Tony WilliamsA side point is that there were problems with jamming in the early fitting of Cannon to Spitfires. IIRC, this was sometimes caused by wing flex in the turn? Can anyone confirm or correct?
There were two main reasons for the problems. One was that the HS 404 was designed to be bolted firmly to an engine block, to fire through the propeller hub. It did not take kindly to being mounted in a far more flexible wing. The specific problem with the Spit 1b was that the guns were mounted on their sides, rather than upright as designed, in order to bury as much as possible of the big 60-round drum within the wing. And they really didn’t like that at all. The net effect was that the installation was a disaster.
There continued to be installation problems which needed to be resolved in each case when the Hispanos were wing-mounted – even with the big Blackburn Firebrand. Basically, the gun mountings had to be ‘tuned’ for each installation. Mounting the guns in the far more rigid fuselage was much simpler.
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Tony WilliamsOf course.. 😉 This figure rather shows *trigger-happiness* of US pilots rather than ineffectiveness of 50 cal rounds.
Not really.
Before modern radar-directed computer-controlled fire systems were developed, the great majority of rounds fired in aerial combat missed, whoever was doing the shooting. The Lufwaffe in WW2 estimated that between 2 and 5% hit the target.
Their response was to step up the destructive effective of each hit in order to make it count – so they went to larger cannon firing high-capacity HE shells. The USAF response was to increase the number of shots fired.
History has demonstrated that the Luftwaffe approach was the right one, and even the USAF moved to cannon immediately after the Korean War as a direct result of the unsatisfactory performance of the .50. However, they didn’t entirely learn the lesson as they’ve stuck at 20mm whereas everyone else long ago moved to 27-30mm, in response to aircraft being bigger.
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Tony WilliamsThe figure I have seen for the average number of .50 cal rounds needed to down an MiG 15 was just over 1,000 (from an American source). These would of course not all have hit – only a small percentage would have.
TW
Tony WilliamsA few comments.
Steerable 20-40mm cannon ammo has been played with for years, but none has made it into service or even seems close: the only service steerable shell is still the old 155mm Copperhead semi-active laser artillery round, which has snap-out fins, although a raft of advanced guided shell designs for both 155mm and 127mm (and even 76mm) naval guns are under development.
On-board laser development is proceeding apace and may well eventually replace the aircraft gun for close-range work; there is a project to develop a system for the F-35. It has the big advantage that with its beam steerable via a mirror, it could rapidly point over a wide arc and could well be used to knock out incoming missiles. Don’t hold your breath, though, I think it will be many years yet before this is operational.
Back to the original question! It is difficult to generalise over the effectiveness of cannon shells because there are so many random factors. Planes have been brought down by a weak shot in right place (I once read that in SE Asia that an F-4 flying on the deck was brought down by a single shot from the .30 Carbine of a panicked guard), while other planes have got back to base despite suffering massive damage which looked as if it should have been instantly fatal. There is one account of an Israeli F-15 making a safe landing after having most of one wing destroyed.
Taking that into account, the 20mm M61 is probably at a disadvantage compared with most other modern aircraft cannon. The shells weigh only around 102g, compared with 180g for the 25mm GAU-12/U, 260g for the Mauser BK 27, around 270g for the Aden/GIAT 30mm, 360g for the Oerlikon KCA and 390g for the current Russian GSh-301 used in the MiG-29 and Su-27 families. Clearly, each 20mm hit will be far less destructive.
Because the 20mm shells are so light, they also have a much shorter range (albeit the later PGU-28 ammo has extended the range compared with the early M56 shells). In ground attack, the 20mm is good for up to 1,200m – the range in air combat depends on the circumstances, but 400-800m would be typical. The 30mm guns can manage around 50% further than this.
Yes, the M61 has a high rate of fire, but it takes a fraction of a second to spin up to maximum rate and that can be important in a dogfight, so from a ‘cold start’ any one of the other guns can throw a much heavier total shell weight in the first half-second.
The USAF tried to replace the M61 around 1970 with a new high-performance 25mm gun – the GAU-7 – which was supposed to debut in the new F-15, but the combustible-case ammo suffered intractable technical problems. The M61 survives today probably because guns are less important than they were, so it hasn’t been thought necessary to replace it.
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Tony WilliamsWell I’ve heard of another, to start with. It was described in a magazine article some years ago, and concerned a Bf 109E in North Africa. Out of ammo, the pilot went low to buzz some British troops. The officer got irritated, pulled out his trusty .38 revolver and fired a couple of shots. One of them hit the cooling system (IIRC) and the plane was forced down. Both men survived the war and met afterwards – there was a photo of them together in the article, I think.
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Tony WilliamsTony WilliamsVl mica has reportedly performed quite well in recent tests against low flying targets.
There are low-flying targets, and then there are low-flying targets. Even the first version of Sea Wolf famously intercepted a 4.5 inch shell in flight. Anti-ship missiles are getting tougher and faster.
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Tony Williamsstandard issue, 7 rounds for the magazine and 2x5round clips for reloads
No – see my previous post. 8 round magazine plus one in the chamber = 9 rounds available, plus spare 8-round mag. That adds up to 17 rounds for two clips fired, which fits the story.
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Tony WilliamsIts a more modern missile, I have heard rumours that the malaysian navy is looking at an improved version of its leiku with VL mika instead of seawolf, and the romanian navy replaced sea wolf with mica.
The Romanian Navy had the original non-VLS Sea Wolf in the sextuple launchers – that was old fashioned. The VLS Sea Wolf in the T23s is a different matter, and has been kept up to date (ther is an update programme running at the moment). It was specifically designed as an anti-missile missile, rather than an adapted AAM, and I would need to see evidence that the Mica is as good in that role before I would believe it.
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Tony WilliamsTony WilliamsMany, many years ago my brother used to work at Cranfield. They had a hangar or two stuffed with prototypes which no-one knew what to do with. I remember TSR-2, the Saro flying-boat fighter, a huge fighter with a chin intake (Hawker P.1121?) and sundry other stuff. All now dispersed to different museums, but an amazing collection of ‘might have beens’.
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Tony Williamssorry JDK but your sly dig is out of date, try the FOI act, ask for something specific and you’ll get it – and sharpish too – I know, we recently declassified a Secret logbook from 2003 because some UFO spotter requested it – nothing was removed, nothing was censored, the appropriate pages were photocopied and sent out as written
Yes, but you have to know exactly what to ask for….the problem is in finding out what exists so you can ask for it!
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Tony WilliamsTony WilliamsTony WilliamsA few comments:
It couldn’t have been a Sten, they weren’t around until 1941.
With any auto pistol you can load one extra round in the chamber, so he could have had nine rounds available in the gun, plus eight in the spare magazine. That fits.
The absolute maximum range of the 9×19 (Parabellum or Luger) round in a pistol is over 1,700m (achieved by elevating the barrel to around 35 degrees and letting fly). However, that is many times more than the practical maximum range, which is limited mainly by the ability of the user to aim the gun accurately. I have used a 9mm pistol at 200 yards, and estimate from the results that I would have hit a man standing in front of the target with about 50% of the shots – but I was taking very careful aim, with the pistol resting on a box!
On test (from a Sten) the British found that the 9mm bullet would drill straight through 0.75 inch of wood, covered by two layers of webbing, at 300 yards. Bearing in mind that the bullet’s velocity would have the forward speed of the aircraft added to it, I think it entirely plausible that it would penetrate the glazing of an aircraft at 500m (I don’t read 500m as being necessarily the altitude, just the distance – which is what an army shooter would be thinking of).
The fact that he gives the measurement in metres is odd – British target shooting distances were in yards until at least the 1970s. But then, it’s odd that he would be carrying a Luger, the approved sidearm of the British Army in 1940 being the .38 revolver (with a lot of .455 revolvers still around as well). He sounds like an individualist…
Tony Williams: Military gun and ammunition website and discussion forum
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