A Pom-Pom question ?

A Pom-Pom question ?

Historically the RN had the Pom Pom developed from early 20s till it was introduced in 1930, later they developed a new HV version with a different shell and none interchangeable gun in 38. (not that that stopped them continuing to make both throughout WW2)

What if they had gone for a larger redesign using the shell and barrel from the 40/56 Bofors ? (available from 37 for the army)(its a much faster shell and larger case but could it be made to work ?)
 
I think you need to look at the weight of the complete mount. I believe the Quad 40mm that was used by the U.S. Navy would be the comparable system to the RN's 8 barrel 2pdr Pom-Pom. I think the ammo feed system of the Pom-Pom would not directly transfer well to the Bofors gun and would be excessively heavy if the 8 gun configuration was maintained.
 
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There was a HV version of the POM POM which increased its velocity over the earlier LV weapon - both were built and used in WW2

LV: 1,920 fps (585 mps)
HV: 2,300 fps (701 mps)

Bofors 40/56

UK Mark NI: 2,720 fps (829 mps)

So not a great deal of difference

Of course we must also consider the size of shell - complete round length =

PomPom = 30.45 cm in length

40/56 Bofors = 45.1 cm in length

Bursting charge for both rounds is very similar 0.071 kgs vs 0.067 kgs

What might have been useful is making the HV Pom Pom weapon (1938) use the longer Bofors shell but this might have made the project more 'high risk' and more likely to fail or be seriously delayed although if successful would have given the weapon a greater range and altitude and therefore marginally more effective.

However the weight of the gun would have gone up significantly - at least 20-30% IMO

Single air cooled Bofors gun (not including mount) = 508 to 528 kg

Single air cooled Pom Pom gun (HV - not including mount) = 385.6 kg

Given the weight of the mount etc I don't think this would be a serious issue and assumes a slightly longer barrel on the Bofors

My only concern would be getting the system to work in a timely fashion to equip or be refitted to the main fleet units in time for any conflict ie WW2 - assuming that starts sometime on the very early 1940s ;)

Otherwise...why not?

All data taken from

http://www.navweaps.com/Weapons/WNBR_2pounder_m8.htm

http://www.navweaps.com/Weapons/WNUS_4cm-56_mk12.htm
 
The perceived lack of effectivness of the Pom Pom was mostly due to the lack of tracer ammunition, rather then any lack of power. Rebuilding the weapon to fire 40mm bofors would have resulted in a absoloute monster that would probably have rivaled some of the heavier 4.7 inch turrets for weight, even more so then the [FONT=Arial,Helvetica]Mark VI sextuple Bofors did.[/FONT]

Admitedly attacking a ship armed as such would have probably been pant browningly terrifying as the sky turns to tracer and explosions(atleast untill there was a feed tray stoppage)
 
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The perceived lack of effectivness of the Pom Pom was mostly due to the lack of tracer ammunition, rather then any lack power. Rebuilding the weapon to fire 40mm bofors would have resulted in a absoloute monster that would probably have rivaled some of the heavier 4.7 inch turrets for weight, even more so then the [FONT=Arial,Helvetica]Mark VI sextuple Bofors did.[/FONT]

Admitedly attacking a ship armed as such would have probably been pant browningly terrifying as the sky turns to tracer and explosions(atleast untill there was a feed tray stoppage)

My biggest issue or rather concern with attempting such a hybrid instead of the HV version is not the weight (the additional weight of the actual guns would be but a small fraction of the overall mounts weight) but the potential of the project failing to deliver a robust and working weapon system in the same sort of time frame that delivered the HV Pom Pom.
 
There was an experimental 35mm 1½ pounder Pom Pom with a velocity of 2,600fps and a rate of fire 130rpm which was cancelled in 1937 after it was found the 6 barrel version came out heavier than the 8 barrel 2 pounder.
 
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