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The Hispano mechanism should have been suitable for synchronisation.
The original French gun (and British copy, the Mk.I) fired at about 700 rounds/minute, but after various trials in 1939 it was found that reliability and breakages were greatly improved if the rate of fire was kept down to about 600 rounds/minute -- so this was specified in the Mk.II gun.
A combination of lighter reciprocating parts with stronger (or extra) recoil springs is the universal way to increase RoF. With gas operation (including the Hispano) a lot can be done with the location and size of the gas port: the closer it is to the chamber, the faster the bolt will unlock.
A bit of nit-picking: the standard .50 cal ball didn't have a lead core, it had a steel one in a thin lead sleeve. From 1944 onwards, the favoured bullet type for fighter aircraft was the M8 API; this had a hardened steel armour-piercing core with a quantity of incendiary material in the jacket tip. It was common to make every fourth or fifth round an M20 API-T (tracer). For bomber defence, the .50 often used the M21 "Headlight" tracer; it had been discovered that attacking Luftwaffe pilots could be distracted by seeing the tracers coming towards them, so the M21 was designed to have a big, bright tracer which could easily be seen from the front.
The standard RAF 20mm Hispano belt make-up from mid-war onwards was two HEI followed by two SAPI (semi-armour-piercing-incendiary). The HEI had a fuze with a slight delay, to ensure that it exploded inside the target rather than on the surface. The SAPI shells used the same shell body as the HEI, but were filled with a large quantity of incendiary material and were given a penetrating steel cap instead of a fuze; the incendiary was ignited by the shock of impact. They both worked pretty well, once the early problems with over-sensitive fuzes were dealt with (the Luftwaffe had the same problem with their 20mm HE).
It's impossible to say - the devil is in the detail.if the lighter less powerful MG151/20 round had of been fired from a Hispano style mechanism what weight reduction and what ROF increase might have been possible? is there a rule, like an inverse of say momentum decrease?
A couple of extracts from my new book (next year)
It's impossible to say - the devil is in the detail.
Anyway, weight comparisons between the Hispano and MG 151/20 are complicated. A couple of extracts from my new book (next year)
On the MG 151/20: "The gun weighed 42 kg including not just the integral belt feed but also the electrical charging device and electric trigger, without which the gun weighed 36-37 kg. It had a cyclic rate of 700 rpm."
On the US Hispano: "The detailed weight breakdown for the AN-M2 is interesting, as the gun's construction was unusually modular. It weighs 46.3 kg as a bare gun, but the muzzle brake (not used with belt feed) weighs 2.1 kg, the front mounting adapter between 3.4 and 6.4 kg depending on the model, the electric trigger and sear mechanism 0.8 kg, the hydraulic charger 1.2 kg, and the ammunition feed 10 kg (60-round drum) or 8.4 kg (belt feed drive), giving a total weight of 60-67 kg depending on the feed mechanism and the mounting adapter. The mounting or support cradle would be additional to this."
How long did it take to "charge" the gun if it jammed due to a failure to extract, fire or load? WW2 fighter pilot anecdotes are full of stories of quarries that escaped due to a jamed guns.
Also could the jam be detected and the charge initiated automatically? For instance if the firing trigger was pressed and a timer detects a failure to cycle within a certain amount of time could the charging be initiated without pressing a separate button?
The hydraulic charging for the US Hispanic suggests that a solenoid valve opens a hydraulic line to charge the gun (or all guns simultaneously) when a button is pressed.
Electrical system possibly simpler but possibly slower. The Germans faced copper shortages so wonder if they used aluminium coils.
If you were a fighter pilot in WWII, would you rather have the high rate of fire of the 50 cal, or the hitting power of the 20mm? I personally feel the 50 cal was plenty hard hitting enough to take out ANY aircraft, and its high rate of fire made it even more effective...the slow rate of fire for the 20mm meant you had to be a much better marksman...
In the late 1950s I was in the Air Scouts and we met a Moffett Field Naval Air Station in Mountain View, California. At one of the meetings at the side of an F-8 Crusader jet we were told how it had shot itself. For gunnery practice a barge was used as a target while being towed, i.e. a moving target. The F-8 would dive at the target while firing the forward facing .50 cal guns, continue the dive, level out and fly over the target. The problem was the plane got ahead of the bullets which hit the F-8. This was the motivation to switch to 20 mm. It was not related to rate of fire but rather to get faster bullets.
While studying W.W.II torpedoes it became oblivious that when the probability of a hit goes down as the travel time of the weapon goes up. I maintain that dumb weapons fail to work when the travel time is too long. This applies to torpedoes, big guns, bombs, &Etc.
See: Torpedoes
In the late 1950s I was in the Air Scouts and we met a Moffett Field Naval Air Station in Mountain View, California. At one of the meetings at the side of an F-8 Crusader jet we were told how it had shot itself. For gunnery practice a barge was used as a target while being towed, i.e. a moving target. The F-8 would dive at the target while firing the forward facing .50 cal guns, continue the dive, level out and fly over the target. The problem was the plane got ahead of the bullets which hit the F-8. This was the motivation to switch to 20 mm. It was not related to rate of fire but rather to get faster bullets.
While studying W.W.II torpedoes it became oblivious that when the probability of a hit goes down as the travel time of the weapon goes up. I maintain that dumb weapons fail to work when the travel time is too long. This applies to torpedoes, big guns, bombs, &Etc.
See: Torpedoes
I don't have any specific information about charging time, but I expect it would be fast. It was obviously not all that important, however, as omitting the charger was one of the weight-saving measures adopted for the Mk V. The guns were loaded and cocked on the ground.
In those pre-electronic days I don't believe there would have been any automatic detection or rectification of firing problems.
US Ballistic Research Laboratories tested some WW2 fire arms in 1947. Title of the reprot is "Airplane Vulnerability and Overall Armament Effectiveness".
They tested 50cal, 60cal(US copied MG151/15), 20mm Hispano, 3cm MK108, 37mm M4.
I am quite sure you will find your own conclusion after read this report.
Personally I believe bigger HE shell is more effective to aircraft. Cuz it can destroy aircraft's structure itself even if shell didn't hit the vital parts.
I'm leaning towards rate of fire as a more important factor for one reason: how far is it between shells?
Say you have a gun firing 1,200 rnds/minute; that's 20 rounds per second (1,200 rounds per minute divided by 60 seconds per minute equals 20 rounds per second).
If the muzzle velocity is 2,400 ft/sec, then there are 120 feet between rounds (2,400 feet per second divided by 20 rounds per second equals 120 feet between rounds).
A M61 Vulcan fires ~3,000 rnds/min at ~3,000 ft/sec; there are 60 feet between rounds.
A M2 .50cal fires ~800 rnds/min at 2,700 ft/sec; 202 feet between rounds!
A M4 37mm fired 150 rnds/min at 2,000 ft/sec; 800 feet between rounds!
Makes me wonder how these guys ever put more than one round on any target!
I'm leaning towards rate of fire as a more important factor for one reason: how far is it between shells?
Say you have a gun firing 1,200 rnds/minute; that's 20 rounds per second (1,200 rounds per minute divided by 60 seconds per minute equals 20 rounds per second).
If the muzzle velocity is 2,400 ft/sec, then there are 120 feet between rounds (2,400 feet per second divided by 20 rounds per second equals 120 feet between rounds).
A M61 Vulcan fires ~3,000 rnds/min at ~3,000 ft/sec; there are 60 feet between rounds.
A M2 .50cal fires ~800 rnds/min at 2,700 ft/sec; 202 feet between rounds!
A M4 37mm fired 150 rnds/min at 2,000 ft/sec; 800 feet between rounds!
Makes me wonder how these guys ever put more than one round on any target!
I'm leaning towards rate of fire as a more important factor for one reason: how far is it between shells?
Say you have a gun firing 1,200 rnds/minute; that's 20 rounds per second (1,200 rounds per minute divided by 60 seconds per minute equals 20 rounds per second).
If the muzzle velocity is 2,400 ft/sec, then there are 120 feet between rounds (2,400 feet per second divided by 20 rounds per second equals 120 feet between rounds).
A M61 Vulcan fires ~3,000 rnds/min at ~3,000 ft/sec; there are 60 feet between rounds.
A M2 .50cal fires ~800 rnds/min at 2,700 ft/sec; 202 feet between rounds!
A M4 37mm fired 150 rnds/min at 2,000 ft/sec; 800 feet between rounds!
Makes me wonder how these guys ever put more than one round on any target!
But why define cannons by mass? I know that's naval tradition.A couple of the heavier British cannon (Vickers 'S', Mollins 'M') are sometimes referred to as 2pdr and 6pdr respectively -- but I think the official designations stuck with metric.
Not just naval. During WW2 the British Army had the 2 pdr and 6 pdr tank/anti-tank guns as mentioned, plus the 17 pdr T/AT and the 25 pdr and 60 pdr artillery pieces.But why define cannons by mass? I know that's naval tradition.