was so costly. Does anyone have any idea?
The idea that the PAK43 used so little compared to the PAK40 does seem to indicate that is just the gun, not the carriage. Of course going by the wikipedia article part of the barrel was designed to be replaced as it wore out quicker, so perhaps that required less overall materials, because it wasn't made to last as long as a long service single piece barrel?
https://en.wikipedia.org/wiki/8.8_cm_Pak_43
KwK 43 and Pak 43s were initially manufactured with monobloc barrels. However, the weapons' extremely high muzzle velocity and operating pressures caused accelerated barrel wear, resulting in a change to a two-piece barrel. This had no effect on performance but made replacing a worn out barrel much faster and easier than before.

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Re: PAK 40 over engineered?

#5

Post by Paul Lakowski » 07 Aug 2016, 00:54

if you compare KWK vs PaK or STu K we have...

http://www.panzerworld.com/7-5-cm-stu-k-40-l-48


7,5 cm Stu K 40 (L/48) Price 13 500 Reichmark Man-hours 1800 Production time 6 months

Iron 2995 kg
Chromium 17.800 kg
Tungsten 0.230 kg
Tin 0.010 kg
Copper 1.800 kg
Aluminum 0.420 kg
Lead 0.008 kg
Zinc 2.600 kg
Nickel 16.500 kg
Silver 1.4 g

Clearly the nickel content is the gun and not the gun carriage, but the chrome was 1/3 of the PaK so it might also be in the carriage.

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Re: PAK 40 over engineered?

#6

Post by stg 44 » 07 Aug 2016, 01:14

Paul Lakowski wrote:if you compare KWK vs PaK or STu K we have...

http://www.panzerworld.com/7-5-cm-stu-k-40-l-48


7,5 cm Stu K 40 (L/48) Price 13 500 Reichmark Man-hours 1800 Production time 6 months

Iron 2995 kg
Chromium 17.800 kg
Tungsten 0.230 kg
Tin 0.010 kg
Copper 1.800 kg
Aluminum 0.420 kg
Lead 0.008 kg
Zinc 2.600 kg
Nickel 16.500 kg
Silver 1.4 g

Clearly the nickel content is the gun and not the gun carriage, but the chrome was 1/3 of the PaK so it might also be in the carriage.
Any idea what chrome would be needed for in the carriage?

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Re: PAK 40 over engineered?

#7

Post by shamirnewell » 07 Aug 2016, 01:54

stg 44 wrote:
Paul Lakowski wrote:if you compare KWK vs PaK or STu K we have...

http://www.panzerworld.com/7-5-cm-stu-k-40-l-48


7,5 cm Stu K 40 (L/48) Price 13 500 Reichmark Man-hours 1800 Production time 6 months

Iron 2995 kg
Chromium 17.800 kg
Tungsten 0.230 kg
Tin 0.010 kg
Copper 1.800 kg
Aluminum 0.420 kg
Lead 0.008 kg
Zinc 2.600 kg
Nickel 16.500 kg
Silver 1.4 g

Clearly the nickel content is the gun and not the gun carriage, but the chrome was 1/3 of the PaK so it might also be in the carriage.
Any idea what chrome would be needed for in the carriage?
Used as a strengthening material. I believe the common tubular steel alloys today are still chromium molybdenum based.

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Re: PAK 40 over engineered?

#8

Post by Clive Mortimore » 07 Aug 2016, 09:42

stg 44 wrote:I was watching a clip from 'Forgotten Weapons' on Youtube about the 75mm PAK 40 and the narrator talked about the weapon being over engineered, but didn't really clarify in what way. Could any experts here describe how the weapon could have been simplified in construction?
I do hate it when someone makes a remark like the one above without specifying what they mean. Any weapon can be made simpler but would it be as good? With a lot of German weapons from the earlier part of the war they were well made, may be a little too well or over engineered compared to weapons made, normally in a hurry, by the allies. When facing defeat, and weapons are needed quickly then most nations can bung something together that will do the job. The Pak 40 was designed at a time when Germany was winning and just in case any potential enemies had tanks with thick armour not as a stop gap like the US 3 inch anti-tank gun.
Clive

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Re: PAK 40 over engineered?

#9

Post by Yoozername » 09 Aug 2016, 00:45

I think it would need to be compared to something from the other armies. I wouldn't compare it to a ZIS-3 since the ZIS-3 did not have the penetration nor the stability that the PAK 40 has. Video of ZIS-3 show them jumping around when fired. The PAK 40 is very stable platform and shows that it is a purpose built weapon. That is, an antitank gun.

The Soviets constantly made changes to the manufacturing costs of the ZIS-3 and drove them down. As far as I know, the Germans did not make any drastic changes but it is possible they did drop the progressive rifling and went to a constant rifling.

I suppose it can be compared to the 17 pdr. and US 3 inch ATG, but one really needs to compare the AP projectiles also.

I don't pay much mind to a lot of those TV shows and the ham-handed remarks they spout out.

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Re: PAK 40 over engineered?

#10

Post by Sheldrake » 09 Aug 2016, 01:20

stg 44 wrote:I was watching a clip from 'Forgotten Weapons' on Youtube about the 75mm PAK 40 and the narrator talked about the weapon being over engineered, but didn't really clarify in what way. Could any experts here describe how the weapon could have been simplified in construction?
Not without a lot more information on the manufacturing processes!

During the war years the 40mm Bofors Gun was modified by British and American production enigneers to reduce the amount of raw materials labour cost and time to build. I don't have the figures to hand but the difference was quite dramatic. Design changes included removing some of the design frills that might be visible. They also included changes to the manufacturing process, such as: finding a way to machine the breach from a smaller piece of steel, reducing the waste.

Compare the British 2 Pdr gun with the 6 Pdr that replaced it. The 2 pdr has a platform with leveling screws traversing and elevating wheels. The 6 Pdr is a much simplified design, layed by eye and hand.

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Re: PAK 40 over engineered?

#11

Post by Yoozername » 09 Aug 2016, 05:57

I believe the Bofors 40mm had some strange drafting issues also. Most (modern) mechanical drawings call out tolerances, etc. Basically, the Bofors guns needed very skilled craftsmen and parts were not always interchangeable!

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Re: PAK 40 over engineered?

#12

Post by Sheldrake » 09 Aug 2016, 10:30

Yoozername wrote:I believe the Bofors 40mm had some strange drafting issues also. Most (modern) mechanical drawings call out tolerances, etc. Basically, the Bofors guns needed very skilled craftsmen and parts were not always interchangeable!
That is another story, linked to the Americans seeking to avoid paying royalties to Bofors and their inability to work with other currencies and the metric system. The US Army had been offered the Bofors before the war, but the evaluation team made an error converting swedish to US currency and thought it was much too expensive. So the Americans built their own plans shared by the Dutch plans. These were, of course drawn using metric measurements, creating opportunities to build ill fitting components. Eventually both problems were ironed out with the bofors heavily used by US forces and the US Government belatedly paying Bofors for their IPR in the 1960s.

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Re: PAK 40 over engineered?

#13

Post by Yoozername » 09 Aug 2016, 15:55

http://www.spectre-association.org/pdfs ... lklore.pdf

I guess the Dutch didn't know how to convert their money to US dollars when bidding? In any case, the US used modern methods and not files to fit the parts and manufactured the weapons in great numbers.

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Re: PAK 40 over engineered?

#14

Post by Sheldrake » 09 Aug 2016, 21:55

Yoozername wrote:http://www.spectre-association.org/pdfs ... lklore.pdf

I guess the Dutch didn't know how to convert their money to US dollars when bidding? In any case, the US used modern methods and not files to fit the parts and manufactured the weapons in great numbers.
The Dutch didn't have very much leverage over the US in early 1942 ;)

The British story of re-engineering the Bofors is similar but they had the help from the parent company.

This is what I wrote for a game fan site a few years ago
In the mid 1930’s the British were looking for an AA gun which could tackle the problem of high speed low levcel aircraft. The first choice was the Vickers 2 Pdr AA gun, originally designed for naval use. However it was too large and heavy for anything by static defences. The British Army saw the Bofors 40mm as offered greater mobility, and firepower. It could also work with a remote control system under development by Colonel Kerrison. In April 1937 the British placed the first order for 100 guns, and followed this with three more, taking production from Sweden, Hungary and Poland. It was clearly a superior weapon to the 2 pdr, which was eventually returned solely for naval use. Licensed manufacture was also started in with main production by Nuffield in Coventry in Britain, Dominion Bridge in Vancouver and Hamilton Canada, and in Maribyrnong in Australia. Nuffield produced the first British built gun in June 1939.

The British made majors changes to the Bofors design to simplify production. The first British built guns took 2,420 man hours to build, which was reduced to 1,500 after redesigning the gun and carriage. Changes included a redesigned simplified carriage with tubular steel legs inserted into holes on the central frame for firing, eliminating the spirit levels, balancing gear and Course and speed sight. The British design also included a shield and was known as the Mk2 carriage.

The carriage was further drastically lightened for airborne use. The Mark 4 platform enabled all four legs to be removed for stowage inside a Hamilacar Glider. The Canadian two wheeled “Bantam” Carriage used a three legged girder carriage carried on a single axle whiich could be towed by a Jeep and carried inside a C47.
The British retained the original Bofors Course and Speed sight on the guns delivered direct from Bofors – known as the Polish sight. This was replaced by the simpler Forward Area Sighting system, which used a wheel like vertical foresight, a gate foresight and crosswire rear sights. Simple range settings could be made and aiming off made on the sights themselves.

Two types of mounting used electrical power controls, either driven from a generator or the mains. Power controls were connected to a central predictor using the Kerrison Predictor. This was an electro-mechanical computer, which would transmit fire controls to the guns depending initial settings of range, speed and angle.
The early forward Area sights were replaced from 1943 by Cartwheel fore sights with three aim off rings for 100,200 and 300 mph (161,322 and 483 kph) Originally these were fixed sights on a common cross bar. In 1944 a new system using the same sights was introduced. This was the Mk4 or correctional sight , known as the “Stiffkey” (pronounced stookey) sight names after a firing range of the same name. This system used an sight operator located on the platform. This operator used a ratchet bar to off set the layers cartwheel sights according to the target speed. All the layers had to do was keep the target in the centre of the sight.

The British also deployed the Bofors gun on two self propelled mounts. Originally there was little interest in SP AA guns. However some Nuffield engineers decided that they could help the Home Guard units formed from the Nuffield workforce by mounting mobile Bofors guns on converted Quad artillery tractors, also produced by Nuffield. The gun was adopted in time for the 1944 Normandy campaign after demonstrating their guns to various army authorities. It is claimed that one demonstration was an unscheduled and invited demonstration at a display on Horse Guards parade where the civilian home guard demonstrated that they could bring their guns into action much faster than the regular army with towed equipment. The Nuffield carriage was called the Platform Carrier Morris 40mm AA Mark 1. This was the Morris Commercial C9/B 30 cwt 4 x4, A development of the earlier Morris c8 FAT (Field Artillery Tractor) which had been used in the earlier Home Guard Conversions. The chassis mounted a special 5 or 5/1 mounting specially developed for the vehicle. The mounting and cab were completely open with no cover for the crew except for some canvas weather shields. The rear axle could be locked to the vehicle frame for firing direct from the carrier. However for prolonged periods or under predictor control four jacks were lowered onto cones and base plates placed on the ground. Seating was provided for a driver and three men. The vehicle also carried storage for 120 rounds. Two of the jacks were at the sides and the others at front and rear. There was a similar vehicle which carried a No3 (Kerrison) Predictor and had a driver and a crew of two. It also had storage space for a further 192 rounds.

In Early 1944 Several obsolescent Crusader III tank were converted into AA tanks. The Crusader III AA Tank Mk1 tanks mounted a single Bofors gun in a tall open topped turret. The gun used was a special version the Mk 6. The used cartridge cases were deflected forwards and upwards. It also had a special type of autoloader. The vehicle had a detachment of four, a gun commander, layer, loader and driver. The layer controlled the powered mounting using a joystick.

In the late 1930’s the US Army and Navy were developing their own AA guns. The US army looked at buying a single Bofors gun in 1938, but through an error the purchase price was transmitted as roughly ten times the true cost which dampened interest. In 1939 a US businessmen visiting the Bofors range was so impressed that he impressed the US Navy so much with his enthusiasm on his return that the US Navy ordered a Twin Barrelled Bofors Gun. After trials in Mid 1940 against various other AA guns including the Army’s Colt Browning 37mm gun, it was obvious that the Bofors gun was superior. Both the US Navy and Army decided to purchase the Bofors gun. The US Army phasing out production of the 37mm gun when Bofors production was under way. In the haste to get the Bofors gun into production, plans and facilities were obtained before any formal agreement with AB Bofors. One consequence was that the US Navy obtained drawings from the Dutch East Indies– in metric which were then converted to US drawing standards and handed to the York Lock and Safe Company at York Pennsylvania, while the US Army obtained drawings and a Gun from Britain, which were passed to Chrysler, who worked in imperial fractions. Thus the initial production of US Army and Navy Bofors guns had a complete lack of interchangeability. Like the British , Chrysler design engineers re-engineered designs and processes to speed mass production. The high tolerances and complex machining were a challenge to mass production. For example, the gun breech block started as a 15.65Kg oblong steel block. After 110 manufacturing operations it emerged as a sculptured component weighing 4KG. The breech-ring took 140 operations to turn a 120.2KG steel Billet into a 47.63 Kg finished product after 625 inspection gauges. The other consequence of the US haste was a long contractual wrangle with AB Bofors over the unlicensed manufacture, sale and disposal of Bofors guns which was only resolved in 1957.

The US Army had only one version of the Bofors Gun, this was the 40mm Automatic Gun M1. The carriage was the 40mm Anti aircraft gun carriage M2. There was a M5 Airborne Carriage, which was the equivalent of the British and Canadian single axle carriages. For fire control the US Army adopted the Sight Computing M7 or M7A1, used by some guns. Fully predicted fire control was achieved using the Director AA M5 , M5A1 or M5A2. The US Army experimented with self propelled mountings of the 40mm Bofors Gun on M3 and M5 tanks and Halftrack mountings before deploying the gun on the Light Tank T24 chassis. This was classified as the 40mm Gun Motor Carriage T65E1, later redesignated the M19 Multiple Gun Motor Carriage. This mounted two 40mm guns in an open turret with a frontal shield. Production started in August 1944.
Fbaldwin techpubs 2004

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Re: PAK 40 over engineered?

#15

Post by Yoozername » 10 Aug 2016, 01:12

Nice write-up. People may not appreciate the 'driver' that WWII was as far as modernizing manufacturing, and also the advent of Quality Control.

The US sherman 75mm could be labeled as 'over engineered'. It was rated for a crazy amount of firings more like an artillery piece than a antitank weapon. Likewise, it had a heavy barrel and small chamber size. The US may have had it's reasons, and the weapon was actually fielded for a time when it was a decent AT weapon, but the bottom line was it was quickly outpaced by the enemy weapons. The German PAK 40 had a fairly wide window of battlefield effectiveness.

The Germans focused on the Pzgr 39 projectile and the various weapon systems to launch it.

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