A.G. Williams
Airman 1st Class
- 182
- Oct 10, 2020
That would be the earlier Becker/Oerlikon family, which used 20 x 70-72 ammo. The MG-FF, developed by Ikaria in Berlin with 20 x 80RB ammo, is generally quoted at 600 m/s.
UK goes all-in on a HMG class gun in the mid-30'ies (1 Viewer)
- Thread starter z42
- Start date
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Glider
Captain
Its interesting that the debate over faster firing, higher MV smaller cannon VS slower firing, slower MV bigger cannon goes on pretty much until now.
Generally speaking the USA went for the 20mm M61 and Europe went for the 30mm Aden/Defta cannon
M61
6,000 rpm, 1050 m/s
Aden
1,300 rpm, 790 m/s
You pays your money and takes your choice. The only observation I can make is a quote from a US Marine pilot when they first received the Harrier. When talking about the 30mm Aden he said that now instead of brushing the leaves off the tree, they could now knock the tree down. No doubt a highly sensationalised and technically incorrect statement, but it does show how he felt about it.
Plus of course, after WW2 the USAAF stuck to ungraded 0.5in whilst Europe and the USN went for the 20mm. (always liked the US Navy)
Generally speaking the USA went for the 20mm M61 and Europe went for the 30mm Aden/Defta cannon
M61
6,000 rpm, 1050 m/s
Aden
1,300 rpm, 790 m/s
You pays your money and takes your choice. The only observation I can make is a quote from a US Marine pilot when they first received the Harrier. When talking about the 30mm Aden he said that now instead of brushing the leaves off the tree, they could now knock the tree down. No doubt a highly sensationalised and technically incorrect statement, but it does show how he felt about it.
Plus of course, after WW2 the USAAF stuck to ungraded 0.5in whilst Europe and the USN went for the 20mm. (always liked the US Navy)
- Thread starter
- #123
Seems that subsequently some convergence has happened in Western designs:
Mauser BK-27, 27mm, 1100m/s, 1000-1700 rpm (Eurofighter, Gripen, Tornado)
GAU-22, 25mm, 970 m/s, 3300 rpm (F-35)
GIAT 30, 30mm, 1025 m/s, 300-2500 rpm (Rafale)
Except no Spitfires operated with 4 x cannon would have been encountered by the LW, would they?
I seem to recollect that although the C wing could in theory carry them, the weight, roll and structural penalty was such that they were not operationally armed with four cannon until March '45 with the F21 with its stiffer wing
There were some that operated from Malta that had 4 cannon but it is suggested here [TMP] "Which Wartime Spitfires Mounted 4 X 20mm Cannon?" Topic that they were flown off HMS Eagle with 4 as a way to get cannon spares there.
That rings bells with me too.
Tomo was getting a tad high-horsey about people not citing a quote regs negative views on the the FF canons in the FW190s - so, the gauntlet is now down to see if he can find a quote where LW pilots encountered four cannon Spitfires
It relies on a sharp eyed LW pilot noticing and reporting it.That rings bells with me too.
Tomo was getting a tad high-horsey about people not citing a quote regs negative views on the the FF canons in the FW190s - so, the gauntlet is now down to see if he can find a quote where LW pilots encountered four cannon Spitfires
Glider
Captain
Its a personal view but I suspect that the last thing Malta needed were spare 20mm cannon. Think of the huge number of Spits and Hurricanes that were damaged on the ground and / or were written off due to damage in the air. I reckon that they had plenty of spares.
Actually, I'm not so sure. Eagle made only the second delivery of cannon armed Spitfires to Malta. The first attempt, Operation Calendar from USS Wasp had been a disaster, with all the aircraft which made it there being written-off/destroyed on the ground by intensive bombing almost as soon as they landed. How many functional or repairable cannons would have been available from the wreckage may well have been quite limited.
Previous to this, Malta had been defended by a mere handful of Gladiators and a dribble of Hurricanes - mainly 0.303 armed mark 1s as far as I can tell. Any Mk2Cs there, they would have been even fewer in number. Pretty much all the other aircraft on Malta (Wellingtons, Marylands, Beauforts etc) would have been armed only with 0.303s.
Given squadrons clearly chose in the vast majority not to ever equip C wing Spitfires with four canons because of the known issues, it seems equally unlikely to me that they would have flown into one of the most intensive air combat theatres in the world with the intention to use that fit out operationally. I'd say the story sounds plausible to me, as they definitely would not have had any issues obtaining 0.303 spares
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Glider
Captain
Clearly I cannot be certain but I will stick to my belief. The Hurricane IIC which were quite extensively used were normally operated with 2 not 4 cannon to try to improve performance. I understand that approx 180 Hurricanes were delivered to Malta by carrier of which I think half were IIc's.
The four cannon armed Spits were normally operated with two due to the impact on climb which was a very high priority for Malta. A lot of fighters were damaged in air raids due to blast damage and a high proportion of these would have had salvageable guns.
IIRC there were a number of attempts to turn surplus guns into AA guns with various jury rigged set ups
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
Clever.
Greatly exaggerated, Spitfire Mk V Performance Testing
So you say - but no apparent evaluation of the comparitive impact on roll in those tests that I can see? Indeed, the detailed report makes no mention of roll-rate *at all*, does it? Spitfire Mk.Vc AA.873 Report
If taken as per your assertion, it begs the very obvious question doesn't it?
If a four cannon armament had no deleterious impact upon the performance or operation of the Spitfire, and at a time when contemporary Whirlwinds, Typhoons and Hurricanes were all using a four canon armament - why did the spitfire continue to be equipped with 2 x 20mm and 4 x 0.303s as its standard armament fit almost to the end of the war? Why have even the E Type wings in later variants usually fitted with .5 cal machine guns in the inner bays rather than 20mm?
For the standard elliptical C type wing, it makes ZERO sense to continue with a 2 x 20mm / 4 x 0.303 fit-out unless there was a known and important s issue preventing 4 x 20mm, surely?
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Geoffrey Sinclair
Staff Sergeant
- 910
- Sep 30, 2021
The Hurricane shipments are from research still in progress, the final figures will probably have some slight variations. It is aircraft sent, not arrivals, and excludes those returned to Britain on the carriers. Note each operation had its RN code name and its different RAF code name.
Some of the reported conversions may have happened after service in Malta. SS Essex was a sailing, SS Parracombe, Operation Temple, was another sailing, the ship was sunk off Cape Bon. The direct was via France, and only 3 retained in Malta. Also Malta was at times used as a quick ferry route to Egypt, 42 from Splice, 19 from Glover, 43 from Tracer, 37 from Scarlet were near immediately sent to Egypt, in return at times Egypt supplied some Hurricanes. The Tiger convoy sent to Egypt through Mediterranean was in May 1941.
Initial Malta Spitfire shipments, OPERATION SPOTTER / QUARTER, 7 March 1942, 15 on board Eagle, all launched and arrived. OPERATION PICKET I / SCANTLING, 21 March 1942, 16 or 17 on board Eagle, 9 launched, 9 arrived. OPERATION PICKET II / SCANTLING, 29 March 1942, 7 or 8 on board Eagle, 7 launched, all arrived. OPERATION CALENDAR / NEWMAN, 20 April 1942, 47 on board Wasp, 46 arrived. OPERATION BOWERY / OPPIDAN, 9 May 1942, 47 on board Wasp, 47 launched, 43 arrived plus 17 on board Eagle, 17 launched, 17 arrived. USS Wasp delivered the first Spitfire Vc.
Of the 46 Spitfires arrived in OPERATION CALENDAR / NEWMAN 12 had been lost by end April, a week later the loss total was 22, with 4 more lost during the remainder of May. Many of the others were damaged.
At least one SAAF Spitfire V squadron used the 4x20mm option, they were mainly doing fighter bomber operations in the Mediterranean. A major reason given for not moving to this as standard, and for the cannon being in the outboard bay in the E wing, is problems with gun heating.
Some of the reported conversions may have happened after service in Malta. SS Essex was a sailing, SS Parracombe, Operation Temple, was another sailing, the ship was sunk off Cape Bon. The direct was via France, and only 3 retained in Malta. Also Malta was at times used as a quick ferry route to Egypt, 42 from Splice, 19 from Glover, 43 from Tracer, 37 from Scarlet were near immediately sent to Egypt, in return at times Egypt supplied some Hurricanes. The Tiger convoy sent to Egypt through Mediterranean was in May 1941.
| Operation | I | I>IIa | IIa | IIa>IIb | IIa>IIc | IIb | IIb>IIa | IIb>IIc | IIc | IIc>IIa | IIc>IIb | Total | Date |
| Direct | 18 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 18 | Jun-40 |
| Argus/Hurry | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | Jul-40 |
| Argus/White | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | Nov-40 |
| Essex | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | Dec-40 |
| Argus/Winch | 0 | 0 | 12 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | Apr-41 |
| Dunlop | 17 | 0 | 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 23 | Apr-41 |
| Splice/H.M.S | 63 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 63 | May-41 |
| Argus/Glover | 4 | 0 | 22 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 28 | May-41 |
| Parracombe/Temple | 0 | 0 | 21 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 21 | May-41 |
| Furious/Tracer | 45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 45 | Jun-41 |
| Furious/Tracer? | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | Jun-41 |
| Nordic/Railway I & II | 0 | 9 | 18 | 2 | 1 | 0 | 0 | 0 | 21 | 0 | 1 | 52 | Jun-41 |
| Nordic/Railway I? | 0 | 0 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | Jun-41 |
| Nordic? | 0 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | Jun-41 |
| Scarlet/Status | 0 | 0 | 0 | 0 | 0 | 57 | 2 | 1 | 0 | 0 | 0 | 60 | Sep-41 |
| Pantaloon/Perpetual | 0 | 0 | 0 | 0 | 0 | 30 | 0 | 0 | 6 | 1 | 1 | 38 | Nov-41 |
| Total | 185 | 13 | 81 | 3 | 2 | 87 | 2 | 1 | 27 | 1 | 2 | 404 |
Initial Malta Spitfire shipments, OPERATION SPOTTER / QUARTER, 7 March 1942, 15 on board Eagle, all launched and arrived. OPERATION PICKET I / SCANTLING, 21 March 1942, 16 or 17 on board Eagle, 9 launched, 9 arrived. OPERATION PICKET II / SCANTLING, 29 March 1942, 7 or 8 on board Eagle, 7 launched, all arrived. OPERATION CALENDAR / NEWMAN, 20 April 1942, 47 on board Wasp, 46 arrived. OPERATION BOWERY / OPPIDAN, 9 May 1942, 47 on board Wasp, 47 launched, 43 arrived plus 17 on board Eagle, 17 launched, 17 arrived. USS Wasp delivered the first Spitfire Vc.
Of the 46 Spitfires arrived in OPERATION CALENDAR / NEWMAN 12 had been lost by end April, a week later the loss total was 22, with 4 more lost during the remainder of May. Many of the others were damaged.
At least one SAAF Spitfire V squadron used the 4x20mm option, they were mainly doing fighter bomber operations in the Mediterranean. A major reason given for not moving to this as standard, and for the cannon being in the outboard bay in the E wing, is problems with gun heating.
Very few Hurricane IIcs delivered over that time - around 30ish tops over 12 months. And one has to assume many of those would have been lost at sea or totally destroyed in action. Doesn't seem to indicate to me an island under siege, awash with spare hispanos.
The effect on performance at altitude was what made the difference, the RAF did comparison tests between Spitfires with both types of armament at altitude and the difference was marked. I believe it was
GrauGeist
that posted it. Prior to reading that I always believed it was a heating/ safety issue, if the extreme cold caused cannon to jam there was at least some sort of backup.re: post #24 here:
ww2aircraft.net
WW2 aviation ammo
If the RAF had the 0.5" that was fitted in 1944 available in 1940 things may have been different, but it is a what if, the USA was also using rifle calibre guns early in the war for the same basic reasons.
ww2aircraft.net
How high were Malta spitfires going to fly?, the climb and speed performance was not affected at normal operating heights to that great a deal but the cannons weren't as reliable as the .303's and the earliest models had 60 round drums so firing time was limited, I believe there is lots of separate reasons that 4 cannons weren't fitted to the MkV.The effect on performance at altitude was what made the difference, the RAF did comparison tests between Spitfires with both types of armament at altitude and the difference was marked. I believe it was
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Its interesting that four hispanos @ 172kg is considered too heavy yet two hispano's and four .50 brownings @ 178kg isn't?.re: post #24 here:
WW2 aviation ammo
If the RAF had the 0.5" that was fitted in 1944 available in 1940 things may have been different, but it is a what if, the USA was also using rifle calibre guns early in the war for the same basic reasons.
Glider
Captain
It isn't I believe a problem regarding how high they could fly, but how fast they could get to the altitude. The flight time from the Axis bases to Malta was very short and every second was needed to gain the altitude. The four x 20mm Spitfires did have a slower climb rate and this would have been the problem.
Twin 20mm and four LMG was quite a punch on its own, few single engine fighters carried more firepower on a regular basis in 1943, the obvious exception being the Fw190.
