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Mar 13 17 12:40 AM
jlyons97 wrote:Actually, all the pom-pom was no more than an enlarged Maxim machine gun. The scale up to 40mm was not a match made in heaven.
Mar 13 17 12:53 AM
Andy01 wrote:See:https://recordsearch.naa.gov.au/NAAMedia/ShowImage.asp?B=480950&S=42&T=Rand note that the Bofors twin/quad mounts are heavier than the quad/octuple pom-pom, when ready use ammo is taken into account. The pom-pom's large magazines meant that RU ammo was carried on-mount.
Mar 13 17 1:20 AM
Throd wrote:On the other hand it says the project was cash starved and did not really get going for many, many years. Hence for a long time there was low usage of ammunition.I have not been in the army but I have experience of research. The freedom to nip into stores for readily available ammo to repeat a test - without going cap in hand to a beancounter - is not to be dismissed lightly.
jlyons97 wrote:Andy01 wrote: https://recordsearch.naa.gov.au/NAAMedia/ShowImage.asp?B=480950&S=42&T=Rand note that the Bofors twin/quad mounts are heavier than the quad/octuple pom-pom, when ready use ammo is taken into account. The pom-pom's large magazines meant that RU ammo was carried on-mount.Carrying the RU ammo on mount meant (wait for it) a heavier mount. Go to Campbell and look it up. This meant heavier drive motors et al.PLUS, the twin bofors was a better AA weapon. Look those specs as well.And we haven't discussed the mk 51 director as compared to the pom-pom director. No comparison, actually.
Andy01 wrote: https://recordsearch.naa.gov.au/NAAMedia/ShowImage.asp?B=480950&S=42&T=Rand note that the Bofors twin/quad mounts are heavier than the quad/octuple pom-pom, when ready use ammo is taken into account. The pom-pom's large magazines meant that RU ammo was carried on-mount.
Mar 13 17 1:35 AM
Throd wrote:What would happen to those 2 million shells if another calibre had been selected?
Mar 13 17 1:36 AM
Mar 13 17 1:41 AM
Mar 13 17 1:42 AM
jlyons97 wrote:Carrying the RU ammo on mount meant (wait for it) a heavier mount. Go to Campbell and look it up. This meant heavier drive motors et al.PLUS, the twin bofors was a better AA weapon. Look those specs as well.And we haven't discussed the mk 51 director as compared to the pom-pom director. No comparison, actually.
Mar 13 17 1:51 AM
Mar 13 17 2:21 AM
* Tracers - I haven't found any records of tracers being issued to naval ships prior to 1942, I have found comments that tracers were not available in the early war years. May I ask the source and dates for where you found tracers issued to naval ships?
Mar 13 17 3:19 AM
Mar 13 17 3:44 AM
MarkLBailey wrote:Tony D: * Tracers - I haven't found any records of tracers being issued to naval ships prior to 1942, I have found comments that tracers were not available in the early war years. May I ask the source and dates for where you found tracers issued to naval ships?Tracer was a standard WWI round for the 40mm 2pdr LV.The story of development of the HET for Mk VIII* is in Norman Friedman's book as quoted above. So they developed a HET round in 1940, but by what Norman said it was not distributed to ships with the better 2pdr director systems at all as they did not need it. It acted as a complicating distraction for the gun captain.The 1943 and 1945 ammo manuals give details of it. I am currently looking for RAN records as to when it was issued aboard our DD and cruisers.Cheers: Mark
Anti-Aircraft Gunnery - Close RangeValue of tracers in observation of fire and proportion to be used. VALUE OF TRACERS IN- OBSERVATION - OF FIRE AND PROPORTION TO BE USEDValue of Tracers1. The problem of observation of fire from the 'M' Pom-Pom is a difficult ones and continuous investigations have been carried out since 1930. The first conclusions reached as a result of trials carried out in that year with single pompoms were:(i) Observation of fire by means of tracers is only 100 per cent. definite when no part of the trajectory crosses the target, as seen from the firing ship.(ii) Tracers are only of value for indicating the existence of large errors in line and relatively very large errors in elevation.2. The reports of firings carried out at sea between that date and 1935 were conflicting, but the general view appeared to be that tracers were of little value, except at very short ranges, and to indicate very large errors.3. Further extensive trials were carried out in 1935, and the following conclusions were reached:(a) Accurate observation of tracer against a target at any range over about 1 000 yards is almost impossible to obtain. At shorter ranges the accuracy may be expected to improve provided the observer is near the gun. (b) It is not possible to make any use of deductions resulting from the observation of traca without affecting the accuracy of aiming. (c) In any case the deductions made are inevitably stale by the amount of the time of flight, and are generally misleading except at very short ranges.(d) The only value of tracer for pom-poms and 0.5-inch machine guns is to show up large errors (errors of 2° and less will not be shown up), and to indicate at what targets the various guns are firing. For the latter purpose, tracer should be fired in bunches from all barrels separated by an interval from the next bunch. CHAP. XV. VALUE OF TRACERSProportion of Tracer to be used1254. It is an important factor that tracer fitted (of small calibres) are less effee ve than non-tracer since some of the explosive is displaced It is necessary that the loss of effective fire in such weapons as the CAMP' pom-pom must be rid to the minima consistent with the miming of r iren s. It is a question, therefore, of co relatmg this r i with that for observation of fire.5. As a result of trials carried out in 1931, instructions were given to reduce the number of tracers to the supply to two barrels only, the number being 5 to each belt of 28 rounds or 3 to each belt of 14. It was hoped that practices in 1932 would enable some decision to be reached, but such was not the case, and it was necessary to allow C-in-C a free hand in investigating the proportion.6. After the 1933 practices the Home Fleet reported that no improve could be made on the proportion indicated in paragraph 4 above, but the Medeteraneab Fleet opinion favoured one tracer in five from all barrels7. The Home Fleet after 1934, favoured the firing of tracers from all barrels in order to portray a complete pattern but in order to reduce the number of barrels in which tracer were fired, and thereby increase the effective density of the pattem, a trial was also made of firing tracers (first and eighth rounds) from the barrels covering the four corners of the pattern and this was favourably reported on.The Mediterranean Fleet established that tracers from two barrels were insufficient, while China suggested that the minimum acceptable was one in five from two barrels.8. Further intensive trials were carried out during 1935 and the recommendation made to continue to use tracer for the purposes mention in paragraph 3(d) in the following manner:- 2 pdr. Mk ' M," pom pom - 1 tracer very 7 rnds from all barrels0.5-in machine gun -3 consecutive tracers very 20 rnds.9. The Admiralty remarked I Apt tracer every 7 rnds from all barrels.3 motive tracers essay 20 rounds.It is possible that the proportion recommended (1 in 7) will be sufficient if fired from the four wing barrels of the pattern only. Further information is required on this point. Pending further reports from sea,arrangements are being made to supply tracer in the proportion of one tracer in 7 rounds for half the outfit only.
Mar 13 17 3:51 AM
Mar 13 17 6:27 AM
Tony D wrote:It's not unusual for the winners to have large amounts of ammunition left over at the end of a war. During the war, ships in service will need full magazines with refills in depots ashore, which keeps the mfg pipeline busy making new rounds. At the end of the war, many ships are decommissioned, their magazines are emptied and depots start to overflow. I can't say if any of the excess WWI-era 2-pdr ammunition was still around in 1939. If it was, it was probably used up pretty quickly during the first year of the war.
To tell a personal anecdote; I was a member of a 81mm mortar platoon during the 1970s. We were still using rounds manufactured in 1943 when I left the service in 1978. Please note, this was after Korea and Vietnam, both hot wars with lots of 81mm expenditures.
Mar 13 17 7:33 AM
Mar 13 17 8:11 AM
MarkLBailey wrote:Thanks Andy. What's the source for that?
Mar 13 17 8:43 AM
Mar 13 17 10:21 AM
Throd wrote:On the other hand why not develope on the round you are already tooled up to mass produce, have fixed price contracts for in place and already have in large numbers?
Because another round is sufficiently better to make the expense of the change worthwhile. Just a SWAG here but how many 2pdr rounds were in the system, contracts in place, etc, etc when it was taken out of service?
The pom pom main rival when it came out fired an identically sized round, so 40 mm seemed to be regarded as the optimum.
There were rivals to the Pom pom in 20mm and especially in 37mmm with a few in 45mm and 47mm. The Bofors round is the same nominal calibre, it is a very much longer round, hence it's greater velocity. In terms of weight the shells are very close but the complete Bofors round weighs 50% more than that of the Pom pom. Which is why the Bofor gun weighs more, of course.
Aside, good as the Bofors was the 3.7cm FlaK43 was probably better. For that modest reduction in calibre you got twice the RoF and a gun designed for rapid production.
The fact that the pom pom came out 20 years earlier just showed how far sighted the designers were.
Hardly. The designers were adapting to the targets faced at the time by incrementally increasing the power then size of the round. 1pdr and 11/2pdr were 37mm, 2pdr followed.
Regardless of the ideas behind the Mk8 it fired the existing shell.It fired the existing round, not just the shell.
So why should not the existance of large stocksI've been saying for a while that two thirds of a barrel life for your existing guns is not a large stock.have been part of the decision process?IMO it was not, not should not have been. That it should not have been is easy enough to show, the round chosen had to be replaced; those mighty two million were LV, the round with which the Pom pom could offer one of the best if not the best close in defemces of the early war years was the HV.
Mar 13 17 10:28 AM
Larrikin22 wrote:The reason the M1 Garand was acquired as a 30/06 weapon rather than the smaller round that it was originally designed for was because of the truly astronomical amount of 30/06 ammunition the US military still had in stores courtesy of WWI. They were still putting WWI manufactured rounds down barrels well into WWII.
The reason the M1 Garand was acquired as a 30/06 weapon rather than the smaller round that it was originally designed for was because of the truly astronomical amount of 30/06 ammunition the US military still had in stores courtesy of WWI. They were still putting WWI manufactured rounds down barrels well into WWII.
Mar 13 17 10:31 AM
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